Trichomycterus uisae : a new species of hypogean catfish ( Siluriformes : Trichomycteridae ) from the northeastern Andean Cordillera of Colombia

Trichomycterus uisae, a new species of hypogean catfish, is described from Cueva El Misterio located in the upper Sogamoso river basin of the Departamento de Santander in the northeastern portion of the Andean range of Colombia. The new species has a characteristic dark bluish-gray band from the head to the origin of the dorsal fin, five to nine opercular odontodes, and the anterior and posterior fontanels separated but connected by a narrow channel. A comparative analysis with epigean species from Colombia and troglobitic Trichomycterus from South America is presented.


Introduction
The catfish family Trichomycteridae comprises small to medium-sized freshwater catfishes that are widely distributed in Central and South America, on both sides of the Andes, from sea level to 4500 m (de Pinna & Wosiacki, 2003;Nelson, 2006).The Trichomycteridae is the third largest family of Neotropical catfishes with more than 207 species and 41 valid genera described (Ferraris, 2007).It is also one of the most successful groups occupying cave habitats in South America.With about 100 nominal species (de Pinna, 1992), Trichomycterus is the most diverse genus in the family, but its monophyletic status has been questioned by several authors (Baskin, 1973;de Pinna, 1989;Costa & Bockmann, 1993;Wosiacki, 2002).

Materials and Methods
Measurements were taken point-to-point with dial calipers on the left side of each specimen with the aid of a stereomicroscope.Methodology and terminology for measurements and counts follow de Pinna (1992).Osteological data were obtained from two non-type specimens prepared following the procedure of Taylor & Van Dyke (1985).Osteological nomenclature follows de Pinna (1989) and for the cephalic laterosensory system, Arratia & Huaquin (1995).Color was determined according to the Munsell soil color chart (1994).Morphological data for troglomorphic species other than Trichomycterus santanderensis Castellanos-Morales (2007) were based on information from the literature.

Trichomycterus uisae, new species
Figs.  various other species of Trichomycterus yet useful for identification include origin of pelvic fin anterior to vertical through dorsal-fin origin; short caudal peduncle (19-21.9% of SL); tip of first pectoral-fin ray prolonged as a long filament (52.1-89% of pectoral-fin length) and pelvic fins not widely separated.
Description.Morphometric data presented in Table 1.Body elongated, deeper than wide, gradually deeper from trunk toward caudal peduncle; dorsal profile of trunk convex.Ventral profile of trunk straight.Dorsal and ventral profiles of caudal peduncle slightly convex.Integument thick with lateral cutaneous folds forming vertical rings between pectoral and anal fins in specimens preserved in alcohol.Anal and urogenital openings closer to pelvic-fin base than to anal-fin origin, totally covered when pelvic fin extended.Free vertebrae 35.Pleural ribs 11-12.Head wide, trapezoidal, depressed in dorsal view.Dorsal profile of head straight, ventral and lateral profiles convex.Eye small, black, rounded, well defined, with variable diameter, positioned dorsally on anterior half of head.Mouth subterminal, with corners oriented backwards.Lower lip with conspicuously fleshy lateral lobes.Teeth conical, curved, arranged in 3-4 irregular rows on upper jaw and three rows on lower jaw.Jaw muscles not particularly developed and not bulging from surface of head.Neurocranium with elongate mesethmoid T-shape.Anterior fontanel small, oval in shape, located between frontals at level of infraorbital laterosensory canal exit 10-11.Posterior fontanel long and broad.Anterior one-third of posterior fontanel situated between frontal bones, with remainder in anterior portion of supraoccipital bone (Fig. 4).Both fontanels connected by a narrow channel.Branchial membranes thick, united to isthmus anteromedially and forming free fold across isthmus.Gill opening wide.Seven branchiostegal rays (Fig. 5a), six externally visible from below.Nasal and maxillary barbels surpassing base of pectoral fin.Maxillary barbel longer than nasal barbel.Anterior nostril surrounded by slightly raised thick integument, continuous with nasal barbel, both forming a tubular-shaped structure around nostril.Posterior nostril oriented transversally, its anterior edge delimited by thin and long flap of integument.Interopecular patch of odontodes well developed, with 27-32 conical and elongated odontodes arranged in four irregular rows, with interopercular odontodes on posterior edge larger.Opercular patch of odontodes small, with 5-9 conical odontodes arranged in three irregular rows (Fig. 5b).
Pectoral fin rounded with i,8 rays.First ray thin and fragile, prolonged as a long filament.Scapulocoracoid with long anteriorly directed process, located close to first pectoral-fin ray base (Fig. 6).Dorsal-fin rounded, located posterior to vertical through midbody, with iv,7 rays (only two unbranched rays externally visible).First pterygiophore inserted between neural spines of 15-16 th free vertebra.Pelvic-fin rays i,4, with a lateral splint.Pelvic-fin origin anterior to vertical through dorsal-fin origin and its posterior edge slightly surpasses urogenital opening.Pelvic-fin bases not widely separated.Basipterygium with two long anterior processes narrowing  from base to distal tip, one or two medial processes and one short posterior process (Fig. 7).Anal-fin similar to dorsal fin, but smaller, with ii, 5 rays, its origin at level of last dorsal-fin ray.First pterygiophore inserted between hemal spines of free vertebrae 20-21.Caudal-fin rays i, 5+6, i. Parhypural and hypurals 1+2 associated with eight rays , hypural 3 with 3 rays , and hypurals 4+5 with 3 rays.17-18 dorsal and 12 ventral procurrent rays.Caudal-fin edge slightly convex, uppermost rays larger.Caudal skeleton with neural spine of preural centrum 2 well developed.Hypurals 1 and 2 fused to parhypural; hypural 3 partially fused to hypurals 4+5 in young specimens (Fig. 8a), and separated in adult specimens (Fig. 8b).

