A new genus and two new species of Stevardiinae (Characiformes: Characidae) with a hypothesis on their relationships based on morphological and histological data

Abstract

Lepidocharax, new genus, and Lepidocharax diamantina and L. burnsi new species from eastern Brazil are described herein. Lepidocharax is considered a monophyletic genus of the Stevardiinae and can be distinguished from the other members of this subfamily except Planaltina, Pseudocorynopoma, and Xenurobrycon by having the dorsal-fin origin vertically aligned with the anal-fin origin, vs. dorsal fin origin anterior or posterior to anal-fin origin. Additionally the new genus can be distinguished from those three genera by not having the scales extending over the ventral caudal-fin lobe modified to form the dorsal border of the pheromone pouch organ or to represent a pouch scale in sexually mature males. In this paper, we describe these two recently discovered species and the ultrastructure of their spermatozoa.O trabalho contém a descrição de um gênero novo, Lepidocharax, e duas espécies novas, Lepidocharax diamantina e L. burnsi do leste do Brasil. Lepidocharax é considerado um gênero monofilético de Stevardiinae e pode ser diferenciado dos outros membros desta subfamília, exceto Planaltina, Pseudocorynopoma e Xenurobrycon principalmente porque as duas espécies nele incluídas têm a origem da nadadeira dorsal verticalmente alinhada com a origem da nadadeira anal, vs. origem da nadadeira dorsal anterior ou posterior a origem da nadadeira anal. Adicionalmente, o novo gênero pode ser distinguido dos mesmos três gêneros por não possuir escamas modificadas localizadas no lobo ventral da nadadeira caudal, formando a borda dorsal do órgão produtor de feromônio ou uma escama modificada do mesmo órgão em machos sexualmente maduros. A ultraestrutura dos espermatozóides das duas espécies recentemente descobertas também é descrita.

A new species of Bryconamericus (Characidae: Stevardiinae: Diapomini) from the upper rio Paraná basin, Brazil

“…teeth in outer tooth series larger than teeth in inner series in Attonitus Ortega, 2000 andCeratobranchia Eigenmann, 1914); few maxillary teeth 10 e170028 [10] restricted to anterior portion of the maxilla (vs. teeth along the greater part or along the entire margin of the maxilla in Acrobrycon Pearson, 1924 andHemibrycon Günther, 1864); dentary teeth perpendicular to main axis of the dentary (except in B. leptorhynchus, B. maromba, and B. poi, vs. dentary teeth anteriorly directed in Attonitus, Ceratobranchia, and Rhinobrycon Myers, 1944), lateral line scales pored (lateral line scales incompletely pored in Bryconacidnus Myers, 1929); caudal fin scaleless (vs. caudal fin with scales of different sizes and arrangements in Xenurobryconini, Glandulocaudini, Stevardiini, Argopleura Eigenmann, 1913, Diapoma Cope, 1894, Knodus Eigenmann, 1911, andMarkiana Eigenmann, 1903); dorsal-fin origin anterior to vertical through anal-fin origin (vs. dorsal-fin origin at same vertical or posterior to vertical through anal-fin origin in Lepidocharax Ferreira, Menezes &Quagio-Grassiotto, 2011, andPiabarchus Myers, 1928 (in part)); and pelvic-fin rays i, 7 (vs. i,8 in Eretmobrycon Fink, 1976, i,6 in Diapoma (in part), and ii,5 rays in Carlastyanax Géry, 1972).…”

Biogeography of freshwater fishes from the Northeastern Mata Atlântica freshwater ecoregion: distribution, endemism, and area relationships

“…The basal and recently described Stevardiinae genus Lepidocharax includes only two species: L. burnsi (endemic to the tributaries of the upper rio São Francisco and Rio Doce basins) and L. diamantina (endemic to the rio Paraguaçu basin; Ferreira et al, 2011). For further information on the remaining examples of "Pattern B" taxa, see Ribeiro (2006: 236-238).…”

Chrysobrycon yoliae, a new species of stevardiin (Characiformes: Characidae) from the Ucayali basin, Peru

“…This is the only character supporting the position of Chrysobrycon within the tribe. The phylogeny and classification of the Xenurobryconini proposed by Weitzman & Menezes (1998) has been maintained in subsequent and related phylogenetic analyses mainly based on morphology (e.g., Castro et al, 2003;Mirande, 2010;Ferreira et al, 2011). Weitzman et al (2005) considered that the origin of the pouch scale within the Xenurobryconini is homologous with that of the group named Stevardiini by Menezes & Weitzman (2009).…”