Harris: The copepod genus Porcellidium 
87 
Adult males (Fig. 9B; Plate IE, p. 67). Colouration as for 
female except that in a few specimens the violet blue colour 
is absent from posterior region of body. Heavily sclerotized 
parts of the antennules and antennule sockets are orange on 
most males. Cephalosome truncated, anterior edge straight 
(not convex in mid-line), shoulders rounded. Rostrum not 
wrinkled ventrally, ventral surface of cephalosome with fine 
wrinkles (Fig. 12A). Dorsal surface with pits as for female. 
Genital somite with dorsal pits, lateral row of three dorsal 
sensilla on each side (Fig. 1 IE). Caudal rami slightly longer 
than wide ( 1 /w = 1 . 1 ), dorsal surface with reticulate markings, 
medial edge straight, lateral edge convex (Fig. 9F). Beta seta 
73 down ramus, terminal setae conspicuously pinnate, space 
between T3 and T4 wider than in female (almost A width 
of ramus) with fringe of fine setules. Antennule (Figs 12D, 
F) with first seta on segment 2 not longer than 1.5 times 
length of second seta, segment 3 with short blade-like ventral 
process, segment 4 with three coupling denticles (proximal 
with serrated edge, middle and distal denticles small with 
botryoidal surface, no denticulate pad), dactylus very 
short, cylindrical (< A length of segments 3+4), distinctly 
two segmented, without pronounced terminal hook. P2 
endopod with two plumose terminal setae (Fig. 1 IB), Setae 
on segments 2 and 3 of P4 endopod all plumose. P5 exopod 
with dorsal pits (Fig. 12B), ventral setules at base of each 
terminal seta (Fig. 12C), apical angle of P5 50°. 
Remarks. Claus did not explain why he called this species 
fimbriatum , but he must have been impressed by the marked 
difference between the narrow pointed caudal rami of his 
Porcellidium tenuicauda and the posterior border fringed 
with bristles of his new 1863 species, (L. fimbriatum 
= separated into shreds or filaments, fringed). Claus 
redescribed the species in 1889 showing several species 
specific characters that allowed animals from Scotland to 
be identified as Porcellidium fimbriatum. The species is 
commonly found with P.viride on Laminaria in samples 
from Scotland. 
Collection data. Porcellidiumfimbriatum has been collected 
from the following algae. Laminaria sp., Plymouth, 
Devonshire, 1970. Alaria esculenta and Gigartina stellata 
at Skokholm Island, Pembrokeshire, 1970. Hymanthalia 
elongata at Great Castle Rocks, Dale, Pembrokeshire, Wales, 
V. A. Harris 1970, 1974. Chondrus crispus at Clachan, 
Seil Sound, Oban Scotland ES2.9/74, 18 25 SS and 
ES18b.il/74, 38 5 SS + 13 SS coupled to juveniles; 
C. crispus and G. stellata ES18a.ll.74, 72 28 
Lithothamnion encrusted stones and boulders ES 14.9/74, 3 
$5, 1 Laminaria saccharina ESI 7.9/74, 7 .$§f, 1 
crispus and L. saccharina ES20.9/97, 76 §.§, 16 $$ + 11 
SS coupled with juveniles; Laminaria digitata ESI 9.9/97, 
5 1 V. A. Harris 1970, 1974, 1987, 1997. 
Porcellidium roscoffensis (Bocquet) comb. nov. 
Figs 13-16 
Porcellidium lecanoides var. roscoffensis Bocquet, 1948: 
250, fig. IX. 
P lecanoides.— Huys, etal. (1996): 308; Wells (2007): 79. 
P. viride. —Bodin (1997):64. 
Material examined. Specimens collected from mixed 
seaweeds, Castle Head, Dale, Pembrokeshire, Wales (3 $ 
2 <$<$) (51°42'N 50°10'W), V. A. Harris, 1970, 1974. Three 
slide-mounted dissections deposited in NHM, London. 
The following account is based on Bocquet’s (1948) 
descriptions of the caudal ramus and genital double-somite 
of P. lecanoides var. roscoffensis. 
Diagnosis. Male antennule with knob or peg-like ventral 
process on segment 3, large proximal pad of fine denticles on 
segment 4, distal denticle with fine comb-like edge, dactylus 
not broad, concave on one side, hooked terminally, segment 
6 inconspicuous, fused to segment 5; ventral surface of 
male rostrum with U-shaped ridges or wrinkles; indentation 
(without border setules) marks boundary between anterior 
and posterior lobes of female genital double-somite, posterior 
lobe with two sensilla at edge; dorsal surface of male genital 
somite with five sensilla on each side; dorsal surface of 
female caudal ramus with pits, (3 seta close to y seta. 
Biometric data. Females (N = 1): body length (L U rs) 0.85 
mm; cephalosome width (W) 0.60 mm; rostrum width (R) 
0.15 mm; genital double-somite width 0.39 mm, length 0.28 
mm; caudal ramus length 0.12 mm, width 0.05 mm. 
Ratios: L U rs/W 1.42; W/R4.0; genital double-somite width 
65% of cephalosome width, w/1 1.4; caudal ramus 14% of 
L U rs, 1/w 2.4, Hicks’ index for |3 seta 16%. 
Males (N = 1): body length L U rs 0.70 mm; body width 0.51 
mm. 
Ratios: L U rs/W 1.4; caudal ramus 1/w 0.8; antennule 46% 
of cephalosome width, segments 3+4 40%, and dactylus 
32% of antennule length. 
Description. Adult females (Fig. 13A): colour (see under 
Remarks ). Anterior of cephalosome broadly rounded, 
rostrum prominent. Dorsal surface ornamented with circular 
pits 3 pm diameter, no obvious ridges but numerous pit 
and collared sensilla present on cephalosome, metasome 
and genital double-somite (see Fig. 13D). Ventral surface 
of cephalosome smooth, but ventral surface of rostrum 
has transverse ridges or wrinkles. Hyaline border without 
striations, 12 pm wide. Labrum without ridge plates or 
setules. Genital double-somite (Fig. 13D) broad, semicircular 
in outline, slight lateral notch without setules at that point, 
two small sensilla at edge of posterior lobe (Fig. 13E), 
posterior arch deep, encloses most of the caudal rami. Genital 
opening (Fig. 13F). Caudal ramus (Fig. 13C) rectangular, 
dorsal surface ornamented with small pits, medial edge 
straight, medial corner slightly bevelled, lateral edge slightly 
convex. Terminal setae pinnate, T1 and y setae recessed at 
lateral corner, |3 seta close to y and posterior edge of ramus, 
T2 and T3 very close, T4 at medial corner, gap between T3 
and T4 less than A width of ramus, fringed with fine setules. 
No finely plumulose setae on segment 2 of antennule, first 
seta on segment 2 less than 1A times length of setae 2 or 3. 
Structure and setation of mouthparts and ambulatory limbs 
