Pseudobunocephalus timbira

description

(Figs. 1, 2; Tables, 1, 2) urn: lsid: zoobank. org: act: 392 F 95 E 0 - 86 E 1 - 4386 - 8779 - C 4 F 71098 DBCC Acanthobunocephalus sp. nov. 3 — Cardoso, 2008: 166 [unpublished phylogenetic study, listed as an undescribed species].

A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil

description

Description. Dorsal, lateral and ventral views of holotype shown in Figure 1. Maximum body length observed 33.4 mm SL. Morphometric data for holotype and 14 paratypes summarized in Table 1. Head and anterior body depressed. Anterodorsal profile of body ascending from tip of snout to dorsal-fin origin. Posterodorsal profile of body descending from dorsal-fin to base of caudal fin. Ventral body profile convex from mouth to insertion of pelvic fin and concave from this point to anal-fin origin. Caudal peduncle rounded, long and slender. Knobs on dorsal surface of skull approximately equal in size. Eye small and positioned dorsolaterally. Skin covering eye dense and pale. Anterior nostril tubular located at tip of snout. Posterior nostril without flap or barbel, located anteromedially to eye. Mouth terminal, upper and lower jaws equal. Maxillary barbel simple, beginning on mouth corner and its posterior end surpassing pectoral-fin spine insertion. Anteromedial mental barbel simple and posterolateral mental barbel bifid with one or more fleshy lobe proximally along posterior margin. Skin of trunk covered with small unculiferous tubercles in longitudinal rows; mid-dorsal row well defined

A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil

diagnosis

Diagnosis. Pseudobunocephalus timbira can be distinguished from all congeners by having the second hypobranchial and the third basibranchial cartilaginous (vs. ossified). Additionally, it can be dintinguished from P. lundbergi by the following putative apomorphic features within Pseudobunocephalus: posterolateral process of premaxilla present (Fig. 2 C vs. absent); bony knobs in dorsal lamina of Weberian apparatus absent (Fig. 2 B vs. present, Fig. 3 A, B); distal end of posterior margin of 5 th parapophysis not enlarged (Fig. 2 B vs. enlarged, Fig. 3 A, C,); three pairs of ribs (Fig. 2 B vs. four or five, Fig. 3 A); infraorbital sensory canal entering neurocranium via frontal (Fig. 2 A vs. via sphenotic, Fig. 3 A). It is distinguished from P. bifidus and P. iheringii by having a gracile body not surpassing 34 mm SL (vs. robust body, reaching 52 and 59 mm SL, respectively); by having the posterior margin of cranial fontanel concave (Fig. 2 A vs. posterior margin somewhat straight with parieto-supraoccipital extending anteriorly, Fig. 3 D); by conspicuously knobby skull ornamentation on its dorsal surface (Fig. 2 A, B vs. skull knobs slightly pronounced, Fig. 3 D, E); by having Webe

A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil

distribution

Distribution. Pseudobunocephalus timbira is known from small tributaries of the lower Tocantins and Mearim river basins in Maranhão, Pará and Tocantins states, Brazil (Fig. 4). Ecological notes. The new species was collected in small and slow flowing streams running over sand or muddy bottom. The type locality in the Mearim River basin (Fig. 5) is a sediment rich tributary with moderate marginal and submersed vegetation.

A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil