Pillai: Serpulid polychaetes from the Australian Kimberleys 
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Apron absent. Last (6th) pair of thoracic uncinal tori located 
close together and meet, if not, almost meet mid-ventrally, 
and may have a very narrow flap posterior to 
them; when present, giving appearance of an 
apron (Fig. 9E). 
Chaetae. Each bayonet-shaped chaeta (Fig. 10B) 
has a squarish basal boss and a long serrated 
blade, but lacks an unserrated notch. Thoracic 
uncini (Fig. IOC) possess 12 or 13 teeth in a 
single row and an anterior gouged process. 
Anterior abdominal uncinal tori are lateral (Fig. 
9E) to somewhat dorsolateral, becoming more 
dorsolateral from about the 11th or 12th segment 
onwards. They are smaller than the thoracic 
uncini and bear 7 or 8 teeth in a single row (Fig. 
10D). Posterior abdominal uncini (Fig. 10E) are 
still smaller but the number of teeth is somewhat 
higher, about 10. 
Ontogenetic observations relating to operc¬ 
ulum. One of the specimens provides evidence 
as to how opercular diameter increases in relation 
to increase in tube diameter as the worm grows 
in size (Fig. 10A). The earliest formed opercular 
tier is located at the distal end of the central 
column, and is the smallest in diameter. Each 
tier consists of a saucer-shaped part of light 
to darker coloured chitin-like material bearing 
marginal scallops and a circle of darker spines just 
beneath it arising from the central column. The 
newly formed saucer-shaped tier is of the diameter 
of the now larger distal end of the opercular plate. 
Both, the newly formed saucer-shaped plate and the 
circlet of spines of the earlier-formed saucer-shaped 
part are enclosed within a transparent membrane. 
The latter extends from a rim-like extension beneath 
the tier (X) to the rim of the opercular plate (Y). As the 
worm grows, larger tiers are produced successively by the 
opercular disc to keep pace with the increasing tube diameter, 
while the central column also extends in length. 
Remarks. Ten Hove (pers. com.) alerted the present author 
to the fact that the species frequently identified from the 
Indo-West Pacific as P. stellatus (Abildgaard, 1789) is 
actually P. actinoceros (Morch, 1863). Reviewing published 
accounts P. stellatus, including that from the Indo-West 
Pacific, Pixell (1913: 78) states, under generic characters,: 
that the abdominal chaetae are “sickle-shaped (setae of 
Salmacina ), and on p. 79: that she had “been able to find 
very few bladed sickles (setae of Apomatus ) among the 
thoracic setae, the majority being rather short, still, simple 
bladed forms. The abdominal setae have the rounded teeth 
described by this author, but have nearly lost their sickle-like 
curve, this is, no doubt, due to their lengthened immersion 
in preservatives 
According to Dew (1959: 42) the posterior thoracic 
chaetigers of P. stellatus bear “simple winged setae (Fig. 
14D), sickle-shaped ( Salmacina ) setae, winged setae in 
majority; Salmacina setae usually lose their characteristic 
shape in preservative.” Zibrowius (1970: 13) states, “Soies 
en faucille (“soies (P Apomatus’') presentes dans les segments 
thoraciques posterieurs, comportant une partie distale dentele 
relativement courte don’t la longeur ne depasse pas guere 
Figure 10. A-E, Pomatostegus actinoceros, specimen from AM 
W21438. (A) 6-tiered operculum, with the seventh in the process 
of being formed at the distal end of the fleshy part of the operculum 
(see text); ( B ) bayonet chaeta from the collar fascicle; (C) thoracic 
uncini; ( D ) anterior abdominal uncini; (E) posterior abdominal 
uncini. 
celles du limbe precedent.” Pillai (1960), Straughan (1967: 
238) and Fiege and Sun (1999: 133) apparently overlooked 
the presence of sickle-shaped chaetae in the posterior 
thoracic chaetigers. The abdominal chaetae are geniculate 
according to Zibrowius (1970), and Fiege & Sun (1999). 
According to Fiege & Sun (1999: 133) a single species 
P stellatus occurs in both the tropical western Atlantic and 
the Indo-West Pacific. In Australia: Shark Bay (Western 
Australia) (Augener, 1914); Thursday Island (Queensland) 
(Dew, 1959); Torres Strait, Pretty Beach, Cairns and 
Havannah Island (Queensland) (Straughan, 1967). 
Many past publications expressed the belief that there is 
a single circumtropical species of Pomatostegus. However, 
according to ten Hove & Kupriyanova (2009: 78) there 
are three species. They consider Pomatostegus macrosoma 
Schmarda, 1861, a junior synonym of Terebella stellata 
Abildgaard, 1789, to be its type species. Ten Hove (pers. 
