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Trichogenes claviger
Trichogenes claviger
Conservation status
Critically Endangered  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	Trichomycteridae
Subfamily:	Trichogeninae
Genus:	Trichogenes
Species:	T. claviger
Binomial name
Trichogenes claviger de Pinna, Helmer, Britski & Nunes, 2010

Trichogenes claviger is a critically endangered species of pencil catfish native to the Atlantic Forest of Brazil.

Taxonomy

Trichogenes claviger is one of three known species within the genus Trichogenes, and the second to be discovered and described. The first species of the genus, T. longipinnis, was described in 1983 from a very local population discovered in an remnant rainforest between the major cities Rio de Janeiro and São Paulo. T. longipinnis was long considered to be unique; a strikingly distinct fish that is not closely related to any other neotropical freshwater fish. Despite several surveys, the species has never been encountered in other areas, being restricted to an area less than 10 km across.

T. claviger was discovered in 2010 by biologists conducting an assessment of the biodiversity and environmental impact of an remnant rainforest in Vargem Alta, Espírito Santo, some 1200 km northeast of the T. claviger population. Specimens, including the holotype (specimen MBML 3289) and 17 paratypes, were collected in February 2010, and became part of the collections of the Museu de Biologia Mello Leitão (MBML) in Santa Teresa and the Museu de Zoologia da Universidade de São Paulo (MZUSP) in São Paulo. The species description was published later in 2010 by the Brazilian ichthyologist Mário C. C. de Pinna and colleagues. The generic name Trichogenes is composed of the words 'Tricho', referring to its family, the Trichomycteridae, and 'genes', referring to the genus Helogenes due to its superficial resemblance to the latter. The specific name claviger is Latin for 'club-bearing' and refers to the distinctive club-shaped hind part of the operculum seen in males.

In 2020, a third species, Trichogenes beagle, was described from three specimens in the collection of the MZUSP; these specimens lack location data and the place of occurrence of the species is unknown. Within its family, the Trichomycteridae (pencil catfishes), the genus Trichogenes is most closely related to the Copionodontinae, which are endemic to the Chapada Diamantina plateau in northeastern Brazil.

Habitat and distribution

The species is known from only from the Mata de Caetés (Caetés forest), a remnant of the Atlantic Forest, in Vargem Alta, Espírito Santo, Brazil. Here, the fish lives in small streams that are part of the catchment area of the Itapemirim River, which is isolated from other catchment areas. This forest is primary, mountainous rainforest interspersed with plantations of exotic trees. A second locality was discovered by a local farmer in 2019, nine years after the discovery of the species, some 4 or 5 km away. The occurrence of the species in the area appears to be patchy.

The type locality, where it was first discovered, is a small shaded stream named Picada Comprida, within primary rainforest at an altitude of around 1150 m. The stream is ca. 30 cm deep, slow flowing and has brown but clear water. The stream bed is sandy but partly covered with dead leaves and other organic material. The fishes tend to dwell in the middle of the water column. It is the only species of fish to occur at the locality.

Ecology

The species feeds on arthropods, as is the case with the related T. longipinnis.

Status, Conservation, and Threats

T. claviger has been classified as Critically Endangered globally by the International Union for Conservation of Nature (IUCN) since 2018. Since 2014, it is also listed as Critically Endangered in the Livro Vermelho, the Regional Red List of Brazil.

Forno Grande farm

References

1. ^ Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) (2022). "Trichogenes claviger". IUCN Red List of Threatened Species. 2022. doi:10.2305/IUCN.UK.2022-1.RLTS.T141159992A141159997.pt. Retrieved 16 December 2024.
2. ^ Pinna, Mário C. C. de; Helmer, José Luiz; Britski, Heraldo A.; Nunes, Leandro Rodrigues (2010). "A new species of Trichogenes from the rio Itapemirim drainage, southeastern Brazil, with comments on the monophyly of the genus (Siluriformes: Trichomycteridae)". Neotropical Ichthyology. 8: 707–717. doi:10.1590/S1679-62252010000400002.
3. ^ Silva, Juliana Paulo; Sarmento-Soares, Luisa Maria; Tonini, Lorena; Freitas, Joelcio (2023). "The contribution of local people to species conservation: the case of the catfish Trichogenes claviger in south-east Brazil". Oryx. 57 (6): 693–693. doi:10.1017/S0030605323000893.
4. Britski, H. A.; Ortega, H. (1983). "Trichogenes longipinnis, novo gênero e espécie de Trichomycterinae do sudeste do Brasil (Pisces, Siluriformes)" [Trichogenes longipinnis, a new genus and species of the Trichomycterinae from the southeast of Brazil (Pisces, Siluriformes)] (PDF). Revista Brasileira de Zoologia (in Portuguese). 1 (3): 211–216. doi:10.1590/s0101-81751982000300011.
5. Pinna, Mário C. C. de; Reis, Vinícius (Vinícius José Carvalho); Britski, Heraldo A. (2020). "A new species of Trichogenes (Siluriformes, Trichomycteridae), with a discussion on the homologies of the anterior orbital bones in trichomycterids and other loricarioids". American Museum Novitates (3951). hdl:2246/7115.
6. Livro Vermelho da Fauna Brasileira Ameaçada de Extinção - Volume I (PDF). Instituto Chico Mendes – ICMBio. 18 August 2023. ISBN 978-85-61842-79-6.

• IUCN Red List critically endangered species