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Records of the Australian Museum (2009) Vol. 61 
Figure 21. A-I, Hydroides spiculitubus n.sp.: from holotype AM 
W21443. (A-C) three different views of operculum; (D) longitu¬ 
dinal section operculum showing interior view; ( E) structure of a 
coronal spine; ( F,G) bayonet-shaped special collar chaetae; ( H) 
thoracic uncini; (7) anterior abdominal uncini. 
hand, and as confirmed after re-examination of the holotype 
during the present study, its two longitudinal ridges run 
along the crest of the tube rather than dorsolaterally, they are 
comparatively thicker, the longitudinal groove between them 
is narrower and deeper, as figured by Pillai (1961: fig. 12G). 
Its entire tube surface has a conspicuous granular overlay. 
Confirmation is required as to whether an inner 
tube consisting of chitinous spicules occurs in “H. 
tambalagamensis ” recorded from Queensland by Straughan 
(1967: fig. 3G), from Japan by Imajima (1976, 1979) and 
Imajima & Hove (1984, 1986), and from China by Chen 
& Wu (2000). 
Etymology. Named after its characteristic inner tube 
constructed from chitinous spicules sloughed off from ventral 
side of the abdominal wall, occurring within the normal 
calcareous tube, within which the worm lives (Fig. 19D,E). 
Hydroides spiratubus n.sp. 
Figs 22A-F, 23A-J 
Material examined. Kimberleys, Western Australia: 
holotype: AM W21392, east side of Fenelon Island, 15°13'S 
124°31'E, 30 m, 24 Jul. 1988, st 101. Paratype: AMW202955, 
east of Montalivet Island, 15°06'S 125°18'E, 6 m, 16 Jul. 1988, 
st 50, intertidal, found in a depression at the base of a piece of 
dead coral; both coll, by P.A. Hutchings. 
Description 
Measurements. Holotype: maximum external 
diameter of tube 1.2 mm; total length of worm 10.9 
mm; thoracic width of 0.6 mm; length of operculum 
and peduncle 2.8 mm, operculum alone 1.0 mm; 
abdomen 6.5 mm, total number of segments 73, 
capillaries start from the 57th segment. Paratype: worm 
only only slightly smaller, 10.3 mm long, its thoracic 
width 0.4 mm, length of operculum and peduncle 2.7 
mm, length of operculum alone 1.0 mm, length of 
abdomen 5.8 mm, and number of abdominal segments 
about 58; capillaries start from about 43rd segment. 
Ttobe. Spirally coiled, in both holotype and paratype 
(Figs 22A, 23 A), unlike in other hitherto known species 
of Hydroides. Coils laid obliquely upon each other in 
holotype (Fig. 22A), upon each other in paratype (Fig. 
23A); bonded together in both; small tubeless area or 
umbilicus present in coil centre of both, similar to that 
occurring in certain species of Spimserpula Regenhardt, 
1961 (vide Pillai & Hove, 1994). In holotype, outer part 
of each coil white, its inner part consisting of a semi- 
translucent caramel-coloured band (stippled areas in 
Fig. 22A); paratype similar (stippled areas in Fig. 23A), 
but colour of its inner band lighter, almost white. Two 
longitudinal ridges may be discernible in certain parts 
of the tube where it may give it a more or less squarish 
cross-sectional appearance. A granular overlay present, 
more prominent along the longitudinal ridges. 
Worm. Corona consists of 9 processes in both specimens; 
its modified dorsal process small, short, vesicular, and with 
a dorsolateral extension on each side and a medial swelling; 
T-shaped when viewed from anterior end (Fig. 22C,E); in 
lateral view, medial swelling is anteroventrally directed (Fig. 
22B,D). Remaining coronal spines, as well as infundibular 
processes, end distally in somewhat T-shaped swellings 
(Fig. 22B,D,E). Holotype has higher number of infundibular 
processes, 25, the paratype 21. Radioles number 8 and 7 in 
holotype, 7 pairs in paratype, their pinnule-free tips long 
and conspicuous, about one-fifth the length of radiole (Fig. 
22B). Prostomial ocelli: clusters of brown prostomial ocelli 
present. Thoracic chaetigers: 7 in both specimens. Thoracic 
glands: not discernible. 
Chaetae. Bayonet collar chaetae (Fig. 23B-G) bear two 
large conical teeth at base, may also have 1 to a few smaller 
accessory teeth. Thoracic uncini rasp-shaped, possess 7 teeth 
(Fig. 23H); anterior abdominal uncini similar, usually with 
5, sometimes 4, teeth (Fig. 231); posterior abdominal uncini 
rasp-shaped. Anterior abdominal segments usually bear 
about 5 flattened trumpet-shaped neurochaetae; posterior 
