Trichomycterus dali

description

Description. Morphometric and meristic data of holotype and paratypes given in Table 1. Body elongate, semi-cylindrical, becoming compressed towards caudal fin. Dorsal profile of body slightly convex, slight and straight slope from tip of snout to anterior portion of trunk; ventral profile of body straight in lateral view. Profile of body triangular in transversal section. Dorsal portion of caudal peduncle concave at beginning of caudal fin; ventral portion of caudal peduncle straight. Dorsal lobe of caudal fin projected upward. Adipose folds well developed in adult and young specimens, ridge-like, anterior (pre-dorsal) and posterior (post-dorsal) to dorsal fin, lining dorsally throughout body, not supported by procurrent rays. Origin of pre-dorsal adipose fold posterior to pectoral-fin base, reaching dorsal-fin base; origin of postdorsal adipose fold at end of dorsal-fin base, reaching caudal fin, with higher width closer to dorsal fin than to caudal-fin (Fig. 2). Urogenital and anal openings on vertical through posterior end of dorsal-fin base, between distal margin of pelvic fins. Head relatively wide and depressed, trapezoidal in dorsal view. Eyes not visible externally (Fig. 3

Trichomycterus dali: a new highly troglomorphic catfish (Silurifomes: Trichomycteridae) from Serra da Bodoquena, Mato Grosso do Sul State, Central Brazil

diagnosis

Diagnosis. Trichomycterus dali is readily distinguished from epigean and hypogean congeners by the presence of two conspicuous, ridge-like adipose folds lining dorsally throughout the body, one anterior (pre-dorsal) and one posterior (post-dorsal) to the dorsal fin, both distinctive autapomorphies in the genus. Other characters that easily distinguish the new species, although not exclusive, are: highly reduced skin pigmentation (except for T. gorgona and caverestricted congeners, T. chaberti, T. itacarambiensis, T. spelaeus, T. sandovali, T. santanderensis and T. uisae); total loss of eyes, not visible externally (except for T. sandovali and T. spelaeus); barbels long, especially the nasal (99.3 - 143.5 % HL) and the maxillary (97.0 - 131.3 % HL) (except for T. longibarbatus and T. spelaeus); scapulocoracoid with a conspicuous anterior process projected forward (except for T. sandovali, T. spelaeus and T. uisae), with a narrow base, a wide apex and a rounded distal margin; and pectoral-fin ray count reaching I, 9 (except for T. hualco). Characters possibly exclusive, but about which many taxa lack information, are listed as complementary diagnoses: cranial fontanel unique, extendi

Trichomycterus dali: a new highly troglomorphic catfish (Silurifomes: Trichomycteridae) from Serra da Bodoquena, Mato Grosso do Sul State, Central Brazil

discussion

Notes on habitat, ecology and behavior. The Buraco das Abelhas Cave is an underwater cave, with more than 2000 m of explored conduits and maximum depths of 55 m, located in the southern portion of Serra da Bodoquena National Park, in the rio Miranda lowlands. The only cave entrance so far known opens into a large room with a lake, whose level increases during rain seasons, completely flooding the saloon and only allowing access through cave diving from the entrance. The cave continues as a large, 1200 m long flooded conduit, called tunnel A. Two hundred meters from the entrance, on the right side, the tunnel A branches into tunnel B, 700 meters long and depth varying from 40 meters to up to 12 meters at the distal explored end of the conduit. Eight hundred meters far from the cave entrance, again on the right side of tunnel A, opens tunnel C; 200 meters inside tunnel C, on the left, tunnel D starts, going to a depth of up to 12 meters. Non-troglomorphic fish, such as the catfish Rhamdia quelen and tetra characins, Astyanax spp., were observed regularly in the entrance room, and farther in tunnel A until 200 m from the cave entrance, reaching a depth of 49 m. At 100 meters from the

Trichomycterus dali: a new highly troglomorphic catfish (Silurifomes: Trichomycteridae) from Serra da Bodoquena, Mato Grosso do Sul State, Central Brazil

distribution

Distribution. Trichomycterus dali is known exclusively from subterranean waters in at least three caves in Serra da Bodoquena karst area: Buraco das Abelhas, Saracura and Morro do Jericó caves.

Trichomycterus dali: a new highly troglomorphic catfish (Silurifomes: Trichomycteridae) from Serra da Bodoquena, Mato Grosso do Sul State, Central Brazil