MARESTE GAMMARIDEAN AMPHIPODA 269 



Neomegamphopiis vShoemaker (1942) is removed to the Aoridae. 

 Pseud eurystheus Schellenberg (1931) is assigned in the Isaeidae as 

 subgenus to Gammaropsis. 



Key to the Genera of Isaeidae 



1. Uropod 3 uniramous (fig. 104/) 2 



Uropod 3 biramous (figs. 104g-j) 6 



2. Lateral cephalic lobes pedunculate, article 6 of pereopods 1-2 elongate 



(figs. 105c, 104c) Ampelisciphotis 



Lateral cephalic lobes and article 6 of pereopods 1-2 not elongate .... 3 



3. Gnathopod 1 simple (fig. I06h) Kuphocheira 



Gnathopod 1 subchelate 4 



4. Antenna 1 with accessory flagellum 5 



Antenna 1 lacking accessory flagellum Microphotis 



5. Coxae 1-4 similar to each other in size and shape (fig. 103a) . Microprotopus 

 Coxae 1-4 of varying shapes and sizes (fig. 105a) Cheiriphotis 



6. Uropod 3 with one distinctly shortened ramus (less than 60% as long as 



outer) (fig. 104/i) 7 



Uropod 3 with subequal rami (fig. 104z) 10 



7. Gnathopods 1-2 simple Haplocheira 



Gnathopod 1 subchelate, gnathopod 2 simple . . Leptocheirus (Aoridae) 

 Gnathopods 1-2 subchelate 8 



8. Antenna 1 lacking accessory flagellum or bearing a vestigial article or scale. 



Photis 

 Antenna 1 with multiarticulate accessory flagellum 9 



9. Uropod 3 scale-hke, peduncle plate-like (fig. 104j) Cheiriphotis 



Uropod 3 cylindrical (fig. 104gf) . . . Protomedeia (subgenus Cheirimedeia) 



10. Gnathopod 1 complexly subchelate (fig. 64a), gnathopod 2 with well- 



developed palm Amphideutopus (Aoridae) 



These characters not combined 11 



11. Article 3 of antenna 1 as long as article 1 or longer 12 



Article 3 of antenna 1 shorter than article 1 16 



12. Accessory flagellum of antenna 1 absent Podoceropsis 



Accessory flagellum of antenna 1 present 13 



13. Accessory flagellum composed of a scale Kermystheus 



Accessory flagellum composed of one or more long articles 14 



14. Accessory flagellum composed of one or two articles. 



Megamphopus (Segamphopus and Audulla), Bonnierella ' 

 Accessory flagellum composed of three or more articles 15 



15. Pereopods 1-5 slightly subchelate (fig. 104a) Isaea 



Pereopods 1-5 simple Gammaropsis (subgenus Pseudeurystheus) 



16. Accessory flagellum absent Dryopoides ^ and Goesia 



Accessory flagellum present ■ 17 



17. Gnathopod 2 subchelate, coxae 1 and 2 visible and of normally balanced 



dimensions 18 



Gnathopod 2 simple (fig. 1061), coxa 1 very small and covered by enlarged 

 coxa 2 Leptocheirus (Aoridae) 



18. Pleonites 4 and 5 separate Protomedeia 



Pleonites 4 and 5 coalesced (fig. 1056) Chevalia 



' See this genus in the Iscliyrocoridac. 



- See male, Stebbing (1910) and Aoridae (p. 153). 



