I 



165 



Dorsal fin round, with one procurrent ray and eight rays. Anal fin small and slightly poin- 

 ted, originated at position slightly posterior the insertion of dorsal fin; with one procur- 

 rent ray, and eight rays. Caudal fin moderately forked (deeper than in P. brachyurus), with 

 four dorsal procurrent rays, four ventral procurrent rays, and 19 (10+9) principal rays. 

 Cephalic lateral line well-developed. Supratemporal canal and otic canal not interrupted, 

 each with four pores. Supraorbital canal not interrupted, except the area between the na- 

 sal and frontal portions, with 10 pores. Infraorbital canal not interrupted, with 10 pores. 

 Preopercular canal not interrupted, with seven pores. Mandibular canal with three pores. 

 Body lateral line short, the last pored scale about halfway between the posterior margin 

 of pectoral fin and base of pelvic fin; lateral line pored scales often 15. Abdomen anteri- 

 or to pelvic fin usually scaleless, but some specimens bear scales in posterior portion of 

 region between isthmus and pelvic fin base (Berg 1949). 



Pharyngeal bone moderately broad, both the posterior and anterior limbs slightly bent; pit- 

 ted surface broad, with six major fossae. Pharyngeal teeth in two rows, 5.1-1.5. Teeth slen- 

 der, hooked at tip in main row; without hooks in minor row. 

 Vertebrae 37, precaudal vertebrae 21, caudal vertebrae 16. 



Intestine short, shorter than standard length, simply looped. Gas bladder short and broad, 

 the anterior chamber almost equal to the posterior one in length, constriction short. Pneu- 

 matic duct connecting with the anterior portion of the posterior chamber. Peritoneum 

 slightly brown in color. 



Tuberculation. No detailed data about tuberculation of this species are available though 

 the male was hypothesized by Howes (1985) to bear tubercles on breast scales during 

 breeding season. According to Berg (1949), breeding males apparently lack tubercles on 

 the head. 



Coloration. A lateral dark stripe present along middle of sides of the body, extending 

 from dorsal end of gill cleft to caudal fin base. Stripe darker posteriorly, darkest on cau- 

 dal peduncle, and faintest anterior to pectoral fin. Some individuals with a few small dark 

 speckles on sides of body. The mid-dorsal dark stripe extending from nape to caudal fin 

 base. Melanophores present on entire body, except abdomen anterior to anal fin origin and 

 ventral side of the head. Few melanophores present on ventral side of caudal peduncle. 

 All fins bearing melanophores. 



Biology 



A 45 mm total length female individual was reported to be ripe (Berg 1949). No other 

 data are available at the present time. 



Distribution 



P. issykkulensis is endemic in Lake Issyk-kul and its tributaries in Kazakhstan (Berg 1949). 

 Etymology 



The epithet "issykkulensis" is derived from the combination of "Issykkur and a Latin 

 suffix "-ensis" to refer the type locality Lake Issyk-kul and its tributary in Central Asia 

 (Kazakhstan) where the species is endemic. 



