Trichomycterus caipora

biology_ecology

Ecological notes. Rio Macabu basin encompasses an area of approximately 1,076 km 2. Rio Macabu flows for about 120 km until it reaches lagoa Feia, an isolated lagoon in northern Rio de Janeiro State (Bizerril & Primo, 2001). Its headwaters are located in serra de Macaé mountain range, at about 1,500 m above sea level, in areas partially covered with secondary Atlantic forest. The impact of human activities is visible along the entire course of rio Macabu. On the mountain slopes the main visible impacts are the presence of several buildings on the river banks, and also the deforestation for several purposes, such as agriculture and cattle raising. Trichomycterus caipora was collected in clear, fast flowing streams and small rivers, with substrate composed mainly by rocks, gravel and coarse sand, in altitudes between 80 and 210 m. Since no sampling was performed above this altitude, it is possible that T. caipora possesses a more extent longitudinal distribution. The original Atlantic forest vegetation is rare along the river banks; marginal vegetation, when present, was composed mainly by grass from adjacent pastures. Specimens were collected on the main channel of streams, in sites

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil

description

Description. Morphometric data for holotype and paratypes given in Table 1. Body moderately deep, subcylindrical on anterior portion, compressed on caudal peduncle. Dorsal profile slightly convex between snout and end of dorsal-fin base, approximately straight from this point to base of caudal fin. Ventral profile convex between lower jaw and end of anal-fin base, straight on caudal peduncle. Head depressed, longer than wider, subtriangular in dorsal view. Eye at middle of head, orbital rim not free. Skin covering eye thin and translucent. Snout blunt. Mouth subventral. Lower lip with conspicuous lateral fleshy lobes. Maxilla slightly longer than premaxilla. Teeth conical. Tip of nasal barbel reaching posterior margin of eye. Tip of maxillary and rictal barbels reaching anterior portion of interopercular patch of odontodes. Base of maxillary and rictal barbels, lips and ventral portion of head covered by papillae. Branchial membranes thick, united to isthmus anteriorly by thin flap of skin. Seven branchiostegal rays. Interopercular odontodes 65 - 70; opercular patch of odontodes wide, with 26 - 28 odontodes; odontodes conical, opercular odontodes wider than interopercular odontodes

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil

diagnosis

Diagnosis. Similar to T. giganteus, T. immaculatus and T. nigricans and distinguished from the remaining congeners from southern and southeastern Brazil by having nine pectoral-fin rays (vs. eight or fewer) and more odontodes (interopercular 59 - 70, vs. 19 - 52, opercular 23 - 30, vs. 10 - 20). Easily distinguished from T. giganteus, T. immaculatus, and T. nigricans by having the caudal fin emarginate (vs. truncate). It further differs from T. giganteus by having shorter nasal and maxillary barbels (nasal reaching posterior margin of eye vs. reaching pectoral-fin base; maxillary reaching anterior portion of interopercular patch of odontodes vs. reaching anterior third of pectoral fin), and from T. immaculatus and T. nigricans by the presence of four irregular longitudinal rows of rounded blotches on trunk (vs. homogeneous colour pattern).

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil

distribution

Distribution. Trichomycterus caipora is only known from the type locality in the mountain streams of the rio Macabu basin, lagoa Feia drainage, serra de Macaé, northern Rio de Janeiro State, southeastern Brazil (Fig. 4). The new species can be found in several sites in the upper and middle reaches of the rio Macabu and its tributary streams.

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil