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Comprehensive Description

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Trichomycterus santanderensissp. nov.

Holotype . CAC-CDMB 035 , 100.7 mm SL; Cave El Puente ( 07° 09’ 49’’ N ; 073° 17’ 21’’ W ), Portugal Street, municipality of Lebrija, upper Lebrija River basin , Santander , Colombia (Figs. 2, 3) collected by: Cesar Castellanos, Leccy Monsalve and Sohath Yusseff10 June 2005 .

Paratype . CAC-CDMB 051 , 78.7 mm SL; collected at the same place as the holotype by: Cesar Castellanos, Mauricio Pardo-Peñaloza , and Natalia Acero-R. 15 July 2005 .

Non-type material. CAC-CDMB 050 , 73.4 mm SL, dissected; CAC-CDMB 052 , 55.5 mm SL, dissected; collected with paratype.

Diagnosis: Trichomycterus santanderensis (Figs. 2, 3) can be distinguished from other species of the genus by the following combination of characters: variable reduction in eyes from visible to imperceptible due to covering by a thick integument; relatively high head (62.5% of HL); enlarged mouth width (49% of HL); extended maxillary, nasal and rictal barbels (113.6%, 106.7% and 75% of HL, respectively); first pectoral ray extending as long filament, about 95% of pectoral-fin length; depth of the caudal peduncle 17.5% SL; caudal fin truncate with a slightly convex edge, upper portion of fin longer than lower portion; color varied from homogeneous light-red pigmentation of adults to pale rose with small grayish round spots on dorsum of young individuals.

Description: Morphometric data are presented in Table 1. Body elongated, deeper than wide, gradually deeper from trunk toward caudal peduncle; dorsal profile of trunk convex, marked by strong dorsal muscles raised from nape to origin of dorsal fin; ventral profile of trunk straight, dorsal and ventral profile of caudal peduncle slightly convex.

Integument thick and opaque, with well defined cutaneous folds forming vertical rings along entire trunk of specimens preserved in alcohol.

Head wide and depressed, triangular in dorsal view; dorsal profile of head straight, ventral and lateral profile convex; jaw muscle not particularly developed and not bulging from surface of head. Eyes positioned dorsally on anterior half of head, reduced in size from visible to imperceptible due to covering by thick integument.

Thick branchial membranes united to isthmus at anterior medial point, forming a free fold across isthmus. Gill opening free. Five or 6 branchiostegal rays barely visible in preserved specimens. Interopecular patch of odontodes well developed, with 31 to 38 conical, elongated and deciduous odontodes arranged in 4 irregular rows, larger odontodes on posterior edge. Opercular patch of odontodes small, with 7-9 conical odontodes arranged in 3 irregular rows.

Barbels extended and fragile at tips. Nasal and maxillary barbels extend beyond opercular patch of odontodes and surpass base of pectoral fin; maxillary barbel extends further than nasal barbel (nasal barbel longer in paratype). Anterior nostril surrounded by slightly raised thick integument, continuous with nasal barbel, both forming a tubular-shaped structure around the nostril. Posterior nostril oriented transversally, its anterior edge delimited by a thin and long flap of integument. Mouth inferior with corners oriented backwards. Lower lip with conspicuously fleshy lateral lobes. Teeth conical, arranged in 4 irregular rows on upper jaw and 3 rows on lower jaw.

Dorsal fin located beyond SL midpoint, rounded, with 2 simple rays and 7 branched rays. Anal fin similar to dorsal fin but smaller, with 2 simple ray and 5 branched rays, its origin at level of last dorsal-fin ray (in the paratype anal fin is located slightly after the last dorsal fin ray). Pelvic fin with 1 simple and 4 branched rays, its posterior edge reaching origin of anal fin; pelvic-fin originates at level of dorsal fin origin (located slightly after origin of dorsal fin in paratype); pelvic-fin widely separated at base, about 45% pelvic-fin base length. Pectoral fin rounded, with 1 simple ray and 8 branched rays, first ray a thin, fragile and long filamentous extension reaching 95% of length of fin of holotype.

Anus and urogenital opening almost equidistant between base of anal fin and base of pelvic fin, covered totally when pelvic fin is extended. Caudal fin obliquely truncated, with a slightly convex edge, dorsal side of larger upper rays longer than ventral side, I/13/I. Vertebrae 35 to 36. Ribs 12.

