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Silva, JP, et al. 2023 (1) Gustavo Magnago (2)

Description: 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). 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 (de Pinna et al 2010). Colouration: A 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). Habitat: 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. 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 (de Pinna et al 2010). Diet: Gut contents revealed numerous disarticulated arthropod remains, indicating that the feeding habits of the species are broadly similar to those of T. longipinnis (de Pinna et al 2010). Etymology: The genus name Trichogenes: meaning A combination of tricho– from Trichomycteridae and –genes from the cetopsid catfishes of Helogenes, referring to superficial resemblance to that genus (specifically, the long anal fin). The specific name claviger: clavus, club; -iger, to bear, referring to peculiar shape of hypertrophied posterior process of opercle in males. Remarks: Trichogenes claviger was recorded at two points in the Picada Comprida stream, Itapemirim river basin, municipality of Castelo, state of Espírito Santo. The species does not occur in larger water bodies in the region. The geographic distribution of T. claviger is certainly restricted, as typically occurs in Trichogeninae. Thus, its area of occupation (AOO) is 8 km 2 . The species occurs in a private area under considerable impact, outside a conservation unit, although it is located between two state parks. The site has altered vegetation, with Pinus sp. and satellite images show that several roads, including a highway, cross the region, and also reveal several points of deforestation; There are also civil constructions on site. The species was collected in an environmental impact study, carried out for enterprise licensing purposes, located in a single location. Therefore, it is assumed that environmental changes in this single location will continue to occur, leading to continued decline in habitat quality. For these reasons, Trichogenes claviger has been categorized as Critically Endangered (CR) by the B2ab(iii) criteria (IUCN). Note: In the paper "The contribution of local people to species conservation: the case of the catfish Trichogenes claviger in south-east Brazil" (2023) a farmer found this species. In May 2023, a local farmer reported its presence in a new location harbouring hundreds of individuals, highlighting the importance of engaging local communities in conservation. Read more in the reference link below.

Venezuelan parasitic catfish

None

Trichomycteridae

South America: Headwaters of the Rio Itapemirim drainage, southeastern Brazil, (only known from the type locality-see note above).

5.0cm. (2ins)

25-28°c (77-83°f.)

6.0-7.0.

de Pinna, M.C.C., J.L. Helmer, H.A. Britski and L.R. Nunes, 2010. A new species of Trichogenes from the rio Itapemirim drainage, southeastern Brazil, with comments on the monophyly of the genus (Siluriformes: Trichomycteridae). Neotrop. Ichthyol. 8(4):707-717.
Fish in the News (2024)
Froese, R. and D. Pauly. Editors. 2023. FishBase. World Wide Web electronic publication. www.fishbase.org, ( 10/2023 ).
Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio). 2022. Trichogenes claviger. The IUCN Red List of Threatened Species 2022.
Oryx—The International Journal of Conservation: "The contribution of local people to species conservation: the case of the catfish Trichogenes claviger in south-east Brazil" (2023).
The ETYFish Project Fish Name Etymology Database © Christopher Scharpf.