M.J. ORLOVA-BIENKOWSKAJA 

Fig. 13 S. vetulus, male 2nd trunk limb. A, general view, B, endite of neonate, C, endite of juvenile, D, endite of adult. 
Kolyma river basin, Zhirkovo lake, 28. 6. 1967, leg. Streletskaja: 
49 Qad.,2 9 Qe. Magadan region, Verkhnee lake, 18. 8. 1981, leg. 
Streletskaja: 13 9 Qad., 82 9 juv. 
DIAGNOSIS. Measurements. 9 9 ad.: 1.3-2.4 mm.,@ Qe.: 1,2- 
1,9 mm, oo: 1.0-1.3 mm. 
Female. Dorso-posterior valve prominence long, with very wide 
base and small diameter (Fig. 24). Its diameter (Fig. 2) less than its 
length. Dorsal valve margin very high, not protruding backward. 
Depressions above and below dorso-posterior prominence wide and 
deep. Ventral head margin straight or slightly concave, sometimes 
with small prominence. Depression on ventral head margin near 
rostrum deep. Ocellus elongate. 
DISTRIBUTION. (Fig. 21) Eastern Siberia S. vetuloides has been 
described from the Jana river basin. Sars (1903) reports it also from 
Kazakhstan. However, the illustration in this article shows that the 
specimens found in Kazakhstan belong to S. mixtus. S. vetuloides is 
reported from China (Chiang & Du, 1979), Mongolia (Flossner, 
1986) and South Africa (Sars, 1916). But the identification of 
species within the subgenus Simocephalus s. str. is rather difficult. 
And probably the name S. vetuloides was misused for other species. 
REMARKS. Behning (1941) and Manujlova (1964) suppose S. 
vetuloides to be a synonym of S. elizabethae. Other authors (Fryer, 
1957; Negrea, 1983; Michael & Sharma, 1988) regard it as a 
synonym of S. vetulus. Investigation of the type material and other 
specimens shows that it is a separate species. It is sympatric with S. 
mixtus and there are no intermediate forms between these species. S. 
vetuloides differs from S. vetulus in the shape of the dorso-posterior 
valve prominence and from S. elizabethae in the head shape. 
Contrary to the opinion of Manujlova (1964), the length of the 
distal seta of the antennal basipod does not differ in this species from 
the others (Fig. 24B). The basipod bears a seta on the outer and a 
spine on the inner side of the distal part. 
S. punctatus sp. nov. 
Fig. 25 
TYPE MATERIAL. Holotype: Shallow eutrophic vernal pool in river 
bottom below a dam on the Friant River, Tulare Co. California, 37°N 
119°45'W, leg. Berner: MPA: 9 ad. (BMNH) 1997. 1698. Paratypes 
collected with holotype: MPA: more than 502 Qad., 202 9 juv., 
202 Ge., 200° 0O(BMNH 1997. 1699-1708 and AC). 
DIAGNOSIS. Measurements. 9 9 ad.: 1.5-2.23mm.,? Qe.: 1,2- 
1,9mm,o'o°: 1,1-1,3mm. 
Female. Dorso-posterior valve prominence absent, dorso-posterior 
angle not separated above and below by depressions (Fig. 25). 
