Danio annulosus, a new species of chain Danio from the Shuvolong Falls in Bangladesh (Teleostei: Cyprinidae: Danioninae).

Danio annulosus, new species, is described from a small pool below the Shuvolong Falls in the Kaptai Lake system in Bangladesh. It shares with chain danios (D. assamila, D. dangila, D. catenatus, D. concatenatus, and D. sysphigmatus) a colour pattern consisting of series of dark rings with light interspaces along the side, complete lateral line, 14 circumpeduncular scales, a produced first ray in the pectoral fin, and a black humeral spot. It differs from other chain danios in possessing much shorter pectoral and pelvic fins, and a humeral spot that is slightly wider than deep instead of round or deeper than wide. The mitochondrial cytochrome c oxidase subunit I (COI) sequence separates D. annulosus from the most similar species, D. catenatus by a p-distance of 3.4%. Although recorded from only a single locality, Danio annulosus is expected to have a wider distribution in the Karnafuli River drainage.