Harris: Male antennule of porcellidiid copepods 
123 
salinity changes. Low water during spring tides tend to occur 
about midday or early afternoon at Urangan leaving the 
seagrass beds exposed to solar radiation for up to three hours. 
On 30 November 2002 at 12.30 pm when the type population 
sample was collected, water temperature in very shallow 
pools containing seagrass was recorded at 31°C, despite 
the fact that the weather was overcast with showers. Heavy 
rain occurring during the low tide period, particularly during 
the cyclone season, will flood the mud flats and subjects all 
organisms living there to lowered salinity or fresh water. 
Distribution. The type series (PCk 3. 11/02) was collected 
from Zostera capricornia on mud flats at low water spring 
tide. It comprised 147 $$ (91 carrying eggs), 122 and 
26 copepodids. This species has been collected from another 
seagrass Cymodocea serrulata in the same area, (PCk 1. 
4/97. 116 ? $ (67 with eggs), 108 and 21 copepodids), 
but it has not been found on two other seagrasses, Halophila 
ovalis and H. spinulosa , both abundant in the same area, V. 
A. Harris 1997, 2002. A coloured form of R. doliocauda 
with large red area on back (Fig. 4E, F) was collected from 
sea grass (? Zostera capricornia ) growing on coral sand in 
shallow water inside the coral reef at Green Island, Cairns, 
Queensland (16°43'S 146°H) 4^9,2 cM, V. A. Harris 1973. 
Genus Synurus gen. nov. 
PorcelJidium. —Ummerkutty, 1970: 158. 
Type species. Synurus ctenocheirus sp. nov. 
Diagnosis. Male genital double-somite fused to metasome 
segment 4 and baseoendopod of P5; epipleural lobe of 
male metasome segment 3 long, stretches back to posterior 
extremity of caudal ramus; male P5 exopod ovate (not 
trapezoidal) with one lateral seta, terminal setae atrophied or 
absent; seta T1 absent from male and female caudal ramus; 
segment 3 of P2, P3 and P4 exopod with only two external 
setae; anterior of male cephalosome deeply concave; anterior 
of female cephalosome truncated; female P5 exopod without 
ventral expansion, P5s reach beyond genital double-somite 
but do not touch posteriorly; spermatophore elongate, 
ephemeral on female. 
Species composition. Synurus unicus (Ummerkutty, 1970) 
comb, nov.; S. ctenocheirus sp. nov. 
The genus is known from Gulf of Mannar, Sri Lanka 
(Ceylon), Okinawa, Japan and the Great Barrier Reef, 
Australia. 
Etymology. The name Synurus (masculine) refers to the 
fusion of the anal segment with the caudal rami on female 
specimens of the type species (G. syn = together, conjoint 
+ our a = tail). 
Remarks. Males of this genus are unique among the 
Porcellidiidae in having an ovate P5 exopod with long lateral 
seta and terminal setae that are atrophied or absent. This limb 
strongly resembles the general form of the female P5, except 
for the absence of a ventral falciform ridge and dorsal setae. 
Synurus ctenocheirus sp. nov. 
Figs 9-12, Plate 1G, H 
Type material. Holotype adult male, length 0.55 mm, 
P81213; allotype adult female, length 0.68 mm, P81214; 
paratype specimens, 6 §$, 4 SS, P81215, deposited at AM, 
Sydney. Additional paratypes deposited at NHM, London. 
All washed from seagrass Zostera sp., collected at Green 
Island, Cairns, Queensland, Australia (16°41'S 145°56'E), 
V. A. Harris, 1973. 
Diagnosis. First (proximal) claw on PI endopod ctenoid 
(comb-like) with recurrent teeth, second claw lamelliform; 
female caudal ramus fused to anal segment; male antenna 
with seta on basis (absent from females, Fig. 10A); male P5 
exopod with long lateral seta, terminal setae absent except 
for two small spine-like atrophied setae; female rostrum 
extremely broad ( l A cephalosome width). 
Biometric data. Females (N = 10): maximum length (L m ax) 
mean 0.68 mm, range 0.67-0.70 mm, body length (L U rs) 
mean 0.66 mm, range 0.65-0.68 mm; cephalosome width 
0.44 mm, range 0.43-0.45 mm; rostrum 0.14 mm; genital 
double-somite width 0.18 mm, length 0.2 mm, arch 0.08 mm; 
caudal ramus length 0.078 mm, width 0.022 mm [length of 
caudal ramus from point of fusion with the anal segment 
(indicated by a slight notch, see Fig. 9)]. 
Ratios: L U rs/W 1.5; W/R 3.0, cephalosome length 60% of 
Lmax; genital double-somite w/1 0.9, height of arch 40% of 
length; caudal ramus 1/w 3.8, 12% of L U rs, Hicks’ index for 
(3 60%, distance between a and (3 setae 25% of ramus length. 
Males (N = 10): maximum length (measured from anterior 
edge of shoulder L max ) mean 0.55 mm, body length 
(from rostrum L ur s) mean 0.48 mm, range 0.47-0.50 mm; 
cephalosome width 0.37 mm; caudal ramus length 0.047 
mm, width 0.028; antennule length (fully extended) 0.10 
mm; spermatophore 0.09 x 0.02 mm. 
Ratios: L U rs/W 1.3, L m ax/W 1.5; cephalosome length 67% 
of Lmax; caudal ramus 1/w 1.7; antennule 18% of body length 
(L urs), antennule segments 3+4 57% and dactylus 18% of 
antennule length; spermatophore 18% of body length (L ur s). 
Description. Adult females (Fig. 9A; Plate 1G, p. 163): 
colour lemon yellow. Body outline an ellipse (e = 0.814) 
strongly truncated anteriorly with slight bulge in midline. 
Cephalosome length greater than half maximum length of 
animal. Rostrum very wide (A body width). Dorsal pits 
inconspicuous (1-1.5 pm), a few dorsal sensilla present. 
Hyaline border clear, 7 pm wide (Fig. 9D), surrounds 
cephalosome, ducts of marginal glands open dorsally. Genital 
double-somite cordate (Fig. 9B), length greater than width, 
no notch or scar to indicate boundary between anterior and 
posterior lobes, no anterolateral ridges (rugosities), border 
setules very small, posterior extremity pointed, terminated by 
four or five small setules. Posterior arch deep, nearly all of 
rami enclosed in arch. Caudal ramus long, narrow, rhomboid 
with parallel sides (Fig. 9F), fused to anal segment. Dorsal 
surface with very small dorsal pits (< 1 pm) and parabolic 
ridge on each ramus that fits the edge of genital double¬ 
somite arch. Seta T1 absent, y seta at lateral comer, posterior 
border oblique, T4 at rounded apex, T2 and T3 very close 
mid-way along oblique edge (they tend to lie parallel to edge), 
terminal fringe of very fine setules between T3 and T4 (Fig. 
