Epalzeorhynchos Bleeker

E Zhang & Maurice Kottelat, 2006, Akrokolioplax, a new genus of Southeast Asian labeonine fishes (Teleostei: Cyprinidae)., Zootaxa 1225, pp. 21-30 : 21-22

[[ Genus Epalzeorhynchos Bleeker ]]

The Labeoninae (sensu Chen et al., 1984), which is essentially equivalent to the Labeines of Reid (1982) or the tribe Labeone (= Labeonini) of Rainboth (1991, 1996), includes cyprinid fishes widely distributed in the fresh waters of tropical Africa and Asia. Most of these fishes are adapted to fast flowing waters. Members of this subfamily show a high degree of morphological modification in oromandibular structures, which is the basis for recognition of most of its included genera. To date, twenty-seven Labeonine genera have been recognized from eastern and southeastern Asia (Rainboth, 1991; Zhang & Chen, 2004). Among these, Epalzeorhynchos Bleeker, 1855 (type species: Barbus kalopterus Bleeker, 1851 ) is diagnosed by having a pair of moveable lateral lobes on the snout, which are also called “fleshy rostral papilla” (Roberts, 1989) or “posteriorly free lateral lobes” (Yang & Winterbottom, 1998). Five valid species have so far been identified in Epalzeorhynchos : E. bicolor , E. bicornis , E. frenatus , E. kalopterus , and E. munensis .

Epalzeorhynchos bicornis was described by Wu et al. (1977), based on a single 140 mm SL specimen from the upper Salween River (= Nu Jiang in Chinese) basin in Liuku County, Yunnan Province, China. Although E. bicornis is currently regarded as valid (Chu & Cui, 1989; Chen, 1998; Zhang et al., 2000), its generic position is still unclear. Kottelat (1989) commented that E. bicornis does not belong in Epalzeorhynchos , but did not elaborate further. Yang and Winterbottom (1998) investigated the relationships among the five currently identified species of Epalzeorhynchos . They demonstrated that E. bicornis is sister to Paracrossochilus when Crossocheilus is used as the outgroup, and that it is basal to the clade that includes Crossocheilus and other species of Epalzeorhynchos , when Paracrossochilus is utilized as the outgroup. These findings led Yang and Winterbottom to conclude that E. bicornis should not be placed in Epalzeorhynchos , but they stopped short of erecting a new genus for its reception.

Kottelat’s (1989) and Yang and Winterbottom’s (1998) observation that E. bicornis is not immediately associated with the other species of Epalzeorhynchos is corroborated by marked differences we found in position and structure of the moveable lateral lobes on the snout and the morphology of the oromandibular structures. Morphology of the oromandibular structures is diagnostic for many Labeoninae genera (Zhang et al., 2000; Zhang & Chen, 2004), and the differences we observed among species of Epalzeorhynchos indicate that E. bicornis belongs to a distinct genus, which we describe and name in the present paper.