Late postnaupliar development of the freshwater copepods Lovenula falicifera and Metadiaptomus colonialis (Calanoida: Diaptomidae) from South Africa.

Abstract

The life cycle of calanoid copepods consists of eggs hatching into nauplii (6 stages) which then moult into copepodids (5 stages), followed by the final moult into the adult female and male. The family Diaptomidae contains two subfamilies, Diaptominae and Paradiaptominae, with paradiaptomids almost exclusively consisting of African taxa. The copepodid stages III, IV and V were described for some freshwater diaptomine genera (i.e., Eudiaptomus Kiefer, 1932, Aglaodiaptomus Light, 1938, Skistodiaptomus Light, 1939, Leptodiaptomus Light, 1938, Megadiaptomus Kiefer, 1936 and Diaptomus Westwood, 1836). Copepods collected from Turfloop Dam, South Africa, with a plankton net were fixed and preserved in 70% ethanol. Calanoid copepods were studied under stereo- and light microscopes, using the wooden slide technique and features drawn. Examined specimens were identified as the copepodid stages of two African species, Lovenula falcifera (Lovén, 1845) and Metadiaptomus colonialis (van Douwe, 1914). Copepodids of the two species can be distinguished by their body size and the structure and size of the maxillipeds. The description and illustrations of three postnaupliar stages (CoIII, CoIV and CoV) are provided for both species. The identification of different stages is based on the number of urosomites, antennule development, the segmentation of legs 1-4, and the development of the fifth leg. These copepodids are compared with those of other described diaptomid genera.