Pillai: Serpulid polychaetes from the Australian Kimberleys 
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examples. They are dorsolateral, separated by a wide gap in 
Hydroides kimberleyensis n.sp. (Fig. 14A); by a moderately 
wide gap in H. spiculitubus n.sp. (Fig. 20B); and by a very 
small gap in Hydroides adamaformis n.sp. (Fig. 1 IB). They 
almost meet along the mid-dorsal line in H. minax (Fig. 15B) 
and H. exaltatus (Fig. 12C). 
Genus Hydroides Gunnerus, 1768 
Type species. Hydroides norvegica Gunnerus, 1768. 
Diagnosis. Operculum chitinous; inserted in position of 
second radiole; consists of a Serpula -like proximal funnel- 
shaped proximal part (or Latin equivalent infundibulum for 
brevity) usually bearing radii and radial lobes, surmounted 
by a distal crown (or Latin equivalent corona, or French 
verticil, for brevity) consisting of spine-like or other 
shaped processes. Number of thoracic chaetigers: seven. 
Special collar chaetae possess two to several teeth at base 
of blade and an unserrated notch of variable length relative 
to length of blade, depending on species. Most anterior 
uncinal tooth: larger than rest. Apron: present. Distal ends 
of abdominal neurochaetae shaped like asymmetrically 
“flattened trumpets”, with one side longer than other, and 
bearing numerous serrations or denticulations. Tube: devoid 
of internal tube structures. 
Remarks. The corona (or verticil) which consists of 
processes borne distally on the funnel-shaped operculum is 
an autapomorphous derivation of the condition in Serpula. 
Differences in its structure as well as of the marginal lobes 
of the proximal funnel-shaped part, besides other characters, 
are useful in distinguishing between species. 
Tubes of many extant species Hydroides bear a pair of 
longitudinal ridges. The latter character could be useful in the 
determination of fossil Hydroides taxa, since the chitinous 
operculum is less likely to be found preserved. 
With its numerous known species, and others still being 
discovered, Hydroides is currently one of, if not, the most 
successful among serpulid genera. 
Hydroides adamaformis n.sp. 
Fig. 11A-J 
Type material. Holotype: AM W21457, south west corner of Lucas 
Island, Kimberleys, Western Australia, 15°13'S 124°31'E, 30 m, coll, by 
P.A. Hutchings, 24 Jul. 1988, st 101. 
Description 
Measurements. Maximum external width of tube, with 
flanges, 2.0 mm; total length of worm 20.0 mm, its thoracic 
width 1.0 mm; length of operculum and peduncle 4.7 mm, 
length of operculum alone 1.5 mm, length of radioles 2.7 
mm, their pinnule-free tips about 0.6 mm, and length of 
abdomen 13.5 mm. 
Tube. White, with two dorsolateral longitudinal ridges and a 
very wide flange on each side giving it a flattened trapezoidal 
cross-sectional appearance (Fig. 11 A); longitudinal ridges 
separated by a wide, shallow, longitudinal groove between 
them; fine, incomplete, transverse grooves are present at 
irregular intervals between them; granular overlay absent. 
Worm. Radioles colourless; scattered brownish specks 
present between thoracic segments; a small patch of brown 
pigment present anteroventral to each thoracic uncinal torus; 
a small patch of brown pigment present at dorsal and ventral 
ends of each uncinal torus in abdomen. 
Operculum in holotype on the right side, rudimentary 
operculum on the left; corona heterospinous; consists of 
6 swollen processes (Figs 11A-E), each shaped roughly 
diamond shaped, arising proximally from its bottom angle, 
widening medially towards its lateral angles and curved 
towards its distal angle where it ends as ablunt point at the 
centre of the crown; its two lateral angles project as two 
short spines. Each process possesses a thick, transparent 
cuticle. One coronal processes is larger than the rest, but 
like the rest, curved towards centre of crown. All lack medial 
and basal processes. Infundibulum cup-shaped rather than 
funnel-shaped, its marginal lobes ending in T-shaped to 
crescent-shaped tips (Figs 11A-E). Small whitish specks 
scattered throughout infundibulum. Radioles: 11 on left, 10 
on the right; their pinnule-free tips as long as and slender 
as pinnules (Fig. 11A,B). Brownish clusters of prostomial 
ocelli present. Number of abdominal segments about 95, the 
last 10-12 bear capillaries. 
Chaetae. Each collar fascicle bears 4 bayonet-shaped special 
collar chaetae. All, including one from deep within fascicle, 
possess two conical teeth each at base of blade (Fig. 11F-H); 
unserrated notch moderately long, about !4 to Vs of total 
length of blade. Uncini: thoracic uncini saw-shaped (Fig. 
Ill) bear 6-7 teeth in a single row; anterior abdominal uncini 
similar (Fig. Ill) bear 4 or 5 teeth; posterior abdominal 
uncini rasp-shaped. Abdominal neuropodia bear about 5-6 
chaetae per fascicle; their tips flattened and trumpet shaped; 
posterior abdominal segments bear capillaries while, a little 
anterior to them, capillaries present together with flattened 
trumpet shaped chaetae. Corresponding pairs of anterior 
abdominal uncini tori separated mid-dorsally by only a very 
small gap (Fig. 1 IB). 
Remarks. Hydroides adamaformis superficially resembles is 
H. tuberculatus Imajima., 1960 (vide Imajima, 1960:132, fig. 
7a-j; andFiege & Sun, 1999:121, fig. 11A-C). As described 
and figured in both latter publications, infundibular lobes of 
H. tuberculatus end in simple pointed tips. On the other hand, 
those of H. adamaformis possess T-shaped to crescentic 
tips (Fig. 11A-E). The number of coronal processes in H. 
tuberculatus is 5; their shape is sub-triangular, and their 
cuticle is thick as described by Fiege & Sun (1999: 123). 
All the coronal processes in H. adamaformis , including 
the modified one, are diamond-shaped, and each bears a 
pointed spine on each lateral angle, while its distal angle is 
blunt and curved toward centre of the crown (Fig. 11A-E). 
On the other hand, all coronal spines in H. tuberculatus 
lack the pair of laterally directed spines occurring in H. 
adamaformis, whilst its modified coronal spine ends in a 
ventrally directed beak-like curved process (Fiege & Sun, 
1999: fig. 11 A). Although the number of coronal spines in 
H. adamaformis appears to be 5 from certain angles (Fig. 
11B,C), it is actually 6 (Fig. 11D). 
The external swelling described in Imajima’s original 
account of H. tuberculatus (1976: 133, fig. 7a-c) is different: 
“each spine of the crown has a small external swelling at its 
shoulder, and a somewhat pointed accessory basal radial 
spine.” As seen in Fiege & Sun’s specimens of S. tuberculatus 
