Saturday, April 18, 2015

[Ichthyology • 2015] Taxonomy of Chain Danio, an Indo-Myanmar Species Assemblage (Teleostei: Cyprinidae), with Descriptions of Four New Species

Danio dangila is widely distributed in the Ganga and lower Brahmaputra basins of India, Nepal and Bangladesh and distinguished by the cleithral spot in the shape of a short vertical stripe (vs. a round spot in all similar species). Four new species are described, similar to D. dangila but with round cleithral spot and each diagnosed by species specific colour pattern. Danio assamila, new species, is reported from the upper and middle Brahmaputra drainage in India. Danio catenatus, new species, and D. concatenatus, new species, occur in rivers of the western slope of the Rakhine Yoma, Myanmar. Danio sysphigmatus, new species, occurs in the Sittaung drainage and small coastal drainages in southeastern Myanmar. Those five species, collectively referred to as chain danios, make up a distinctive group within Danio, diagnosed by elevated number of unbranched dorsal-fin rays, long rostral and maxillary barbels, complete lateral line, presence of a prominent cleithral spot, horizontal stripes modified into series of rings formed by vertical bars between horizontal dark stripes, and pectoral and pelvic fins each with the unbranched first ray prolonged and reaching well beyond the rest of the fin. Danio meghalayensis is resurrected from the synonymy of D. dangila, with D. deyi as a probable junior synonym. Danio meghalayensis has a colour pattern similar to that of chain danios with vertical bars bridging parallel horizontal stripes but usually predominantly stripes instead of series of rings, a smaller cleithral spot and shorter barbels, and the unbranched ray in the pectoral and pelvic fins is not prolonged. Danio meghalayensis is known only from the Brahmaputra drainage in Meghalaya, India. The geographical distribution of the chain danios represents a unique pattern for the region, and may be explained by different climate and river drainage systems during the latest glacial period.

Kullander, S.O. 2015. Taxonomy of Chain Danio, an Indo-Myanmar Species Assemblage, with Descriptions of Four New Species (Teleostei: Cyprinidae). Ichthyological Exploration of Freshwaters. 25 (4): 357–380.