ISSN:
1573-5117
Keywords:
Cladocera
;
Chydoridae
;
North America
;
non-cosmopolitanism
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The cladoceran taxon from Mississippi that Chien (1970) described as Alonella leei, and which subsequently was considered by Frey (1974) to be closely related to Disparalona rostrata (Koch, 1841) in Europe and possibly a synonym of it, is here established as a new species of Disparalona. It differs from D. rostrata in a number of consistent features including the lack of any tooth on the shell, a marked reduction in setulation along the posterior margin of the shell, a marked reduction in setulation laterally and ventrally on the female and male postabdomens, and the presence of two basal spines on the male postabdominal claw versus none in D. rostrata. Besides, the male postabdomens of the two species are markedly different in shape and armament. These characters and many more are treated by detailed descriptions and illustrations. A number of other characters shared by these two species may eventually be found to be diagnostic of the genus, including: (1) the sharply angled ecdysial line, (2) the ephippial egg being surrounded by a foamy mass secreted into the broodpouch, and (3) three IDL setae in the female but only two plus a special non-homologous seta in the male. The extensive sweeper seta in the filter comb of trunklimb III, which Fryer (1968) considered distinctive in establishing the genus Disparalona, is much less distinctive than believed. The members of this pair of species are restricted to the Northern Hemisphere, D. leei occurring in eastern North America, D. rostrata in Eurasia, but with populations in eastern Asia probably being from a different species.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00018107
Permalink
