A new species of Silvinichthys (Siluriformes, Trichomycteridae) lacking pelvic fins from mid‐elevation localities of the southern Andes, with comments on the genus

Abstract

Silvinichthys huachi new species, is described from a stream along the lower slope of the Andean Cordillera in the Provincia de San Juan, Argentina. It shares the distinctive modifications characteristic of Silvinichthys, but is distinguished from the four previously described congeners by the combination of a lack of the pelvic fin and the pelvic girdle, details of pigmentation and various meristic and morphometric features. Silvinichthys huachi is apparently endemic to the type locality situated within an arid region of western central Argentina in the Andino Cuyana Province. Major gaps in the range of species of Silvinichthys may indicate that the origin of the genus predates the uplift events that subdivided drainages along the eastern slopes of the Andean Cordillera in west central Argentina. Silvinichthys huachi is hypothesized to be the sister species of Silvinichthys bortayro.

The Laterosensory Canal System in Epigean and Subterranean Ituglanis (Siluriformes: Trichomycteridae), With Comments About Troglomorphism and the Phylogeny of the Genus

“…In Eremophilus and Scleronema the nasal canal is variably present (Arratia and Huaquin, ; DoNascimiento et al, ). In Silvinichthys , the frontal canal is absent, and the nasal canal is present in S. mendozensis, S. leoncitensis , and S. gualcamayo , but is absent in S. bortayro and S. huaichi (Arratia, ; Fernández and de Pinna, ; Fernandez et al, ). In the more speciose genera of the subfamily, Trichomycterus and Ituglanis , the canals may be continuous or interrupted.…”

“…When reductions or absences of one or more of these canals occur, they involve mostly the otic canal only. For instance, in Silvinichthys , the otic canal is absent and the laterosensory system is comprised usually of the postotic and scapular canals, plus the nasal and a very short trunk canal (Arratia, ; Fernández and de Pinna, ; Fernandez et al, ). Within Ituglanis , reductions and absences occur only in the more troglomorphic subterranean species: I. bambui (otic absent in a few specimens), I. ramiroi (otic absent or reduced in some specimens), I. passensis (otic canal reduced in all specimens), and I. epikarsticus (otic usually absent).…”

Description of Silvinichthys pedernalensis n. sp. (Teleostei, Siluriformes) from the Andean Cordillera of southern South America

“…The genus Silvinichthys was erected by Arratia (1998) for a species previously placed in Trichomycterus (T. mendozensis Arratia et al, 1978) mainly based on the reduction of the cephalic laterosensory canal system to the nasal portion of the supraorbital canal and the postotic canal and the entire skin surface perforated by pores of the ampullary organs. In later years, four new species of Silvinichthys have been described (Fernández et al, 2011(Fernández et al, , 2013(Fernández et al, , 2014 and other known new species await formal description. The genus inhabits headwaters and temporary endorrheic streams, characterized by cold waters and rocky bottom, and included one species from phreatic waters.…”

Trichomycterus alterus (Marini, Nichols & La Monte, 1933) and T. corduvensis Weyenberg 1877 (Siluriformes: Trichomycteridae): new records from the High Andean Plateau

“…However, they were not collected in high altitudes until now. Several genera of trichomycterid catfishes are endemic to the Andean Cordillera, such as Silvinichthys Arratia, 1998 (Argentina), Hatcheria Eigenmann, 1909 (Argentina and Chile), Rhizosomychthys (Miles, 1942) (Colombia), as well as many undescribed species of Trichomycterus Valenciennes, 1832 (Fernandez 2013;Fernandez et al 2014;Reis et al 2016). Trichomycterid catfishes are highly specialized for life in uplands along the Andean mountains, and they occur in a remarkable variety of environments, including temporary streams, subterranean drainages, high elevation streams, and warm thermal water (Fernandez & Vari 2012).…”

“…Unfortunately, the Argentine government has strong conservation policies directed to the protection of salmonids and catfishes are largely ignored (Fernandez 2005(Fernandez , 2013. On the other hand, it is difficult to provide reliable conservation recommendations for Andean catfishes when data-geographic distributionsare deficient (Fernandez et al 2014(Fernandez et al , 2017. Presently, contributions such as these new records are necessary for the establishment of protected areas and promotion of conservation programs in the High Andean Plateau.…”