A Guide to Identifying the Genera of Cyclopidae (Crustacea: Copepoda: Cyclopoida) from Japan

Two methods are introduced for identifying Japanese freshwater copepods of the family Cyclopidae. The following 14 features, which are all visible without or with minimal dissection, prove to be useful for generic-level identification: (1) segment number of antenna 1, (2) relative length of antenna 1, (3) segment number of exopodites of legs 2 and 3, (4) segment number of exopodite of leg 4, (5) width of coupler of leg 4, (6) segment number of leg 5, (7) number of setae on terminal segment of leg 5, (8) relative lengths of terminal segment of leg 5 and its inner seta, (9) precise location of this inner seta on the segment, (10) relative lengths of inner and outer setae on terminal segment of leg 5, (11) condition of spinule row on outer margin of caudal ramus, (12) condition of dorsal spinule row or setal row on caudal ramus, (13) condition of dorsal chitinous ridge on caudal ramus, and (14) relative length of caudal ramus. Based on these characters, two kinds of key to the genera of Cyclopidae in Japan are provided, a dichotomous branching key and a matrix key. The manner of use of these keys for identification is explained, and the utility of cyclopoids in school education is discussed