Abnormalities in a Pleuroxus aduncus (Jurine, 1820) population (Crustacea: Cladocera: Chydoridae)

Abstract

The morphological variation in a population of Pleuroxus aduncus (Jurine, 1820) from a well in Germany is described. The number of denticles at the postero-ventral corner of the valve are more numerous than normal and abnormalities occur regularly. The observations are discussed in the context of the described variation in number of posteroventral denticles of this species and the causes given for abnormalities in recent literature.

Abnormalities in two Bosmina longirostris s.l. (OF Müller, 1785) populations (Crustacea: Branchiopoda: Bosminidae)

“…There are several causes of abnormalities in cladocerans suggested in the literature. These include toxic substances [11,14,17,19] , eutrophication [18] , and extreme environments [15,20] . De Melo et al (2017) [18] observed abnormalities in Bosmina intestines, which were probably due to the eutrophication of the reservoir.…”

“…The description of Lynceus longirostris is very brief and there is wide morphological variation in Bosmina longirostris (Müller, 1785) [5] . Several European species are described: B. cornuta (Jurine, 1820) [20] ; B. brevicornis Hellich, 1877; B. brevirostris Fischer, 1854; B. pelagica Stingelin, 1895; B. pellucida Stingelin, 1895; and B. similis (Sars, 1890). The primary differences between the species are the shape and length of the trunk (antenna I and rostrum grown together) and shell spine.…”

“…Predation influences morphology through chemical cues, kairomones [14] , and physical stimulation [13] . Morphological abnormalities in Cladocera have recently been described for the genera Ilyocryptus [15,16] , Daphnia [17,18] , Coronatella [19] , Ceriodaphnia, Chydorus, and Bosmina [18] , and Pleuroxus [20] . This article describes morphological abnormalities in B. longirostris s.l.…”