116 FLABELLIFERA • AEGIDAE 



Pleopods biramous, bearing plumose marginal setae. Uropods forming tail- 

 fan with plcotelson. Pleon of four or five free pleonites plus pleotelson. 



REMARKS Although these large isopods (up to 60 mm) are often referred to 

 as fish parasites, Brusca (1983) prefers the term "carnivorous scavengers and 

 micropredators," as they attach to fish hosts infrequently and only long 

 enough to feed. When feeding, they engorge themselves on the host's blood. 

 Aegids show almost no host- (or rather prey-) specificity, being opportunistic 

 feeders, and are most frequently captured by bottom trawls on the ocean bed. 

 In ovigerous females, the maxillipedal articles become expanded and, along 

 with the anterior oostegites, cover the buccal field, thereby making feeding 

 impossible. 



Key to genera and subgenera of Aegidae 



1. Maxillipedal palp of two or three articles; frontal lamina small, narrow 



Rocinela 



Maxillipedal palp of five articles; frontal lamina large, broad 2 



2. Antennular peduncle articles 1 and 2 expanded; cephalon lacking true 



rostrum, not completely separating antennular bases .... Aega (Aega) 



Antennular peduncle articles 1 and 2 not expanded; cephalon with true 



rostrum completely separating antennular bases . . . Aega (Rhamphion) 



Aega Leach, 1815 



DIAGNOSIS Eyes large, contiguous or separate. Cephalon with or without 

 true rostrum. Frontal lamina broad, separating bases of antennae. Mandibu- 

 lar palp article 2 elongate. Maxilla 1 bearing strong apical and subapical 

 spines. Maxilla 2 of two usually unequal lobes bearing stout spines. Max- 

 illipedal palp of four or five articles, terminal article often small, with setae or 

 recurved spines; article 4 with stout recurved spines; endite small, seldom 

 reaching beyond palp article 2. Pleon not much narrower than pereon. 



REMARKS Brusca (1983) published a useful account of the genus Aega in the 

 Eastern Pacific. 



