Phagooata nivea Kenk, 1953 



Synonyms '.Phagooata nivea nivea Kawakatsu, 1968; Fontiaola nivea nivea: Ball, 

 1969. 



46 



47 



ode bd 



vd pb 

 Fig. 47 after Kenk (1953). 



gp 



Up to 8 mm long and 1.5 mm wide. Head truncated, with slightly bulging 

 frontal margin and rounded lateral corners. No distinct neck. Body 

 unpigmented, white. Eyes normally two, close together, rather far 

 removed from the frontal margin. The species resembles P. movgani ex- 

 ternally and can be separated from it only by anatomical characters. 

 Testes numerous, predominantly ventral although a few testes may move 

 toward the dorsal side between the branches of the intestine. They are 

 arranged on either side in a zone extending to almost the posterior end 

 (in P. movgani this zone ends at the level of the mouth) . The penis 

 consists of a spherical bulb and a bluntly conical papilla. The two 

 sperm ducts open separately into the elongated penial cavity which is 

 not clearly divided into a seminal vesicle and an ejaculatory duct, 

 though it gradually narrows posteriorly. It opens into the atrium on 

 the ventral side of the papilla. There is no special muscular differ- 

 entiation or wart at the tip of the papilla (such as is seen in P. mor- 

 gani) . The atrium may appear divided into two chambers, the male and 

 common atria, but this division is not always evident. The two oviducts 

 unite in the space above the male atrium, the common oviduct opening 

 into the atrium posterodorsally. Copulatory bursa large, bursal duct 

 displaced to the left of the midline and surrounded by a coat of inter- 

 mingled circular and longitudinal muscle fibers (in P. morgani it has 

 two separate layers, a circular one adjoining the epithelium and a lon- 

 gitudinal layer). Cold-stenothermic, occurring in mountain streams in 

 Alaska. Literature: Kenk (1953). 



42 



