New species of thorny catfish, genus Leptodoras Boulenger (Siluriformes: Doradidae), from Tapajós and Xingu basins, Brazil

Abstract

A new species of thorny catfish (family Doradidae) is described as a member of genus Leptodoras Boulenger by having a modified oral hood and first gill arch with enlarged accessory lamellae extending well onto medial face of gill filaments. The new species is distinguished by three characteristics unique within Leptodoras: gas bladder moderately sized (not reduced) with simple walls (diverticula absent), and paired bony capsules on anteriormost vertebrae reduced to paired cup-like laminar ossifications separated by triangular septum. The new species was discovered from material recently collected in the Tapajós basin at Serra do Cachimbo and in the headwaters of rio Xingu. The species description is supplemented by a detailed osteological description, discussion on its placement among congeners, and a re-evaluation of the diagnosis of Leptodoras and its relationships with sister taxon Anduzedoras oxyrhynchus. In addition, the distributions of several species of Leptodoras are expanded based on recent collecting efforts and identification of museum specimens not previously studied.Uma nova espécie de botoado da família Doradidae é descrita. A nova espécie é incluída no gênero Leptodoras Boulenger por possuir capuz oral modificado e primeiro arco branquial com lamelas acessórias bem desenvolvidas estendidas sobre a face medial dos filamentos branquiais. A nova espécie distingue-se dentre Leptodoras por três características únicas: bexiga natatória de tamanho moderado (não reduzida), com paredes simples (sem divertículos), e cápsulas ósseas pares sobre as vértebras anteriores reduzidas a um par de ossificações laminares em formato de cuia separadas por septo triangular. A nova espécie foi descoberta a partir do material coletado na bacia do rio Tapajós na Serra do Cachimbo e nas cabeceiras do rio Xingu. A descrição da espécie é suplementada por uma descrição osteológica detalhada, discussão sobre o seu posicionamento dentre os congêneres, re-avaliação da diagnose de Leptodoras e sua relação com o táxon irmão Anduzedoras oxyrhynchus. Além disso, a distribuição de diversas espécies de Leptodoras é revisada com base nos recentes esforços de coleta e na identificação de espécimes de museus não previamente estudados.

New Species of the Thorny Catfish Genus Leptodoras (Siluriformes: Doradidae) from Rio Fresco, Xingu Basin, Brazil

“…The osteological description provided by Birindelli et al (2008) for Leptodoras oyakawai fits well for L. marki, its sister taxon (see Discussion and Fig. 7 for a dorsal view of the cephalic shield).…”

“…Leptodoras marki has a welldeveloped anterior nuchal plate and parieto-supraoccipital not contacting middle nuchal plate (Fig. 7), vs. anterior nuchal plate reduced, permitting contact between parietosupraoccipital and middle nuchal plate in most specimens of L. praelongus; and nuchal foramina, vs. absent in medium to large specimens of L. copei, L. hasemani, and L. praelongus (see Birindelli et al, 2008, for extensive discussion of this character).…”

“…The sister-group relationship between Leptodoras and the monotypic Anduzedoras oxyrhynchus (Higuchi, 1992;Sabaj, 2002;Moyer et al, 2004;Birindelli, 2006;Birindelli et al, 2008) is supported by the shared presence of two exclusive (and non-reversed) characters: a pair of conjoined bony capsules on the ventral surface of the anteriormost vertebrae ( Fig. 6; Birindelli et al, 2008:fig.…”

“…America that comprises about 85 valid extant species arranged in 31 genera Higuchi et al, 2007;Sabaj Pérez et al, 2007;Birindelli et al, 2008;Sabaj Pérez and Birindelli, 2008;. The species of Doradidae can be easily recognized by having midlateral scutes usually with posteriorly directed thorns, cephalic shield well developed and continuous with the dorsal-fin pterygiophores (nuchal plates), and welldeveloped posterior process of cleithrum.…”

“…Birindelli et al (2008) subsequently described L. oyakawai, having a more restricted distribution, known only from the Tapajó s and Xingu rivers, Brazil. Based on morphological characters such as the absence of reduced gas bladder, L. oyakawai was hypothesized as the sister taxon of a clade including all congeners .…”