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

0 RS, superior distal margin with 2 RS; merus inferior
margin with 2 RS, set as two groups, superior distal
angle with 0 RS (2 simple setae); carpus . as long as
merus, inferior margin with RS; propodus .8 times
as long as proximal width, inferior margin with RS
(distal), propodal palm simple, without blade or process,
dactylus smoothly curved, . as long as propodus.
Pereopod 2 ischium inferior margin with 0 RS, superior
distal margin with 2 RS; merus inferior margin with
4 RS, set as two groups, superior distal margin with 0
acute RS (3 simple setae); inferodistal angle with RS.
Pereopod 3 similar to pereopod 2. Pereopods 5–7 inferior
margins of ischium–carpus with short RS. Pereopod 6
similar to pereopod 7. Pereopod 7 basis 2.9 times as
long as greatest width, inferior margins with 9 palmate
setae; ischium 0.5 as long as basis, inferior margin
with 3 RS (set as and 2), superior distal angle with 4
RS, inferior distal angle with 2 RS; merus .2 as long
as ischium, 2.7 times as long as wide, inferior margin
with 4 RS (set as 2 and 2), superior distal angle with 9
RS, inferior distal angle with 5 RS; carpus .0 as long
as ischium, 3. times as long as wide, inferior margin
with 3 RS (set as and 2), superior distal angle with
2 RS, inferior distal angle with 8 RS; propodus .0
as long as ischium, 5.7 times as long as wide, inferior
margin with 6 RS (set as , , 2 and 2), superior distal
angle with 2 slender setae (and RS and palmate
seta), inferior distal angle with 3 RS.
Penes low tubercles; penial openings separated by
2% of sternal width.
Pleopod 1 exopod .9 times as long as wide, distally
broadly rounded, lateral margin straight, mesial margin
weakly convex (proximally angled), with PMS on
distal two-thirds; endopod .8 times as long as wide,
distally rounded, lateral margin straight, with PMS on
distal margin only, mesial margin with PMS on distal
half; peduncle .8 times as wide as long, mesial margin
with 6 coupling hooks. Pleopod 2 appendix masculina
basally swollen, 0.9 times as long as endopod, distally
acute. Exopods of pleopods –3 each with distolateral
margin digitate (prominent, acute); endopods of pleopods
3–5 each with distolateral point; pleopods 2–4
peduncle distolateral margin with prominent acute RS.
Uropod peduncle ventrolateral margin with 2 RS,
posterior lobe about two-thirds as long as endopod.
Endopod apically not bifid, lateral margin straight, without
prominent excision, proximal lateral margin with
RS, distal lateral margin with 2 RS, mesial margin
weakly convex, with 5 RS. Exopod not extending to end
of endopod, 3.0 as long as greatest width, apically not
bifid; lateral margin weakly convex, with 10 RS; mesial
margin straight, distally convex, with 4 RS.
femaLe: As for the male, but lacking sexual characters.
92
size: Males 2.3– 8.0 mm (mean = 5.0, n = 8), ovi-
gerous females 5.4– 6.0 mm, non-ovigerous 2.8 and
5.2 mm.
Variation: Pleotelson (n = 2) always without RS. Uropod
(n = 24, all margins) exopod mesial margin usually
with 3 (8%) or 4 (92%) RS, lateral margin with 9 (each
42%) or 0 (each 50%) RS ( occurring on one specimen);
uropod endopod mesial margin with 4 ( 7%) or
5 (83%) RS (one specimen with 3), lateral margin with
+ ( 00%) RS.
remarks: Aegiochus bertrandi sp. nov. is best identified
by the narrowly united eyes, weak rostral point in dorsal
view, anteriorly acute frontal lamina, small robust
setae on pereopod , the inferior margin of the carpus of
pereopods 2 and 3 distinctly lobed with one prominent
robust seta, pleopodal exopods with digitate margins,
relatively wide and serrated pleotelson that lacks robust
setae, pleotelson posterior margins converging to
a distinct sub-acute apical point, and the characteristic
shape and setation of the uropodal rami.
This species is very similar to the sympatric Aegiochus
coroo Bruce, 983, but differs consistently in a
number of characters, including larger robust setae on
pereopods –3, a distinct lobe on the inferior margin of
the carpus of pereopods 2 and 3, narrower eye join (as
few as two ommatidia), narrower pleotelson posterior
margin, narrower (or more acute) uropod endopod
which extends beyond the pleotelson, the uropodal
endopod mesial margin has five robust setae (three
or four in A. coroo) and the most distal notch on the
uropodal exopod lateral margin always has a robust
seta (slender setae only in A. coroo); A. bertrandi is also
larger (male average length 5.0 mm) than A. coroo
(male average length .4 mm). The counts for uropodal
robust setae do not differ much between the two
species but the differences are consistent.
distribution: Not recorded from New Zealand nearshore
waters to date, but is present within the northern
New Zealand chart area (CANZ 997). The most southerly
record is at 24°44’S on the Norfolk Ridge, most
northerly at 9°S in the vicinity of New Caledonia; it
is quite probable that the species is more widespread
in the region. At depths of 230 to 448 metres.
etymoLogy: Named for Dr Bertrand Richer de Forges,
recognising his superb efforts in developing collections
of marine invertebrates from the southwestern
Pacific and his contribution to taxonomy of the decapod
crustaceans.