24 

M.J. ORLOVA-BIENKOWSKAJA 
I 7 | ae 


Fig. 24S. vetuloides, lectotype, parthenogenetic female. A, general view, B, distal part of antenna basipod with a seta on outer side and a spine on inner 
side. 
assign it to the genus Simocephalus. But their descriptions are 
insufficient. Some authors supposed S. exspinosus to be the junior 
synonym of S. vetulus (Daphnia sima) (Lievin, 1848; Baird, 1850). 
Lilljeborg (1900) was the first to describe this species appropriately. 
S. australiensis was originally described insufficiently (Dana, 
1852). Dana’s collection with the type was lost on a ship which sank 
(D. Frey, personal communication through N.N. Smirnoy). Sars is 
often supposed to be the author of this species (Negrea, 1983) 
because he is the first to describe it appropriately (Sars, 1888). He 
believed S. australiensis to be a separate species closely related with 
S. exspinosus and differing from it by ‘the peculiar oblique form of 
the carapace and well-marked, though obtuse, projection of its 
posterior extremity; likewise too by the broad tail, and more espec- 
ially by the highly characteristic armature of the caudal claws’. 
Dumont (1983) regards S$. australiensis as a subspecies of S. 
exspinosus. Other authors regard it as a synonym (Floéssner, 1972; 
Negrea, 1983; Margaritora, 1985; Michael & Sharma, 1988). agree 
with the latter opinion, because the diagnostic characters used by 
Sars and Dana are rather variable and because all available speci- 
mens of the S. (exspinosus) species group from Australia do not 
differ from European S. exspinosus. 
According to Sars (1898, 1903), S. sibiricus and S. productus 
differ from each other and from S. exspinosus in the head shape, the 
size of the dorso-posterior valve prominence and the armature of the 
postabdominal claw. Manujlova (1964) mentions S. sibiricus as a 
separate, highly variable species. Judging from illustrations, she 
confuses two species under this name. S. productus is believed to be 
a synonym of S. exspinosus (Manujlova, 1964; Michael & Sharma, 
1988). Investigation of the type has shown that S. productus and S. 
sibiricus do not differ from S. exspinosus. The frons shape varies 
from rounded to almost right-angled. The head height also varies 
within populations. Therefore these features cannot be diagnostic 
characters. 
S. himalayensis is described from the Himalayas (Chiang & Du, 
1979). The type is in China and I have not seen it. Reference to the 
original description and illustrations suggests that S. himalayensis is 
a synonym of S. exspinosus. 
According to Rane (1985b), S. vamani, described from Jabalpur 
(India) differs from S. exspinosus in its moderate size, a compara- 
tively small rostrum, and the presence of 6-7 denticles on the 
postabdomen near the insertion of the claw. This author also states 
that S. austarliensis differs from S. vamani in the upturned rostrum. 
According to my data, the group of 6—7 denticles near the claw 
occurs in all Simocephalus species and the size and orientation of the 
rostrum is subject to individual variability. The type is deposited in 
the National collection of the Zoological Survey of India (Calcutta). 
