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

articulating with article 4, distally convex, with 6 RS
(5 straight, curved).
Pereopod 1 basis .9 times as long as greatest width;
ischium 0.5 times as long as basis, inferior margin with
0 RS, superior distal margin with 2 RS (and simple
seta); merus inferior margin with RS (or 2), set as
distal group, superior distal angle with 0 RS (2 slender
setae); carpus 0.5 as long as merus, inferior margin with
0 RS; propodus .3 times as long as proximal width,
inferior margin with 0 RS, propodal palm with small
distal lobe, dactylus abruptly hooked, .5 as long as
propodus. Pereopod 2 ischium inferior margin with
RS, superior distal margin with 3 RS (and slender
seta); merus inferior margin with 6 RS (set as 4 + 2), set
as two groups, superior distal margin with 0 acute RS
(4 slender setae); carpus longer than that of pereopod
, with inferodistal lobe, inferodistal angle with 0 RS,
propodus without large club-shaped distal RS. Pereopod
3 similar to pereopod 2 (7 or 9 RS); propodus without
large club-shaped distal RS. Pereopods 5–7 inferior
margins of ischium–carpus with short RS. Pereopod 6
similar to pereopod 7 (slightly larger, inferior margins
with more RS). Pereopod 7 basis 3.3 times as long as
greatest width, inferior margins with 5 palmate setae
(or more); ischium 0.5 as long as basis, inferior margin
with 9 RS (set as , 2, 3 and 3), superior distal angle with
6 RS, inferior distal angle with 7 RS; merus 0.8 as long
as ischium, .9 times as long as wide, inferior margin
with 9 RS (set as , 4 and 4), superior distal angle with
0 RS (and 2 slender setae), inferior distal angle with
8 RS; carpus 0.8 as long as ischium, 2.6 times as long
as wide, inferior margin with 7 RS (set as 3 and 4),
superior distal angle with 0 RS, inferior distal angle
with 0 RS; propodus 0.6 as long as ischium, 3.0 as
long as wide, inferior margin with 5 RS (set as , 2 and
2), superior distal angle with 2 slender setae, inferior
distal angle with 3 RS.
Penes low tubercles; penial openings separated by
4% of sternal width.
Pleopod 1 exopod .9 times as long as wide, distally
narrowly rounded, mesial margin weakly oblique,
lateral margin straight, mesial margin strongly convex,
with PMS on distal two-thirds; endopod 2.5 times
as long as wide, distally subtruncate, lateral margin
strongly concave, with PMS on distal margin only, mesial
margin with PMS on distal half; peduncle .9 times
as wide as long, mesial margin with 8 coupling hooks.
Pleopod 2 appendix masculina with straight margins, 0.8
times as long as endopod, distally narrowly rounded
(with small apical point). Exopods of pleopods –3
each with distolateral margin not digitate; endopods
of pleopods 3–5 each with distolateral point; pleopods
2–4 peduncle distolateral margin without prominent
acute RS.
Uropod peduncle ventrolateral margin with 2 RS,
posterior lobe about three-quarters as long as endo-
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pod. Uropod rami with endopod and exopod weakly
oblique, rami extending to pleotelson apex, marginal
setae in single tier (dense), apices narrowly rounded.
Endopod apically not bifid, lateral margin proximally
convex, with prominent excision (shallow), positioned
about three-quarters along ramus, proximal lateral
margin with RS, distal lateral margin with 3 RS,
mesial margin weakly convex, with 6 RS. Exopod not
extending to end of endopod, 3.3 times as long as
greatest width, apically not bifid; lateral margin weakly
convex, with 2 RS; mesial margin sinuate, proximally
concave, with 3 RS.
femaLe: Similar to the male, but for the sexual characters;
no ovigerous females present.
size: Present material 3 mm.
Variation: The two specimens differ in a number of
details, though without more material it is impossible
to say whether this is regional variation or potentially
specific differences. The robust setae on the merus of
pereopods –3 present a constant pattern, although the
number of robust setae varied with the holotype having
only RS on the pereopod merus and the New
Zealand specimen having 2, the merus of pereopod 2
has 4+2 but pereopod 3 merus had 5+2 (holotype) or
6+3 (New Zealand).
The shape and proportions of the uropod are the
same between the two specimens but there is a difference
in the number of robust setae, notably on the
uropodal endopod lateral margin with the holotype
having a pattern of +3, the New Zealand specimen
+2. Both specimens had somewhat damaged uropods
so these numbers may be an artefact of that damage.
remarks: Aega falklandica can be identified by the antennule
peduncle articles 1 and 2 being flattened and
expanded, uropodal endopod lateral margin being
medially indented with the anterior portion conspicuously
convex, by the short propodus with a simple
palm and small distal lobe, and by the pattern and
number of robust setae on pereopods –3. Similar species
include Aega magnifica which is readily separated
by pereopods –3 having a conspicuous blade on the
palm of the propodus.
There are two similar Pacific species: Aega acuminata
Hansen 897 and Aega maxima Hansen, 897. The
former has far smaller eyes than A. falklandica, the propodal
lobe on pereopod is larger and the uropodal
exopod is proportionally longer, extending just beyond
the apex of the endopod (Brusca 983; Hansen 897).
The principle differences between A. falklandica and
A. maxima are, in A. maxima, slightly smaller eyes, the
palm of pereopods –3 without any trace of a distal
lobe, and the uropodal endopod distal margin appear-