MARENTB GAMMARIDEAN AMPHIPODA 513 



COXAE 



Size: 



Normal: like basic gammaridean; 1-4 of medium length, subquadrate, 5-7 



shorter, successively smaller, 5-6 slightly lobed. 

 Elongation (example, Stegocephalidae). 

 Reduction (example, Podoceridae). 

 Disproportional sizes of 1-4: 1 long, 2 shorter, 3 shorter, 4 long (example, 



Argissidae). 

 Coxa 1 absent or vestigial (rare examples, Bateidae, Anamixis). 

 Coxa 1 reduced in size and partially to fully covered by following coxae (example, 



Stenothoidae). (Caution: keep amphipod specimen in unflexed condition 



for proper observation.) 

 Coxae 1-2 or 1-3 reduced in size and covered by following coxae (primarily 



genera of Lysianassidae). 

 Coxa 3 larger than 4 (example, Synopiidae). 

 Coxa 5 as long as 4 (rare). 

 Position : 



Serial contiguity: coxae contiguous or overlapping. 

 Serial discontiguity (example, Podoceridae, Eophliantidae) . 

 Concealment of one coxa by another (see above). 

 Lateral splaying (Phliantidae) . 

 Shape : 



Coxae 1-4 subquadrate. 



Acumination of coxae 1, 2, 3, 4- 



Excavation posteriorly of coxa 4'- posterior margin straight, concave or deeply 



excavate and/or bearing posterior lobe (contrast Stegocephalidae and 



Isaeidae). 

 Coxa 1 tapered, expanded, oval, semicircular, quadrate, conical, acutely lobed. 

 Ventral serrations. 

 Special patterns: 



Disproportional sizes of 1-4 (Argissidae, see above). 



Crescentic curve formed ventrally by coxae 4-5 together (example Epimeria) . 



HEAD 



Size: 



Length as a function of one or more pereonites (1, 1-2, 1-3), head measured 

 on horizontal axis from front of lateral lobe to perpendicular line from 

 posterior cephalic extent. 



Massive (see definition in glossary). 

 Shape: 



Normal gammaridean: head cuboidal, with lateral lobes. 



Globular: subspheroid; neck cylindrical. 



Galeate (see definition in glossary). 

 Rostrum : 



Length in relation to head ( %) and to article 1 of antenna 1 ( %). 



Shape: acute, spatulate; horizontal, defiexed. 

 Lateral lobe: 



Shape and extent of projection. 



Notch or ornamentation. 



Ocular bulge on side of head. 



Marginal details of anteroventral corner of head near insertion of antenna 2. 