Coloration in alcohol.
All specimens preserved in alcohol with ground color yellowish (M 10YR -5/6).Base of all fins with yellow tones (M 2.5Y -7/6), with exception of two nontype specimens with ground color brown-yellowish.
Ecological notes.The Cueva El Misterio is located at the east side of a plateau known as Mesa de los Santos, in the Municipio de los Santos.The plateau has Cretaceous sedimentary rocks and limestones of the Rosablanca Formation (Williams, 1990); reaches 1800 meters above sea level and is located on the oriental versant of the Chicamocha Canyon, in the Colombian Andes, of Santander Department.The cave, with a total of 110 m of explored passages, is isolated from the  epigean stream and is oriented longitudinally with galleries formed by gentle slope tunnels and narrow passageways.The cave has small wells interconnected by reduced descending channels where water infiltration was observed.In dry months, an isolated sump pool was observed at each gallery.The bottom of each well is rocky and contains much sediment composed chiefly of bat excrement.Cydnid bugs (Hemiptera: Heteroptera) were found inside the wells.Diptera, crayfish and bats were observed in the interior of the galleries (Fig. 9).Water temperature, when the holotype was collected, was 20°C and cave temperature was 18.5°C.
Etymology.The specific epithet "uisae" refers to the acronym UIS corresponding to the Universidad Industrial de Santander, in the Departamento de Santander, Colombia.The name is used as a noun in apposition.

Discussion
According to Trajano (2005), troglomorphic species are restricted to subterranean environments.Characteristics such as some degree of reduction in eye development and pigmentation (Trajano & de Pinna, 1996;Romero & Paulson, 2001;Bichuette & Trajano, 2008) and relatively long barbels (DoNascimiento et al., 2001), are commonly observed in troglomorphic fishes.Trichomycterus uisae exhibits two additional features (well defined lateral cutaneous folds encircling body and dorsal caudal-fin rays longer than ventral rays), that are also present in at least two other hypogean species of the genus: T. santanderensis and T. spealeus.A more comprehensive analysis focusing on the distribution of these conditions in the remaining species of Trichomycterus, both epigean and hypogean, could provide indication as to whether they are related to a hypogean life.
Trichomycterus uisae is most similar to T. straminius, from which it differs by the position of the dorsal fin, located posterior to the vertical through the pelvic-fin origin (vs. at vertical through the dorsal-fin origin), and by the caudal-fin edge slightly convex (vs.rounded; see Plate 49 in Eigenmann, 1918).Trichomycterus uisae differs from the remaining species by the slightly convex caudal-fin edge with uppermost rays longer (vs.rounded in all species with the exception of T. retropinnis, which has a round truncated caudal fin, and T. banneaui which has a distinctively emarginated caudal fin; Eigenmann, 1918), and by reduced pigmentation consisting of a narrow predorsal dark bluish-gray stripe and ground coloration light-brown without spots (vs.pigmented body with dark spots).
Trichomycterus uisae is distinguished from epigean species of Trichomycterus distributed throughout northern South America, with exception of Trichomycterus gorgona, by the presence of troglomorphic characters such as: small eyes, reduced pigmentation of head and body, and elongated barbels.It is distinguished from T. gorgona, by its conical teeth (vs.spatulate), pelvic-fin bases not widely separated (vs.widely separated) and nine pectoral-fin rays (vs.eight).
From the troglomorphic species of Trichomycterus from South America, Trichomycterus uisae is distinguished from T. sandovali and T. spelaeus by the presence of eyes (vs.absence), the origin of the pelvic fin anterior to the vertical through the dorsal-fin origin (vs. at vertical through the dorsal-fin origin) and fontanels connected by a narrow channel (vs.fontanels separated by epiphyseal bar).Trichomycterus uisae differs from T. santanderensis by having the pelvicfin bases not widely separated (vs.widely separated), and the posterior edge of the pelvic fin not reaching the anal-fin origin (vs.pelvic fin reaching anal-fin origin).Trichomycterus uisae is distinguished from T. chaberti by the presence of nine pectoral-fins rays (vs.10) and a long filament on the first pectoral-fin ray (vs. a short filament).Trichomycterus uisae also differs from T. itacarambiensis in body and head pigmentation, consisting of brown-yellowish without spots in the first species (vs.with small, irregular, roundish dark spots in T. itacarambiensis), nine pectoral-fin rays (vs.6-7) and anal and urogenital openings closer to pelvic-fin base than to anal-fin origin (vs.anal and urogenital openings nearly equidistant from bases of anal and pelvic fins).
The troglomorphic status of Trichomycterus uisae is further supported by the fact that the epigean stream is not Table 1.Morphometric data of Trichomycterus uisae.Standard length is expressed in millimeters.Measurements 2 to 11 are expressed as percents of standard length, measurements 12 to 19 are expressed as percents of head length.connected with the El Misterio cave, no specimens of Trichomycterus have been found in the epigean streams from Mesa de los Santos plateau, near the cave El Misterio, and T. uisae has the classical troglomorphic character states (Trajano & de Pinna, 1996;Romero & Paulson, 2001;Bichuette & Trajano, 2008).
Map of Santander Departament in northeastern Colombia with the approximate location of the collecting site of Trichomycterus uisae, in Cueva El Misterio, upper Sogamoso River basin.