A new characoid (Erythrinidae or new family) from Maastrichtian and early late Paleocene formations of Bolivia.

Mireille Gayet and Michel Jégu

Fossil remains of dentaries, premaxillaries and isolated teeth of jaws from the Maastrichtian El Molino Formation and the early late Paleocene of the Santa Lucía Formation (Bolivia) are reported to a new Characoid genus close to the African Hepsetus (Hepsetidae) and South American Hoplias (Erythrinidae). They show the following characters: 1) as in Hoplias and Hepsetus: the conical teeth are laterally flattened; on the dentary, there are two large anterior canines, a large sub-anterior depression for the insertion of the premaxillary canines and an inner (lingual) dentary series of small morphologically similar teeth; two cavities are present on the internal side of the premaxillary for the insertion of the two anterior large dentary canines. 2) as in Hepsetus: the inner (lingual) dentary series begins just behind the symphysis and not posterior to the lateral teeth series as in Hoplias. 3)as in Hoplias: an anteriomost secondary depression for insertion of the anteriormost premaxillary canine is present; teeth posterior to the main depression are subequal in size (absence of small intercalary teeth as in Hepsetus). 4) unique for the Bolivian fossil: the trench for teeth replacement is completely open and there are no teeth around and medial to the dentary depressions. The scarity of the Bolivian fossil remains does not allow us to resolve its phylogenetic relationships with the Erythrinidae and Hepsetidae families.

UMR CNRS 5565, UFR Sciences de la Terre, 27-29 Bd du 11 novembre 1918; 69622 Villeurbanne Cedex, France Email: gayet@univ-lyon1.fr

The species of piranhas, genera: Pygopristis, Pygocentrus, Pristobrycon and Serrasalmus of Venezuela.

Antonio Machado-Allison and William L. Fink

«Piranhas» or «caribes» as they are commonly known, are the most notorious living aquatic animals in South America. The great speculation, tales with nonsense and fantastic stories grown around them exceeds their scientific knowledge. Their high diversity and predatory habits make them an important part of our aquatic communities. So far more than 30 nominal species have been recognized belonging to 4 genera: Pygopristis, Pygocentrus, Pristobrycon and Serrasalmus. The last one include de majority of the species. Machado-Allison (1982, 1985), recognized the monophyletic origin of this clade. However, some inner relationships still to solve. For example the condition of Pristobrycon, with species with pre-anal spines and no ectopterigoid teeth ( P. striolatus), and species with those conditions such as P. calmoni. Recently, Fink & Machado (1992), described 3 new species for Brazil and Venezuela: Pristobrycon careospinus, P. maculipinnis and Serrasalmus gouldingi. This report presents only in the Venezuelan species. We recognized 4 genera and 16 species in Venezuela. Pygopristis (P. denticulata); Pygocentrus (P. cariba); Pristobrycon (P. calmoni, P. careospinus, P. maculipinnis and P. striolatus); and Serrasalmus (S. altuvei, S. eigenmanni, S. elongatus, S. gouldingi, S. irritans, S. manueli, S. medinai, S. nalseni, S. neveriensis, and S. rhombeus). However, there are at least 2 more new(?) species that are share with the Amazon Basin of Brazil and Colombia. Also, we discuss aspects of their distribution on the Orinoco, Amazonas, Essequibo and Caribe Basins, and information on the feeding habits.

Universidad Central de Venezuela, Museo de Biologia, Apto Correos 47058, Caracas, 1041-A. Venezuela. email: machado@dino.conicit.ve

Quantitative shape analysis of Serrasalminae otoliths

Paulo Petry

Elliptic Fourier Analysis was used to quantify lapillus shape differences in four species of serrasalmin fishes, Colossoma macropomum, Mylossoma aureum, Mylossoma duriventre and Piaractus brachipomus. Normalized harmonic coefficients were used as input vectors on a multivariate analysis to compare shape differences among and within taxa. The results indicate that M.aureum has much higher otolith shape variability than any of the other species. The within taxa shape differences for this species suggests two distinct otolith shapes groups. Shape classification using a discriminant function analysis revealed that the two shape groups within M.aureum are more distinct among themselves than either group is to the remaining species analyzed. A hypothesis of environmental factors influencing otolith shape will be discussed.

INPA/CPBA C.Postal 478 Manaus AM Brasil 69011, Email: petryp@cr-am.rnp.br

Phylogeography and chromosomal evolution within the Hoplias malabaricus Bloch, 1794 (Erythrinidae, Characiformes, Ostariophysi) species complex.

Jorge A. Dergam, William C. Black IV, Jorge Porto and Eliana Feldberg

We analyzed patterns of congruence of molecular and karyotypical data of the Neotropical fish Hoplias malabaricus. At the molecular level, within-population variation of mitochondrial DNA was assessed by means of the Single Strand Conformation Polymorphism. Phylogenetic analyses were performed on two segments of mitochondrial DNA: 545 base pairs of ribosomal 16S, and on 450 base pairs of cytochrome b. In samples from Río Aguapey (Province of Corrientes, Argentina) the rio Grande and rio Mindu (states of Minas Gerais and Amazonas respectively), two divergent groups of sequences were congruent with karyotypical data, and we inferred for each case, sympatry of two different species of the complex. The best supported tree (in terms of bootstrap values) was the one combining both mitochondrial segments. Mitochondrial DNA variants (haplotypes) from the rio Paraná, from populations with 2n=40/40 from middle Paraná and 2n=40/39 (for females and males respectively) from the upper Paraná are the sister group of all other haplotypes of the complex. Coastal populations from rio Guaíba to rio Doce, together with other populations from the continental slope of the serra do Mar, all with 2n=42/42, comprised a well supported clade, a geographic pattern also compatible with other fish taxa. Overall, however, correlation between diploid numbers and mitochondrial data was poor, suggesting that chromosomal rearrangements leading to chromosome numbers of 40 and 42 did not happen only once, of that conditions of fixation of chromosomal rearrangements did not involve bottleneck and/or negative heterosis of heterozygotes for rearrangements. Financed by CAPES, Universidade Federal de Viçosa and Colorado State University.

Departamento de Biologia Animal, Universidade Federal de Viçosa, 36571-000 Viçosa, MG, Brazil. Email: dergam@mail.ufv.br

Mitochondrial DNA phylogeography of Mylesinus paraschomburgkii (Characiformes, Serrasalmidae) from the eastern Amazon basin as inferred from sequence data.

Jorge I.R. Porto, John R. Gold and Michel Jégu

M. paraschomburgkii is a reophilic serrasalmid species with a strong habitat specificity that occurs only in the rapids and waterfalls of Amazon rivers that drains the Guianean shields. Morphological and parasitological data suggests differentiation among populations of M. parashomburgkii from Uatumc, Trombetas and Jari river drainages in the Eastern Amazon basin. We have used mtDNA sequence to test a biogeographic hypothesis in which Jari population is considered a sister group of Trombetas and Uatumc populations. A total of 432bp encompassing ND4L/ND4 genes and up to 402bp within the mtDNA control region were sequenced in individuals of M. paraschomburgkii from Pitinga and Jatapu rivers (Uatumc drainage), Trombetas river (Trombetas drainage) and Iratapuru river (Jari drainage), and a individual of Tometes sp from Xingu river as outgroup taxa. We observed population-level separations among river drainages (average sequence divergence of ~3% for ND4L/ND4 and ~5.5% for control region), and a east-west phylogeographic split that is concordant with the former biogeographic hypothesis. Congruence of morphological, parasitological, and molecular data will be evaluated and association of these data with historical events occurred in the Quaternary will be discussed. INPA/CNPq/ORSTOM/Ministhre Frangais de l'Environment/Texas A & M University.

INPA/CPBA, Alameda Cosme Ferreira, 1756 - Manaus-AM, 69083, Brasil. Email:jirporto@internext.com.br

Preliminary results from a survey of mtDNA variation among Prochilodus species (Characiformes) from several river drainages in South America

Guillermo Ortí and Eldredge Bermingham

Prochilodus species are widespread, abundant, and highly migratory fishes that live throughout most of South America. We present a preliminary assessment of the population structure of the species within the Paraná-Paraguay basin based on DNA sequences from the mitochondrial ATPase genes (840 bp). Fish were sampled from localities including the Mogui-Guassu river (upper Paraná), middle Paraná, Rio de la Plata, headwaters of the Paraguay river (Mato Grosso), lower Paraguay, middle (Salto Grande) and lower Uruguay river. An overall low level of intraspecific differentiation within P. lineatus detected among these samples (less than 1.6 % sequence difference) suggests historically high levels of gene flow within this river basin. Sequence divergence among samples from the Paraná-Paraguay and other river basins were as follows: 0.8% - 1.6% from the Amazon (Pitinga and Manu); 1.8 - 3.0% from the Apure river; and 4.3 - 5.1 % from the Magdalena basin. A phylogeny, rooted with Semaprochilodus, shows that P. magdalenae is the sister group to the rest of the clade; next to branch off is P. mariae (from the Apure), then the Amazonian forms (P. rubrotaeniatus from the Pitinga river and P. nigricans from Peru), and finally the Paraná-Paraguay samples (P. lineatus), that form a poorly structured, derived clade. This research is part of an ongoing effort to assess mitochondrial phylogeographic patterns of Neotropical fishes. Financial support came from the Molecular Systematics program at the Smithsonian Tropical Research Institute, the Smithsonian Institution's Restricted Endowment and a grant (INT9117104) from the National Science Foundation (USA).

School of Biological Sciences, 348 Manter Hall, University of Nebraska-Lincoln, Lincoln, NE 68588 USA. FAX 402-472-2083, email: gorti@bscr.uga.edu

Studies on a monophyletic lineage of the large and specialized fishes of genus Leporinus in South America (Pisces, Characiformes, Anostomidae)

Julio Cesar Garavello and Pedro Manoel Galetti Junior

The studies on the genus Leporinus concomitantly conducted by the authors on systematics and the sexual chromosome system of commom species, offered the opportunity of examine a monophyletic lineage of this genus, widely distributed over the large South American river basins. The species L. obtusidens (Valenciennes, 1847), L. elongatus Valenciennes, 1849, L. trifasciatus Steindachner, 1876, L. reinhardti Lutken, 1874, L. conirostris Steindachner, 1875, L. macrocephalus Garavello & Britski, 1988, and L. aff elongatus proved to be related by series of specialized morphologic and chromosomic characters. These species were previously considered (first author) as a specialized lineage of Leporinus with reductions in the dental formulae, each species showing only six teeth in the jaw, differing from the remaining Leporinus species which always showed more teeth in the jaws. Studying sex chromosomes (second author and co-workers), a sexual dimorphism involving a ZZ/ZW system in these species was described, and they were considered a natural and monophyletic lineage within this genus. A list of twenty characters concerning to shape of infraorbital bones, number and ramifications of cephalic lateral line channels, snout and mouth position, number and shape of teeth series, size and number of scale series and gill rakers, sex chromosomes and other chromosome features, was studied under the phylogenetic method. Six phylogenetic trees were constructed through the Hennig 86 computer program. All of them support the monophyletic hypothesis for this lineage showing synapomorphies of teeth reduction and presence of sex chromosomes. Financial support: CNPq

Departamento de Ecologia e Biologia Evolutiva, UFSCar, Caixa Postal 676, 13565-905, São Carlos, São Paulo, Brazil. Email: djga@power. ufscar.br

Phylogenetic relationships and morphometrics of the characid fishes, genus Bryconops

Barry Chernoff and Antonio Machado-Allison

Fishes of the genus Bryconops are widely distributed through the Amazon and Orinoco river basins of South America. Bryconops is a monophyletic group that is either the sister group to the Iguanodectinae or to the Iguanodectinae plus the Characinae (sensu Buckup). Bryconops contains at least thirteen species which are divisible into two monophyletic subgenera: Bryconops with five species; and Creatochanes with at least eight species. Both traditional multivariate morphometrics and landmark-based analyses (e.g., thin plate splines) support the hypothesis that shape differences among species and lineages are functions of ontogenetic chances in shapes. Furthermore, coordinated patterns of shape-change within and among functional regions of the body are consistent with patterns of phylogenetic relationships. This work has been supported by Field Museum and Universidad Central de Venezuela.

Department of Zoology, Field Museum, Roosevelt Rd. at LakeShore Drive, Chicago, IL 60605 Email: chernoff@fmppr.fmnh.org

Karyotypes of diplomystid and certain loricarioid catfishes

Gloria Arratia and Hugo Campos

The chromosomes of the most primitive catfishes (e.g., Diplomystes camposensis and D. nahuelbutaensis), of the most primitive loricarioid (Nematogenys inermis) and of several trichomycterines (e.g., Trichomycterus areolatus, Bullockia maldonadoi, Hatcheria macraei) were researched in both males and females of each species, and the results were compared to the available literature in other catfishes and other ostariophysans, as well. The karyotypes of Diplomystes camposensis and D. nahuelbutaensis have the same diploid chromosome number (n=56); however, there are large differences in the chromosomal C-banding patterns between both species. In contrast to diplomystids and trichomycterines, Nematogenys has a high number of chromosomes (n=94), most of them being telocentrics (t) and subtelocentrics (st). Trichomycterines have a variable number ranging from 50 to 62 chromosomes, most of them being metacentric (m) and submetacentrics (sm); however, differences in the types of chromosomes characterize them. For instance: Trichogenes has: 48 m,sm+6st,t; Trichomycterus areolatus: 56m,sm+0st,t; T. chiltoni, 44m,sm+8st,t; Trichomycterus laucaensis, 42 m,sm+16st,t; Trichomycterus sp.: 44 m,sm+6st,t; Bullockia: 46 m,sm+14st,t; and Hatcheria: 30 m,sm+22st,t. Comparisons with gymnotiform, characiform and cypriniform karyotypes do not allow for any conclusion in regard to the plesiomorphic siluriform condition, because the karyotypes of the outgroups are too variable. In addition, information about the most primitive gymnotiforms and characiforms is not yet available. Characiforms, gymnotiforms and diplomystid catfishes share the presence of more metacentric-submetacentric than subtelocentric-telocentric chromosomes. The present research is supported by grants from the Fondo Nacional de Investigacion Cientifica y Tecnologica (FONDECYT) and Universidad Austral de Chile.

