82 
Records of the Australian Museum (2014) Vol. 66 
Porcellidium fimbriatum Claus, 1863 
Fig. 9-12 
Porcellidium fimbriatum Claus, 1863:140, taf. xxii, fig. 1. 
P. fimbriatum.—^ Claus, 1889: 32, figs. VII 1-18, VIII 1-8 
(redescription); Bocquet, 1948: 247-250; Harris & 
Robertson, 1994: 301; Huys et ah, 1996: 308; Walker- 
Smith, 2001: 656; Wells, 2007: 79. 
P. viride. —Lang, 1948: 420. 
P. lecanoides. —Norman & Scott, 1906: 182. 
Thy one viridis. —Vervoort, 1964: 119. 
Type material. The description and illustrations Claus 
gave of P. fimbriatum (1863) are misleading for they do not 
show a single species specific character that would confirm 
the animal’s identity. It is possible that Claus was looking 
at mixed material because, as shown above, P. fimbriatum 
and P. viride may be found in the same sample. In 1889 
Claus redescribed his P. fimbriatum giving eight or more 
species specific characters which should have cleared up 
any misunderstanding between the two species, but his 
synonymies show that he believed his animals were the 
same species as Brady’s P. “fimbriatum ” which is known 
to be the female of P. viride. Moreover, P. lecanoides Claus, 
1889 is a junior synonym for P. viride. In order to stabilize 
the taxonomy of Porcellidium fimbriatum in the apparent 
absence of a type specimen, a male with antennules extended 
to show species specific features has been selected as a 
neotype for Porcellidium fimbriatum Claus, 1863. 
Neotype designation. Neotype adult male with antennules 
extended, to show coupling denticles, length 0.56 mm, 
P92561 deposited at the Australian Museum, Sydney; 
collected from Laminaria saccharina, LW spring tide at 
Clachan, Seil Sound, Oban, Scotland (56°19'N 5°35'W), V. 
A. Harris, September 1997. 
Material examined (specimens determined to be conspecific 
to the neotype): slide material in NHM ( Porcellidium 339), 
(see Appendix 1); specimens from Castle Heads, Dale 
Pembrokeshire, Wales (51°42'N 5°10'W) and Clachan, 
Seil Sound, Oban, Scotland (56°19'N 5°35'W), identified 
as P. fimbriatum from Claus (1889); specimens collected 
from Laminaria digitata at Clachan, Scotland, AM P89055 
(15^,8 SS + 3 coupled V. A. Harris, 1997). Other 
specimens (60 $ 30 SS + 8 coupled SS, V. A. Harris, 
1997) and slide mounted dissections have been deposited at 
NHM, London. The following description is based on the 
neotype and material examined. 
Diagnosis. No finely plumulose setae on male antennule 
segment 2, first seta on segment 2 not longer than remaining 
setae, short blade-like ventral process on segment 3, three 
coupling denticles on segment 4 (proximal with serrated 
edge, two distal denticles small, botryoidal, no denticulate 
pad present), dactylus short (< % length of segment 4) 
segment 5 not expanded, segment 6 clearly visible, not fused 
to segment 5; no U-shaped wrinkles on ventral surface of 
male rostrum; female caudal ramus long, rectangular (1/w = 
2.7-2.8), terminal setae T1-T4 all conspicuously pinnate, 
gap between T3 and T4 < 14 width of ramus, Hicks’ index 
for |3 seta 25%; female genital double-somite with deep cleft 
or scar between anterior and posterior lobes (clear triangular 
area absent), no sensilla on border of posterior lobe; male 
genital segment with two rows of three dorsal sensilla; 
ventral surface of male and female cephalosome with fine 
lines (wrinkles); male P5 exopod trapezoid, apical angle 50°. 
Spermatophore elongate, ephemeral on female. 
Biometric data. Females (N = 43): maximum length (L max ) 
0.77 mm, body length (L U rs) 0.76 mm (range 0.73-0.79 mm); 
cephalosome width 0.45 mm (range 0.43-0.47 mm); rostrum 
(R) 0.095 mm; genital double-somite width 0.32 mm, length 
0.27 mm; caudal ramus length 0.14 mm, width 0.05 mm. 
Ratios: L U rsAV 1.7; W/R4.7; genital double-somite width 
70% of cephalosome width, w/1 1.2; caudal ramus 18% of 
L U rs, 1/w 2.8, Hicks’ index for p seta 25%. 
Males (N = 25): maximum length (L m ax) 0.56 mm, body 
length (L urs ) 0.50 mm; cephalosome width (W) 0.38 mm; 
spermatophore 0.15 x 0.03 mm; antennule fully extended 
0.135 mm. 
Ratios: L m ax/W 1.47, L U rs/W 1.32; antennule 35% of 
cephalosome width, segment 2 30%, segment 3+4 42% 
and dactylus 15% of antennule length; spermatophore 27% 
Of Lurs- 
Description. Adult females (Fig. 9A; Plate 1C, p. 67): 
colourless or pale yellow with broad band of deep violet or 
dark blue down middle of back, including genital double¬ 
somite and caudal rami. Body outline elongate oval, sides 
of body almost parallel, rostrum narrow (W/R = 4.7). Dorsal 
surface of cephalosome, metasome and genital double-somite 
ornamented with dorsal pits (5-6 pm in diameter), ventral 
surface of cephalosome with fine wrinkles (see Fig. 12A). 
Hyaline border 8 pm wide. No patch of setules on labrum. 
Genital double-somite (Fig. 9H) relatively long (w/1 = 1.2), 
posterior arch deep, slight notch or indentation between 
anterior and posterior lobes with transparent scar (scar appears 
as deep cleft when compressed with cover glass, cf Claus’ 
1889 illustration). No sensilla on edge of posterior lobe (Fig. 
9E), border setules on posterior lobe longer than those on 
anterior lobe. Genital opening (Fig. 9G). Caudal rami (Fig. 
9C, D) long (18% of body length), rectangular (1/w = 2.8), 
almost completely enclosed in arch of genital double-somite, 
dorsal surface with network of fine ridges but no pits. Medial 
edge straight, slightly bevelled distally, lateral edge slightly 
convex, both edges with setules posteriorly. Beta seta about 
down ramus (Hicks’ index = 25%), terminal setae T1-T4 
conspicuously pinnate, equal in length, T2 and T3 very close 
on slight prominence midway between T1 and T4, distance 
between T3 and T4 equal or less than % width of ramus, very 
fine terminal fringe of setules between T3 and T4. No finely 
plumulose setae on segment 2 of antennule. Structure and 
setation of mouthparts and ambulatory limbs typical of family. 
Antenna (Fig. 10C). Mandible with small group of setules on 
anterior lobe of palp (Fig. 10B). Segment 1 of PI endopod 
elongate triangular, narrow (1/w =1.5), coxa with internal 
seta (Fig. 10A inset). Serrulate spinous seta on segment 2 of 
P3 endopod (Fig. 11C) shorter than endopod (0.8:1), large 
serrate spinous seta on terminal segment considerably longer 
than endopod (1.7:1). P4 with internal serrulate spinous seta 
on segments 2 and 3 (Fig. 11 A). P5 (Fig. 10F, G), exopod 
broadly lanceolate, with dorsal pits, one sub-terminal dorsal 
seta and two apical setae. Females carry 12-14 eggs per brood. 
