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Records of the Australian Museum (2014) Vol. 66 
Hicks (1971), Hicks & Webber (1983), Harris & Robertson 
(1994), Harris (1994, 2002), Walker-Smith (2001). These 
studies provided a wealth of information on porcellidiid 
structure and a clearer understanding of the wide range of 
features that could be used as taxonomic characters. 
Many of the new species collected from Australia could 
not be assigned to Porcellidium as understood at that time. 
This led Harris & Robertson (1994) and Harris (1994) to erect 
five new genera to accommodate the rejected species. Huys 
et al. (1996) considered that these new genera were “based 
on dubious grounds” and “without any prior revision of the 
highly speciose type genus Porcellidium it does not seem 
justified to maintain these Australian genera.” The problem 
was that Porcellidium viride Philippi, 1840 had never been 
described in sufficient detail to compare it with the Australian 
species, despite the fact that it is considered the type species 
to the genus. Without a detailed description of both male 
and female of the type species it was impossible to give a 
definitive diagnosis for Porcellidium. 
Among recent authors there is no complete agreement 
on the characters that define Porcellidium. The diagnoses 
of Harris & Robertson (1994), Huys et al. (1996), Harris 
& Iwasaki (1996) and Walker-Smith (2001) all fail on 
the following grounds: (a) there is no clear statement as 
to the criteria upon which genera are defined, (b) absence 
of detailed information about males of the four European 
species upon which the genus is based and (c) freedom from 
the ideas and synonymies of previous authors, such as Lang 
(1948). The description of Japanese and Australian species 
have provided a wealth of information on fine morphological 
detail, particularly of the male antennule, and a clearer 
understanding of the range of apomorphic and plesiomorphic 
characters that can be used for taxonomic purposes. Walker- 
Smith (2001) has pointed out that genera should be based 
on apomorphic characters and it can be shown that the new 
genera proposed by Harris & Robertson (1994), Harris (1994, 
2002), Harris & Iwasaki (1996b, 1997, 2009) all display 
apomorphies that separate them from one another. 
Porcellidium is no longer regarded as the only genus in 
the Porcellidiidae. Tectacingulum and Brevifrons, Harris 
(1994) and Clavigofera and Kushia, Harris & Iwasaki 
(1996b) have been accepted by Bodin (1997), Walker-Smith 
(2001) and Wells (2007). Dilatatiocauda Harris (2002) has 
been accepted by Wells (2007). But the genus Porcellidium 
still remains poorly defined and the number of species that 
should be assigned to it is uncertain. It is important, therefore, 
that the European species, upon which Porcellidium was 
originally based, should be redescribed in detail so that a 
new diagnosis can be given for the genus. 
A description of Porcellidium viride was given by 
Brady (1880). Although this description is inaccurate and 
hopelessly confused, his illustration does show one species 
specific character (related to the male’s antennule) that 
makes it possible to recognize the species with a high degree 
of certainty. Consequently it has been possible to identify 
specimens, collected from Scotland in the present study, as 
Porcellidium viride. This enabled a full redescription of the 
species to be made with a clearer understanding of its species 
specific characters. Porcellidium viride is regarded as the 
type species to the genus (Apostanov & Marinov, 1988) and 
so it is now possible to give a definitive diagnosis for the 
genus Porcellidium from the new description of P. viride. To 
give taxonomic stability to the taxon, an adult male P. viride 
collected at Clachan, Seil Sound, Oban is designated as the 
neotype. Among other places in Scotland, Brady records 
the species from Loch Fyne not far from Seil Sound, Oban. 
Brady (1880) misidentified the adult female of his P. viride 
and called it Porcellidium fimbriatum. This was largely 
due to the inadequate description Claus (1863) gave for P. 
fimbriatum , but the error was perpetuated by other early 
authors, Thompson & Scott (1903), Sars (1904), Monard 
(1928), Lang (1948), (see also Appendix 1). 
In 1889 Claus redescribed Porcellidium fimbriatum and 
his illustrations show species-specific characters that allowed 
positive identification of animals collected from Oban, 
Scotland. The species is redescribed in detail. 
A direct consequence of re-diagnosis for Porcellidium is 
that many species originally placed in that genus are now 
excluded and must be assigned to other genera. For example 
Porcellidium tenuicauda Claus, 1860 and P. scutatum Claus, 
1889 both have apomorphic characters that are not found in 
Porcellidium or any other genera of the Porcellidiidae. It is 
proposed to assign them to a new genus, Porcelloides gen. 
nov., as Porcelloides tenuicaudus (Claus, 1860) comb, nov., 
and Porcelloides scutatus (Claus, 1889) comb. nov. 
The new descriptions of European species means that 
they can now be compared with Japanese and Australian 
species to expand our understanding of character diversity 
in the family. 
Methods and nomenclature 
Longitude and latitude of collecting sites were made by 
extrapolation from Ordinance Survey maps and are only 
approximate. Dates are given as day/month/year. 
Animals were collected by washing a sample of 
seaweed for about three minutes in a bucket containing 
a 50/50 mixture of soda water saturated with CO 2 (from 
soda siphon or bottled soda water) and fresh water. This 
appears to anaesthetize copepods and other small marine 
animals, these were then collected by removing the seaweed, 
allowing another three minutes for the animals to sink to 
the bottom and then pouring off most of the water (which 
was used again). Five percent formalin was then added 
to fix the animals. Porcellidiid copepods were extracted 
using a dissecting microscope and then preserved in 5% 
borate buffered formalin. This method of collection has the 
advantage that the male antennule remains fully extended and 
is easy to study. Specimens usually retain their colouration 
for several years in the buffered formalin. 
For each new Australian species an adult male was 
chosen as holotype and an ovigerous female as allotype from 
the type series selected from one of the samples washed 
from seaweeds. Nearly all the illustrations are drawn from 
paratype material. This is because fine details that show 
species specific characters are difficult to measure or draw 
from the type specimens without dissection. To overcome 
this problem, paratype specimens from the type series 
were dissected and used to draw the unique and general 
structures of each species. Dissections were mounted in 
polyvinyl lactophenol. Drawings were made either by means 
of a drawing-tube attachment or from digital photographs. 
Numbers on some of the drawings refer to the slides from 
which they were drawn. Measurements were made using a 
calibrated micrometer eyepiece or from calibrated digital 