Museum fur Naturkunde der Humboldt Universitaet zu Berlin, Germany.

Redescription of "Arius" platypogon Günther (Siluriformes: Ariidae), with comments on its ecology, distribution and relationships

Arturo Acero P.

"Arius" platypogon was described by Albert Günther (1864) based on four syntypes from San Jose (Guatemala). The species is easily recognized by having 4-6+9-11 gill rakers on the first arch; eye large, 4.4-6.5 in head length; adipose fin short-based, its base length 0.5-0.7 the dorsal-fin base length; and the dorsal spine much thinner than in other eastern Pacific sea catfishes. It grows to at least 47 cm. The type series is recorded in the British Museum (Natural History)as 1864.1.26.316-319; the largest of the four specimens (219 mm standard length) is herewith designated as the lectotype of the species. "Arius" platypogon is the most sea going member of the family in the eastern Pacific, usually appearing in the captures of the shrimp trawlers, and very rarely entering freshwater. Consequently, its distribution is very wide in the tropical and subtropical continental shelf of western Americas, going from the northern tip of the Golfo de California to at least Ecuador. The species is clearly different from the other eastern Pacific ariids usually included in the catchall genus because it lacks the temporal fosset, the foramen delimited by the frontal and the lateral ethmoid is closed, and the lapillus otolith is relatively small and tear-shaped. It may be related to the sea going western Pacific members of the "A". thalassinus species-complex because they share a lateral line bifurcate at base of caudal fin and a posteriorly located and short-based adipose fin, but such relationships must be carefully assessed.

Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA, and Universidad Nacional de Colombia (Instituto de Ciencias Naturales), Apartado 1016 (INVEMAR), Santa Marta, Colombia.

Comments on miniaturization within Gelanoglanis Bölhke (Siluriformes, Auchenipteridae, Centromochlinae)

Luisa M. Soares-Porto

Miniaturization, which results in the presence of numerous apparently paedomorphic morphological features associated with reduced size, is a common phenomenon among South American fishes. Paedomorphic traits commonly present in miniatures include reductions on degree of development of the latero-sensory canal system, number of fin rays and scales and amount of ossification. Within the Auchenipteridae, Gelanoglanis is characterized by the following synapomorphies: absence of cranial fontanel; absence of outer mental barbels; posterior nostril long and narrow; mouth large. It represents the first recognized group of Auchenipteridae to possess putatively reductive characters, in association to a small adult size. The two recognized Gelanoglanis reach maturity at about 17 mm (Gelanoglanis sp.n.) or 22 to 36 mm in standard lenght (G. stroudi), a small size when compared to members closely related to this genus, such as Centromochlus, that reach maturation at about 80 mm in standard lenght. Gelanoglanis stroudi has putatively reductive characters, such as: (a) incomplete infraorbital series, with only the lachrimal bone ossified; (b) lack of mandibular ramus of cephalic latero-sensory system; and (c) reduction of preopercle. The new Gelanoglanis species is under description in collaboration with J. Maia Netto, S. Walsh, and L. Nico. Although the cranial features have not been observed yet, the reduction in the number of anal fin rays and the substitution of soft unbranched rays for pectoral and dorsal spines are recognized as associated to a reduced size, and this new Gelanoglanis is treated as a miniature species.

Setor de Ictiologia, Museu Nacional do Rio de Janeiro- Quinta da Boa Vista, s/no.- S. Cristóvão- Rio de Janeiro, RJ, Brasil. CEP. 20940-040.

An extinct Phractocephalus species (Siluriformes, Pimelodidae) from the Mio-Pliocene Solimões formation of Acre State, Brazil

Jean Bocquentin, Michel Jégu and Paulo Brito

The skull of a fossil siluriform fish was discovered in the Solimões Formation (Mio-Pliocene) from the Cachoeira do Bandeira region, Upper Acre river (State of Acre, Brazil). This fossil is attributed to the genus Phractocephalus (Pimelodidae). However many autapomorphies relative to the supraoccipital bone (lateral wings oriented upwards and possessing an angular posterior process, a well developed carina, with the central part of the distal border clearly protuberant), as well as the rounded anterior border of the mesethmoid, indicate that this specimen is distinct from Phractocephalus hemioliopterus.The latter is the living representative of the genus mentioned above which was up to now considered as being monotypic. The Cachoeira do Bandeira site displays an array of vertebrate forms among which are crocodilians (Purussaurus brasiliensis, Caiman sp., Gavialidae ind.), aquatic turtles (Chelus, Stupendemys), birds (Anhinga n. sp.) and rodents (Neoepiblema). This vertebrate fauna which does not include any living forms, seems to be endemic to the Solimões Formation of Acre. Paradoxally, in the vertebrate fauna from La Venta (Colombia) which is dated earlier, some representatives of living fish species are present , among which is Phractocephalus hemioliopterus.

Lab. Paleontologia - D.C.N. Univ. Fed. do Acre. Campus Universitário, Km 4; C.P. 500; Cep: 69.915-900 Rio Branco - AC, Brasil. Fax: (68) 229-1246

Phylogeny of the subfamily Corydoradinae (Siluriformes: Callichthyidae)

Marcelo R. Britto

A phylogeny among the genera Aspidoras von Ihering, Brochis Cope and some species groups of Corydoras Lacepede of the subfamily Corydoradinae is hypothesized. Six synapomorphies sustain monophyletism of the subfamily: a smaller preopercle, dorsal process on premaxilla, a smaller first hypobranchial, a more ossified second hypobranchial, an expanded inner process of basipterygium and a lanceolate urogenital papilla on males. Several synapomorphies sustain species groups of Corydoras as monophyletic assemblages. Moreover, some of these assemblages are more related to other genus of Corydoradinae (i.e. Brochis) than to other Corydoras groups, suggesting that this genus is non-monophyletic. An ankylosed opercle defines the genus Aspidoras that is the sister group of all other Corydoradinae, defined by an elongate hyomandibula. Corydoras barbatus group is the sister group of all Corydoradinae non-Aspidoras. Corydoras reticulatus group is sister group of corydoradines non-Aspidoras non-C.barbatus group. All other corydoradines are distributed in four major clades: Corydoras prionotus group, C.stenocephalus group, C.punctatus group and an assemblage encompassing the groups C.ellisae, C.acutus, C.blochi, C.hastatus, C.nanus, C.elegans, C.undulatus, C.nattereri, C.ornatus, C.garbei, C.aeneus, C.eques and the genus Brochis. The latter defined by a synchondral contact between quadrate and metapterygoid. The Corydoras eques group is more related to Brochis then to other groups, having C.aeneus group as its sister group.

Laboratorio de Ictiologia Geral e Aplicada, Departamento de Zoologia - Instituto de Biologia, Bloco A - CCS - Cidade Universitaria, UFRJ. Cx. Postal 68049 21944-970 Rio de Janeiro, RJ. TEL(FAX) (021)560-5993 E-mail mrbritto@acd.ufrj.br

Three new species of Gymnotus (Gymnotiformes, Teleostei) from central Amazonia, with descriptions of electric organ discharges and ecology

James S. Albert and William Crampton

Three new species of Gymnotus are described from the Mamiraua Ecological Reserve near Tefe in central Amazonia. Morphological, meristic, pigmentation and electric organ discharge patterns are used to distinguish these species. A phylogenetic diagnosis of Gymnotus and a key to the recognized species is provided.

Nippon Medical School, Department of Anatomy; Sendagi 1-1-5, Bunkyo-ku, Tokyo 113, Japan. Tel : +81 3-3822-2131 ext. 5319. Fax: +81 3-5685-6640. Email: albert@nms.ac.jp

Comparative data on anatomical and cytological features of electric organs in the genus Eigenmannia in the context of systematics

Frank Kirschbaum, Annemarie Cöllen and Margarete Burek

The systematic status of many genera of the gymnotiform fishes is not very clear as far as number of valid species is concerned; this applies also to the genus Eigenmannia. By comparing the anatomy of the electric organ and cytology of electrocytes of three morphologically very similar Eigenmannia-forms (tentatively called E. virescens, E. lineata and E. sp.) and E. macrops we tried to find out if the above mentioned features allowed to distinguish valid species from each other. In addition to general features common to all three forms and E. macrops we were able to find features at the level of the electric organ (e.g. number of electrocyte rows) and concerning the cytology of the electrocytes (e.g. size and form of electrocytes and morphology of the caudal, innervated face), which differed consistently between the three forms and also E. macrops and clearly showed the three forms to be valid species, tentatively called E. virescens, E. lineata and E. sp. (perhaps E. trilineata).These data show that electric organ characteristics are indeed valid and useful features to distinguish between species in the order of the gymnotiforms and help to clarify the systematic status of the groups investigated.

Institut of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany; E-mail: fkirschb@igb-berlin.de

Comparative biology and ecology of the cichlid fishes in the Venezuelan Llanos

Carlos A. Lasso

The biology & ecology of the cichlid fishes, in two aquatic systems (Guaritico river and peripheral flooded areas) in the Llanos of Apure, Venezuela, was studied. The study included different aspects of their diversity, abundance, distribution, feeding habits and reproduction. Twelve species of Cichlidae was identified, one of these ( Caquetaia kraussii) has been introduced to the Llanos. The main channel and the floodplain of the Guaritico river showed a higher species richness (12 sp.) than the peripheral flooded areas (8 sp.). Among the peripheral flooded areas, lowland streams ( termed inactive caños), had the highest cichlid diversity (8 sp.). In Guaritico river the beach habitat had most species. (11 sp.). Aequidens sp and C. kraussii were the two species with the highest degree of constancy, and the species with highest relative abundance in the peripheral flooded areas.In Guaritico river an elevated proportion of constant species was observed, which species dominated depended on the habitat. Half of the species were omnivores, with marked tendencies towards herbivory, insect feeders, planktivory and piscivory. The rest of the species were basically carnivores (piscivores, insect feeders and planktivores). A seasonality in the diet of the two omnivores (Aequidens sp and Papiliochromis ramirezi) and a secondary zooplanktivore (Geophagus altifrons) was observed. Ten species of cichlids were considered substrate spawners or guarders, while only G. altifrons and Satanoperca leucosticta were mouth brooders. Except for Chaetobranchus flavescens, Astronotus ocellatus and Cichlasoma orinocense, which only reproduce once in the rainy season, the species studied reproduced all the year. Field work was funded by NGO Asociación Amigos de Doñana-Spain.

Museo de Historia La Salle, Aptdo. 1930, Caracas 1010, Venezuela & Instituto de Zoología Tropical, Universidad Central de Venezuela.

Inventories and distribution of French Guiana freshwater fishes.

Philippe Keith, Pierre Yves Le Bail and Michel Jégu

The fishes data collected in French Guiana since 1949 have been standardized and stocked in a data base, named "Fauna-Flora", in the Muséum national d'Histoire naturelle in Paris. Complementary inventories have been realized since 1994 in non prospected areas. This data base is specialized in computer processing and automatic mapping of information collected and validated. It contains nearly 20,000 data about French Guiana fish distribution and it permitted the publication of the first "atlas of French Guiana freshwater fishes". This is the first book which talk about freshwater fishes of French Guiana. It contains 155 pictures (further new species), 400 draws and 160 maps of distribution included all the fisheries realised during 50 years in this country. This work confirms the break of streams into two different faunistic groups. Data's updating will permit the monitoring of species settlement.

Muséum national d'Histoire naturelle, Institut d'Ecologie et de Gestion de la Biodiversité, Service du Patrimoine naturel, 57, rue Cuvier, 75231 Paris cedex 05, France. Email : keith@mnhn.fr

New aspects concerning the cyclical reproduction of tropical freshwater fishes

Frank Kirschbaum

Cyclical reproduction of tropical freshwater fishes is based on cyclical maturation and regression of gonads. Experimentally - confirmed by field data later on - it has been shown that the environmental cues responsible for gonad maturation are conductivity decrease, water level increase and imitation of rain (high water conditions). Thus we had been able to induce gonad maturation/breeding in captivity in one african mormyrid species, one south-east-asian silurid catfish and three neotropical gymnotiform species; during our recent experiments we added additional species: two more mormyrid species, one african schilbeid catfish and one more gymnotiform species, i.e. Rhamphichthys sp. These data indicate that this kind of regulation of cyclical reproduction mentioned above is more widespread in the tropics than expected before. Some data on the reproduction of the neotropical Rhamphichthys sp. shall be reported here: a group of five fish, two males (the largest 85 cm long) and three females (each about 50 cm long) spawned over a period of three months seven times, each time about 1000 sticky eggs of two mm in diameter were deposited. Embryos hatched on day three and transition to exogenous feeding (Artemia nauplii) occured on day ten (beginning of electric discharge on day eight). Three month old juveniles grew up to 11cm length. Our results demonstrate that this species of Rhamphichthys breeds during the rainy season, and not as supposed for other species of Rhamphichthys, during the dry season. As Rhamphichthys is a valuable food fish in some parts of South America aquaculture trials with this species should be envisaged.

