Key to species of Caligus trichiuri -group (females only)

1. Abdomen 1-segmented, shorter than genital complex......................................................... 2

- Abdomen 2-segmented, longer than genital complex............................................ C. unguidentatus

2. Genital complex wider than long, with convex lateral margins................................. C. cultellus nom. nov.

- Genital complex longer than wide, with more-or-less parallel lateral margins...................................... 3

3. Genital complex large, almost as long as cephalothorax............................................... C. trichiuri

- Genital complex small, less than half length of cephalothorax............................................. C. rufus