Harris: Male antennule of porcellidiid copepods 
151 
(Fig. 26F). Caudal ramus (Fig. 26E) rhomboid with pinnate 
T4 at apex, medial edge with setules, a and (3 setae not very 
close, T 1 very small at lateral end of bevelled posterior edge, 
T2 and T3 close, equally spaced between y and T4, setules 
along bevelled edge. No setules on labrum. Structure and 
setation of mouthparts and ambulatory limbs are typical of 
family. Geniculate setae on segment 2 of antenna endopod 
with plain terminal segment, terminal claw not comb-like, 
as long as first geniculate seta (Fig. 29A). Maxillule (Fig. 
29C), P3 does not have internal seta on segment 1 of endopod 
(0:2:1,3,1). The serrate spinous terminal seta on P3 endopod 
is slender and not much longer than the endopod ( 1 . 2 : 1 ). 
No internal seta on segment 1 of P4 (0:1:1,2,1), (Fig. 26C). 
P5 is broad and partly covers the genital double-somite, 
it is rounded posteriorly with an apical seta and one sub¬ 
terminal dorsal seta (Fig. 26G). Mature females carry four 
or five large eggs. 
Adult males (Fig. 26B) colourless. Anterior of 
cephalosome only slightly truncated, shoulders rounded 
bearing two rows of dorsal pits arranged along a ridge 
(Fig. 29D). The rostrum has a prominent anterior point 
that is not obscured dorsally. The rostrum and antennule 
sockets are recessed in a medial anterior concavity of the 
cephalosome (Fig. 26H). Dorsal pits and hyaline border 
as for female. Caudal ramus sub-quadrate (1/w = 0.8), a 
and (3 setae close together (Vlo of ramus length), terminal 
setae appear to be plain, T1 is very short, recessed, T2 
and T3 close, gap between T3 and T4 is Y 3 -V 2 width of 
ramus (Fig. 28B). Antennule is unique for the length of its 
setae (Fig. 28G). Both the terminal seta on dactylus and o 
seta on sensory lobe are as long, or longer, than length of 
extended antennule, 8 seta 73 length of antennule, annulate 
seta associated with the distal denticle is equal to segment 
3+4 in length. No denticle on segment 3, two denticles on 
segment 4 (Fig. 28F). Structure and setation of mouthparts 
and ambulatory limbs as for female, but P2 has two terminal 
setae on segment 3 of the endopod, P5 acute trapezoid (Fig. 
28D), no rows of setules at base of each terminal seta. 
Etymology. The species has been named after Dr Nozomu 
Iwasaki in recognition of his studies on Dactylopusoides 
species that burrow into brown algae. 
Remarks. Nearly all animals in the present study are 
heavily burdened with protozoan organisms (large thecate 
and small naked suctoria as well as other thecate protozoa) 
which obscure detail of important organs such as the caudal 
rami and male antennules (see Fig. 27A). For this reason 
it was necessary to base identification and description on 
three newly metamorphosed specimens that had not been 
colonized by protozoa. 
Animals were found living inside the shells occupied by 
the hermit crab Pagurus sinuatus, but not on empty shells or 
those occupied by the mollusc, thus the relationship appears 
to be commensal. 
Acutiramus cumulus sp. nov. 
Figs 27-29 
Type material. Holotype adult male, length 0.55 mm, 
dissected, P89051, and allotype, adult female not carrying 
eggs, length 0.78 mm, both mounted on a slide [1651], 
P89052, deposited at AM, Sydney. Additional paratypes 
deposited atNHM, London. All collected from inside Turbo 
torquatus shells inhabited by hermit crabs of the species 
Pagurus sinuatus , O’Hara Head, Kioloa, NSW, (25°34'S 
150°25'E, estimated), V. A. Harris, 1976. 
Diagnosis. Male rostrum without anterior point, anterior 
border of cephalosome convex in midline obscuring rostrum, 
slightly concave on each side with angular shoulders; T 1 on 
male caudal ramus large, pinnate, a and (3 setae not close 
together (% length of ramus apart); anterior border of female 
rostrum straight, cephalosome bulged above rostrum; female 
caudal ramus rhomboid with conspicuous network of ridges; 
terminal setae T2, T3 and T4 pinnate, equal in size and 
bunched up together at posterior apex; no internal seta on 
segment 1 of P3 endopod (0:2:1,3,1); P4 has plain internal 
seta on segment 1 of endopod ( 1 : 1 : 1 , 2 , 1 ); setae on male 
antennule not longer than antennule (< 14 antennule length). 
Biometric data. Females (N = 8 ): maximum length (L m ax) 
mean 0.78 mm, length to posterior of genital double-somite 
(L U rs) mean 0.72 mm; width of cephalosome (W) 0.51 mm; 
rostrum width (R) 0.12 mm; genital double-somite length 
0.16 mm, width 0.26 mm, arch 0.09 mm; caudal ramus length 
0.10 mm, width 0.03 mm. 
Ratios: L m ax/W 1.5, L U rsAV 1.4; cephalosome W/R 4.2; 
genital double- somite width 50% of cephalosome width, w/1 
1.65, arch /1 0.55; caudal ramus 1 /w 3.1, ramus as % of L U rs 
14%, Hicks’ ratios a 88 %, (3 61%, a-(3 27%. 
Males (N = 2): maximum length 0.58 mm; cephalosome 
width 0.42 mm. 
Ratios: Caudal ramus 1/w 1.0, Hicks’ index for a = 70%, 
(3 42%, a-(3 28%. 
Description. Adult females (Fig. 27A): colourless, anterior 
of cephalosome semicircular with a distinct bulge above the 
rostrum. Rostrum prominent with slightly convex anterior 
border (Fig. 27G). Dorsal surface without hair-like sensilla, 
dorsal pits large (6-9 pm) conspicuous over all parts of the 
body except the caudal rami. Genital double-somite posterior 
lobe pointed, separated from anterior lobe by a distinct cleft 
(Fig. 27B). Caudal ramus (Fig. 27F) rhomboid, long (length 
214 times width) with conspicuous dorsal network of ridges, a 
and (3 setae not close (> % length of ramus). The arrangement 
of terminal setae is unique, T2, T3 and T4 are clustered 
together at the posterior apex of the ramus (Fig. 27F), T1 is 
small at the lateral end of the bevelled posterior edge and 
there is a gap between y and T2. A terminal fringe of setules 
could not be seen on specimens available. Labrum without 
setules. Structure and setation of mouthparts and ambulatory 
limbs typical of family except for P3 which lacks internal seta 
on segment 1 of endopod. Serrated spinous seta on segment 
3 of P3 much longer than endopod (1. 6 :1). P4 endopod (Fig. 
27C) has plain internal seta on segment 1, P5 broad, rounded 
posteriorly with apical seta and one sub-terminal seta (Fig. 
27D). Mature females carry four or five large eggs. 
