REVISION OF SIMOCEPHALUS DAPHNIIDAE 
38 

Fig. 34S. congener, parthenogenetic female. A, postabdominal claw, B, lateral view. 
DIAGNOSIS. Measurements. 9 9 ad.: 1.0-3.0mm. 
Female (Fig. 38). General body shape ovoid. Frons with small 
obtuse prominence not separated above and below by depressions. 
Dorso-posterior valve prominence distinct, separated above and 
below by deep depressions. Dorsal margin with denticles. Diameter 
of circle inscribed in it small. Proximal and distal supra-anal angles 
small, embayments of postabdomen shallow, proximal angle rounded. 
DISTRIBUTION. (Fig. 32) U.S.A., Canada. 
REMARKS. ‘The original description of this species is not provided 
with an illustration (Herrick, 1884). It is evident from the descrip- 
tion that it is closely related with S. acutirostratus. ‘The spine is as 
in S. americanus’ (S. serrulatus) and ’the head is produced below 
the eyes in an angle, like a right angle, which is not spiny’. I had 
serious doubt about the taxonomical state of this taxon (Orlova- 
Bienkowskaja, 1993), because there were no other records of S. 
(acutirostratus) species group from North America. The examina- 
tion of specimens from Canada has shown that they belong to this 
group and differ from S. acutirostratus, S. victoriensis and S. 
brehmi in the shape of the dorso-posterior valve angle. Obviously, 
they belong to S. rostratus. 
There is one undescribed species of S. (acutirostratus) group in 
North America. I have about forty specimens of this species from 
California and Washington, but I do not name this new species 
