106 U.S. NlATIONAli MUSETIM BULLETIN 271 



2. Maxillipeds absent HYPERIIDEA (pelagic, ?500 species) 



Maxjllipeds bearing palps (except one rare family) 3 



3. Movable compound dactyl of gnathopods 1-2 formed of articles 6-7 together; 



head occasionally with articulate ocular scale; pleopods when present, all 

 reduced in size, leaf-like. 



INGOLFIELLIDEA (caves and marine, 15+ species) 



Dactyl of gnathopods 1-2 formed only of article 7; head never bearing ocular 



scale; pleopods biramous, elongate, rarely reduced except in terrestrial 



species. 



GAMMARIDEA (marine and limnetic scuds; beachhoppers; 3300 species) 



Nomenclatural Changes in Gammaridean Families 



Amathillopsidae are combined with the Paramphithoidae. 

 AnatyHdae are combined with the Dexaminidae. 

 Hyalellidae are included with the superfamily Talitroidea. 

 Hyalidae are included with the superfamily Talitroidea. 

 Photidae are combined with the Isaeidae. 

 Pontogeneiidae are combined with the Eusiridae. 

 Talitridae are included with the superfamily Talitroidea. 

 Tironidae are combined with the Synopiidae. 



Key to the Families of the Suborder Gammaridea ' 



("exceptional" refers to rare occurrence of familial members in this 



category) 



SECTION A 



1. Article 3 of gnathopod 2 elongate (fig. 3) Section B 



Article 3 of gnathopod 2 not elongate 2 



2. Urosomites 1-2 coalesced, urosomite 3 free (fig. 1056). 



some species of phli antidae ; Kamaka (Corophiidae) ; and Chevalia (Isaeidae) 



Urosomites 2-3 or 1-3 coalesced Section C 



Urosomites separate 3 



3. Coxa 1 small or absent, mostly hidden by a following coxa (some of following 



coxae longer than wide) (occasionally gnathopod 1 absent or vestigial). 



Section D 



Coxa 1 small or large but usually subequal to coxa 2 and never hidden by 



following coxae (occasionally coxa 1 partially hidden but all following 



coxae wider than long), (gnathopod 1 always fully developed) .... 4 



4. Uropod 3 uniramous, or lacking rami, or absent Section E 



Uropod 3 biramous, inner ramus often reduced 5 



5. Mandibular palp absent (use alternate if Section F unsatisfactory, because 



of uncertain loss of palp) Section F 



Mandibular palp present (with very rare exception absent) 6 



6. Mandibular molar absent or if present not triturative, lacking numerous 



ridges and teeth (occasionally with articulate spines), occasionally large 

 or immense and dominating mandible (fig. 166d) Section G 



' Gurjanova (1962) also has a modem key to the families. 



