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Records of the Australian Museum (2014) Vol. 66 
renamed P. sarsi by Bocquet in 1948) have the same long 
first seta on segment 2 of the male antennule and must be P. 
viride. Claus’ (1889) description of Porcellidium lecanoides 
does not show the male antennule, but he illustrates five other 
species specific characters which show his animals are P. 
viride , thus, P. lecanoides and P. sarsi are junior synonyms 
for Porcellidium viride. 
The second species found in the samples from Clachan, 
Scotland, is smaller and distinguished by a dark blue stripe 
down the back (Plate 1C,E, p. 67). Comparison of these 
with P. viride from the same locality show that the first seta 
on segment 2 of the male antennule (Figs 12D) is not much 
longer than the second or third seta, moreover, details of 
the female genital double-somite (Fig. 6E) and caudal rami 
(Fig. 6D) are very different and conform to Claus’ (1889) 
description of Porcellidium fimbriatum. 
The “ ovatum ” problem 
Porcellidium ovatum Haller, 1879 and P. scutatum Claus, 
1889 have caused problems even to this day because of 
Haller’s poor description. Lang (1948) and Wells (2007) 
consider them synonymous, but Bodin 1997 does not list 
either (presumably because he considers both synonymous 
with Claus’ Porcellidium tenuicauda). The illustration Haller 
(1880) gives of Porcellidium ovatum Haller, 1879 shows a 
remarkable resemblance to Porcelloides tenuicaudus. It is 
not clear why Haller (1879) regarded his animal as a separate 
species, but the body proportions of Claus’ (1860) original 
drawing appear distorted and not obviously egg-shaped. This, 
together with the apparent difference in shape of the caudal 
rami, may have led Haller (1879) to regard them as different 
species. The caudal rami on most preserved specimens of 
Porcelloides tenuicaudus are depressed and appear short in 
dorsal view, just as Haller (1880) shows in his illustration, 
but when dissected and laid flat the rami are elongate as 
shown by Claus (1860). 
Monard (1935) states Porcellidium ovatum is identical 
to Porcellidium tenuicauda, but gives no evidence for this. 
There are, however, good reasons for accepting his opinion. 
Both Claus (1863) and Haller (1879) record a length of 1.3 
mm. This is unusually large for members of the Porcellidiidae 
and is only exceeded by two other species: Dilatatiocauda 
bipartita (Kim & Kim, 1997), 1.45 mm and Murramia 
magna Harris, 1994, 1.38 mm. Haller (1880) describes his 
animal as “egg-shaped” in outline (hence the trivial name 
ovatum ), but Porcelloides tenuicaudus is also “egg-shaped” 
or ovoid, although this is not obvious from Claus’ (1860) 
drawing (the “egg shape” is more obvious when the animal 
conglobates). 
Most members of the Porcellidiidae are coloured or 
have a colour pattern, due to the colour of the chitinous 
exoskeleton and/or pigment localized immediately under 
the cuticular exoskeleton, but Porcelloides tenuicaudus 
shows a marked departure from this arrangement. Specimens 
from Scotland contained a large number of dark orange or 
brown oil droplets in the haemocoel that gave the animals an 
orange or reddish-brown colouration (these are lost in spirit 
preserved specimens). In his description of Porcellidium 
ovatum, Haller (1880) states that the animals are coloured 
due to the presence of red and yellow fat globules in the 
body that glitter through the colourless cuticle. It should be 
noted that Porcelloides scutatus, the only other egg-shaped 
European species, does not have oil droplets and its dorsal 
red patch is due to sub-cuticular pigment. However, by far 
the most compelling reason for regarding Porcellidium 
ovatum synonymous with Porcelloides tenuicaudus is the 
presence of two reniform spermatophores on the female’s 
P5 limbs shown in Haller’s (1880) illustration. Claus (1860) 
and Bartsch (1987) both showtwo reniform spermatophores 
in their illustrations of Porcellidium tenuicauda. This is in 
contrast to the rest of the Porcellidiidae where only one 
spermatophore is deposited on a female and this only stays 
attached for a matter of hours. 
Lang (1948) treats Porcellidium scutatum Claus, 1889 
and Porcellidium acuticaudatum Thompson & Scott, 1903 
as synonyms for P. ovatum Haller, 1879, thus, anyone 
using Lang’s key will misidentify Porcelloides scutatus 
as Porcellidium ovatum. Three other species have been 
misidentified through Lang’s key. Geddes (1968) referred 
animals from Barbados to P. ovatum , but they do not show 
any of the characteristics of Porcelloides tenuicaudus and 
probably belong to Acutiramus. Holmes & O’Connor (1990) 
referred specimens in the NMI of Porcelloides scutatus 
collected from Loch Hyne by D. Minchin (July 1982) to 
Porcellidium ovatum. Animals from Oshoro Bay, Hokkaido, 
Japan (Kito 1977) and Guandong Province, China (Zhang 
& Li 1976) both referred to as P. ovatum are unlikely to 
belong to that species. The porcellidiid fauna of Japan is 
reasonably well known but the genus Porcelloides has not 
been recorded from that region. It is probable that the animals 
from Hokkaido and Guandong are a species of Kensakia 
because the caudal rami of Porcelloides and Kensakia are 
superficially similar. Anyone using Lang’s (1948) key for 
identification would misidentify species of Kensakia as 
P. ovatum. Porcellidium acuticaudatum almost certainly 
belongs to Kensakia. 
Haller (1879) described another species, Porcellidium 
parvulum, also from Messina, which he illustrated the 
following year, Haller (1880). One of his animals appears to 
be a stage III or IV female copepodid (it does not have typical 
stage V P5 limbs and is only 0.55 mm). The other animal is 
a male but its antennules are not transformed and therefore it 
is not an adult. With a body length of 0.71 mm, it is likely to 
be a stage IV or possibly stage V male copepodid. The large 
size of these juveniles suggests they belong to Porcelloides 
tenuicaudus , but their identity cannot be established with 
certainty from Haller’s (1880) description. 
Reproductive biology of Porcellidiidae 
Perhaps the most significant fact revealed through study 
of the European species is a fundamental difference in the 
reproductive biology between Porcelloides tenuicaudus and 
all other members of the Porcellidiidae. 
From observations on living animals in Scotland and 
Australia it was found that shortly after metamorphosis 
an adult male will seek and couple with a juvenile female 
copepodid (usually stage II or III) by clasping the posterior 
region with his antennules. This coupling has been referred 
to as mate guarding behaviour, Huys & Boxshall (1991). 
Each time the female copepodid moults to the next stage the 
guarding male re-couples with it until stage V is reached. 
About this time the spermatophore develops in the male. The 
spermatophore of Porcellidium viride is typical of nearly 
all members of the family. It is a long tubular sac (sausage- 