Müggelseedamm 310, 12587 Berlin, Germany; E-mail: fkirschb@igb-berlin.de

The eye-muscles in the Hypoptopomatinae catfishes (Siluriformes, Loricariidae).

Adriana Elbia Aquino

The topography of the eye-muscles is described for four hypoptopomine species (Hypoptopoma inexspectata, Otocinclus flexilis, O. vittatus and Microlepidogaster maculipinnis). Myological and osteological material was prepared following standard techniques. As in other teleosts, there are four recti muscles, which insert onto the dorsal, inferior, posterior and anterior sides of the eye, respectively, and two obliquii muscles, which insert onto the dorsoanterior and ventroanterior sides. The recti muscles originate from a one-chambered orbitotemporal cavity formed by parasphenoid, prootics and basioccipital. Regarding the origin of the obliquii, two states have been recognized. In H. inexspectata, the origin is from the posteroventral border of the lateroethmoid. In the other species, the muscles originate from a tendinous sheet of tissue attached to inner ethmoidal surfaces, and before passing into the orbital cavity, they run along a short canal-like path of the lateroethmoid. Authors have usually placed catfishes among teleosts with posterior myodome wanting or non-functional and without anterior myodome. However, this study provides morphological evidence that support the presence of a functional posterior myodome in the Hypoptopomatinae. The ethmoidal formation also described would not be homologous, though similar in position and function, to the anterior myodome of other fishes. When comparing with the condition of other siluriforms, the presence of longer eye-muscles in the Hypoptopomatinae can be related with their relatively larger eyes capable of rapid eye movements. A similar topographical pattern of the eye muscles was also observed in members of other loricariid subfamilies. Finantial institution: CONICET, Argentina.

Instituto de Limnologia "Dr. Raúl A. Ringuelet", C.C. 712, (1900) La Plata, Buenos Aires, Argentina; E-mail: aquino@ilpla.edu.ar

Evolutionary and cytotaxonomic considerations on the genus Bryconamericus (Pisces, Characidae, Tetragonopterinae)

Adriane Pinto Wasko and Pedro Manoel Galetti Junior

Useful chromosome markers for evolutionary and cytotaxonomic studies were identified by cytogenetic analysis on different species of the genus Bryconamericus, which are awaiting more precise taxonomic identification. Despite the diploid number of 52 chromosomes, the karyotype structure of Bryconamericus sp A (Piracicaba river, SP), Bryconamericus sp B (Piracicaba river, SP), Bryconamericus sp C (Tibagi river, PR) and Bryconamericus sp D (Araguaia river, MT) varied widely. Bryconamericus sp E (Araguaia river, MT) presented a more distinct karyotype with a diploide number equal to 54 chromosomes. Different locations of the nucleolar organizer regions (NORs) were observed by silver nitrate and mitramycin staining and twelve NOR phenotypes could be identified among species. Bryconamericus sp A presented 1s and 2s phenotypes, Bryconamericus sp B presented 3s and 4s, Bryconamericus sp C presented 1s, 2s, 2l, 4s, 5, 6, 7l and 8l, Bryconamericus sp D presented 3s and 4s and Bryconamericus sp E presented 9, 10s and 11. The data indicate that the ancestral karyotype of the group could be made up of 52 chromosomes and could be closer to the karyotype structure of Bryconamericus sp B. Bryconamericus sp E presented the most derived karyotype, probably due to chromosome fissions. Alternatively, this latter species belong to other group than Bryconamericus and has to be redefined. (NOR phenotypes: 1s=short arm of a medium SM; 2s=short arm of a large SM; 2l=long arm of a large SM; 3s=short arm of a medium A; 4s=short arm of a medium ST; 5=an arm of a medium M; 6=an arm of a small M; 7l=long arm of a medium ST; 8l=long arm of a medium SM). Financial Support: CNPq

Depto. de Genética e Evolução, Universidade Federal de São Carlos, 13565-905. São Carlos, SP. E-mail: papw@iris.ufscar.br

Rhamdella sp. nov. (Siluriformes, Pimelodidae), from subtropical Argentina.

Amalia M. Miquelarena and Roberto C. Menni

The northwestern Argentine ichthyofauna is still a rather neglected subject. In the framework of a wide project on systematic and distribution of Argentine fresh water fishes, we described Rhamdella sp. nov., a new pimelodid from the Itiyuro river, in northwestern Argentina. It differs from practically all known species of the genus in the smaller eyes and largest interdorsal distance. Current methods were used for morphometrics, and for clearing and staining specimens. The new species belongs in the "Brachyrhamdia" clade but the fifth transverse process is not expanded and notched as in that group. The vertical osseus lamina over the composite center is somewhat lower and no so straight as in Rhamdia sp. or Rhamdella longiuscula. The basin where the new species was found is usually endorrheic, but probably connections are established with the Pilcomayo and/or Bermejo basins following slight modification of the hydrological regime.

This paper is a partial result of the research project 3925/92 from the National Research Council (CONICET), Argentina.

Reproductive biology of Lycengraulis grossidens Agassiz, 1829 (Teleostei, Engraulididae) in a coastal lagoon, Rio Grande do Sul, Brazil.

Andréa Garcia de Oliveira and Nelson Ferreira Fontoura

Lycengraulis grossidens is a dominant species in the coastal lagoons of Tramandai basin. Egg laying is done in brackish water on spring and summer, with juvenile migrating to freshwater soon after. The present study was realized from July/95 to June/96, through bimonthly samples in the Lagoa Itapeva and Lagoa dos Quadros, Rio Grande do Sul, Brazil. The animals were captured using a seine net, 20m long 3m high and 5mm mesh size. The specimens were immersed in 10% formalin and carried to the laboratory, where the fishes were measured, weighted and the gonads analyzed for sex and maturation stage identification. By the analysis of the frequency of mature females for each month and gonadossomatic index, it was identified the presence of reproductive animals only from October to January, with a greater reproduction activity in December. The size at the first maturation was 7.98cm. It was observed a number of 2371 to 6847 mature ovocites in males ranging from 6.9 to 9.5cm. (CNPq)

Departamento de Biologia, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga, 6681, CEP 90619-900, Porto Alegre, Rio Grande do Sul, Brazil. E-mail: nfontoura@music.pucrs.br

The stomach contents of Lycengraulis grossidens Agassiz, 1829 (Teleostei, Engraulididae) in a coastal lagoon, Rio Grande do Sul, Brazil.

Andréa Garcia de Oliveira and Nelson Ferreira Fontoura

Lycengraulis grossidens is a dominant species in the coastal lagons of Tramandai basin. Egg laying is done in brackish water on spring and summer, with juvenile migrating to freshwater soon after. The present study was realized from July/95 to June/96, through bimonthly samples in the Lagoa Itapeva and Lagoa dos Quadros, Rio Grande do Sul, Brazil. The animals were captured using a seine net, 20m long 3m high and 5mm mesh size. The specimens were immersed in 10% formalin and carried to the laboratory, where the diet components and food preferency were examined. Analysis of the results of frequency of ocurrence (f) and numerical ocurrence (ON) of stomach contents, indicate the preference for copepods and cladocerans. The secondary are amphipods, teleostei, palaemonids and diptera. The accidental are isopoda, annelida, sements and aracnidae. It was also observed, through the numerical ocurrence (ON) the preference for Copepoda (31%), Cladocera (30,6), Amphipoda (17,2), Teleostei (8,04%), Palemonidae (5,75%), Isopoda (3,45%), Diptera (2,30%), Annelida (0,75%), Sements (0,38%) and Aracnidae (0,38%).(CNPq)

Departamento de Biologia, Pontifícia Universidade Católica do Rio Grande do Sul. Av. Ipiranga, 6681, CEP 90619-900, Porto Alegre, Rio Grande do Sul, Brazil. Phone:(051)339-1511 ex. 3579 FAX: (051)339-1564 E-mail: nfontoura@music.pucrs.br

Study of the phylogenetic relationships of the genus Brycon Müller & Troschel, 1844 (Characiformes; Characidae)

Angela M. Zanata

As presently recognized Brycon is one of the largest neotropical characiform genus containing over 60 nominal species - of which perhaps about 40 are "valid" species, occurring from Mexico south to Central and South America until Rio de La Plata. Brycon belongs to the family Characidae and is currently defined by a combination of morphological characters, especially dentition: presence of two inner synphyseal teeth in the lower jaw and 3 or 4 rows of premaxillary teeth. These characters have been considered plesiomorphic by several authors and is questionable whether Brycon as it now stands is a monophyletic unit. Hypothesis of relationships of this and others characid genera have been based, usually, on one or a few representative species of presumed subunits of the genus. In the present work species of Brycon and other characiforms have been studied to examine the hypothesis that the genus is monophyletic, and to determine a hypothesis of relationships within de genus and of Brycon to proximate outgroups. This study is based primarily on osteological characters, although myological and other anatomical features will be also utilized. The preliminary analysis presented here suggests that Brycon possible is not a monophyletic group. Some species present characters that can relate them closely to species of other Characidae genera. (Financial support - FAPESP).

Museu de Zoologia da Universidade de São Paulo, Seção de Peixes, Av. Nazareth, 481, São Paulo, SP, 04263-000. E-mail: zanata@usp.br

Osteological variability among the Pimelodus blochii Group

Beatrice M. Parisi

Pimelodus blochii (Valenciennes, 1840) (Pimelodidae: Siluriformes) is described from the Guianas (Cayenne (French Guiana), Suriname) and its type locality was restricted to Suriname by Mees in 1974. In the Parana basin a related species of Pimelodus is reported as P. cf. blochii or P. clarias (the name "clarias" being the original designation of P. blochii by Bloch in 1785). Previous studies on specimens from the Parana basin show slight morphological and meristical differences with the lectotype of P. blochii. The osteological study of material collected from Bolivia (Rio Mamore, Rio Guapore) and Brasil (Rio Negro, Rio Solimoes) and identified as P. blochii shows a significant variability. Can we still consider these specimens as part of P. blochii or should we place them in new species?

Laboratoire d'Ichtyologie Générale et Appliquée (MNHN), 43, rue Cuvier - 75231 PARIS Cedex 05 FRANCE tel: +33 1 40 79 37 35 fax: +33 1 40 79 37 71 E-mail: parisi@mnhn.fr

Description of a new species of Steindachnerina Fowler (Characiformes: Curimatidae) from Corumbá River, upper Paraná River basin, Goiás State, Brazil

Carla Simone Pavanelli and Heraldo Antônio Britski

The genus Steindachnerina comprehends 21 species recognized today. The upper Paraná river Steindachnerina species, S. insculpta Fernández-Yépez, the only species marked on upper Paraná basin, is very common and easy to recognize. However, in the populations of Steindachnerina from Corumbá river, tributary of Paranaíba river, were found breeding females with two very distinct types of oocytes. It led us to discover that on of that oocytes types belonged to a new species which is very like S. insculpta. The new species is distinguished from congeners by the following traits: roof of the oral cavity in adults with three thick folds, longitudinally aligned; back and belly scales in adults with smooth edge and without reticulate surface; lower jaw not lozenge shaped in ventral view; lack of a dark spot on the basal portion of the dorsal fin and presence of a dark midlateral stripe along the flanks. Its distribution is known only from Corumbá river, upper Paraná basin. This study was partially supported by grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) to HAB. Research associated with this study was supported by Furnas Centrais Elétricas and UEM/Nupélia.

Nupélia (Núcleo de Pesquisas em Limnologia, Ictiologia e Aquacultura)/Universidade Estadual de Maringá, Av: Colombo, 5790, 87020-900-Maringá, Paraná-Brazil, Phone number +55-44-263-1616, Fax +55-44-263-1424, Email carlasp@uem.br

Osteological and morphometric description of three species of the genus Pamphorichthys Regan, 1913 (Poeciliidae; Cyprinodontiformes), P. hollandi (Henn, 1916), P. hasemani (Henn, 1916), P. araguaiensis Costa (1991)

Carlos Augusto de Figueiredo

Pamphorichthys, a poeciliid genus distributed in most part of Brazilian and Paraguayan territory were considered by Rosen & Bailey in 1963 a subgenus of Poecilia Bloch & Schneider (1801). This subgenus (sensu Rosen & Bailey) would include Poecilia (Pamphorichthys) minor (Garman,1895), Poecilia (Pamphorichthys) heterandria (Regan, 1913), Poecilia (Pamphorichthys) hollandi (Henn, 1916), Poecilia (Pamphorichthys) hasemani (Henn, 1916). Pamphoria scalpridens (Garman, 1895) Regan (1913) was considered a member of the Poecilia (Lebistes) subgenus together with other species (e.g. P. reticulata and P. parae). Later, Costa (1991) described Pamphorichthys araguaiensis and reinstated the Pamphorichthys genus status since there was no phylogenetic evidence for its inclusion as a Poecilia subgenus. Special attention is given to the pelvic fin osteology, which is an exclusive character of Pamphorichthys and the gonopodium anatomy since it is traditionally used as a source of differentiation of poeciliid species. In P. araguaiensis and P. hollandi the body depth is 0.20 of the standard length, in P. hasemani it is 0.18 of the SL. The gonopodium and pelvic fins are longer in P. hasemani than in the other two species (0.43 and 0.27 vs. 0.36 and 0.24 of SL). P. hollandi is diagnosed by the small number of modified elements on the second pelvic fin ray (usually 4 vs. 6-9). P. araguaiensis are slender and have the largest and most anterior dorsal fin base. P. hasemani the smaller species of the genus (max. SL analyzed: 13.76 mm males and 17.96mm females), have it's gonopodium structure simplified. Bolsista CAPES.

Universidade Federal do Rio de Janeiro, Depto.de Zoologia - Bloco A - CCS, Laboratorio de Ictiologia Geral e Aplicada, Cidade Universitaria, RJ - Brasil, CEP 21941-569, Phone: (055)(021) 560-5993 ext-25, email: carlosaf@acd.ufrj.br

Freshwater fish fauna of the rio Ribeira basin, SP, Brazil: taxonomic diversification and biogeographic patterns.

Carlos Roberto S. F. Bizerril

The rio Ribeira basin is one of the most important fluvial system of southeastern Brazil, with a drainage area of 30.474 km2. For the present study, the freshwater fish fauna of the rio Ribeira hidrographycal basin were surveyed. Samples were taken in 30 sample units, from 1991 to 1996. Each species were characterized for its maximum length, longitudinal distribution and geographical range. Biogeographic patterns were assessed considering the occurrence of each species sampled in the following geographic areas: (1) rio Ribeira basin; (2) eastern Brazilian fluvial systems located south of rio Ribeira basin; (3) eastern Brazilian fluvial systems located north of rio Ribeira basin; (4) upper rio Tietê basin; (5) upper rio Iguaçu basin, (6) rio Paraná basin, (7) rio São Francisco basin, (8) rio Amazonas basin. Statistical analysis were conduced applying association methods and correlation coefficient. A total of 77 species were sampled, more than 50% of them belonging to the order Siluriformes. Most of the species occurred both in the upper and lower reaches of the basin. A positive correlation between specimen size and spatial distribution range was observed. The similarities observed between the fish fauna of rio Ribeira and those present in the upper courses of rio Iguaçu and Tietê suggest that these basins share a common origin. The affinity between the rio Juquiá (rio Ribeira tributary) and the upper section of rio Paraíba do Sul basin was also observed, indicating a possible relationship between these two areas.

Universidade do Rio de Janeiro (UNI-RIO), Departamento de Ciências Naturais, rua Frei Caneca, n 94, 5 andar, Rio de Janeiro, RJ. CEP: 20211-040

The relationship between fluvial morphology and biodiversity and its application in the process of environmental evaluation.

Carlos Roberto S. F. Bizerril

The relationship between the physical environment and the biological diversification of fish communities was studied and the use of fluvial morphology as an indicative of priority areas for conservation was examined. As a case study the upper course of rio Macacu, State of Rio de Janeiro, Brazil was selected. Biotic data were obtained during 4 year of samples, conduced in 13 sample units. Each environment explored were characterized for its area, order, extension, slope and number of tributaries. Two new indices for environmental analysis (environmental diversity and environmental turnover ratio) were proposed. To asses the correlation between the physical and biotic matrixes the data were compared using the Mantel test. A total of 28 species were collected. After comparing species richness and geomorphologic characteristics of each river, a strong correlation between the physical variables and biodiversity were observed. This result leads to the elaboration of an index to measure the ecological relevance of fluvial ecosystems based on the physical attributes. The index were calculated applying the MAVT technique. The scores produced were correlated with biological diversity at the significance level of P = 0,002, indicating that the methodology created can be applied to identify areas with greater icthyofaunistical biodiversity in studies using the Rapid Environmental Evaluation Procedure (REEP).

Universidade do Rio de Janeiro (UNI-RIO), Departamento de Ciências Naturais, rua Frei Caneca, n 94, 5 andar, Rio de Janeiro, RJ. CEP: 20211-040

Dynamic biogeography of southeastern Brazilian freshwater fishes

Carlos Roberto. S. F. Bizerril and Neuza Rejane W. Lima

Dynamic biogeography concerns the study of biological patterns and processes on broad geographical and temporal scales. We applied dynamic biogeography methods to describe the distribution patterns of southeastern Brazilian freshwater fishes. The results summarize 6 years of samples carried on the hydrographical basins located between the rio Itapemirim and the southern most section of Serra Geral. Affinity between sample units were assessed by the presence of monocentric species. This procedure results in the identification the follow biogeographic domains: Paraiba do Sul (middle and lower sections of the rivers Paraíba, Itabapona, Itapemirim and coastal streams localized between the mouth of rio Itapemirim and lower course of rio São João, RJ), Fluminense (upper course of the rivers São João and Grande, a tributary of rio Paraíba basin, drainages of the Baia da Guanabara and of Baixada de Jacarepaguá), Paulista Plateau (upper course of the rivers Paraíba, Tietê and Juquiá, a tributary of rio Ribeira basin), Coastal streams (streams between Baía de Sepetiba and the mouth of rio Ribeira), Ribeira (middle and lower sections of the Ribeira basin and small streams localized between the mouth of rio Ribeira and Baía de Paranaguá), Iguaçu (upper section of the rivers Ribeira, PR, Iguaçu, PR and Cubatão, near Joinville, SC), Catarinese (rivers between Baía de Paranaguá and rio Cubatão, near Palhoça, SC) and Austral (rivers between Palhoça, SC and the southernmost section of Serra Geral). This pattern was interpreted as an indicative of the occurrence of stream capture events and evolutionary affinities between the rivers studied.

Universidade do Rio de Janeiro (UNI-RIO), Departamento de Ciências Naturais, rua Frei Caneca, n 94, 5 andar, Rio de Janeiro, RJ. CEP: 20211-040

An approach of the evolutionary history of Schizodon (Anostomidae, Characiformes) based on cytogenetic characters

Cesar Martins and Pedro M. Galetti Junior

Cytogenetical studies have been demonstrated useful to taxonomic and phylogenetic propositions in fishes and can give good contributions for the comprehension of the evolutionary history of different groups. With the purpose to contribute to the evolutionary history of the genus Schizodon, chromosome studies were carried out on seven species from different South America hydrographic basins: S. nasutus - Paraná river, Posadas, Argentina and Mogi-Guaçu river (Paraná basin); S. altoparanae - Paranapanema river (Paraná basin); S. knerii - São Francisco river (São Francisco basin); S. vittatus - Araguaia river (Amazon basin); S. fasciatus - Solimões and Madeira rivers (Amazon basin); S. borelli - Cuiabá, Miranda and Paraguay rivers (Paraguay basin) and S. isognathum - Miranda river (Paraguay basin). C-banding and mitramicyn staining identified a great conservatism among the species of the Anostomidae family, which (as well as other related families) presents a karyotype with 54 biarmed chromosomes. However, significant variations occur within some lineages, like Leporinus. The present data showed a small level of chromosome variation on Schizodon and suggest that this genus has a model of chromosome evolution based on a conserved and symmetric karyotype. Compared to Leporinus, the Schizodon species represent a group with a little diverstity on morphology and ecology. Thus, the low chromosome diversity might be related to the low ecological and morphological divergence among these fishes. Financial institution: CNPq.

Universidade Federal de São Carlos, Depto. de Genética e Evolução, Laboratório de Citogenética, 13565-905, São Carlos/SP, Brazil. E-mail: pcma@iris.ufscar.br

The trophic ecology of Creagrutus brevipinnis Eigenmann, 1913 (Pisces, Characiformes, Characidae) in the Vieja River basin, alto Cauca, Colombia

Cesar Roman-Valencia

Between July 1995 and December 1996, 465 specimens were examined of characid fish C. brevipinnis. Occurrence frequency and numerical, coefficient of stomach repletion, condition factor were utilized for analysis of contents, activity alimentary and voracity. Fecundity, mean size at maturity, sex, length-weight relationships and communities fish were determinated. C. brevipinnis is an insectivorous fish specialized for feeding on Diptera ( Simulidae) and Ephemeroptera. Trophic activity registered differences on the rainy season and aridest months ( F= 19.04 P< 0.0001=. The ethology alimentary is realized on the substrate ( 6:00 hours-18:00 hours) and is not a migratory fish it. Was observed correlation negative between stomach weight and voracity index. The species in reproductive season the food consumed is little, The results of this work shows that C. brevipinnis is a predator of second level in the trophic web and is undernourished. Most ovary development a occurs during the months of May to January. The proportion of sexes is 1:1 ( x : 2.56 p< 0.1 d.f.= 1 ). the fecundity is low ( 613 oocytes) and ovocyte is small ( 0.6254 mm). The mean size of maturity is 4.0 cm standar length. The length-weight correlation is hight ( r= 0.75, n= 465) and the regression equation is Y= 1.7812+0.434X . To live together with 30 sympatric species Brycon henni ( 25.83%), C. brevipinnis (24.93%) and Chaetostoma fischeri ( 14.19%) are the taxa most abundant. Temperature average was 21.70C, pH around the neutrality and the oxigen is high ( 8 ppm).

P.O. Box 33022, Cali, Colombia; E-mail: croman@uniquindio.edu.co

Comparative study of the reproductive biology of internally and externally fertilized characids

Daniela Gelain, Marco A. Azevedo, Filipe A. G. Melo, Clarice B. Fialho and Luiz R. Malabarba

Neotropical characids usually present external fertilization, except for some small groups (Glandulocaudinae and part of the Cheirodontinae) which show internal fertilization mostly detected by the presence of spermatozoids in ovaries. It is not known, however, how internal fertilization reflects changes in reproductive biology of these fishes and what kind of information it carries about the evolution of these small characins. This is a comparative study developed with two internal fertilizing glandulocaudines (Pseudocorynopoma doriae and Diapoma speculiferum) and one external fertilizing cheirodontine (Cheirodon calliurus) whose are 3 commom habitants of the arroio do Ribeiro, a rio Guaíba tributary, southern Brazil. We have compared seasonality of the reproductive cycle and fecundity of these 3 fishes. All of them had its Gonadosomatic Index (IGS) calculated for the determination of the reproductive period and some ovaries had ovocites counted for the analysis of fecundity. Additionally we have prepared some female histological gonadal slides in order to examine the presence of spermatozoids in the ovaries of Glandulocaudinae species and to determinate the kind of spawing presented by C. calliurus. We find D. speculiferum and C. caliurus have their reproductive periods limited to spring. P. doriae has its breeding season during the final fall and winter. This is not usual among Neotropical Characiform Fishes.

Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS). Av. Paulo Gama s/n, CEP 90.046-900, Porto Alegre, RS, Brazil. gelain@vortex.ufrgs.br

Taxonomic revision of the genus Hemipsilichthys Eigenmann & Eigenmann, 1889 (Teleostei, Siluriformes, Loricariidae)

Edson H. L. Pereira

The species of Hemipsilichthys are taxonomic reviewed. Sixteen species are recognized in the genus: H. gobio (Lütken, 1874), H. duseni Ribeiro (1907), H. cameroni Steindachner (1907), H. garbei Ihering (1911), H. steindachneri Ribeiro (1918), H. regani Giltay (1936), H. cerosus Ribeiro (1951), H. vestigipinnis Pereira & Reis (1992), H. splendens Bizerril (1995), H. mutuca Oliveira & Oyakawa (1996), H. stephanus Oliveira & Oyakawa, (1996) and five new species, H. sp. A. and H. sp. B from coastal rivers of Santa Catarina; H. sp. C and H.sp. D from upper rio Uruguai and rio Jacuí drainages and H. sp. E from coastal rivers of northeastern Rio Grande do Sul and rio Araranguá in Santa Catarina. A proposal of monophyly of Hemipsilichthys is presented. The genus is phylogenetically diagnosed by two shared characteres: (1) the presence of soft fleshy lobes on the lateral margin of head and (2) the presence of bristlelike hypertrophyated odontodes along the lateral margins of the head of adult males. With exception of H. regani, from rio Negro, Amazon basin, all species of Hemipsilichthys are from the Brasilian Shield between Rio Grande do Sul and southern Bahia. Lectotypes are designated for the nominal species H. cameroni and H. steindachneri. Upsilodus victori Ribeiro (1924) is regarded as junior synonym of H. gobio; Isbrueckerichthys duseni is transferred to the genus Hemipsilichthys; and H. steindachneri is resurrected from the synonymy of H. cameroni. A key, descriptions and illustrations are provided for all species included. Financial support CAPES.

Museu de Ciências e Tecnologia - PUCRS, Av. Ipiranga, 6681; Caixa Postal 1429; 90619-900 Porto Alegre, Brasil. E-mail: edsonhlp@music.pucrs.br

Review of the species of Pimelodus from rio Uruguai and laguna dos Patos drainages (Teleostei: Siluriformes: Pimelodidae)

Edson S. Vidal

The present study analyzed 556 specimens of the genus Pimelodus Lacépède 1803, from the laguna dos Patos system and rio Uruguai drainage. The morphometric, meristic and color pattern analysis allow us to identify three species of Pimelodus: P. absconditus Azpelicueta 1995, from the rio Uruguai and rio Paraná drainages; P. maculatus Lacépède 1803, from the laguna dos Patos system and rio Uruguai dranaige and an undescribed species, restricted to the upper rio Uruguai. The populations of P. maculatus from the laguna dos Patos system and rio Uruguai drainage were compared, and the results demonstrated that there is no reason for their recognition as distinct species. It is provided an identification key for the species inhabiting of the Rio Grande do Sul State rivers.

