Harris: Synopsis of genera and species 
177 
Remarks. This species is remarkable for a number of 
unusual features. Nothing corresponding to the dorsal 
organs and their cuticular outgrowths has been found 
on any other member of the Porcellidiidae. They do not 
appear to be derived from any ancestral or pre-existing 
structure. They first appear on stage III copepodids, but after 
metamorphosis to adult the trough is completely obscured 
by the massive honeycomb cuticle. These structures occur 
on both sexes and first appear on stage III copepodids in a 
simple form. They are best interpreted from juvenile stages 
because the mass of cuticular honeycomb is shorter and 
does not obscure the dorsal organs (Fig. 4B). The dorsal 
organ on stage V copepodids appears as a longitudinal 
trough with thickened rim (Fig. 4F). This is surrounded 
by a clear oval area which is bounded by a ridge and pits, 
similar to the ridge parallel to the edge of the cephalosome 
but greatly extended in height to form the folds of the 
cuticular honeycomb. In adults the honeycomb is massive 
and completely obscures the dorsal trough (Fig. 1A, 4C; 
Plate 1A, p. 172). The function of the dorsal organ and 
cuticular honeycomb is not known. 
Ducts from marginal glands of male animals open 
individually close to the hyaline border as in other 
porcellidiid species (Fig. 4D), but similar ducts are not 
found in female animals in the region of microtubule blocks 
(Fig. 4E, left hand side). From the body cavity passages run 
through the thickened cuticular border of the cephalosome 
and end in fine branches under the blocks of microtubules 
(Fig. 4E, right hand side). It is assumed that secretions from 
the marginal glands exit through the microtubules. Blocks 
of microtubules are not found on juvenile animals, but first 
appear at the moult from stage V copepodid to adult female. 
The caudal rami of copepodid stages bear typical thin 
pinnate setae. The large pinnate setae with hollow shaft 
do not appear until the final moult to the adult stage (Fig. 
4A shows a pharate stage V female copepodid with both 
juvenile and adult terminal setae). Unlike the clavate setae 
of Clavigofera , the pinnae do not originate from a thin 
lateral expansion of the shaft, but from the shaft itself. 
The male antennules are also unique for they have finger¬ 
like structures on segment 4 that appear to take the place 
of coupling denticles found on all other species. They may 
perform the same function of increasing friction during 
mate guarding behaviour. 
Etymology. The specific name refers to the wart-like 
appearance of the dorsal organs (L. verruca = a wart). 
Distribution. Cereudorsum verrucosum has only been found 
on partly decomposed Ecklonia radiata in muddy water at the 
entrance to Gunnamatta Bay, Port Hacking. This is unusual 
for it is very rare to find porcellidiids on rotting algae and 
only one or two species can tolerate muddy water. Nearly all 
the animals in the sample are covered with diatoms, suctorian 
protozoa, moulds and sand particles, which make critical 
observation of detail difficult. The type series, Cr34. 2/77, 
contained 82 $ 54 SS (8 coupled to female copepodids) 
and 8 copepodids. V. A. Harris 1977. 
Genus Geddesia gen. nov. 
Porcellidium. —Geddes, 1968: 11. 
Type species. Geddesia quadrata sp. nov. 
Diagnosis. Male antennule unique, no denticle or comb on 
segment 3, two serrate denticles and two spherical structures 
on segment 4; female cephalosome truncated anteriorly, male 
deeply concave anteriorly; hyaline border to lateral edge; no 
dorsal organ with cuticular honeycomb; no ridge plates or 
setules on labrum; female caudal ramus pentagonal, medial 
corner 90°, posterior border between T2 and T4 straight, 
T3 absent; maxillule endopod with six setae; coxae of 
maxillipeds touch in mid-line; female P5 exopod without 
ventral expansion, not truncated posteriorly, dorsal and apical 
setae not pinnate. 
Species composition. Geddesia trisetosa (Geddes, 1968) 
comb, nov.; Geddesia quadrata sp. nov. 
Etymology. The genus is named after Dr D. C. Geddes. 
Remarks. The genus is defined on the unique structure of 
the male antennule, number of setae on maxillule endopod 
and absence of T3 seta on caudal ramus (compare with 
Mucrorostrum, Clunia and Brevifrons). 
Geddes’ Porcellidium trisetosum is included here on the 
assumption that its maxillule exopod has six setae (Geddes 
states that “...mouthparts like those of P. viride (Philippi) 
as described by Sars (1911)”, this implies six setae on the 
maxillule, Geddes (1968: 11). 
The genus is known from Bahamas and Great Barrier 
Reef, Australia. 
Key to species of Geddesia 
1 Male P2 endopod with two terminal setae. Male T2 and T4 
on caudal ramus short (< Vs ramus width). Gap between T2 
and T4 > 3 A of maximum width of male caudal ramus. Colour 
yellow. (Plate ID, p. 172) . G. quadrata sp. nov. 
- Male P2 endopod with three terminal setae. Male T2 and T4 
on caudal ramus long (> !4 ramus width). Gap between T2 and 
T4 I /2 maximum width of caudal ramus. Colour brown-red. G. trisetosa (Geddes, 1968) 
