Trichomycterus caipora, Lima & Lazzarotto & Costa, 2008

Lima, Sergio M. Q., Lazzarotto, Henrique & Costa, Wilson J. E. M., 2008, A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil, Neotropical Ichthyology 6 (3), pp. 315-322 : 316-319

Trichomycterus caipora , new species

Figs. 1-2

Holotype. UFRJ 6583 , 114.6 mm SL; Brazil, Estado do Rio de Janeiro: Município de Conceição de Macabu, lagoa Feia drainage, rio Macabu basin, rio Macabu upstream the confluence of rio Carocango and rio Macabu , 22 o 04’51.8”S 41 o 58’55.3”W, 28 June 2006, S. Lima, H. Jabor & H. Lazzarotto.

Paratypes. UFRJ 7247 , 12 , 69.6 - 116.2 mm SL ; UFRJ 7614 , 3 (c&s), 69.1-75.0 mm SL ; MNRJ 31924 , 77.9 - 87.6 mm SL; all collected with holotype . UFRJ 7257 , 69.0-69.9mm SL; Brazil, Estado do Rio de Janeiro, Município de Conceição de Macabu, rio Macabu basin, rio Carocango , upstream Cachoeira da Amorosa, tributary to rio Macabu , same collectors and date as holotype .

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).

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; opercular odontodes arranged vertically. Medial margin of autopalatine slightly concave; posterior process of autopalatine slightly shorter than autopalatine without posterior process. Lacrimal about one fourth supraorbital length; supraorbital rod-like. Metapterygoid small, without distinct processes. Anterodorsal surface of hyomandibula with weak concavity ( Fig. 3 ). Third supraorbital pore fused (9 in 16 specimens), sometimes paired with each pore closer to symmetrical pore than to orbit. Anterior section of infraorbital canal present.

Pectoral-fin rays i,8. Pectoral fin somewhat triangular, lateral and posterior edges slightly convex. First pectoral-fin ray terminating as long filament, about 20-40% of pectoral-fin length. Pelvic fin about 2/3 of anal fin length, tip not reaching anal fin or covering urogenital pore, tip at vertical through base of first branched dorsal-fin ray; pelvic-fin bases separated by interspace. Dorsal and anal fins approximately triangular. Dorsal-fin origin at vertical between centrum of 17 th and 18 th vertebra. Anal-fin origin posterior to vertical through dorsal-fin base, and through centrum of 23 rd or 24 th vertebra. Caudal fin emarginate. Dorsal-fin rays vii,5-6; anal-fin rays v,5; pelvic-fin rays i,4; principal caudal-fin rays 6+7, dorsal procurrent rays 12-16, ventral procurrent rays 11-15. Free vertebrae 35-36; precaudal vertebrae 12; caudal vertebrae 23-24; pleural ribs 12. Upper hypural plates separated, dorsal plate as wide as ventral plate.

Coloration. Side of body orangish yellow, dorsal half yellowish brown, forming rounded blotches on trunk arranged in four irregular longitudinal rows: one along dorsal region, one along dorsolateral region (both in vertical from opercular patch of odontodes to caudal peduncle), one along midlateral region (from opercular patch of odontodes to caudal peduncle), all rows with chromatophores present both in superficial and deep layer of integument, and one along ventrolateral region (from behind pectoral fin to posterior margin of anal-fin base), with chromatophores restricted to inner layer of integument, and faint brown dots below lateral midline, venter yellowish white. Some specimens show dorsal and dorsolateral rows coalescent, forming single dark band on dorsal portion of body and head. Midlateral blotches sometimes coalesce forming well-defined or interrupted stripe ( Fig. 2 ). Head orangish yellow, with chromatophores concentrated in the supraorbital and preopercular regions. Opercular and interopercular patches of odontodes light yellow; nasal barbel dark grey, maxillary and rictal barbels light grey. Iris yellow. Dorsal fin pale yellow with orangish brown spots on basal half, hyaline with brown dots on distal half. Caudal fin pale orangish brown with small dark brown spots, distal fourth hyaline. Pectoral and anal fins yellow with brown spots on proximal region. Pectoral-fin filament white. Pelvic fin pale yellow. Fins yellowish hyaline. Juvenile specimens with lighter homogeneous grayish pattern.

Etymology. From the Tupi, kaa’pora (forest dweller), a forest dwelling creature of the Tupi mythology, with orange hair and a protector of the wildlife; an allusion to the fact that the new species is endemic to the Atlantic Rain Forest and possesses orangish yellow head. A noun in apposition.

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.

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 ranging from about 6 m to 15 m stream width, in depths of about 50 cm, on substrate composed by varied size rocks, in spots with medium to fast water current.

Trichomycterus caipora seems to be nocturnal species. Only five juvenile specimens were captured in daylight, whereas 16 specimens were easily collected at dawn and night time. Underwater observations during daytime did not detect active individuals of Trichomycterus caipora . Only one individual was seen hiding under plant debris and rocks, in a shallow area of a pool just downstream from Cachoeira Amorosa, a 15 m high waterfall. Furthermore, three specimens of T. aff. zonatus were caught at this period always in sand beds, while 17 specimens were captured during daylight, when they were swimming active or buried in sand. This could suggest diel and microhabitat segregation between these congeneric species.

Other species collected with Trichomycterus caipora were Neoplecostomus microps (Steindachner) , Ancistrus multispinnis (Regan) , and Characidium sp. Furthermore, individuals of Geophagus brasiliensis (Quoy & Gaimard) and Astyanax sp. were also observed.

Figures

Fig. 1. Trichomycterus caipora, lateral, dorsal and ventral views. Holotype, UFRJ 6583; 114.6 mm SL. Brazil, Rio de Janeiro, Conceição de Macabu, rio Macabu upstream the confluence of rio Carocango and rio Macabu.

Fig. 2. Trichomycterus caipora immediately after preservation, showing phenotypic color variation, paratypes, UFRJ 7247; a, 116.2 mm SL; b, 100.4 mm SL. Brazil: Estado do Rio de Janeiro: Conceição de Macabu.

Fig. 3. Left suspensorium and opercular series of Trichomycterus caipora, UFRJ 7614, 69. 1 mm SL. Lateral view.Abbreviations: HY, hyomandibula; IO, interoperculo; MT, metapterygoid; OP, opercle; PO, preopercle; QU, quadrate. Scale bar = 1 mm.

Fig. 4. Map of southeastern Brazil showing geographic distribution of Trichomycterus caipora. Symbol represents more than one sampling locality.