Museu de Ciências e Tecnologia, PUCRS; Av. Ipiranga, 6681; Caixa Postal 1429; 90619-900 Porto Alegre, Brasil Email: vidal@music.pucrs.br

Relictual distribution in subterranean organisms: cave fishes from northeastern Brazil

Eleonora Trajano and Flávio Bockmann

Environmental stability and persistence of water bodies make the subterranean habitat a suitable refuge for aquatic communities during periods of climatic stress, such as general epigean drought. Populations which survive the conditions of permanent darkness and food shortage prevailing in the subterranean biotope may speciate during these vicariant events, accumulating modifications (troglomorphisms) that include eyes and pigmentation regression. After a long evolutionary time in isolation (e.g., in semiarid areas), the high degree of specialization, eventually associated with the extinction of surface relatives, can make the taxonomic position of these species unclear, difficulting their assignment to any previously known taxa (phylogenetic relicts). In other cases, epigean relatives may be recognized, but occur in distant areas, constituting examples of disjunct distribution (distributional relicts). Among fishes and invertebrates as well, good examples of both kinds of relictual distribution have been found in semiarid regions of Bahia State, northeastern Brazil. Two undescribed species of heptapterine catfishes (Pimelodidae) were found in isolated pools and lakes formed by the water table inside caves of Chapada Diamantina and Campo Formoso regions, respectively. The first one is probably a phylogenetic relict, previously assigned to the genus Imparfinis. The second species is a troglomorphic Taunayia, a genus with an epigean distribution currently restricted to shaded streams of the Tietê and Paraíba river basins, São Paulo State, southeastern Brazil. The cave species is an example of distributional relict, and its occurrence in Bahia is a paleoclimatic evidence of expansion of subtropical forests to the north.

Departamento de Zoologia, Instituto de Biociências da USP, C.P. 11461, 05422-970 São Paulo, Brazil. E-mail: etrajano@usp.br

Comparison of fish species composition in different water bodies of rio Tramandaí drainage, Rio Grande do Sul, Brazil.

Fernando G. Becker, Sandra M. Hartz, Clarice B. Fialho and Willi Bruschi Jr.

The rio Tramandaí drainage, situated in northeastern Rio Grande do Sul (29o45, - 30o15, S, 50o00, - 50o30, W) is a small river system running into the Atlantic Ocean and can be divided in two different sub-regions considering historical origin and geological and ecological characteristics. The wide variety of aquatic habitats in the system along with the differences in historical origin are probably related to the considerable fish species richness of the region. We present a comparison of the fish species composition in four different water bodies representing the main types of aquatic environment in the system: rio Maquiné (river), lagoa Caconde (isolated freshwater lagoon), lagoa do Peixoto (freshwater lagoon connected to drainage system) and lLagoa das Custódias (connected lagoon with influence from sea water), using data on species richness and frequency of occurence in each water body. A total of 83 species (in 30 families) was collected. The main similarity among the water bodies is that Characidae is the most species rich family in all of them. Cichlidae is the second most species rich family in lagoa Caconde and lagoa do Peixoto, Atherinidae in lagoa das Custódias and Loricariidae in rio Maquiné. The environmental variability represented by salinity variations in lagoa das Custódias and presence of lotic and semi-lentic habitats in rio Maquiné could be related to the higher species and family richness in these water bodies. Conversely, lagoa Caconde and lLagoa do Peixoto, with less temporal or spatial variability, present lower species and family richness. (CAPES, CNPq, FAPERGS).

Departamento de Ecologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS). Caixa Postal 15007, CEP 90.540-000, Porto Alegre, RS, Brazil. ecomki@if.ufrgs.br

Characterization of the reproductive behavior and early life history stages of Cichlasoma dimerus (Heckel, 1840) (Perciformes, Cichlidae) under laboratory conditions.

Fernando J. Meijide and Graciela A. Guerrero

Cichlidae is a fresh and brackish water family found in Central and South America (one species extending north to Texas), Africa, Madagascar, West Indies, Israel, Syria, coastal India and Sri Lanka. It is a large family that comprises about 105 genera and 1300 species, making it the second largest perciform family. There is a vast literature on the reproductive behavior, most of which describes spawning behavior and parental care, but considering the number of species, their wide distribution and importance, it is surprising that there is little descriptive information on the early development of cichlids. Larval fishes often display characteristic pigment patterns which can be used to identify species at a very early point in their lives. Moreover, early life history characters may be useful in studying intrafamilial relationships. The main objective of this study is to describe the early life history stages of Cichlasoma dimerus. The geographical distribution of this species includes the rivers Paraguay, lower Alto Parana, Parana Medio and Parana Inferior. In addition, the reproductive behavior under laboratory conditions is characterized. Eggs and larvae were obtained from adults captured in Esteros del Riachuelo, Corrientes, Argentina (27º 20' S, 58º 45' W). Adults were kept in large aquaria at 25 + 0.5 ºC and 12:12 hours photoperiod, in which pairs were usually formed. For observation, single pairs were transferred to smaller aquaria with a layer of gravel and smooth stones for egg deposition on the bottom. A part of the fry guarded by parents was sampled day by day. Specimens were observed and measured microscopically. The main morphological and functional features of each stage are described and the hours or days of development determined. Photomicrographs and camera lucida drawings characterize the stages pictorially. The present study was supported by a grant from the University of Buenos Aires (EX 095).

Laboratorio de Embriología Animal. Departamento de Ciencias Biológicas. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Ciudad Universitaria. Pabellón II, 4º piso. (1428). Buenos Aires. Argentina. E-mail: embrio@bg.fcen.uba.ar - Fax: (54-1) 782-0582

On the origins and monophyly of the neotropical freshwater stingrays and their parasites: a total evidence approach

Fernando P. L. Marques

Recent phylogenetic hypothesis for the myliobatoids is re-evaluated and implemented with partial sequences of 12S rDNA for some taxa with emphasis on the origins and monophyly of the potamotrygonid neotropical freshwater stingrays. Also, the parasitological data available for the potamotrygonids and the marine myliobatoids is briefly discussed. I argue that the phylogenetic analysis based on morphological data is dependent on a priori assumptions of character evolution. The parasitological data need to be reevaluated before any inferences can be drawn from this data set. A phylogenetic hypothesis of the myliobatoids is provided based on the combination of morphological and molecular data which suggests that potamotrygonids are not a monophyletic group. A reinterpretation of the historical biogeography of the neotropical freshwater stingrays is discussed briefly, and recommendations for a better understanding of origins and diversification patterns are given.

Department of Zoology, University of Toronto, Toronto, Ontario Canada M5S 3G5 Email: fernando@zoo.utoronto.ca

Amplification of DNA markers using single primers of simple sequence repeats: a good marker in Gymnotidae (Pisces: Gymnotiformes) studies

Flora M. C. Fernandes-Matioli, S. R. Matioli, L. F. Almeida-Toledo and S. A. Toledo-Filho

Family Gymnotidae comprehends only one genus of weakly electric fishes, genus Gymnotus, that presents wide neotropical distribution. Previous karyotypic studies in species sampled from this genus disclosed a wide chromosome number and formulae variability both inter and intraspecifically. Single sequence repeats (SSR) are very good molecular markers, and amplification by conventional PCR (polymerase chain reaction) using single primers of SSR has been effective for the characterization of populational genetic structure of species of plants and vertebrates. The length and number of fragments between SSR loci (microsatellites) presenting intrapopulational polymorphism are a powerful tool for genetic structure studies. When it comes to the species belonging to the family Gymnotidae, the tetranucleotide repeat primers were most effective in amplifying polymorphic patterns. In the present study we analyzed this kind of molecular markers in the species Gymnotus carapo, G. pantherinus and Gymnotus spl. We have found extremely conservative interspecific patterns using (GACA)4 and conservative intraspecific patterns using (GGAT)4 + (TAGG)4. In the first case 8 fragments from 500 to 1600 bp were amplified in both species analyzed. In the second case, 2 fragments were amplified (-500 and 700 bp) in G. carapo, 1 large fragment with approximately 2500bp in G. pantherinus and 2 fragments (-800 and 1900 bp) in Gymnotus spl. The usual pattern was the presence of some bands shared by the three species, and a few polymorphic bands specific for each species. In a pilot experiment, we found an intrapopulational polymorphism in a sample of 10 individuals of G. carapo from the Paranapanema river basin at Primeiro de Maio, PA, Brazil, using (GACA)4 + (AAGC)4 and (GGAC)4 as primers. The pattern obtained for each individual with the first combination of primers was coherent with the results obtained with the second combination of primers. The use of this approach in other populations of Gymnotus will certainly benefit our studies on systematics of closely related populations and species. Grants from CNPQ and FAPESP.

Departamento de Biologia, Instituto de Biociêancias, USP, Cidade Universitária, São Paulo, SP, Brasil.

Morphological variation and color pattern in Phalloceros caudimaculatus (Hensel, 1868) population of coastal drainages of the Rio Grande do Sul (Cyprinodontiformes: Poeciliidae: Cnesterodontini)

Francisca Lúcia Rodrigues de Barros

Phalloceros caudimaculatus (Hensel, 1868), is the single species of the genus. Morphometric characters obtained by traditional and truss networks methodology, and color pattern were analyzed in sample from coastal drainages of Rio Grande do Sul, Brazil. Morphometric characters were analyzed by multivariate techniques, particularly the size free-canonical variate analysis. These analyses indicate that the population of the lagoa dos Patos is taxonomicaly distinct from the Torres population. The characters which discriminate these populations are: head length, mouth length, (1) oblique distance from base of the upper pectoral-fin ray to base of first ray of dorsal fin, (2) the horizontal distance from base of last dorsal-fin ray to base of the upper caudal-fin ray, (3) the oblique distance from the base the last dorsal-fin ray, to the base of the lower caudal-fin ray, (4) the oblique distance from base of last anal-fin ray to base of the upper caudal-fin ray, (5) and the horizontal distance from base of the last anal-fin ray to base of the lower caudal-fin ray, and the presence of an additional spot in the caudal peduncle. Based on this morphometric and color pattern analysis, the Torres population presents diagnostic characters that indicate its possible independent taxonomic status.

Departamento de Ciências Físicas e Biológicas, URCA, Crato Ceará, Brasil.

Reproductive biology of Geophagus brasiliensis (Teleostei: Perciformes: Cichlidae), at Águas Belas reservoir (Viamão, RS, Brazil)

Gil Ortiz Santos and Nelson F. Fontoura

From September 1995 to August 1996, samples of Geophagus brasiliensis were caught off in the Águas Belas Reservoir through a beach seine and circular fishing net. From a total of 903 captured animals, 460 were females, with total lengths ranging from 3.98cm to 18cm. The reproductive period, analyzed by the frequency of mature females and gonadosomatic index (GSI), begins on November finishing on April, with greater values of GSI on November and February, reaching 1.30% and 1.59% of total weight, respectively. To obtain the oocytes diameter, samples of forty ovaries were measured. The mean diameter of immature stage remain in 0.13 mm, ranging from 0.06mm to 0.20 mm in the same animal. The mature stage is reached with an average of 1.56mm of oocytes diameter, with values between 1.20 to 1.80 in the same individual. Evaluation of potential fecundity was done by counting all mature oocytes of twenty four ovaries of females with 7.28cm to 13.17cm of total length. Average fecundity was 567, ranging from 310 to 777 oocytes. Fecundity presents an allometric relation to total length or weight, being described by the following equations (length in centimeters, weight in grams). Fecundity = 204.5751*Total Weight^0.3530 (r=0.78). Fecundity = 45.7543*Total Length^1.0984 (r=0.75). Fecundity = 359.3621+205.1632*Gonadal Weight (r=0.84).

Intituto de Biociências, PUCRS, P.O.Box 1429, 90619-900 Porto Alegre, RS, Brazil. Email: nfontoura@music.pucrs.br

Revision of the species of Pimelodella Eigenmann & Eigenmann, 1888 (Teleostei; Siluriformes; Pimelodidae) in the river systems of south and southeastern Brazil

Gizelani Müller Guazzelli

Pimelodella is the largest genus in family Pimelodidae, with more than 60 species, distributed from the La Plata basin, on southern South America, to Panama. The genus is not monophyletic, and is currently diagnosed by having a narrow supraoccipital process, extending to the pre-dorsal plate, and by the fontanel reaching the anterior margin of the supraoccipital process. The main objetive of this study is to make a review of the species inhabiting the coastal river systems of south and southeastern Brazil (Rio Grande do Sul to Rio de Janeiro). Eight species are recognized in this area: P. australis, from the laguna dos Patos system, rio Uruguai, and rio Tubarão; P. ignobilis, from the rio Cubatão drainage; P. pappenheimi, from the rio Itapocu, and rio Paranaguá; P. transitoria and P. kronei, from the rio Ribeira do Iguape; P. brasiliensis, P. lateristriga and an additional new species from the rio Paraíba do Sul. The Pimelodella harttii and P. pectinifera, are regarded as junior synonyms of P. lateristriga. The type-locality of the P. lateristriga is restricted to rio Paraíba do Sul drainage. Funded by CNPq.

Museu de Ciências e Tecnologia, PUCRS. Av. Ipiranga, 6681, Cx. Postal 1429. 90619-900. Porto Alegre, Brazil E-mail: guazelli@music.pucrs.br

High levels of mitochondrial Cytochrome B divergence and phylogenetic relationships in the annual killifishes of the genus Cynolebias Steindachner 1876 (Cyprinodontiformes, Rivulidae).

