Trichomycterus guaraquessaba

biology_ecology

Ecological notes: The rio Bracinho, type locality of Trichomycterus guaraquessaba, is a typical Atlantic Rain Forest stream, with clear water, falls, rapids and moderate current flowing over the rocky beds, intercalated with pools. The river runs in an alluvial valley bordered by the slopes of adjacent hills, and the riparian vegetation is a dense, well preserved forest. Trichomycterus guaraquessaba occurs associated with stones and plant debris on the bottom and is syntopic with Astyanax sp., Deuterodon langei Travassos, Hollandichthys multifasciatus (Eigenmann & Norris), Mimagoniates microlepis (Steindachner), Characidium sp., Oligosarcus hepsetus (Cuvier), Rhamdioglanis sp., Pimelodella sp., Acentronichthys leptos Eigenmann & Eigenmann, Rhamdia quelen (Quoy & Gaimard), Ancistrus sp., Pseudotothyris obtusa (Miranda-Ribeiro), Scleromystax barbatus (Quoy & Gaimard), and Gymnotus carapo Linnaeus.

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from south Brazil and redescription of T. iheringi (Eigenmann).

description

Description: Morphometric data for holotype and paratypes are given in Table 1. Body elongate, roughly cylindrical close to head and gradually more compressed in trunk towards caudal fin. Profiles of trunk straight dorsally and slightly convex ventrally. Dorsal and ventral profiles of caudal peduncle straight (Fig. 2). Integument thick, especially over base of dorsal and anal fins. Small papillae on lips and scattered over lateral surface of head. Head depressed, trapezoidal, or longer than wide (18.9 - 19.9 % SL), the transversal section at posterior tip of opercle wider than anteriorly at nostril, anterior margin straight (Fig. 4). Lateral region of eye slightly swollen by jaw muscles in both large and small specimens. Profiles of head straight dorsally and convex ventrally. Eyes rounded, well defined rim, dorsally oriented, covered by thin skin, not distinctly separated from surface of eyeball. Ocular structures readily visible on surface of skin, not deeply sunken. Orbital rim not free. Anterior nostril larger than posterior, surrounded by fleshy flap of integument. Posterior nostril surrounded anteriorly by thin flap of integument. Anterior nostril same size as eye diameter. G

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from south Brazil and redescription of T. iheringi (Eigenmann).

diagnosis

Diagnosis: No uniquely derived features were found to diagnose T. guaraquessaba. Trichomycterus guaraquessaba shares with T. castroi de Pinna, T. davisi (Haseman), T. iheringi, T. mboycy Wosiacki & Garavello, T. naipi Wosiacki & Garavello, T. papilliferus Wosiacki & Garavello, T. plumbeus Wosiacki & Garavello, T. stawiarski (MirandaRibeiro), and T. zonatus (Eigenmann) the first pectoral-fin ray not prolonged as a filament and differs from all other congeners from south and southeastern Brazil [T. albinotatus Costa, T. alternatus (Eigenamnn), T. auroguttatus Costa, T. bahianus Costa, T. brasiliensis Luetken, T. candidus (Miranda-Ribeiro), T. caudofasciatus Alencar & Costa, T. concolor Costa, T. giganteus Lima & Costa, T. goeldii Boulenger, T. immaculatus (Eigenmann & Eigenmann), T. itacambirussu Triques & Vono, T. itatiayae Ribeiro, T. jequitinhonhae Triques & Vono, T. landinga Triques & Vono, T. longibarbatus Costa, T. maracaya Bockma & Sazima, T. mimonha Costa, T. mirissumba Costa, T. nigricans Valenciennes, T. pantherinus Alencar & Costa, T. potschi Barbosa & Costa, T. taroba Wosiacki & Garavello, T. trefauti Wosiacki, T. reinhardti (Eigenmann), T. triguttatus (Eigenmann), T. var

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from south Brazil and redescription of T. iheringi (Eigenmann).

discussion

Remarks: Trichomycterus and Trichomycterinae are not monophyletic groups, but the allocation of T. guaraquessaba to this genus is the best solution for maintaining nomenclatural stability. Trichomycterus guaraquessaba does not have the features observed in Bullockia, Eremophilus, Hatcheria, Rhizosomichthys, Silvinichthys, all formerly included in Trichomycterinae, and can not be allocated to any of these genera. The morphological similarity among Trichomycterus species is high and the identification is, often, impossible without the examination of type material. Few species present distinct autapomorphies (T. castroi, T. ramosus Fernandez, T. papilliferus, T. trefauti), and most species have been diagnosed by the combination of characters. The last revision of the group was made by Eigenmann (1918) and included the transcriptions of the original descriptions of all species known for the time. It is the best reference for the identification of Trichomycteridae species, but its descriptions, keys and drawings are outdated. Trichomycterus guaraquessaba could be correctly recognized as a new species only after the examination of the type material of T. iheringi. Trichomycterus guaraque

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from south Brazil and redescription of T. iheringi (Eigenmann).