42 



mies 
a 
@ S. serrulatus 
inae ww: 
Fala 
PU aL TT SEs 
CWE TTR a7 
O Ss. semiserratus 
M.J. ORLOVA-BIENKOWSKAJA 

\ 4 

y, 
© S. mirabilis 
Fig. 43 Locations, where the studied material of S. (Coronocephalus) was collected. 
because of these variations. However, I believe, that S. serrulatus has 
no subspecies. First, there is no morphological hiatus between 
populations. There are always some specimens with intermediate 
characters (Orlova-Bienkowskaja, 1995a). Second, the variability is 
not geographical and sometimes neighbouring populations differ 
more strongly than populations from different continents. 
This interpopulational variability is probably the consequence of 
the founder-effect, which is strong in Cladocera because of parthe- 
nogenesis. It conforms with the data of Hann & Hebert (1986), who 
studied the genetic structure of North American Simocephalus 
populations. Based on a study of enzymes, these authors came to the 
conclusion that the genetic diversity within populations 1s less than 
between populations. They supposed it to be a consequence of the 
founder-effect. 
The original description of S. serrulatus was supported by good 
illustration and contains most of the characters which differentiate 
this species from others (Koch, 1841). 
S. brandtii and S. intermedius, described from Europe, are tradi- 
tionally regarded as synonyms of S. serrulatus. The types are 
probably lost, but the original descriptions (Fischer, 1848; Lievin, 
1848) show that this opinion is correct. The name S. vetulus var. 
brandtii Cosmovici, 1900 is the junior secondary homonym of S. 
brandtii (Daphnia brandtii Fischer, 1848). Accorging to Article 59a 
of the International Code of Zoological Nomenclature (1988), it is 
invalid. It is not necessary to propose the replacement name (Art. 
60a), because S. vetulus var. brandtii is the junior synonym of S. 
vetulus. The name S. intermedius Studer is not the secondary 
homonym of S. intermedius (Lievin) (Daphnia intermedia Lievin, 
1848) (Art. 60c), because the species described by Studer (1878) is 
assigned to the genus Simocephalus erroneously and belongs to the 
genus Daphnia. 
S. serrulatus var. montenegrinus Werestchagin, 1912 was described 
from Montenegro (Fig. 41A). Itis regarded as a subspecies (Behning, 
1941), or as a synonym of S. serrulatus (Sramek-Husek et al., 1962; 
Negrea, 1983). Werestchagin (1912) writes that this variety differs 
from the typical form in the higher head and the longer dorso- 
posterior valve prominence. Statistical analysis of these metric 
characters in type specimens shows that there is no morphological 
hiatus between this variety and S. serrulatus (Orlova-Bienkowskaja, 
1995a). 
S. surekhae Rane is described from Jabalpur (India) (Rane, 
1985a). The author does not point out any differences between this 
species and S. serrulatus. Sharma & Sharma (1990) have studied the 
types and sunk S. surekhae into the synonymy of S. serrulatus. This 
conforms with my data, because the available specimens from 
Jabalpur belong to the latter species. 
S. serrulatus var. rotundifrons Brehm is also a synonym of S. 
serrulatus (Sramek-Husek et al., 1962; Fléssner, 1972). In the opin- 
ion of Brehm (1933) this variety described from Gao (Mal1) differs 
from the typical S. serrulatus in its rounded head and the shorter 
dorso-posterior valve prominence. The types are lost (Smirnov 
N.N., personal communication). Statistical analysis shows that speci- 
mens available from Niger do not differ from those from Europe in 
these characters (Orlova-Bienkowskaja, 1995a). 
S. capensis Sars was described from the vicinity of Knysna (South 
Africa) (Fig. 41C). Sars (1895) writes that this species is closely 
