Henrique Lazzarotto

A new glanapterygine catfish of the genus Listrura (Siluriformes: Trichomycteridae) from southeastern Brazil, corroborated by morphological and molecular data

Listrura costai, new species, is described from small streams in a swampy coastal plain in the rio Jurumirim basin, Angra dos Reis Municipality, Rio de Janeiro State, southeastern Brazil. The new species is morphologically very similar to L. nematopteryx and L. picinguabae, all possessing only one long pectoral-fin ray. It differs from its congeners by possessing an autapomorphic character: first hypobranchial with an anterior process (vs. process absent). Other features such as coloration, numbers of opercular and interopercular odontodes, number of anal-fin rays, head length, and shape of some bone structures help to distinguish the new species from L. nematopteryx and L. picinguabae. Molecular analyses using partial sequences of the mitochondrial DNA genes cytochrome oxidase c subunit 1 and cytochrome b from the new species and morphologically similar species are provided. The results about both molecular markers corroborate the validity of the new species by significant genetic distance values between it and congeneric species, and by its phylogenetic position in the hypotheses performed by maximum-parsimony method.

Parotocinclus halbothi, a new species of small armored catfish (Loricariidae: Hypoptopomatinae), from the Trombetas and Marowijne River basins, in Brazil and Suriname

Parotocinclus halbothiis described as a new species from the Trombetas and Marowijne river basins, in Brazil and Suriname. The new species is distinguished from its congeners in the Guianas, Orinoco, and Amazon basins by details of color pattern, form and arrangement of bony plates, body shape, and morphometric features. It is distinguished from all other species of Parotocinclusby the elongation of the canal cheek plate on the ventral surface of head posteriorly to contact the cleithrum. The new species is differentiated from Parotocinclus collinsae, the most similar species in terms of color pattern, by the small, circular, median abdominal plates, the poorly developed preanal shield with two or three plates, and by having the adipose fin rudimentary. This new species is one of the smallest loricariid catfishes known to date.

Morphological variation among populations of Hemigrammus coeruleus (Characiformes: Characidae) in a Negro River tributary, Brazilian Amazon

We explored patterns of phenotypic variation in Hemigrammus coeruleus from the Unini River basin, a blackwater river in the Brazilian Amazon. Geometric morphometrics was used to evaluate variation in body shape among populations from four tributaries (UN2-UN5). We found no evidence for sexual dimorphism in body size and shape. However, morphological differences among populations were detected as the analyses recovered significant groups corresponding to each sub-basin, with some overlap among them. The populations from UN2, UN3 and UN5 had more elongate bodies than fish from UN4. The most morphologically divergent population belonged to UN4, the tributary with the most divergent environmental conditions and the only one with seasonally-muddy waters. The morphological variation found among these populations is likely due to phenotypic plasticity or local adaptation, arising as a product of divergent ecological selection pressures among sub-basins. This work constitutes one of the first to employ a population-level geometric morphometric approach to assess phenotypic variation in Amazonian fishes. This method was able to distinguish subtle differences in body morphology, and its use with additional species can bring novel perspectives on the evaluation of general patterns of phenotypic differentiation in the Amazon.

Life-history features of a rapids-dwelling loricariid catfish from Atlantic forest streams, Brazil

Spatial distribution, suitable spawning sites, and sexual dimorphism were investigated in armored catfish Neoplecostomus microps in the Macae River from March 2004 to March 2005. Individuals of N. microps (n=290) were limited to fast-flowing stretches, and the distribution was related to ontogenetic development. Larvae in post-flexion occurred in the marginal vegetation, and adults only in gaps between boulders and stones in the river channel. Juveniles occurred in both environments. Spawns were found in the natural habitat in rapid stretches, with the eggs attached to the lower surface of stones in openings formed in the riverbed. The number of eggs per stone ranged from 62 to 375, with significant differences among the mean sizes of the eggs. Sexual dimorphism was noticed to N. microps. The anal and urogenital papillae are separated in males and merged in females and there is an epidermal growth along the pectoral-fin spine of males.

A new Centromochlus Kner, 1858 (Siluriformes: Auchenipteridae: Centromochlinae) from the transition between Amazon floodplain and Guiana shield, Brazil

Especies de Centromochlus tem ampla distribuicao pela America do Sul, com registros para as principais bacias como o Amazonas e Orinoco, rios com drenagens no Escudo das Guianas como Essequibo, Corentyne, Copename, Maroni e Oiapoque, e ainda pelas drenagens do Escudo Brasileiro como Alto Parana e Sao Francisco. Nos ultimos quatro anos foram descritas tres especies de Centromochlus elevando o numero de especies validas para dezesseis. A nova especie de Centromochlus aqui descrita e diagnosticada pela presenca de dorso escuro abruptamente separado de um ventre branco por uma barra ondulada conspicua. A nova especie foi descoberta no rio Nhamunda um igarape de agua clara do baixo Amazonas com rede de drenagem a partir da porcao brasileira do Escudo das Guianas. Apesar de aparentemente similar a algumas especies de Tatia (e.g. Tatia musaica , T. carolae e T. melanoleuca ), individuos da nova especie apresentam uma morfologia particular do aparelho de Weber ate entao reportadas apenas para C. heckelii e C. existimatus , entre os bagres centromoclineos, e que merecem maiores discussoes. O novo Centromochlus inclui pequenos bagres com adultos entre 48 e 57 mm CP.

A new species of the catfish Neoplecostomus (Loricariidae: Neoplecostominae) from a coastal drainage in southeastern Brazil

A new species of loricariid catfish is described from the rio Pereque-Acu and surrounding basins, Parati, Rio de Janeiro State. The new species has the accessory process of ceratobranchial 1 more slender than the main body of the ceratobranchial, and a very large sesamoid ossification, markedly greater in size than the interhyal. Additionally, the new species presents a distinct dorsal color pattern consisting of a conspicuous horseshoe shaped light blotch with a central dark area posterior to the supraoccipital.

New distribution record for the threatened armoured suckermouth catfish Pareiorhaphis garbei (Ihering, 1911) (Siluriformes: Loricariidae) in São João river basin, Rio de Janeiro, southeastern Brazil

The present study records the first occurrence of the threatened armoured suckermouth catfish Pareiorhaphis garbei (Ihering, 1911) in Sao Joao river basin and also its presence in four conservation units in the coastal basins of Serra dos Orgaos mountains, Rio de Janeiro state, Brazil. In Sao Joao river basin, P. garbei was only captured in a single locality at 111 m a.s.l., consisting in the lower registered altitude for the species, previously found in high altitudes, usually above 800m.

A New Species of Scoloplax with a Remarkable New Tooth Morphology within Loricarioidea (Siluriformes: Scoloplacidae)

A new species of Scoloplax is described with a remarkable new tooth morphology, possessing dentary teeth with four cusps and premaxillary teeth with two to four cusps, features unique among all Loricarioidea and rare among Siluriformes. Scoloplax baileyi, new species, is further distinguished by eight diagnostic features. The new species is found in the small tributaries of Rio Unini, an important tributary to the Rio Negro, and in the Anavilhanas Archipelago, lower Rio Negro, Amazonas State, Brazil. Based on a review of scoloplacids, a new record of S. baskini is given to include the Rio Negro, increasing the number of species of Scoloplax from that basin to four.