Coloration in live specimens: Body color light-red (M 2.5YR - 6/8), base of all fins yellow (M 2.5Y - 7/ 6). Paratype yellowish (M 10YR - 7/8) from head to origin of anal fin. The smallest specimen has small, irregular, circular, soft grayish blue stains (M 2GLEY 6/1) in 3 bands from head to origin of dorsal fin.

Coloration in alcohol: Body unpigmented, evenly clear or creamy yellow. Paratype with yellow tones at base of all fins (M 2.5Y - 7/6).

Ecological data: The Cave El Puente is located in the center of a mountain to the west of the Andean mountain range in Colombia and is not registered in the speleological inventory of Santander. The cave is oriented vertically with narrow, rocky passageways and galleries (Fig. 4) where water infiltration was observed. The wells are small, shallow, blocked by ceilings of rock and interconnected by reduced descending channels that drain the limited water flow. Water temperature during the sampling was 21.5 °C and cave temperature was 19.9 °C. The bottom of the wells is rocky and contains much sediment (only four specimens of T. santanderensis were collected here). Bloodsucking bats and a diversity of arthropods inhabit the interior of the galleries. The cave is located in an area untouched by agrochemical products, where the practice of sustainable agroforestry has maintained the flora and fauna relatively well conserved, and where the Autonomous Regional Corporation for the Defense of the Bucaramanga Plateau is preparing a conservation program (Castellanos, 2005).

Discussion

Identifying a new species of hypogean fish is difficult because physical characteristics such as lack of pigment and absence of eyes may correspond to epigean individuals highly modified for cave life. For this reason, a comparison with other troglomorphic species of Trichomycterus and with epigean species from the north of Colombia was conducted. The results indicate that T. santanderensis is a new species (sensu Wheeler & Platnick, 2000) because it presents a unique combination of characteristics that differentiate it from previously reported epigean and hypogean populations.

Of the species reported as strictly hypogean, Trichomycterus santanderensis differs from T. chaberti ZBK by the origin of its dorsal fin close to the anal papilla, and short filament on first pectoral-fin ray, whereas T. santanderensis has the dorsal-fin origin near the origin of the pelvic fin, and a very long filament on the first ray of its pectoral fin. Trichomycterus santanderensis presents a variable reduction in eye size, which does not occur in T. spelaeus ZBK , and it has a wider mouth than T. spelaeus ZBK (49% vs 32.5% HL); the pelvic-fin tip reaches the anal-fin base in T. santanderensis whereas the pelvic-fin tip in T. spelaeus ZBK reaches the urogenital opening. The origin of the pelvic fin of T. santanderensis is even with or slightly behind the dorsal-fin origin, while T. itacarambiensis ZBK has the origin of the pelvic fin anterior to the dorsal-fin origin. Also, in T. santanderensis , the anal-fin origin is located along a vertical line that passes the last ray of the dorsal fin, while in T. itacarambiensis ZBK the anal-fin origin is located midway from the base of the dorsal fin.

According to Dahl (1971) and Maldonado et al. (2005), the following Colombian species of Trichomycterus have sharp conical teeth, like those of T. santanderensis : T. banneaui , T. bogotense , T. latistriatum , T. nigromaculatum ZBK , T. retropinne , T. stramineum and T. striatum . Trichomycterus stramineum is the most similar to T. santanderensis , from which it differs by the rounded form of the dorsal and ventral extremes of the posterior edge of the caudal fin (see Plate XLIX in Eigenmann, 1918) and by the position of the urogenital opening in relation to the pelvic fins: in T. stramineum the pelvic fins cover slightly the urogenital opening, while in T. santanderensis the urogenital opening is totally covered and almost equidistant between the base of the pelvic fin and its distal edge. The remaining species differ by the posterior origin of the dorsal fin with respect to the origin of the pelvic fin, located on or slightly behind the anus as in T. retropinne (Eigenmann, 1918) and also differ in the shape of the caudal fin, described as rounded in all species with the exceptions of T. retropinne , which has a round truncated caudal fin, and T. banneaui which has a distinctively emarginated caudal fin (Eigenmann, 1918).

Etymology: The specific epithet "santanderensis" refers to the Colombian department (Santander) where the specimens were collected.

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