Dimorphostylis

Akiyama, Tadashi, 2011, The Cumacean Dimorphostylis elegans Gamô, 1960 (Crustacea), D. bathyelegans n. sp. and D. brevicarpus n. sp. from Japan, Zootaxa 2994, pp. 45-59 : 58

Key to Japanese species of Dimorphostylis

1. Frontal lobe of carapace with transverse ridge............................................................... 2

- Frontal lobe of carapace without transverse ridge............................................................ 4

2. Adult male telson with spiniform setae laterally......................................... .. D. asiatica Zimmer, 1921

- Adult male telson with simple short setae laterally............................................................ 3

3. Adult male telson with 3 terminal setae, median seta longer than 3 times as long as outer pair; female carapace with numerous short hairs......................................................................... D. hirsuta Gamô, 1960

- Adult male telson with 3 terminal setae, median seta less than 2 times as long as outer pair; female carapace without hairs..................................................................................... D. valida Harada, 1960

4. Carapace with 4 lateral ridges..................................................... D. quadriplicata Gamô, 1960

- Carapace with 3 lateral ridges............................................................................ 5

5. Pleonite 6 with a pair of spines on dorso-posterior margin...................................................... 6

- Pleonite 6 without a pair of spines on dorso-posterior margin.................................................. 11

6. Lateral ridges of carapace with brunt spines.............................................. D. coronata Gamô, 1960

- Lateral ridges of carapace smooth or with minute tubercles..................................................... 7

7. Dorsolateral ridge of carapace with no spine on anterior end.................................................... 8

- Dorsolateral ridge with 1–3 spines on anterior end............................................................ 9

8. Pereopod 1 propodus 2 times dactylus.................................................. D. gibbosa Harada, 1960

- Pereopod 1 propodus 3 times dactylus................................................ D. cornigera Harada, 1960

9. Dorsolateral ridge of carapace with 2–3 spines on anterior end................................. D. brevicarpus n. sp.

- Dorsolateral ridge of carapace with 1 spine on anterior end.................................................... 10

10. Uropod peduncle 2.5–2.7 times endopod, telson length less than 2 times width, shorter than or as long as pleonite 6........................................................................................... D. elegans Gamô, 1960

- Uropod peduncle 2.9–3.3 times endopod, telson length 2 times width, longer than pleonite 6......... D. bathyelegans n. sp.

11. Uropod endopod article 1 much longer than combined length of articles 2 and 3.................................. 12

- Uropod endopod article 1 as long as or shorter than combined length of articles 2 and 3............................. 13