Graciela Garcia, Gabriela Wlasiuk and Enrique P. Lessa

Phylogenetic relationships based on 324 base pairs of the mitochondrial cytochrome b gene are examined in fourteen species of the genus Cynolebias (thirteen from Uruguay). Monophyly of the genus was resolved by the sequence data based on comparison to other three outgroup taxa belonging the family Rivulidae. Bootstrap values corroborated the existence of intrageneric monophyletic units in both parsimony and Neighbor joining analyses. These include a Cynolebias bellottii - C. wolterstorffi clade, a C. adloffi-2, C. duraznensis, C. viarius and C. adloffi-1 group, and a C. gymnoventris, C. luteoflammulatus pair and the strongly supported assemblage that include C. prognathus and C. cheradophilus clade. Phylogenetic relationships remain poorly supported for a C. nigripinnis, C. affinis and C. alexandri group and unresolved among the previous ingroup clades. Cytochrome b sequences reveal an unexpectedly high level of divergence among species of the genus Cynolebias. Consequenly, cytochrome b shows good resolution of recent cladogenetic events but limited phylogenetic information at depeer nodes. High levels of sequence divergence spans a large range within Cynolebias. The highest sequence divergence (in average 28%) occurred between C. antenori and the remaining species of the genus. The minimum divergence value (4.4%) is exhibited by sympatric species C. cheradophilus and C. prognathus. The estimates for calibration of molecular clock in Cynolebias indicate that the recent clade differentiation could occur during the Pleistocene.

Genética Evolutiva. Instituto de Biología. F. de Ciencias. Tristán Narvaja 1674. Montevideo, Uruguay. ggarcia@genetica.edu.uy

Comparative study of the feeding behaviour of some glandulocaudines and tetragonopterines (Ostariophysi: Characidae)

Gustavo Graciolli, Marco A. Azevedo and Filipe A. G. Melo

This work deals with a comparative analysis of dietary habits of four syntopic species of characid fishes. Keith Nelson, proposed the glandulocaudines be more superficie feeders than tetragonopterines. The main purpose of this work is to test this hypotesis, analyzing 2 species of glandulocaudines (Pseudocorynopoma doriae and Diapoma speculiferum) and 2 species of tetragonopterines (Astyanax fasciatus and Hyphessobrycon luetkenii), all specimens captured in the same tributary of rio Guaiba (arroio do Ribeiro), near Porto Alegre from March to December 1996. We also compare the feeding behavior of these 2 glandulocaudines to test a second hypothesis of Nelson, that P. doriae is more superficial feeder than other glandulocaudines. Food itens were analised according to its occurence frequency. We found terrestrian insects as the main food item of both glandulocaudines, but no clear differences between the diets of these two species. The first set of stomachs analized of the tetragonopterines showed plants debris as the first item, followed by aquatic Crustacea and terrestrian insects.

Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS). Av. Paulo Gama s/n, CEP 90.046-900, Porto Alegre, RS, Brazil.

Systematics of Pareiorhina Gosline from southeastern Brazil, South America (Ostariophysi, Loricariidae)

Isabel C. Santana and Julio C. Garavello

The studies on a large collection of Hypostominae fishes which precedes the revision of genus Pareiorhina Gosline, permit us to examine the phylogenetic position of this genus in this subfamily. The specialized genus Pareiorhina is related to Hemipsilichthys Eigenmann & Eigenmann, including five new species from the southeastern river basins. A list of 23 osteological characters from the neurocranium, suspensorium, mandibular arch, branchial and axial skeletons, pectoral girdle and caudal fin skeleton was studied under the phylogenetic method. Five phylogenetic trees were constructed through the Hennig86 computer program, and the consensual tree joined synapomorphies to support the hypothesis for a specialized monophyletic ramus with Pareiorhina and Hemipsilichthys in the Hypostominae. Pareiorhina includes P. rudolphi from the Paraiba do Sul River basin and five new species from upper Paraná, São Francisco, and Paraiba do Sul drainages. Hemipsilichthys is presently under revision. The analysis also includes species of the genera Corymbophanes Eigenmann, Kronichthys Ribeiro, Ancistrus Kner, Hypostomus Lacepédè and Neoplecostomus Eigenmann & Eigenmann. Both genera related to Pareiorhina showed ecological preferences for the upper streams, with clean, cold water and cobblestones, differing from their relatives which are normally found downstream under different ecological conditions. CNPq fellowships.

Departamento de Ecologia e Biologia Evolutiva da UFSCar, Caixa Postal 676, 13.565-905, São Carlos, SP, Brasil.. E-mail: picrs@iris.ufscar.br; djga@power.ufscar.br

A history of tropical South American rivers: 89 ma to recent

John G. Lundberg and Larry G. Marshall

Today, 93 percent of fresh water drainage off South America runs into the Atlantic. South America's drainage pattern was shaped by its persistent continental shields, the emerging Andes and their fluctuating foreland basin, and subsurface structural arches. The Andes were built during tectonic episodes that began at ~89, ~73, ~59, ~43, ~29 and ~11 Ma. Crustal shortening and thickening uplifted mountains progressively eastward. Concomitant subsidence eastwardly adjacent to the thrust front created the long, narrow foreland basin. When underfilled with Andean sediment, the foreland basin served to guide major rivers northward and southward, and to receive, at ~73-68 Ma, ~61-60 Ma, and ~11 Ma, marine transgressions of varying extent from the Caribbean and South Atlantic. The western Río Parana system had an early history of growth northward by watershed capture of a proto-Amazon(?) that previously had its headwaters in Chile and Argentina. The modern divide between the Parana and Amazon systems was established beginning ~29 Ma with formation of the Bolivian Orocline. Prior to mid-Miocene the foreland basin drained the vast region of western Amazonia, western Orinoquia and the Magdalena into the Caribbean near Maracaibo. The Río Magdalena system formed by ~11 Ma with final uplift of the Eastern Andes. Development of the Merida Andes, beginning ~8 Ma, began closure of the Caribbean portal of the western Amazon-Orinoco river, and by ~7 Ma the present day pattern of west to east drainage of the rios Amazon and Orinoco was established. As the Andes were built episodically, so too developed the major drainage systems of South America. It is overly simplistic to view Andean vicariance as a singular event at ~10 Ma. Models for the evolutionary diversification of the Neotropical aquatic biota must consider multiple occurrences of vicariance as well as drainage system coalescence.

Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, Arizona USA 85721. E-mail: dclade@ccit.arizona.edu

Taxonomic review of Bryconamericus species from southeastern Brazil (Ostariophysi, Characidae)

José F. Pezzi da Silva

A taxonomic review of Bryconamericus species from the coastal systems of southeastern Brazil, rio Uruguai and laguna dos Patos drainages is presented. Fifteen species are recognized, nine being described as new. Three new species are from the rio Uruguai drainage: Bryconamericus sp. 1 restricted to the headwaters of rio Pelotas and rio das Antas (laguna dos Patos system); Bryconamericus sp. 2 from rio Canoas and its tributaries; and Bryconamericus sp. 3 from the middle rio Uruguai. Two new species are restricted to the laguna dos Patos system: Bryconamericus sp. 4 from the arroio Buriti (a tributary of rio das Antas) and Bryconamericus sp. 5 from the arroio Sampaio (a tributary of rio Taquari). Four new species are recognized from the coastal systems of southeastern Brazil, all from Santa Catarina State coastal drainages: Bryconamericus sp. 6 from rio Itajai-Açu and rio Itapocu; Bryconamericus sp.7 from rio Itajai-Açu; Bryconamericus sp. 8 from rio Itapocu; and Bryconamericus sp. 9 from rio Cubatão. Bryconamericus iheringii (Boulenger, 1887) is redescribed, and the variation between different populations from the laguna dos Patos system and rio Uruguai is described and discussed. Bryconamericus microcephalus (Ribeiro, 1908) is also redescribed and its range is increased to include the rio Nhundiaquara (PR) and coastal rivers of southern Rio de Janeiro State. Diagnosis are presented for Bryconamericus stramineus Eigenman (1908), Bryconamericus tenuis Bizeril & Araújo (1992), Bryconamericus lambari Malabarba & Kindel (1995) and Bryconamericus ornaticeps Bizeril & Peres-Neto (1996).

Museu de Ciências e Tecnologia - PUCRS; Av. Ipiranga, 6681, Caixa Postal 1429; 90619-900 Porto Alegre, Brasil. Email: pezzi@music.pucrs.br

A new species of blind armoured catfish, genus Ancistrus, from caves of Bodoquena region, Mato Grosso do Sul, southeastern Brazil

José Sabino and Eleonora Trajano

Loricariids are an important taxa in the subterranean fish fauna in South America, along with trichomycterids and pimelodids. Two species of cave armored catfishes showing reduction of eyes and pigmentation have been previously described: Ancistrus cryptophthalmus Reis, 1987, from Goiás, central Brazil, and A. galani Perez & Viloria, 1994, from western Venezuela. A third troglobitc (cave-restricted) species of Ancistrus was recently found in flooded caves, the Formoso and Buraco do Ducho resurgences, located in the Bodoquena karstic region, Mato Grosso do Sul. Two specimens, both collected below depths of 25 m, were measured (30 measurements and counts usual for loricariid taxonomic studies) and compared to eyed Ancistrus from epigean sections of the same basins. The troglobitic armored catfishes from Bodoquena differ from the epigean ones by the absence of dark pigmentation (pink-yellowish in life, white when preserved) and reduced eyes, not visible externally, and also by shorter interorbital width, caudal peduncle width and depth, and body width. The degree of eyes and pigmentation regression in the new species is similar to that in A. galani, and more extreme than that in A. cryptophthalmus. The high degree of troglomorphism suggests that the species from Bodoquena is a specialized troglobite that has long been isolated in the subterranean habitat. The hypothesis of an ancient isolation in caves is corroborated by the co-occurrence of other highly troglomorphic species, such as spelaeogriphaceans, Potiicoara brasiliensis, amphipods and trichomycterid catfishes.

E.Trajano - Departamento de Zoologia, Inst.Biociências da USP, C.P. 11461, 05422-970 São Paulo SP, Brasil.

Allozyme and morphological divergence in naturalized populations of rainbow trout from Chile

Julio E. Crespo, Oscar Dmaz and Gonzalo Gajardo

Rainbow trout (Oncorhynchus mykiss) is a valuable salmonid species for commercial and recreational fisheries in Chile. However, current knowledge on biological aspects and populational structure are still scarce. In this study the allozyme and morphological variation in three naturalized populations from rivers located in two Andean lakes of southern Chile was studied in order to evaluate intra and interpopulational differences. Fishes were collected from rivers in two Andean lakes of southern Chile (Region X): Pilmaiquin (Puyehue Lake, 40:40'S, 72:37'W), Huillmn (Rupanco Lake, 4050'S, 7242'W) and Pescadero Grande (Rupanco Lake, 4044'S, 7227'W). Meristic and osteological counts as well as 18 morphometrical traits were recorded for uni and multivariate analysis. The same specimens were then subjected to electrophoresis. A total of 32 loci were successfully resolved: nine were polymorphic in Pilmaiquin, seven in Huillmn and five in Pescadero Grande. High heterozygosity values and proportion of polymorphic loci (H=0.060-0.082; 15.6-28.1%) were observed. Levels of genetic differentiation (Fst=0.052; Nei's D=0.001-0.005) ranked within those previously described for salmonids. Statistically significant differences were found for lateral scale counts, number of gill rakers, and rays in the dorsal, pectoral and anal fins. Principal components analysis discriminated the three populations based on head morphology, fin position and body shape. Results suggest local genetic and phenotypic differentiation of populations. Preliminary information provided will help in further characterization, management and conservation of these genetic resources.

Depto. Ciencias Basicas, Universidad de Los Lagos, P.O. Box 933, Osorno, CHILE. E-mail: Jcrespo@puyehue.di.ulagos.cl

Taxonomy and phylogenetic relationships of South American freshwater Sciaenidae (Perciformes, Percoidei)

Lilian Casatti

The fish family Sciaenidae (croakers or drums) is one of the most important families of Percoidei in number of described species, morphological diversity and broad geographical distribution. In South America, three genera - Pachypops, Pachyurus and Plagioscion - are restricted to freshwater and, despite of their fisheries importance, they never have been thoroughly revised. This ongoing research will include a taxonomic revision, a genus-level phylogenetic analysis and a biogeographical discussion. So far, I have examined morphometric and meristic data of 473 lots of South American freshwater Sciaenidae and, based on this sample, I was able to identify four species of Pachypops, seven of Pachyurus, at least five species of Plagioscion and an additional species of an undetermined genus. I have diagnosed all such species based on unique character traits. In-group and out-group specimens have been cleared and stained for a phylogenetic study. FAPESP nº 96/3286-5.

