Trichomycterus balios

description

Description. Morphometric data for holotype and paratypes in Table 1. Body elongate, trunk roughly cylindrical and gradually compressed towards caudal fin. Dorsal profile of trunk convex along anterior half then straight to insertion of dorsal fin. Ventral profile of trunk straight to slightly convex. Dorsal and ventral profile of caudal peduncle straight to slightly concave. Head depressed, trapezoidal from dorsal view, wider posteriorly. Dorsal profile straight and ventral profile straight to slightly convex. Snout rounded from dorsal view. Eyes readily visible, anteroposteriorly elliptical to rounded, dorsally oriented; orbital rim not free, eyes covered with skin thin and transparent. Each eye located over posterior termination of shallow and small longitudinal crest beginning at posterior nostril and making eyes visible from lateral view. Nostrils of same size and smaller than eye diameter. Anterior nostril surrounded by fleshy flap of integument posterolaterally continuous with nasal barbel. Posterior nostril surrounded anterolaterally by thin flap of integument. Gill openings not constricted but united with isthmus anteriorly forming a free fold. Mouth subterminal with corne

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil

diagnosis

Diagnosis. Trichomycterus balios is distinguishable from all congeners except T. davisi (Haseman, 1911); T. diatropoporos; T. papilliferus Wosiacki & Garavello, 2004; T. payaya Sarmento-Soares, Zanata & Martins-Pinheiro, 2011; T. perkos Datovo, Carvalho & Ferrer, 2012; T. plumbeus Wosiacki & Garavello, 2004; and T. tropeiro by the modal possession of I + 6 pectoral-fin rays (one among 108 specimens with I + 7; vs. I + 5, I + 7, or more pectoral-fin rays) and the first ray of the pectoral fin not prolonged as a filament (Fig. 1; vs. the first ray of the pectoral fin prolonged as a filament). Trichomycterus balios is distinguished from T. davisi, T. diatropoporos, T. papilliferus, T. payaya, T. perkos, and T. plumbeus by the color pattern of the dorsal and lateral surfaces of body, which presents circular black blotches variable in size (Fig. 1; vs. the head and trunk with dark irregularly shaped spots scattered in T. davisi; lateral surface of body with dark blotches variable in size and shape progressively larger and coalescent dorsally thus forming extensive black pigmented regions with light yellow gaps in T. diatropoporos; dorsal and lateral surfaces of body pale brown to light

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil

discussion

Remarks. The type series includes only specimens from laguna dos Patos system. Data of specimens from the rio Mampituba identified as T. balios are not included in the species description.

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil

distribution

Distribution and ecological notes. Trichomycterus balios is distributed in the upper portions of the rio das Antas and rio Caí tributaries to the laguna dos Patos system and in the headwaters of the rio Mampituba (Fig. 8). The type locality is located at approximately 792 m a. s. l. and the remaining localities of collection between 681 and 941 m a. s. l. The lower portions of the laguna dos Patos system and of the rio Mampituba are widely separated by the rio Tramandaí drainage, were T. balios is unknow to occur (Malabarba et al., 2013). The occurrence of the species in the headwaters of these two unconnected and distant drainages (laguna dos Patos system and of the rio Mampituba) is possibly related to headwater capture events. The localities where the types were collected had clear water with current water and rocky bottoms (Fig. 9 a). Trichomycterus balios was collected with Cnesterodon brevirostratus Rosa & Costa, 1993; Pareiorhaphis hystrix (Pereira & Reis, 2002); and Bryconamericus patriciae da Silva, 2004 at the type locality, other species that show some degree of endemism in the region associated with high altitudes (Rosa & Costa, 1993; Pereira & Reis, 2002, da Silva, 200

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil