广西鲇属一新种及其性状讨论(鲇形目,鲇科)

A NEW SPECIES OF THE GENUS DUANENSIS (SILURIFORMES, SILURIDAE) FROM GUANGXI, CHINA

根据采自广西都安县的 1 6尾鲇类标本鉴定描记了鲇属鱼类 1新种 ,即都安鲇Silurusduanensissp .nov .。新种具有下颌突出于上颌 ,背鳍条i 3,臀鳍条数较少 ;颌须长 ;犁骨齿带分成两片 ;胸鳍硬刺前缘有颗粒状突起 ,后缘有明显的锯齿 ;后鼻孔呈短管状 ,且呈圆形张开等综合特征。

In the present paper, we describe a new species Silurus duanensis sp. nov. of the genus Silurus based on 16 specimens collected from Guangxi,China. The new species differs from its congeners by having following combination characters: D. i 3, A. 55 63, maxillary barbels much surpassing backwards the base of pectoral fin, vomerine teeth patches separated into two elliptical parts, the pectoral spine wi thout clear serration on its fore margin, the posterior nostril round and open. We also revise the key to the Chinese species of the genus Silurus. Silurus duanensis sp. nov. (Figs 1 2) Holotype. No. ASIZB73176, total length 374?mm, standard length 341?mm, collected from underground rivers of Disu Town (23°34′N, 108°01′E), Du′an County, Guangxi, where belongs to the Hongshui River of the Pear River Basin, in May 1996. Paratypes. Nos. ASIZB73172 73, 73175, total length 215 361?mm, standard length 176 319?mm, the collection data is as the holotype; ASIZB73174, total length 302?mm, standard length 278?mm, collected in May 2001 in the same collection site as the holotype; ASIZB73317 18, total length 82 85?mm, standard length 72 76?mm, collected in May 2001 in the same collection site as the holotype; ASIZB73319 27,total length 100 123?mm, standard length 86 108?mm, collected in June 2001 in the same collection site as the holotype. All the type specimens are kept in the Fish Collection of the Institute of Zoology, Chinese Academy of Sciences, Beijing. D. i 3; P. i 11 14; V. i 8 12; A. ii 55 63. gill rakers 10 12, vertebrae 4+56 57. Depth of body 5 6 (5 3 6 0), length of head 4 5 (4 3 4 7), length of predorsal 3 1 (3 0 3 2) in standard length. Length of snout 2 6 (2 5 3 0), diameter of eye 10 5 (8 7 12 8), interorbital length 1 7 (1 5 2 0), width of head 1 2 (1 1 1 3) in head length. Depth of caudal peduncle 3 3 (2 9 3 6) in depth of body. The new species differs clear from S. gilberti and S. cochinchinensis but similar to the other species of the genus distributed in China by having longer lower jaw than upper jaw. And the new species can be separated from the other species by the following comparison. 1) The new species shares the common character in having 3 branched dorsal fin rays with S. microdorsalis, but later was only found in Yalu River basin in Northern China and the two species are also very different in appearance. 2) The mouth split of the new species only reaches backwards to the position under the fore margin of the eyes and the length of the two labels of the caudal fin is almost equal, which differs from S. meridionalis and S. soldatovi (mouth split reaching backwards to the position under the middle point of eyes or more back and length of upper label of caudal fin longer than lower label). 3) The new species differs from S. asotus but similar to S. mento, S. grahami and S. lanzhouensis in having the two separated elliptical patches of vomerine teeth (vs continuous vomerine teeth patches in S. asotus ) and without clear serration on fore margin of pectoral fins (vs clear serration in S. asotus). 4) The new species differs from S. lanzhouensis in having less branched anal fin rays and vertebrata (55 63 and 56 57 vs 77 86 and 63 66, respectively); differs from S. mento in having maxillary barbels much surpassing backwards base of pectoral fin (vs at most reaching base of pectoral fin in S. mento ); differs from S. grahami in having invisible teeth patch of the lower jaw when the mouth closed (vs visible teeth patch of the lower jaw when the mouth closed in S. grahami ) (Table 1).