| Trichomycteridae (Pencil or parasitic catfishes), subfamily: Trichogeninae |
| 5.08 cm SL (male/unsexed) |
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demersal; freshwater |
| South America: known only from the type locality, an upland tributary of the headwaters of the rio Itapemirim drainage in southeastern Brazil. |
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Three autapomorphies distinguish T. claviger from all other members of the family: the sexually dimorphic posterior process of the opercle, much elongated in males (vs. short in both males and females); the terminal mouth (vs.subterminal or inferior); and the presence of an anterodorsal claw-like process on the dorsal surface of the neural arch of each of the anterior four free vertebrae. This species is distinguished from T. longipinnis, by several additional characteristics (some of which may also be autapomorphic, pending more detailed analysis): shape of the interopercle, with odontodes extending onto the posterodorsal margin of the interopercle on a bony expansion (vs. odontodes mostly restricted to ventral and posterior margins of the bone); posterior naris broader than long (vs. round); presence of an entirely differentiated fleshy lobe laterally on the lower lip (vs. fleshy lobe mostly continuous with the lower lip); no branched anal-fin rays in specimens of any size (vs. most rays branched in specimens over 41 mm SL); less deep caudal peduncle, 9.3-11.5 (vs. 10.3-12.6% SL); deeper head, head depth 72.9-86.6 (vs. 50.3-62.8% HL); no antorbital (vs. plate-like antorbital present dorsally to antorbital process of lateral ethmoid); deep coronoid process of the lower jaw (vs. coronoid process approximately one-third less deep); flattened bifurcated tooth cusps, with roundish margins (vs. bifurcated tooth cusps conical, pointed); vertebrae 35 (vs. 38 or 39); branchiostegal rays 6 (vs. 7); no pelvic splint (vs. present); pleural ribs 8 (vs. 10 or 11); few sparse dark spots on body (spots more numerous and more densely arranged); well-defined thin dark line along base of anal fin, formed by a regular row of slanted elongate spots on the distal portion of each pterygiophore (vs. no such line); no dark spots on the sides of head (vs. lateral surfaces of head with roundish spots); dark spots on body not extending onto base of caudal fin (vs. spots covering bases of principal caudal-fin rays). The deepest part of the body of T. claviger is at the middle of the abdomen, continuously less deep posteriorly to the base of the caudal fin, and the dorsal and ventral profiles of the head forming broad symmetrical arcs with the body profile, and these result in a rather different general aspect when compared to T. longipinnis, where the deepest part of the body is at the origin of the anal fin, and the body depth is approximately even along its entire length, only slightly decreasing towards the caudal fin. Also, the dorsal and ventral profiles of the head and body are not symmetrical, in T. claviger, it is gently convex and in T. longipinnis it is approximately straight (Ref. 85858). |
| The specimens were collected in a shallow sector (ca. 30 cm) of the córrego Picada Comprida, on a plateau at ca. 1150 m altitude, water is darkly tea-stained and transparent, with slow current and negligible altitudinal gradient. The stream runs through an area of moderately impacted high-altitude rainforest mingled with sectors of exotic pine culture. The substrate is mostly exposed sand, with masses of accumulated leaf litter and other vegetable debris in many spots. Fish were concentrated on quiet shaded areas with litter, swimming in midwater, and were collected with hand seines. No associated fish species were found with this species. Gut contents revealed numerous disarticulated arthropod remains, indicating that the feeding habits of the species are broadly similar to those of T. longipinnis. The species were also observed swimming in two other nearby spots in tributaries to the córrego Picada Comprida, but were not seen in four additional collection points in the same stream system and their distribution seems to be patchy (Ref. 85858). |
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Critically Endangered (CR); Date assessed: 07 November 2018 (B2ab(iii)) Ref. (130435)
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| harmless |
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