KARYOLOGY OF CYCLOPS INSIGNIS, THERMOCYCLOPS CRASSUS, AND MEGACYCLOPS VIRIDIS (COPEPODA, CYCLOPOIDA)

摘要

The aim of the present study is to describe the standard karyotypes of some species of copepods belonging to the Cyclopidae (Copepoda, Cyclopoida) and to compile the information available in the literature for this group. Cyclopoid representatives were investigated from freshwater habitats of northwestern Germany and Russia. Data have thus become available on Cyclops insignis Claus, 1857 (n = 11), Thermocyclops crassus (Fischer, 1853) (n = 7), and Megacyclops viridis (Jurine, 1820) (n = 6). The study reveals substantial karyotype diversity between cyclopoid genera. If literature data are trustworthy, there is remarkable interspecific variability in Thermocyclops and Megacyclops, whereas Cyclops spp. generally show the same chromosome number (2n = 22) with the exception of C. signatus Koch, 1838 (2n = 8). Methodological problems, chromosome variability, and evolutionary implications of karyological investigations are discussed.