Subterranean Fishes of the World

5238

1991

Proceedings of the Academy of Natural Sciences of Philadelphia

97-143

143

ABSTRACT.-The Pangasiidae comprises two genera, Pangasius Valenciennes, 1840 and Helicophagus Bleeker, 1858. Pangasianodon Chevey, 1930, Pteropangasius Fowler, 1937, and Sinopangasius Chang and Wu, 1965 are synonyms of Pangasius. Study of type specimens and other material of Pangasiidae (39 nominal species or subspecies) results in recognition of 18 previously described species as valid. Helicophagus hypophthalmus Sauvage, 1878 is a valid species of Panga- sius and senior synonym of P. sutchiFowler, 1937, which should henceforth be known as P. hypophthal- mus (Sauvage, 1878). Pteropangasius cultratus (Smith, 1931) and Sinopangasius semicultratus Chang and Wu, 1965 are synonyms of Pangasius pleurotaenia Sauvage, 1878 and Pangasius krempfi Fang and Chaux, 1949, respectively. Pangasius paucidens Fang and Chaux, 1949, P. ponderosus Herre and Myers, 1937, and P. tubbi Inger and Chin, 1959, are synonyms respectively of P. gigas (Chevey, 1930), P. nasutus Bleeker, 1862, and P. micronema Bleeker, 1847. Pangasius bocourti Sauvage, 1878 and P. djambal Bleeker, 1846 are valid species. Three new species are described, P. myanmar from Myanmar, P. conchophilus from the Chao Phraya and Mekong basins, and P. kinabatanganensis from northeastern Borneo, bringing to 21 the total number of species recognized in Pangasiidae. The generic type species, P. pangasius, is restricted to India, Pakistan, and Bangladesh, where it is the only pangasid, and Myanmar. Thailand has 11 species, Indonesia ten, and peninsular Malaysia only three. Four species are apparently endemic to the island of Borneo. Some species have extremely rapid growth, particularly P. gigas, which attains 300 kg or more and apparently can grow to at least 200 kg in its first three years. Apparent adaptations for rapid growth include voracious or gluttonous feeding behavior; specialized larval dentition; and abdomen, alimentary canal, and vent capable of exceptional expansion. Although most species are confined to fresh water, P. polyuranodon frequently occurs in brackish tidal reaches, and at least two species, P. pangasius and P. krempfi, occur in the sea. The latter species, previously known only from the South China Sea, is reported from the Mekong River for the first time. The molluscivorous genus Helicophagus comprises two species, H. wandersii Bleeker, 1858 from Sumatra and the Chao Phraya and Mekong basins, and H. typus Bleeker, 1858, from Sumatra and perhaps Borneo. They have marked differences in shape of oral and palatal toothbands and in numbers of gill rakers and anal fin rays. [distribution, food habits, Helicophagus, larvae, Pangasius, reproduction]

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