广西云南鳅属鱼类一新种记述

A New Nemacheiline Loach of Genus Yunnanilus (Balitoridae) from Guangxi,China

2003年5月,在广西壮族自治区都安县高岭乡红水河水系采集到一批条鳅标本。经鉴定,为云南鳅属(Yunnanilius)一未经发表的新种。新种长须云南鳅(Yunnanilus longibarbatus sp.nov.)属于黑斑云南鳅种组(Yunnanilus nigromaculatusgroup),并与黑斑云南鳅[Y.nigromaculatus(Regan)]、钝吻云南鳅(Y.obtusirostris Yang)、长背云南鳅(Y.longidorsalisLi,Tao et Lu)和巴江云南鳅(Y.bajingensisLi)等4种最为相似。长背云南鳅背鳍分枝鳍条11根,颌须短,仅达眼中部,背鳍起点距吻端较距尾鳍基为近,可与包括本种在内的其余4种相区别(背鳍分枝鳍条8-9根,颌须达到或超过眼后缘,背鳍起点距吻端较距尾鳍基为远)。本种和钝吻云南鳅上颌中央无齿状突、下颌中央无缺刻,可与黑斑云南鳅和巴江云南鳅相区别。本种在鳍条数、上下颌、背鳍起点的位置、尾鳍形状、鳞片、头部侧线管孔、体侧纵纹等方面与钝吻云南鳅最为相似,但本种可藉多个特征与后者相区别:颌须伸过眼后缘至鳃盖后缘的中点至鳃盖后缘,是已知云南鳅中须最长的;背鳍不分枝鳍条下1/3处具一不显著黑色斑点(vs.无斑);体侧纵纹,其宽窄于眼径,较大个体背鳍之前的纵纹被虫状纹取代(vs.体侧纵纹始终存在,其宽约等于眼径);头背具斑点(vs.无斑);尾柄较细长,体长/尾柄长=5.3-6.1(vs.7.4-9.0,尾柄长/尾柄高=1.3-1.8vs.0.8-1.1)。

A nemacheiline loach Yunnanilus longibarbatus sp. nov. （Holotype： KIZ 2003050255, 52.6mm SL） has been recognized based on collections from a Hongshui River Drainage in Gaoling Township, Du-An county, Guangxi, China, in May 2003. Yunnanilus longibarbatus is a new member of the Yunnanilus nigromaculatus group and is closely related to Y.nigromaculatus （Regan）, Y.obtusirostris Yang, Y.longidorsalis Li et al and Y.bajingensis Li. Yunnanilus longidorsalis can be distinguished from the other species using the following characters： branched dorsal fin rays 11 vs. 8-9; maxillary barbel only reaching mid-eye vs. posterior edge of eye; and dorsal-fin origin closer to snout tip than caudal-fin base vs. vice versa. Yunnanilus longibarbatus and Y. obtusirostris have neither a precessus dentiformis on the upper jaw nor a median notch on the lower jaw, making them different from Y. nigromaculatus and Y. bajingensis. Yunnanilus longibarbatus is most closely related to Y. obtusirostris through sharing many features, such as： fin-ray count; jaw structure; position of dorsal-fin; shape of caudal- fin; coverage of scales; absence of cephalic lateral line system; and presence of a lateral stripe on the body. Yunnanilus longibarbatus can be distinguished from Y. obtusirostris using the following characters： maxillary barbel reaching to the posterior edge of the opercle, making it the longest barbel in the genus Yunnanilus; presence of a non-prominent dark spot on the lower 1/3 unbranched dorsal-fin rays; lateral stripe width smaller than eye diameter vs. almost equal; lateral stripe on anterior body dissolved into blotches in large-sized specimens vs. not dissolved; has dots on dorsal head vs. absent; caudal-peduncle slender, with length 5.3-6.1 times the standard length vs. 7.4-9.0 and length 1.3-1.8 times its depth vs. 0.8-1.1.