Laboratório de Ictiologia. Av. Bandeirantes, 3900, Dep. Biologia/FFCLRP-USP, 14040-901 Ribeirão Preto, SO, Brazil. Voice: (016) 602-3710; E-mail: licasatti@hotmail.com

Composition and similarity of the fish fauna of the Passo Fundo River drainage, Rio Grande do Sul, Brazil

Lisiane Hahn, Luis Fernando da Câmara and Janaina Bruschi

The Passo Fundo River drainage belongs to the hydrographic basin of the Uruguai River and is situated in northern Rio Grande do Sul, Brazil. The present study undertook a survey of the fish fauna in three tributary rivers: the Caraguatá, the Butiá and the Passo Fundo itself. Four sample stations were established in each river and four seasonal field expeditions were made for each station. We utilized a diversity of gears: gillnets, dipnets and seine nets. Up to now, 34 species were captured on the three rivers (27 species in Passo Fundo River, 14 species in Butiá River and 17 species in Caraguatá River). We applied the Jaccard similarity index to compare the fish fauna of these three rivers. The Caraguatá and Butiá rivers presented the highest similarity, 57.14%. The Passo Fundo River presented 32.25% similarity with the Butiá River and 33.33% with the Caraguatá River. The diversity index of the Caraguatá and Butiá rivers were 2,53082 and 2,51152 respectively. The most frequent species were Astyanax sp. "A" (18.66% in the Caraguatá River and 19.66% in the Butiá River) and Bryconamericus sp. (15.73% in the Caraguatá River and 28% in the Butiá River). To the present moment, the same species have been observed to be the most frequent in the Passo Fundo River. Financial support: ELETROSUL S/A, Universidade de Passo Fundo/ RS, FAPERGS and CNPq.

Universidade de Passo Fundo, BR 285 Campus Universitário, Passo Fundo, CEP 99100-000, RS/Brasil, E-mail: lihahn@pro.via-rs.com.br

Speciation of Odontesthes argentinensis (Atheriniformes: Atherinopsidae) in Patos Lagoon estuary, Brazil: the importance of population genetic structure assessment in classification and phylogeny of neotropical silversides

Luciano B. Beheregaray, Jose A. Levy and Germano Phonlor

Silversides are considered as a marine coastal group with an overall uniformity of life history strategies and a striking ability to invade and to speciate within freshwater niches. We report data from our studies into the two morphologically indistinguishable, but ecologically distinct, forms of the silverside Odontesthes argentinensis from southern Brazil. The first study is a genetic investigation from 23 allozyme gene loci, and reveals the existence of two populations: one homogeneously distributed in the marine zone from southern Brazil to Uruguay, the other restricted to the Patos Lagoon estuary. Marine and estuarine populations show remarkable genetic heterogeneity, different heterozygosities, and a time of lineage separation broadly consistent with the estimate of geological formation of the estuary. Results support the hypothesis that the estuarine population was established by a founder effect in the estuary with subsequent population bottlenecks. The second study describes in detail the early ontogeny, from fertilisation to larval metamorphosis, and registers noteworthy differences in the eggs and larvae of the two populations. The genetic divergence and the unique early ontogeny of the estuarine population show that, at very least, a speciation process is taking place in the Patos Lagoon estuary. Cladogenetic splitting of lineages in coastal environments is of central interest in elucidating phylogenetic relationships of Neotropical silversides. Therefore, it is proposed here that studies on Neotropical silversides that aim to present consistent classifications and evolutionary hypotheses should try to interpret the population genetic structure of the species examined and the possible influences of history in shaping that structure. Financial institutions: CNPq and FAPERGS.

School of Biological Sciences, Macquarie University, 2109, NSW, Australia. E-mail: lbehereg@rna.bio.mq.edu.au

Reproductive biology of Platanicthys platana (Regan, 1917) (Teleostei, Clupeidae) in the canal Cornélios, Terra de Areia, Rio Grande Do Sul, Brazil

Luís Fernando dos Reis Guterres, Nelson Ferreira Fontoura and Patrícia Macedo de Castro-Guterres

The reproduction biology of the pisces Platanicthys platana was studied in the Canal Cornélios, Terra de Areia, Rio Grande do Sul, Brazil, through bimonthly samples taken from July 1995 to June 1996.The animals were captured using a seine net 15m long,3m high and 5mm of mesh size. In laboratory, the specimens were measured, weighted and the gonads were analyzed for identification of sex and maturation stage.Were caught total 1088 specimens, 211 males, 418 females (129 females for identification of mature stage) and 459 juveniles.The reproductive period begins on Setember ending in December, with a greater reproduction activity in October. The gonadosomatic index suggest that the reproductive period occurs in October too. The sex-ration was 0,5 males to 1 female. The reproductive females measured from 5,26cm to 9,22cm. The size at the first maturation was 7,00cm. A sample of 33 females of maturation stage showed size mead 8,11cm and fecundity mead 2.486 eggs. The fecundity/width relationship was described by the following equation: F = 984,54.W0,55. Where F is the eggs number.(CAPES/CNPq)

Laboratório de Dinâmica Populacional Instituto de Biociências Bloco C Pontifícia Universidade Católica do Rio Grande do Sul - Av. Ipiranga, 6681 C.P. 1429 90619-900 Porto Alegre RS Brasil

Morphological phylogenetic evidence on infraorder Gymnotia (Gymnotiformes: Ostariophysi).

Mauro L. Triques

The infraorder Gymnotia was erected to include the gymnotiform Neotropical freshwater electric fishes belonging to the families Gymnotidae, Electrophoridae, Hypopomidae and Rhamphichthyidae, based on out-group comparison method of phylogenetic systematics. Recent criticism of this hypothesis based on the same method presented Gymnotidae + Electrophoridae as the sister group of Apteronotidae, Sternopygidae, Hypopomidae and Rhamphichthyidae. The last four families were included in the Sternopygoidea, suggesting that Gymnotia is not a monophyletic group. An assessment of the hypotheses erecting and dismembering Gymnotia is presented herein, based on the same method. New synapomorphies together with other already presented by previous authors indicate that Gymnotia should not be discarded. Synapomorphies of Gymnotia are (1) anterior nostril very close to or on the upper lip, (2) presence of multiple oblique, pale bands along lateral surface of body (except for Electrophorus); (3) presence of an antero-dorsal depression on the basi-hial (except for Gymnorhamphichthys); (4) presence of P and T electrorreceptors and (5) absence of anal fin distal radials. Evidence on Sternopygoidea is commented and in part discarded. Financial support was obtained from FAPESP and CNPq.

DZ - ICB - UFMG Caixa Postal 486, Av. Antonio Carlos no. 6627. CEP 31270-901. Belo Horizonte - MG - Brazil. FAX (031) 448-1236

On the monophyly of Gymnotus Linnaeus, 1758 (Gmnotiformes: Otariophysi)

Mauro L. Triques

The Neotropical freshwater genus Gymnotus includes species ranging from Southern Mexico to Orinoco, Amazon, Parana-Paraguay Basins, Guyanensis Shield and Eastern and Northeastern Brazilian Basins. Gymnotus is the sister group of Electrophorus, the large South American freshwater electric eel. Out-group comparison method of phylogenetic systematics was applied to external morphology features. Studied specimens of Gymnotus include material from Suriname, Venezuela, Rio Uruguai, Rio São Francisco, Rio Tocantins, Rio Negro and streams delivering to Atlantic Ocean in São Paulo State, Brazil. Monophyly of the genus is corroborated by five new synapomorphies: (1) strong lateral depression of snout around the anterior nares; (2) anterior tubular nostril curved upward; (3) eyes low in the head, the inferior eye margin on a horizontal imaginary line passing by the mouth corner; (4) mouth corner downward directed and (5) lower jaw strongly prognathous. In out-groups, including Electrophorus and most gymnotiform genera, the region nearby the anterior nostril is not conspicuously depressed; the anterior tubular nostril is straight; the eyes are placed above the horizontal passing the mouth corner; the mouth corner is straight or upward directed except for Adontosternarchus species, deeply nested in Apteronotidae and the mouth is never strongly prognathous, except for Magosternarchus duccis, deeply nested in Apteronotidae. Sponsor organs: FAPESP and CNPq.

DZ - ICB - UFMG Caixa Postal 486. Av. Antonio Carlos, 6627. CEP 31270-901 Belo Horizonte - MG, Brazil. FAX (031) 448-1236.

The genus Rineloricaria (Siluriformes, Loricariidae) in the upper Uruguay River: high diversity in a small area

Miriam Sant'Anna Ghazzi

Rineloricaria, with about 60 species, is a widespread genus, distributed from Panama to the La Plata basin in South America. In Rio Grande do Sul, the species R. cadeae, R. strigilata and R. longicauda are assigned to the laguna dos Patos drainage and R. quadrensis is assigned to the rio Tramandaí drainage. R. microlepidogaster was described from Rio Grande do Sul State without, however, stating any type-locality. This species is presently restricted to the laguna dos Patos drainage. R. felipponei, R. pareiacantha, R. thrissoceps were described from the Río Santa Lucia, a coastal streams of southern Uruguay. The main objective of this study is to undertake a revision of Rineloricaria in the upper rio Uruguay drainage, identifying the geographic distribuition of species and suggesting characters for phylogenetic studies. In the present work, 876 specimens were morphologically analyzed, and no character exclusive of Rineloricaria were found, but the combination of a set of characters allows its distinction from the remaining Loricariinae: males with dense bristles at edges of head and dorsum of pectoral fins; lips covered by papillae and with fringed margin; short rictal barbel; bilobed teeth, outer cusp being smaller than inner. This revision shows that none of the species known in Rio Grande do Sul State, Río de La Plata system and Republic of Uruguay occur in the upper rio Uruguay. Ten new species are described from the rivers Pelotas, Passo Fundo, Buricá, Ijuí, Alegre, Piratini and Uruguay at Iraí. The upper rio Uruguay shows high diversity of species of Rineloricaria, when compared to other drainages in the Brazilian Shield. Financed by CNPq.

Museu de Ciências e Tecnologia - PUCRS. Av. Ipiranga, 6681, P.O. Box 1429. 90619-900. Porto Alegre, RS, Brasil. E-mail: ghazzi@music.pucrs.br

Project Piaba - towards a sustainable ornamental fishery in the Rio Negro basin

Ning Labbish Chao, Paulo Petry, Maria Lucia Goés Araújo, Evaldete Ferraz de Oliveira Randall, Gregory Prang, José A. Alves-Gomes and Richard C. Vogt

Fishes and aquatic environments are often not included in long-term conservation and sustainable development projects in Amazonia, yet the diversity of fishes (>2,000 species) and the socio-economic value of the fisheries and the aquatic habitats have a great importance for the region. Fishes are not only the principal source of protein for rural Amazonian, many are also traded as ornamental fishes in a worldwide market. The middle Rio Negro basin is one of the major fishing grounds for live ornamental aquarium fish. Nearly 20 million live fishes are exported from the region annually, generating about US$ 2,000,000 annually for the local economy. The trade in ornamental fish now contributes over 60% of the income revenue in the municipality of Barcelos (population 12,000; area 122,490 km2). Unpredictable fluctuations in fish production, mortality rate and market demand are the main constraints on the fishers' subsistence. At times, when incomes from ornamental fishing are reduced, some fishers intensify swidden and hunting foraging activities (e.g. turtle poaching), while others migrate to urban areas hoping to find "modern" employment. Fortunately, the annually inundated, flooded forest habitats of the mid-Rio Negro basin have remained largely intact. Many forest fishes have a short life cycle (1-2 years), and fish populations can be quickly replenished. Ornamental fishery can be an alternative resource for the subsistence of local community and greatly reduce the risk of deforestation and other environmentally destructive activities. Our goal is to promote an ecological sustainable as well as an economically viable fishery in the region. Objectives of our on going efforts are: (1) To collect baseline data on the ecosystem, fish diversity, fishing efforts and socio-economy, and to analyze the impact of the ornamental fish and turtle trades on social and natural environments. (2) To diagnose diseases and introduce fish care techniques, to improve the survival and quality of fishes and turtles explored by the ornamental fish industry. (3) To provide environmental education to local fishers, distributors and public, and to encourage career development of local students in aquatic conservation. (4) To participate in the policy making processes of regulatory agencies in order to protect vulnerable species and maintain the economic viability of local fishery. The purpose of this poster is to inform and seek collaborators for the Project. Immediately, we need help to identify fish and to recommend a clean list of ornamental fish that can be legally traded to the Brazilian environmental agency, IBAMA

Cytogenetic and phylogeny of Characiformes with emphasis in Anostomidae, Chilodontidae, Curimatidae, Prochilodontidae, Hemiodontidae and Parodontidae.

Paulo C. Venere and Pedro M. Galetti Junior

Anostomidae, Chilodontidae, Prochilodontidae and Curimatidae has been considered a monophyletic unit among Characiformes. Several morphological studies have shown closer relationship between and within these groups than any other family of the order. Other Characiformes, morphologically similar to this clade, i.e. Anodontinae, had already been included among Curimatidae members, and nowadays are placed in Hemiodontidae. Therefore, this situation is still unclear, and, at this point, the cytogenetic may provide important information. In the present paper, karyotypes of several Anostomidae, Chilodontidae, Curimatidae, Prochilodontidae and Hemiodontidae species were analyzed. The results showed a very similar karyotype macrostructure in all species of the first four families, confirming previous data. A common karyotype showing 54 chromosomes, preferentially of Meta-(M) and Submetacentrics (SM) might support the hypothesis of monophyletism for this group. However, Hemiodontidae species also showed 2n=54 with predominance of M and SM chromosomes, although Subtelo-(ST) and Acrocentric (A) chromosomes were also identified in this group. Parodontidae seems to share this characteristic with hemiodontids. The presence of ST-A chromosomes in some Curimatidae species probably represents an isolated event. Other than these already commented groups, Colossoma and Piaractus, are the unique characiform groups which show a similar karyotype pattern (2n=54M-SM). Thus, the results suggest two possibilities: (i) 2n=54 Meta- and Submetacentric chromosomes represent a basal characteristic that could relate Colossoma and Piaractus to the families above discussed, or (ii) it is an homoplasic feature and evolved at least twice among these Characiformes. Financial support: CNPq.

