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Records of the Australian Museum (2014) Vol. 66 
looks very different from Porcelloide tenuicaudus. The 
caudal rami are not acutely pointed or excluded from the arch 
of the genital double-somite. However, two features show 
that Claus’ P. scutatum belongs to the genus Porcelloides. 
The arrangement of denticles on the male antennule closely 
resembles that of Porcelloides tenuicaudatus , but differs 
from all other known species in the family. This together 
with the fact that two females from Loch Hyne carry eggs 
and an empty spermatophore on their P5 limb shows that 
Claus’ P. scutatum should be assigned to the new genus as 
Porcelloides scutatus ( Claus, 1889), comb. nov. 
Distribution. Living specimens of this species were 
collected from a red alga (IGelidium) in shallow water (10 
to 40 cm) on the west side of Loch Hyne,Co. Cork, Ireland, 
in deep shade from overhanging trees, LH4.9.97,11 $ ?, 12 
S&, V. A. Harris 1997. 
Claus (1889) collected this species from rocks and 
Laminaria in Trieste Harbour, Adriatic Sea, but it has not 
been recorded anywhere else since. It is not found on the 
coast of Ireland, or the west coast of England and Scotland. 
Its presence in Loch Hyne is surprising for it implies two 
widely separated isolated occurrences. 
Loch Hyne (Ine) in County Cork, Ireland, is a deep tidal 
marine loch, about one square kilometre in area, situated 
about one kilometre inland. It is connected to the sea by a 
very narrow channel and rapids through which sea water 
flows at high tide on the coast. Tidal swing in the Loch is 
only a few centimetres. It supports an extremely rich marine 
fauna that includes many Mediterranean (Lusitanian) species 
not found elsewhere round the coast of Ireland, England or 
Scotland. The inland location of the Loch would protect 
it from the extreme weather of the open coast and this 
suggests it may contain a relic fauna from a period when 
the climate was warmer. The Loch’s origin is uncertain but 
may represent a glacial lake that was replaced by sea water 
when sea-levels rose above the level of the rapids, due to 
changes in land or sea level. It is possible that Porcelloides 
scutatus represents a relic Lusitanian species that was once 
more widely distributed. 
Animals belonging to Porcelloides have not been recorded 
from the Pacific region (Australia or Japan). 
Discussion 
The absence of a precise diagnosis for Porcellidium 
viride until now stems from the inadequacy of published 
descriptions and figures that has resulted in significant 
taxonomic confusion. This has led to wide difference of 
opinion among authors as to where the boundaries of the 
genus Porcellidium should be drawn. 
There are two aspects to this problem. First there is the 
disagreement as to the synonymy of the species. Lang (1948) 
lumped together P. fimbriatum and P. lecanoides under 
the one name P. viride Philippi. Vervoort (1964) followed 
Lang and included P. sarsi under Thyone viridis. Bocquet 
(1948) recognized P. lecanoides , but renamed P. fimbriatum 
(sensu Sars 1904) as P. sarsi. Other authors recognize P. 
fimbriatum as a valid species. Harris & Robertson (1994) 
recognized P. viride, fimbriatum and sarsi , while Huys et 
at. (1996) recognized P. fimbriatum, sarsi and lecanoides. 
Walker-Smith (2001) and Wells (2007) recognize P. 
viride, fimbriatum and lecanoides. However, the detailed 
descriptions given above for P. viride, P. fimbriatum and P. 
roscoffensis clears up this uncertainty and shows that P. sarsi 
and P. lecanoides are synonyms for P. viride. 
The second problem relates to the validity of new genera. 
Huys et al. (1996) reject five new genera proposed by Harris 
& Robertson (1994) and Harris (1994) on the grounds 
that new genera should not be erected until the genus 
Porcellidium had been settled, but they maintain that the 
family has only one genus Porcellidium. However, a number 
of their characters for the family are seriously inaccurate; 
for example, they maintain that the male antennule has five 
segments and is haplocer—features that would exclude all 
known species from the family. 
Waker-Smith (2001) accepts that the family has more than 
one genus, but does not recognize five of the new genera 
and places them in Porcellidium. This move is recognized 
by Wells (2007). However, by doing this new characters are 
introduced into the diagnosis of Porcellidium that are not 
found in the type species, P. viride. Walker-Smith correctly 
asserts that new genera should be based on apomorphic 
characters and not unique combinations of characters. 
In 1840 Philippi gave a diagnosis for a new genus, 
Thyone, for three new species, one of which he named 
Thyone viridis. From his drawing this appears to be a male 
stage IV copepodid belonging to the Porcellidiidae, but its 
shape is very strange and cannot be identified with any other 
known copepodid or adult within the family. Claus (1860) 
pointed out that Thyone was preoccupied and introduced 
the replacement generic name Porcellidium for his two 
new species, but he does not appear to recognize Philippi’s 
Thyone viridis for he does not mention the name in any of 
his works. 
However, Brady (1880) thought that one of his specimens 
was the same species as Philippi’s animal and corrected 
the name to Porcellidium viride (Philippi, 1840). He gave 
a written description of a copepodid which he thought was 
the adult female of P. viride , but his illustration shows that 
it was a male copepodid. 
Neither Claus nor Brady understood the significance of 
“mate guarding behaviour”, where an adult male clasps a 
stage III, IV or V female copepodid with his antennules 
until the copepodid undergoes metamorphosis to an adult 
female. At that moment the male places his spermatophore 
on the nubile female. Adult males do not couple with male 
copepodids, consequently their P5s are easily seen—they 
terminate with six clearly visible setae. In contrast, the shape 
and setation of juvenile female P5s cannot be seen during 
the time they are clasped by the guarding male. As nearly 
all female copepodids are coupled to a male, the majority of 
free copepodids are males. Both Claus and Brady appear to 
have thought that P5s with six setae was a common feature 
of male and female animals and wrongly assumed that all 
copepodids, whether coupled or free, were adult females of 
the same species as the guarding male. Claus (1860), for 
example, labelled a male copepodid as the adult female of 
his Porcellidium dentatum\ the true adult female, which is 
much larger and has differently shaped P5 limbs and caudal 
furca, he considered to be another species and named it 
Porcellidium tenuicauda. Similarly, Brady (1880) labelled 
a male copepodid “adult female”, but the true adult female 
he incorrectly identified as another species— Porcellidium 
fimbriatum. 
This confusion caused by sexual differences was further 
