Revision of the Pangasius kunyit catfish complex, with description of two new species from South-East Asia (Siluriformes; Pangasiidae)

Abstract

A detailed morphological and molecular analysis was carried out on the widespread catfish species Pangasius kunyit from South-East Asia. Results revealed the presence of two new species: Pangasius sabahensis sp. n. is described from the Kinabatangan River Basin (North Borneo, Sabah State, Malaysia) and P. mekongensis sp. n. is described from the lower Mekong River (Vietnam). These new species, which belong to the subgenus Pangasius (Pangasius), are morphologically and genetically closely related to P. kunyit sensu stricto. Pangasius sabahensis sp. n. is distinguished from the other species in the subgenus in the combination of the following characters: a broad and rounded head (snout length 44.2–49.6% HL; head depth 11.8–14.0% SL; head width 15.2–18.3% SL); the short distance from the snout to the isthmus (90.9–102.8% SNL); the long mandibular (56.0–66.0% HL) and maxillary barbels (77.6–96.7% HL); the slender dorsal spine (width 4.4–5.7% SL); the short palatine toothplates (length 6.4–10.0% HL); and the presence of 19-23 gill rakers on the first branchial arch. Pangasius mekongensis sp. n. is characterized by the combination of a long, broad and rounded head with an elongated snout (head length 22.1–26.9% SL; head depth 11.3–13.9% SL; head width 14.8–20.0% SL; snout length 43.4–54.0% HL); the short distance from the snout to the isthmus (88.4–102.4% SNL); a robust dorsal spine (width 6.6–8.7% HL); the short palatine toothplates (length 6.6–12.8% HL); and the possession of 16–23 gill rakers. Pangasius kunyit is re-described. It differs from the newly described species and other congeners by a higher number of gill rakers on the first branchial arch (24–32). The distribution of the species is restricted to Sumatra and Central (Tengah), East (Timur) and West (Barat) Kalimantan (Indonesia).