Morphological character and karyotype of Ptychidio jordani Myers in Pearl River

Ratmouth barbell (Ptychio jordani Myers) is a member of the family Cyprinidae and mainly distributes in Pear River of southern China, especially in Xijiang River – the branch of Pearl River. It has high values for food and for aquaculture in China. In this paper, the morphology and karyotype of ratmouth barbell collected from Pearl River were studied and analyzed. More than 450 individuals length from 165mm to 236mm and weight from 167.8g to 586.3g were collected from Pearl River in Zhaoqian, Yunan, Guiping and Liuzhou. Two kinds of shape of ratmouth barbell were found. One has a high back mainly come from Guiping and lower reaches of Pearl River and another has a calm back come from Liuzhou and upper reaches of Pearl River. There are three different colors, milk-white and yellow and brown, at abdomen of ratmouth barbell. No sexual differences in morphology were found. The mouth of ratmouth barbell is on the base of head and roll inside. The pharynx teeth are powerful and scale is middling size. The scale formula on lateral line is 37～46,5～8/5～6-A. Stomach is thin and the length of intestines is 1.36～1.51times of body length. There are 14 pairs ribs and 38～40 vertebras. The number of diploid chromosome is 2n=50 and the karyotype formula is 12m+16sm+18st+4t, NF=78.