Accepted by R. Pethiyagoda: 27 Jun. 2009; published: 21 Jul. 2009 41 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2009 · Magnolia Press Zootaxa 2164: 41–48 (2009) www.mapress.com/ zootaxa/ Article Danio aesculapii, a new species of danio from south-western Myanmar (Teleostei: Cyprinidae) SVEN O. KULLANDER & FANG FANG Department of Vertebrate Zoology, Swedish Museum of Natural History, PO Box 50007, SE-104 05 Stockholm, Sweden. E-mail: sven.kullander@nrm.se; fang.kullander@nrm.se Abstract Danio aesculapii, new species, is described from small rivers on the western slope of the Rakhine Yoma in south-western Myanmar. It is superficially similar to D. choprae from northern Myanmar in having a series of vertical bars anteriorly on the side, but differs from it and other species of Danio in having six instead of seven or more branched dorsal-fin rays, and from all other species of Danio except D. erythromicron and D. kerri in having 12 instead of 10 or 14 circumpeduncular scale rows. Key words: Rakhine Yoma, Thandwe, Danio choprae, endemism Introduction The cyprinid fish genus Danio Hamilton includes 14 small species in South and Southeast Asia (Kullander et al. 2009), as a rule diagnosable by distinct species-specific colour patterns. About half of the species of Danio have a pigment pattern that consists of one or more dark or light horizontal stripes (Fang, 1998). Among the others, Danio kyathit Fang differs in having the stripes broken up into rows of small brown spots, D. margaritatus (Roberts) has a pattern of small light spots on the sides, D. dangila (Hamilton) has rows of dark rings with light centres, and D. choprae Hora and D. erythromicron (Annandale) possess a distinct pattern of vertical bars. Danio choprae was described by Hora (1928) from near Myitkyina in the upper Ayeyarwaddy River drainage, and noted to have a very characteristic colour pattern, including several dark vertical bars anteriorly on the side. Later, Hora (1937) reported another four specimens, this time in a collection made in Sandoway, located on the west coast of Myanmar, in the Rakhine State and presently known as Thandwe. Hora’s (1937) identification appears to have been focused on the vertical bars, and he noticed differences in other colour marks and lateral line development from the type series of D. choprae. Collections from near Thandwe made in 1998 included many specimens of a very small species with a diffuse pattern of vertical bars, similar to D. choprae, and agreeing with the figure of D. choprae reported by Hora (1937: fig 2) from Thandwe (Fig. 1). In the meantime, this species was also imported to Europe as aquarium fish with the code names “pantheri”, “snakeskin”, and “TW03”, and further collected to the north and south of Thandwe. This paper is dedicated to the formal description of this species. Material and methods Specimens were fixed in formalin in the field, eventually transferred to 70 % ethanol for storage, and are kept in the fish collection of the Swedish Museum of Natural History, Stockholm (NRM) or the Natural History