方口鲃属鱼类一新种(鲤形目:鲤科)

本文记述采自云南的鲤科鱼类一新种。Sauvage(1878)以上下唇具乳突等特征建立了方口鲃属Cosmochilus,迄今共3个种。新种命名为南腊方口鲃C.nanlaensis sp.nov.以乳突不发达、呈绒毛状;第一鳃弓鳃耙稀疏;上颌须呈退化状,口角须亦不发达;背鳍末根不分枝鳍条较短;侧线鳞数目偏少等特征易与本属其他种类相区别。文末附本属鱼类之检索表。

ON A NEW CYPRINID FISH OF THE GENUS COSMOCHILUS SAUVAGE FROM YUNNAN, CHINA (CYPRINIFORMES: CYPRINIDAE)

A species of the genus Cosmochilus is given as new to science in the present paper and briefly described as follows:Cosmochilus nanlaensis, sp. nov. (fig. 1)Holotype No.88XI0836, total body length 105 ram. standard body length 80 mm. Para-types 3 specimens, total body length 42-86 mm, standard body length 32-66 mm, They are all collected from Mengla County, Yunnan Province, belonging to Mekong River system. Syn-types are kept in the Freshwater Fish Museum of the Institute of Hydrobiology, Academia Sinica.D. iv-8; A. iii-5; P. i-14; V. i-9-10. Scales in L. 1. 32 4.V/6.5 35; predorsal scales 13-14;circumpedunculer scales 16. Gill-rakers 6 (outer) and 8-9 (inner). Lower pharyngeal teeth 2.3.5-5.3.2. Vertebrate 4+29-30.Depth of body contained in body length 3.1-3.4, length of head 3.6-3.7, length of caudal peduncle 6.4-7.1, its depth 7.6-8.0 Length of snout contained in length of head 3.3-3.7, diameter of eye 3.0-3.7, interobital space 3.0-3.3, width of head 2.0-2.3. Depth of caudale peduncle contained in its length 1.1-1.2.The new species differs from the other species of the genus in: (1) the papillae of lips undeveloped; (2) the gill-raker of the first gill arch very sparse and short; (3) the rostral barbels very undeveloped and the maxillary barbels not developed neither; (4) length of the last simple dorsal fin ray equal to or slightly shorter than length of head; (5) the number of scales in a longirudinal series 32-35.