Occurrence of Two New Plateauindicator Loaches of Nemacheilinae (Balitoridae) in Guangxi with Reference to Zoogeographical Significance

Two new loaches of subfamily Nemacheilinae have been recognized on basis of collections from Hongshuihe River,a tributary of Xijiang in Du an County,Guangxi,China.All type specimens of Yunnanilus pulcherrimus sp.nov.(Holotype:KIZ 995001,39.6 mm SL) were collected from an underground river,and had diagnosis characters:dorsal-fin 3,8-9 (occasionally 3,9);anal-fin 3,5-6 (occasionally 3,6);pectoral-fin 1,8-10;pelvic-fin 1,6-7 (occasionally 1,6);branched caudalfin rays 14-16 (occasionally 14);gill rakers 11-12 on the inner side of 1st gill arch;vertebrae (1 ex.) 4+29.The new species is closely related to Yunnanilus pleurotaenia (Regan,1904) in length of lateral-line,pattern of scale coverage,count of fin rays,shape of caudal-fin and length of rostral barbels,but can be distinguished from all congeners by its unique color pattern and the elongated papillae on upper and lower lips,and can be further distinguished from Y.Pleurotaenia by some morphometric characters:standard length/body depth 4.3-5.6 (5.0) vs.3.9-4.9 (4.2),standard length/head length 4.4-5.1 (4.7) vs.3.7-3.9 (3.8),standard length/caudal-peduncle length 5.7-7.1 (6.3) vs.7.7-9.1 (8.4),head length/snout length 2.7-3.5 (3.0) vs.2.5-2.8 (2.6),caudal-peduncle length/depth 1.2-1.7 (1.4) vs.1.1-1.2 (1.1).All type specimens of Triplophysa flavicorpus sp.nov.(Holotype:KIZ 995004,76.4 mm SL) were diagnosticated by characters:dorsal-fin 3,10;anal-fin 3,6-7;pectoral-fin 1,11;pelvic-fin 1,6-7 (occasionally 1,6);branched caudal-fin rays 8+8;gill rakers 5-9 on the outer side and 11-12 on the inner side of 1st gill arch;vertebrae (1 ex.) 4+34.The new triplophysid species is closely related to Triplophysa nandanensis Lan et al.1995 by dorsal-fin origin at mid point of body,lateral-line complete and deep forked caudal-fin,and can be easily distinguished from all congeners by following characters:10 branched dorsal fin rays,6-7 branched anal fin rays,body covered by tiny scales,lateral-line complete,6-7 broad vertical bars on body and 1 narrow longitudinal stripe along lateral-line,caudal-fin deeply forked,a large black spot on caudal-fin base,2 black bars on both lobes of caudal-fin,posterior tip of pelvic-fin surpasses anus,a developed axillary lobe present at pelvic-fin base,upper lip completely interrupted at the middle.Both genera of Yunnanilus and Triplophysa are plateaus-indicator fishes.The genus of Yunnanilus is endemic to the eastern Yunnan Plateau.The genus of Triplophysa occurs mainly in Qinghai-Tibet Plateau.The geographical location of the two new loach species in Guangxi are far away from the distribution centers of their genera.Their distribution patterns are obviously disjunct.A preliminary phylogenetic analysis on both new species and their relatives demonstrates that disjunct patterns might have been yielded by vicariant mode of speciations.