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Records of the Australian Museum (2009) Vol. 61 
rudimentary operculum absent; opercular plate oval, 
the broader part being anteroventral, the whole having a 
posterodorsal slope (Fig. 38A-D, 39A,C,D,I,J, 40A-C). 
As also seen in latter figures, a pair of horns, borne on a 
short common base arises posterodorsally from it; each 
horn has a short bifid dorsomedial spine towards its base, a 
short posterolateral spine towards its middle, and ends in a 
bifid tip. Tips of main horns and spines are wasted through 
abrasion against the tube, the operculum evidently being 
withdrawn obliquely into the tube, unlike in other species of 
Spirobranchus. Peduncular wings unfringed (Figs 38A-C, 
39A,B, 40A-C). Variations observed in arrangement of 
spines on the opercular horns: in an older specimen from 
AM W202959, tips of the main horns curved, pointed, 
and directed anteroventrally (Fig. 39B-D), as also figured 
by Morch (1863: fig. 26). In addition, a small, anteriorly 
directed conical swelling may be present at the base of 
the short column from which the main horns arise (Fig. 
39C), apparently uncommon; latter is lacking in specimen 
shown in (Figs 38C, 391, 40C). A long medial process may 
occasionally be present in place of the conical process (Fig. 
40A,B). Radioles numerous and arranged spirally on each 
side. Four out of the five specimens in AM W202960 possess 
7 spirals on each side, the fifth 5. However, 10 spirals are 
Figure 40. A-C, Spirobranchus comiculatus (Grube, 1862). (A, B) from AM W202960, two views 
of operculum; (C) operculum of specimen BMNH 1938.7.25.2, labelled type specimen of Spiro¬ 
branchus giganteus var turbinatus nov., locality, Hulule, Male Atoll, Maldives, collected by J.S. 
Gardiner. D-F, Spirobranchus sp. 1, cf . polytremus (Philippi, 1844), from AM W21404: (D) whole 
worm, including operculum; ( E,F ) two more views of operculum showing fringed peduncular wings. 
present on each side in the specimen from AM W202958. 
A broad membrane extends between the radiolar whorls. 
Translucent ocelli-like structures present laterally along the 
radioles and at the bases of their pinnule-free tips. Inter- 
radiolar membranes unfringed (Fig. 38A). Highest number 
of abdo min al segments counted, 226 in a worm from AM 
W202959. Long-shafted neurochaetae and notopodial 
uncinal tori are present in all except the first 3-6 or so 
abdominal segments. 
Chaetae. In bayonet-shaped special collar chaetae (Fig. 
39E), a serrated area of the chaetal shaft precedes boss; latter 
squarish, prominent; unserrated notch absent between boss and 
blade; serrations along distal part of blade elongated and wavy, 
those of proximal part much shorter; blade about twice as long 
as combined length of the serrated part of chaetal shaft plus 
boss. Uncini saw-shaped, anterior process gouged; thoracic 
uncini (Fig. 39F) very long compared to those of the other 
species of Spirobranchus, and with a higher number of teeth, 
around 22 to 24; anterior abdominal uncini much smaller, with 
about half the number of teeth (Fig. 39G); posterior abdominal 
uncini similar, with about 13 teeth (Fig. 39H). 
Remarks. Spirobranchus comiculatus is a widespread 
Indo-Pacific species (see ten Hove 1970: 14). Material 
described as S. giganteus (Pallas) by Straughan (1967: 243) 
from Queensland, with its characteristic oval operculum 
and structure of opercular horns (Straughan, 1967: fig. 
14e), belong to S. comiculatus. Likewise, specimen BMNH 
