Stygiopontius, Humes, 1987

Uyeno, Daisuke & Shimanaga, Motohiro, 2018, A new dirivultid copepod (Siphonostomatoida) from hydrothermal vent fields of the Izu-Bonin Arc in the North Pacific Ocean, Zootaxa 4415 (2), pp. 381-389 : 388

Key to species of Stygiopontius from Western Pacific

1 Leg 4 bearing seven elements (i.e., three spines plus four setae) on the third exopodal segment....... S. senokuchiae n. sp.

- Leg 4 bearing eight elements (i.e., four spines plus four setae) on the third exopodal segment......................... 2

2 Caudal rami less than twice long as wide .............................................. S. pectinatus Humes, 1987

- Caudal rami more than twice long as wide................................................................. 3

3 Leg 4 bearing distal endopodal segment with pointed outer process............. S. senckenbergi Ivanenko & Ferrari, 2013

- Leg 4 bearing distal endopodal segment without pointed processes.............................................. 4

4 Genital double somite bearing two pairs of processes..................................... S. stabilitus Humes, 1990

- Genital double somite bearing one or no pairs of processes..................................................... 5

5 Genital double somite bearing pair of processes on posterolateral corners; basis of the leg 1 bearing an inner pointed process.................................................................................. S. lauensis Humes, 1991

- Genital double somite without pairs of lateral processes; basis of leg 1 without inner pointed processes.................................................................................................. S. brevispina Humes, 1991