MARESFE GAMMARIDEAN AMPHIPODA 275 



Ischyroceridae 



Figures 107, 108 



Diagnosis. — Accessory flagellum variable; telson short, entire, 

 fleshy; coxa 4 not excavate posteriorly except in one genus; pereopods 

 glandular; uropod 3 rarely projecting beyond uropods 1 and 2, peduncle 

 elongate, rami styliform, shorter than peduncle, outer ramus usually 

 uncinate, either with hooked tip, or hooked spine at tip, or denticles. 

 See Isaeidae, Ampithoidae, Calliopiidae, Pleustidae, Corophiidae. 



Description. — Accessory flagellum varying from uniarticulate to 

 multiarticulate; body smooth; rostrum absent; coxae rounded or 

 quadrate below, varying from long to short, fourth not excavate 

 posteriorly (with exception in Bathyphotis) ; mouthparts basic, possibly 

 epistome always acutely produced anteriorly; gnathopods usually 

 powerfully subchelate; structure of uropod 3 as in diagnosis but 

 merging with conditions typical of Isaeidae by tendencies to elongation 

 of rami and lack of uncination; telson entire, subcircular or nearly 

 square, thick. 



Relationship. — The Isaeidae (=Photidae) differ from the Ischy- 

 roceridae by the lack of uncination on the outer ramus of uropod 3, 

 the longei rami and shortened peduncles, but some species now 

 assigned to Isaeidae bear third uropods merging with the Ischyro- 

 ceridae. 



Calliopiids and pleustids have a nonfleshy telson and a short 

 peduncle of uropod 3. 



Ericthonius in the Corophiidae has an ischyrocerid uropod 3 without 

 an inner ramus. Dryopoides and Paradryope in the Aoridae have 

 third uropods which technically are ischyrocerid. Parapherusa in the 

 Gammaridae lacks pereopodal glands but has uropod 3 similar to 

 that of ischyrocerids. 



Key to the Genera of Ischyroceridae 



1. Coxae minute, not touching Bogenfeisia 



Coxae small or large, overlapping or barely touching 2 



2. Gnathopod 1 distinctly larger than 2. 



Dryopoides (Aoridae) and Paradryope (Aoridae) 

 Gnathopod 1 smaller than 2 or gnathopods subequal to each other ... 3 



3. Second articles of pereopods 3-5 narrowly linear, palp article 4 of maxilliped 



claw-like, longer than article 3 Bonnierella 



Second articles of pereopods 3-5 suboval or broadly rectangular, palp article 4 

 of maxilliped shorter than article 3, blunt,' or subconical,' (setose) (fig. 

 107A-) 4 



1 Not including terminal spine. 



