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Records of the Australian Museum (2009) Vol. 61 
Worm. Thorax has a pair of brownish-black clusters of 
ocelli (Fig. 35A,C); 7 chaetigers; lacks an apron; possesses a 
deep ventral abdominal longitudinal groove (Fig. 35A-D) to 
accommodate ventral internal tube structures (Fig. 34C-E). 
Chaetae. Special collar chaetae bayonet-shaped, possess a 
long serrated blade and several teeth on the basal boss, but 
lack an unserrated notch (Fig. 35E-G). Thoracic uncini saw¬ 
shaped (Fig. 35H), with 4 or 5 teeth in a single row; anterior 
and mid-abdominal uncini different in shape, but possess 
a similar number of teeth (Fig. 351,J, respectively); 
posterior abdominal uncini rasp-shaped. Anterior 
and middle abdominal segments possess 2 or 3 
flattened trumpet-shaped chaetae per fascicle. 
Anterior abdominal tori are short and laterally 
located up to about the eleventh chaetiger, then 
gradually become dorsolateral and longer, after 
which they almost meet mid-dorsally, being 
separated by very short distance, from about 
the twenty-fourth pair onwards (Fig. 35A-D). 
Remarks. The single specimen available 
is significantly larger than those described 
by Pillai and ten Hove (1994) and provides 
additional data on intra-specific size and meristic 
variability. In the material described in 1994, 
external tube diameter did not exceed 0.6 mm; 
maximum total length of worms was about 12.5 
mm and maximum abdominal length 11.2 mm. 
The number of thoracic chaetigers in the present 
specimen, 7/7, falls within the range encountered in 
1994. However, its thoracic membranes extend further 
backwards, to thoracic chaetiger 6/6. Maximum number of 
abdominal segments encountered in the 1994 specimens was 
only 48 for an abdominal length of 11.2 mm. It is very much 
higher in the Kimberleys specimens, 158 for an abdominal 
length of 16.8 mm. 
Subfamily Spirobranchinae 
Uchida, 1978 
Type genus. Spirobranchus Blainville, 1817 
Type species. Spirobranchus giganteus (Pallas, 1766) (= 
Serpula gigantea Pallas, 1766) 
Diagnosis (emended): Operculum calcareous; depending on 
the taxon, opercular plate may be circular or oval, simple 
and flat or corrugated, concave, convex or conical, with or 
without branched spiny processes arising from it, or may 
consist of stacked disks; peduncle winged; wings may or 
may not be fringed. Operculum inserted in position of second 
dorsal radiole of left side, extremely rarely on the right; 
rudimentary operculum absent on opposite side. Branchial 
radioles may be arranged in a circle or a spiral, or may be 
in a circle in juveniles and spiral in adults. Inter-radiolar 
membranes present; may or may not be fringed. Thoracic 
membranes present; apron present. Thorax consists of seven 
chaetigers. Depending on the taxon, collar chaetal fascicles 
may be present in both juveniles and adults, or may be 
reduced or absent in adults but present in some juveniles. 
Special collar chaetae: may be bayonet-shaped, with a 
squarish serrated boss; latter may be reduced to various 
extents, even completely, when they may be similar to the 
Figure 34. A-E, Spiraserpula snellii Pillai & ten Hove, 1994, from 
AM W21475. (A,B) external view of tube; (C-E) showing internal 
tube structures. 
simple bladed chaetae hat accompany them; distal part of 
chaetal shaft preceding boss serrated in both well-developed 
and reduced bayonet-shaped special collar chaetae; an 
un-serrated notch absent between the serrated boss and 
blade. Serrations of blade may be fine, short and hair-like 
in some taxa, longer and wavy in others. Thoracic uncini 
saw-shaped; their anterior process gouged. Abdominal tori 
lateral; uncini similar to those of the thorax, usually with 
fewer teeth; posterior uncini may be rasp-shaped. Abdominal 
neurochaetae have flattened trumpet-shaped ends, with 
