The Irrawaddy River crosses international borders throughout South-Eastern Asia, though several heads of different streams connected to the river are found in China. In the present study, two species never previously described were identified during taxonomic works on Schizothorax species distributed in the Irrawaddy drainage area in China, and were named Schizothorax leukus sp. nov. and Schizothorax heteri sp. nov. Schizothorax leukus can be distinguished from its congeners by a combination of the following characters: surface of lower lip covered with papilla, posterior edge of lower lip straight; low jaw developed, almost full the oral cavity, anterior edge of low jaw covered with horny sheath; breast and belly before pectoral-fin tip scaleless; barbels equal to eye diameter; last un-branched dorsal fin ray soft, lower third of the ray enlarged with posterior edge serrated; lateral line scales 94-105, scales between dorsal-fin origin to lateral line 26-34, scales between pelvic-fin origin to lateral line 21-27; outer side of the first gill arch with 16-20 gill rakers; body dark brown, without dark spots. Schizothorax heteri can be distinguished from its congeners by a combination of the following characters: rostral fold equal to upper lip; lower lip developed, trilobed, the median lobe minute, its width equal to diameter of the rostral barbel base; postlabial groove continuous; low jaw without horny sheath; breast and belly before pectoral-fin tip scaleless; barbels equal to eye diameter; last un-branched dorsal fin ray strong, posterior edge serrated; dorsal-fin origin posterior to pelvic-fin origin; lateral line scales 89-104, scales between dorsal-fin origin to lateral line 24-33, scales between pelvic-fin origin to lateral line 19-29; body light brown, without any spots. Likewise, we discuss the validation of S. rotundimaxillaris and the questionable records of S. molesworthi, S. griseus and S. paoshanensis. In total, eight valid species of Schizothorax were found and recorded from the Chinese Irrawaddy drainage area, with a key for identification is provided.
该文对伊洛瓦底江水系的裂腹鱼属进行分类订正。发现了两种未被描记的鱼类新种, 即白体裂腹鱼(Schizothorax leukus sp. nov.)和奇异裂腹鱼(Schizothorax heteri sp. nov.)。白体裂腹鱼下唇完整不分叶、表面具发达乳突, 下唇后缘平直呈横带形;下颌内侧角质突起甚厚, 充满整个口腔, 角质前缘锐利;胸鳍末端之前的峡部和腹部裸露无鳞;须长约等于眼径;背鳍末根不分枝鳍条较软, 基部~1/3扩大变硬、后缘具明显锯齿;侧线鳞94~105, 侧线上鳞26~34, 侧线下鳞21~27;第一鳃弓外侧鳃耙16~20;体侧暗褐色, 无明显黑斑。这些特征可将白体裂腹鱼与本属其他种类相区分。奇异裂腹鱼吻皮与上唇约等厚;下唇发达, 分三叶, 中间叶小, 约与触须基部直径相当;唇后沟连续;下颌无锐利角质;胸鳍末端之前的峡部和腹部裸露无鳞;须长约等于眼径;背鳍末根不分枝鳍条扩大, 为粗状的硬齿, 后缘具强锯齿;背鳍起点位于腹鳍起点之后;侧线鳞89~104, 侧线上鳞24~33, 侧线下鳞19~29;通体浅灰色, 体侧无斑纹;这些特征可将白体裂腹鱼与本属其他种类相区分。该研究否定了圆颌裂腹鱼(S. rotundimaxillaris)的有效性, 澄清了墨脱裂腹鱼(S. molesworthi)、灰裂腹鱼(S. griseus)和保山裂腹鱼(S. paoshanensis )等在伊洛瓦底江水系的记录均属误订, 确定该水系中国境内裂腹鱼属有效种为8种, 并制定了伊洛瓦底江裂腹鱼属种检索表。
Keywords: Irrawaddy River; Schizothorax; Taxonomy; Yunnan.