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Records of the Australian Museum (2014) Vol. 66 
and not autapomorphies. To overcome this problem, type 
material has been re-examined for each genus to assess 
whether the diagnostic characters chosen can be considered 
autapomorphic or not. This is relatively simple for genera 
with several species that possess the same character set 
as the type species, but not for genera based on a single 
species. The three new species described here will illustrate 
this problem. They do not fit the diagnosis of any existing 
genus, but display unique features that suggest each should 
be placed in a separate genus. 
A revised list of the apomorphic and autapomorphic 
characters for each of the genera is given to bring their 
definition into line with Hennigian principles (Table 1). This 
enables the 71 species of Porcellidiidae recognized in this 
study to be placed in the appropriate genus. The genus to 
which a species excluded from Porcellidium has been placed 
is shown in a check list (Table 2). 
The family is well represented on the eastern coast of 
Australia where 32 species have been described. Their 
distribution along the coast is discussed. 
Methods and terminology 
Methods and terminology follow Harris & Robertson (1994) 
and Harris (2014a,b). Measurements of caudal ramus and 
genital double-somite are taken from dissections, laid flat 
and the male antennule fully extended. The following 
method was used to extend the antennule. Seaweed was 
washed in 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 the copepods which were then 
fixed in 5% formalin with their antennules fully extended. 
Drawings and measurements were made from calibrated 
digital photographs of paratype specimens mounted in 50% 
glycerol or dissections mounted in polyvinyl lactophenol. 
Two measurements of length are given, L max from rostrum 
to posterior extremity of caudal furca and L U rs from rostrum 
to posterior extremity of the genital double-somite. Scanning 
electron micrographs (Plates 1 and 2, pp. 172-173) were 
taken on an Hitachi S225 ON SEM from gold coated, 
formaldehyde fixed material. The abbreviation AM for 
Australian Museum, Sydney and NHM for the Natural 
History Museum, London are used. 
No information is available for the manner in which the 
three specimens from Cocos Keeling Islands were obtained 
or their exact location. 
Systematics 
Family Porcellidiidae Boeck, 1865 
Genus Cereudorsum gen. nov. 
Type species. Cereudorsum verrucosum sp. nov. 
Diagnosis. Dorsal organs present (trough-like depressions 
in cuticle), surrounded by massive honeycomb-like cuticle 
(Figs 1 A, 4F); male antennule unique, no denticle on segment 
3, segment 4 with group of four or five swollen finger-like 
structures in place of typical cuticular denticles; maxilliped 
coxal lobes wide apart; no ridge plates on labrum; male and 
female caudal ramus rectangular, T1 small pinnate, deeply 
recessed, setae T2, T3 and T4 large pinnate, equally spaced 
(not pinnately clavate); maxillule with six setae on endopod; 
male P5 trapezoid, no reduction in number of terminal setae; 
spermatophore elongate, ephemeral on female. 
Species composition. Only the type species is known, 
Cereudorsum verrucosum sp. nov. Recorded from Sydney, 
NSW, Australia. 
Etymology. Cereudorsum , (L. cereus = waxen, honeycomb 
+ dorsum = the back). 
Remarks. Dorsal organs surrounded by massive honey- 
comb-like growth of cuticle are not known elsewhere 
in the Porcellidiidae; their presence is considered an 
autapomorphic character that defines the genus. 
Superficially, the large pinnate terminal setae (T2-T4) 
on the caudal rami resemble the pinnately clavate setae of 
Clavigofera but in the latter genus the pinnae arise from a 
flattened expansion of the seta shaft, not the shaft itself (Fig. 
12R), and T1 is the same size and shape as T2-T4. 
The maxillipeds of Cereudorsum resemble those of 
Dilatatiocauda, which do not meet in the midline or possess 
a fimbriate process, but the basis is elongated typical of other 
Porcellidiidae. 
Cereudorsum verrucosum sp. nov. 
Figs 1-5; Plates 1, 2 
Type material. Holotype adult male, length 0.73 mm, 
P81216; allotype adult female, length 0.92 mm, P81217; 
paratype specimens 10 $ $, 6 SS, P81218, deposited at AM, 
Sydney. Additional paratypes deposited at NHM, London. 
All collected from rotting Ecklonia radiata near entrance to 
Gunnamatta Bay, Port Hacking, Sydney, New South Wales 
(34°05'S 151°08'E), V. A. Harris, 1977. 
Diagnosis. Female with blocks of microtubules near edge 
on anterior half of cephalosome, microtubules absent from 
male cephalosome; both male and female have two dorsal 
organs with honeycomb-like cuticle on cephalosome and 
one each on metasome segment 3 and genital double-somite; 
numerous dorsal sensilla (> 100) on cephalosome, metasome 
and genital double-somite; female caudal rami with two 
longitudinal ridges; internal seta absent from segment 1 of 
male and female P4 endopod; first (lateral) seta on male P5 
with five strong ventral setules, each terminal seta with row 
of three setules at its base. 
