The Marine Fauna of New Zealand: Isopoda, Aegidae (Crustacea)

Figure 18. Aega monophthalma Johnston, 834. NIWA 23755. A, uropod exopod, ventral view; B, uropod exopod, apex; C,
uropod endopod, apex.
tolateral point; pleopods 2–4 peduncle distolateral margin
with prominent acute RS.
Uropod peduncle ventrolateral margin with 3 RS
(and continuous PMS), posterior lobe about as long as
endopod. Uropod rami extending to pleotelson apex,
marginal setae dense, in several tiers, apices broadly
rounded. Endopod apically not bifid, lateral margin
proximally convex, without prominent excision, proximal
lateral margin with 3 RS, distal lateral margin
with 2 RS, mesial margin strongly convex or concave,
with 7– 0 RS. Exopod extending to end of endopod,
2.9 times as long as greatest width, apically not bifid;
lateral margin convex, with 7– 8 RS; with 3–4 RS.
femaLe: Eyes narrowly separated; ovigerous female
ocular surface depressed, dorsal body surfaces not as
nodular as male; uropodal margins lacking prominent
RS; non-ovigerous female similar to male with the
exception of sexual characteristics.
size: Specimens from the southwestern Pacific: males
from 40 to 49 mm, females 48 to 73 mm; single manca
8.5 mm.
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Variation: Only a small number (5) of specimens were
available at the time of writing the description for this
species, and the fact that the uropod and pleotelson
apices are mostly damaged means that it is not possible
to precisely detail the variation present. The pleotelson
has from about 44 to 48 (22+22 to 24+24) robust setae.
The uropod endopod lateral margin has 2– 7 RS, the
mesial margin 7– 0 RS; the exopod lateral margin has
6– 8 RS, the mesial margin 3–5 RS. The robust setae
on the merus of pereopods –3 are constant: pereopod
merus with +2, pereopod 2 merus with 3+2 and
pereopod 3 merus to 4+2.
The extent to which the antennule peduncle articles
and 2 are produced varies, with the large specimen
from off Great Barrier Island being less strongly produced;
in some specimens the dorsal pitting is weaker
than in others, and the robust setae on the uropods and
pleotelson are not always as prominent as illustrated;
uropod apices are also frequently damaged and regrowth
may appear more rounded that in undamaged
specimens.
remarks: This spectacular and large isopod, at the time
of first description only the seventh in the genus, is im-