Ceriodaphnia dubia Richard, 1894

Dartnall, Herbert J. G. & Hollwedel, Werner, 2007, A limnological reconnaissance of the Falkland Islands; with particular reference to the waterfleas (Arthropoda: Anomopoda), Journal of Natural History 41 (21 - 24), pp. 1259-1300 : 1269

Ceriodaphnia dubia Richard, 1894

Although Ceriodaphnia dubia is regarded as a cosmopolitan ( Alonso 1996) or polytypic species ( Flössner 2000), it has not been previously reported from the Falkland Islands nor indeed from any of the subantarctic islands. The species is closely related to C. quadrangula , with which it has often been confused ( Flössner 1972).

Female: size of adults 0.7–0.85 mm, valves broad oval, head separated by deep notch, post-abdomen before anal teeth slightly concave. The distinctive feature is a row of small spines, one-third of which are longer, on the concave margin of the post-abdominal claw, visible under high magnification on most of our specimens. The specimens from Pebble Island represent a polymorph population, have a proximal pecten comprising 13–14 denticles twice the length of the spines and becoming shorter distally ( Figure 14 ). The variability of this characteristic has been confirmed (D. Berner, personal communication).

Male: size 0.55 mm, valves dorsally not oval, posterior-dorsal angle pointed, antennulae rather long, post-abdomen similar to female, claw with setules, but no pecten.

Figures

Figure 14. Ceriodaphnia dubia, female, post-abdomen.