6 - Sphaeromatidae::“Cute As Buttons”

116 FLABELLIFERA • AEGIDAE
Pleopods biramous, bearing plumose marginal setae. Uropods forming tail-
fan with plcotclson. Pleon of four or five free pleonitcs 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.