Universidade Federal de São Carlos, Depto. de Genética e Evolução, Laboratório de Citogenética, 13.565-905 - São Carlos/SP, Brasil. E-mail: pcesar@iris.ufscar.br

Structure and development of the urohyal in Gymnotiformes (Teleostei: Ostariophysi)

Ricardo Campos-da-Paz

Overall structure and development of the urohyal in representative members belonging to the order Gymnotiformes are described, and a brief discussion on the relevant features noted concerning this bone in examined material is also provided on the basis of phylogenetic schemes recently made available for the group. While early ontogenetic stages of the urohyal development in gymnotiforms resemble those of characiforms usually pointed out as primitive taxa (e.g., Xenocharax), the adult condition varies among several gymnotiform genera. The presence of an antero-median foramen in the urohyal is a feature shared by both adult members of the Gymnotiformes and Siluriformes, although it is recognized that it arises from different developmental pathways in each group. The urohyal of some species belonging to the family Apteronotidae exhibits unique features within the gymnotiform clade. This work was partially funded by the Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP).

Laboratório de Ictiologia Geral e Aplicada (LIGA), Departamento de Zoologia, Instituto de Biologia/CCS (Bloco A), Universidade Federal do Rio de Janeiro, Ilha do Fundão - Rio de Janeiro - RJ, 21941-590, Brasil.

Cytotaxonomyc diagnosis and phylogenetic relationship of probable four species of the genus Trichomycterus (Siluriformes, Trichomycteridae) from Tietê and Paranapanema River basins, southeastern Brazil.

Rodrigo A. Torres, Fausto Foresti and Cláudio Oliveira

Since 1986 probable five new species of the genus Trichomycterus are identified in the Cuesta of Botucatu. Four of them were studied cytogenetically with the objective of adjust chromosomic features to the phylogenetic metodology, to understand the relationship between the cytotypes of the species and also to purpose a pool of new characters for evolutive studies in fishes. Therefore, cytotaxonomic analysis were performed in specimens of Trichomycterus sp. A from Pardo river (tributary of Paranapanema river left banks), of Trichomycterus sp. C from Capivara river (tributary of Tiete river left banks), of Trichomycterus sp. D from Jacutinga stream (tributary of Tiete river left banks) and Trichomycterus sp. E from Quinta stream (tributary of Paranapanema river left banks) utilizing Trichogenes longipinnis as the outgroup. Somatic methaphases were obtained by kidney cells suspension technique and the methodology for constructing the cladogram was the Hennig 86 program, across the Treegardner sub-program. The used chromosomic markers for the construction of the polarization matrix were the chromossomic number, the number of metacentric, submetacentric and subtelocentric pairs, the NOR position, the chromosome type with the NOR, the position of heterochromatic band in each chromosome pair and its occurrence in the nucleolar organizer region. The polarization of these characters resulted in a cluster where Trichomycterus sp. A is more related to Trichogenes longipinnis and thus would be the sister-species to the others species here studied, which ones would constitute another cluster without inherent levels of chromosomic evolution by the phylogenetic view. Financial Institutions: CAPES and FAPESP

FF & CO. UNESP, Departament of Morphology, District of Rubião Jr., 18618-000 Botucatu (SP) Brazil

Allozyme variation and genetic relationships within the genus Ancistrus (Siluriformes, Loricariidae).

Sonia Muller

Species boundaries and phylogenetic relationships between populations of the genus Ancistrus were studied with allozyme electrophoresis. Allozyme variation was examined for a total of 340 specimens of Ancistrus from 33 locations, belonging to 14 putative species. One species was represented by numerous close populations in order to examine intraspecific variation. Additionally, samples of Ancistrinae species belonging to other generera were examined for outgroup comparison. Protein electrophoresis was performed with a Pharmacia Phastsystem; the gels were stained for seven enzymatic systems. All of the 10 presumptive loci analysed are polyallelic. Percentage of polymorphic loci and average heterozygosity is highly variable among populations within a single species. Fixed allelic differences among two Paragayan sympatric populations reveal their reproductive isolation and prove the taxonomic rank of species hardly discernable by morphology. An analysis of the genetic distances between allopatric populations in relation to the species boundaries is presented. Using phenetic and cladistic methods, hypothesis of phylogenetic relationships are given and compared to the phylogenetic tree obtained by J.-I. Montoya-Burgos with mitochondrial 12S and 16S rRNA gene sequences on part of the same material. This work was supported by the Swiss National Science Foundation (No 31-9443.88).

Museum of Natural History, Department of Herpetology and Ichthyology, case postale 6434, CH-1211 Geneva 6, Switzerland. E-mail: sonia.muller@mhn.ville-ge.ch

The phylogenetic relationships of the catfish genera of the sorubiminae subfamily (Siluriformes, Pimelodidae).

Tatiana X. Abreu

The subfamily Sorubiminae, as it is recognized in this work, consists of ten genera: Brachyplatystoma; Goslinia; Hemisorubim; Merodontotus; Platynematichthys; Pseusoplatystoma; Sorubim; Sorubimichthys; Steindachneridion and Zungaro; and it is distributed in the basins of the Amazon river, the Orinoco river, Magdalena river, the Paraná-Paraguai rivers, in the basins of Eastern Brazil and in that of the São Francisco river. There is a high level of overlapping in the areas where these genera occur. Since no synapomorphies supporting the monophyletism of Sorubiminae have been presented up to this moment and since the phylogenetic relationships among its genera are not known, a general-level phylogenetic study of this subfamily is being carried out with basis on the osteologic characters. Cleared and stained or dry skeleton, representative specimens of the type species of the ten recognized genera of Sorubibiminae were prepared for the study: Brachyplatystoma vaillanti; Goslinia platynema; Pseudoplatystoma fasciatum; Sorubim lima; Hemisorubim platyrhynchos; Steindachneridion amblyura; Platynematichthys notatus; Merodontotus tigrinus; Sorubimichthys spatula e Zungaro zungaro. Besides, 14 additional specimens from the following genera have been cleared and stained as well as dissected up to the moment in order to be used as extra group: Genidens; Phractocephalus; Leiarius; Megalonema; Calophysus; Duopalatinus; Pimelodus; Platystomatichthys e Exalodontus. The hyphothesis on the inter-generic phylogenetic relationships will be expressed in the form of a cladogram. The osteologic characters analyzed will also be used to diagnose and limit taxonomically the groups recognized as valid. Receiving a MSc grant from FAPESP Process no. 95/9589-7.

Laboratório de Ictiologia, Departamento de Biologia da FFCLRP-USP. Av. Bandeirantes, 3900 Ribeirão Preto, SP, Brazil 14040-901, FAX (016) 633-5015, Telefone (016) 633-1010 ramal 352, E-mail: xando@usp.br

Relative frequency distribution of total length of Astyanax bimaculatus, Astyanax fasciatus (Characidae) and Parapimelodus nigribarbis (Pimelodidae) in the Guaíba Lake, Rio Grande do Sul, Brazil

Vinicius de Araújo Bertaco

From November/1995 to October/1996 beach seine and gill net samples were made in six stations in the Guaíba Lake - Saco da Alemoa, Ponta da Cadeia, Foz do arroio Celupa, Praia da Alegria, Ponta da Figueira and Barra do Ribeiro -, Rio Grande do Sul, Brazil. The relative frequency distribution of both the total length of specimens and the number of individuals were analysed in relation to seasonality and sampling stations in three species considered constant in the community. Data on relative abundance and biomass are also provided. Astyanax bimaculatus was numerically more representative at Ponta da Cadeia and Ponta da Figueira. During the late fall and winter individuals of that species were rare or absent at all sampling stations. The smallest specimens were collected during summer (January and February), except at Saco da Alemoa where they were registered during late summer and early fall (March and April). Astyanax fasciatus was numerically more representative at Saco da Alemoa and Ponta da Cadeia. Concerning total length the distribution was uniform in all sampling stations, except for Saco da Alemoa, where there were more smaller specimens. Parapimelodus nigribarbis was numerically more representative during the summer at Foz do arroio Celupa. During the whole sampling period, individuals of that species were rare or absent at Ponta da Cadeia. In the other stations they were rare or absent mainly during the winter. Specimens of Parapimelodus nigribarbis were captured mainly with gill nets. Individuals smaller than 95 mm of total length were unusual in the sampling. Grant research - undergraduate of PUCRS.

Museu de Ciências e Tecnologia da PUCRS, Av. Ipiranga 6681 - Caixa Postal 1429, 90619-900, Porto Alegre, RS, Brasil.

Behavioral characters of Gymnogeophagus species (Perciformes: Cichlidae) and their phylogenetic content.

Walter L. A. Santos and Roberto E. Reis

Behavioral characters have been employed in an increasing number of papers dealing with phylogenetic reconstructions. The present study aims to record sequences of recognizable movements that are unique to all species or to groups of species of Gymnogeophagus and study their phylogenetic information content. The various behavior patterns were described, sketched and video recorded during the past sixteen months for Gymnogeophagus balzanii, G. rhabdotus, G. gymnogenys, G. labiatus, and two undescribed species. Additionally, Geophagus brasiliensis, Cichlasoma portalegrensis, and Papiliochromis ramirezi are being studied as outgroups. Some of the features under study are: (1) a especial display preceding aggression movements by territorial individuals, which is likely to represent a multistate character corroborating the phylogeny of Reis & Malabarba and providing information of the two new species; (2) the appearance of a lateral longitudinal dark stripe in territorial females, grouping G. gymnogenys, G. labiatus and the two new species, and distinguishing them from the remaining Gymnogeophagus and outgroup species; and (3) a less intense transportation of bottom gravel by most of the species is also a possible behavioral synapomorphy for Gymnogeophagus species except G. balzanii. Some species are still under investigation and other behavioral patterns potentially informative phylogenetically are being studied. This project is funded by PICD, CAPES.

Laboratório de Etologia, Depto. ECZ, CCB, UFSC; Caixa Postal 476; 88010-970, Trindade, Florianópolis, Brazil. E-mail: walters@ccb.ufsc.br

A revision of the trichomycterid genus Homodiaetus Eigenmann & Ward, 1907 (Teleostei: Siluriformes)

Walter Rudolf Koch

The genus Homodiaetus Eigenmann & Ward, 1907 is revised and four species are recognized. Its distribution is restricted to southeastern South America, from Uruguay to Paraguay river at west to the coastal drainages of Rio de Janeiro State, Brazil. The genus Homodiaetus is currently distinguished from the other stegophilinae by the combination of the following characters: origin of ventral fin at midlength between the snout tip and the caudal-fin origin; opercle with at least three odontodes; gill membranes confluent with the isthmus. The monophyly of the genus, as well as its interrelationships, could not be evaluated, and will be unraveled when a thorough phylogenetic revision of the subfamily be done. Four species were recognized: H. anisitsi Eigenmann & Ward, 1907, diagnosed by the caudal fin with black middle rays, margin of upper and lower procurrent caudal-fin rays with dark stripes extending to the caudal fin, and 3-6 opercular odontodes; H. passarellii (Ribeiro, 1944) with 6-7 opercular odontodes, 21-24 lower procurrent caudal-fin rays and 23-26 upper procurrent caudal-fin rays; Homodiaetus sp. A with 9 opercular odontodes, 17-19 lower procurrent caudal-fin rays, 17-22 upper procurrent caudal-fin rays, reduction of fourth pharyngobranchial with only three teeth and untoothed fifth ceratobranchial; and Homodiaetus sp. B with 5-6 dentary rows, 7-9 opercular odontodes and 16-23 upper procurrent caudal-fin rays. This study was partially supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

Laboratório de Ictiologia; Museu de Ciências e Tecnologia PUCRS; Av. Ipiranga, 6681; Caixa Postal 1429; 90619-900, Porto Alegre, RS, Brazil. E-mail: Koch@music.pucrs.br

Two new species of Phenacogaster Eigenmann, 1907 and comments on its nominal species (Characiformes)

Zilda Margarete S. de Lucena

Two new species are described in the genus Phenacogaster: one from Suriname and one from the Orinoco River drainage, Negro River and Casiquiare Channel. Each species is distinguished on basis of meristic and morphometric data, presence of humeral spot and hooks on branched rays of pelvic fins of males. The genus is widely distributed, occurring from the Orinoco system to the Paraguay River basin, including rivers in northeastern Brazil. Ten nominal species have been previously referred to Phenacogaster: P. pectinatus (Ampiyacu River drainage, Pebas); P. tabatingae and P.bairdii (Tabatinga, Amazon drainage) both synonyms of P. pectinatus; P. megalostictus and P. microstictus (lower Potaro River, Tumatumari, Guiana); P. franciscoensis (Boqueirão, São Francisco River drainage), P. beni ( Beni River), P. jancupa (Espinheiro Creek, upper Paraguay River); P. tegatus (upper Paraguay basin), P. calverti (Fortaleza, Ceará, eastern Brazil); P. suborbitalis (type locality not precise, eastern coast of Brazil). Comments on the nominal species are provided.

Museu de Ciências e Tecnologia, PUCRS. Av. Ipiranga 6681; Caixa Postal 1429. 90619-900, Porto Alegre, RS, Brazil. Email margarete@music.pucrs.br