Taxonomic revision on the genus Abbottina Jordan & Fowler, 1903 (Cypriniformes, Gobionidae)

The genus Abbottina Jordan & Fowler, 1903 comprises small benthic gobionid fishes widely distributed in East Asia. However, due to the unclear generic characteristics as defined in the original description, the taxonomic status of the species within this genus remains controversial, and its definition needs clarification. This study examined the morphology of the type species, Abbottina rivularis (Basilewsky, 1855), to more accurately redefine generic characteristics. The genus Abbottina can be distinguished from all other gobionid genera by the following characteristics: mouth inferior; lips thick, relatively smooth, with small less-developed papillae or shallow grooves; lower lip with anterior fold, medial pad forming two oval protuberances; jaws covered by lips, without horny margin; barbel one pair; the last unbranched dorsal-fin ray thin and soft; with five branched anal-fin rays; pharyngeal teeth in one row; air-bladder moderately large, possessing two soft chambers; anterior chamber enclosed in membrane capsule. Based on morphological characters and phylogeny of mitochondrial genome sequences, Abbottina lalinensis has been reassigned to the genus Microphysogobio. Further, based on the morphology of Abbottina binhi from Cao Bàng Province, this species is reassigned to the genus Oriengobio. Thus, the genus Abbottina becomes a monotypic genus.