Pillai: Serpulid polychaetes from the Australian Kimberleys 
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of varying sizes, operculum circular in juveniles and 
intermediate sizes (Figs 4IE, 42A,C,E,F); somewhat oval 
in some older specimens (Fig. 41M,N). Arising vertically 
from opercular plate in holotype is a column bearing a pair 
of dorsolateral horns and a bifid ventromedian horn (Fig. 
41B-E); tips of ventromedian horn curved towards opercular 
plate. Dorsolateral horns not dichotomously branched (Fig. 
41B-E); each ends in an anteroventrally curved, more or 
less pointed tip, and bears three short accessory spines, one 
located ventrolaterally towards its middle or at the point 
where it joins the central column, and the other two located 
sub-terminally; paratypes and other specimens similar (e.g., 
Figs 41K-N, 42A-E). Central column itself may be short 
and stout as in holotype (Fig. 41B-E) and other specimens 
(e.g., Fig. 42A,B), or comparatively longer and less stout 
(Fig. 42E,G). Peduncular wings unfringed in holotype and 
paratypes (Fig. 41B,C,K), and all other specimens si mil ar 
(e.g., Fig. 43A-D,K). 
Radioles numerous, arranged in 4 V 2 whorls on each 
side in holotype, the maximum number observed; up to 
3 V 2 whorls in other specimens; smallest specimen (from 
AM W21442) has 19 radioles plus the operculum on the 
left and 25 radioles on the right, arranged in a partial spiral 
on both sides. Inter-radiolar membranes unfringed (Fig. 
42B); pinnule-free radiolar tips as long as, and of same 
thickness as the pinnules. A pair of blackish clusters of 
prostomial ocelli present ventrolaterally, anterior to the first 
pair of thoracic tori (Fig. 42E). Seven thoracic chaetigers; 
the distances between corresponding pairs of thoracic tori 
decreasing toward thorax where they meet or almost meet; 
apron present (Fig. 42B,D,E,H); Number of abdominal 
segments 145 in holotype; maximum number in 165 in one 
of the other specimens. 
Chaetae. Special collar chaetae bayonet-shaped, possess 
a serrated area along the shaft preceding the squarish 
basal boss (Fig. 4IF in holotype and Fig. 43E, in another 
specimen); blade, only slightly longer than serrated part of 
chaetal shaft plus boss; unserrated notch absent; boss may 
be abraded. Thoracic uncini: saw-shaped, bear about 15-20 
teeth and an anterior gouged process (Fig. 41G in holotype; 
Fig. 43F in another specimen). Anterior abdominal uncini 
(Figs 41H for holotype; Fig. 43G for another specimen) 
bear about 10-13 teeth plus anterior gouge. Posterior 
abdominal uncini (Figs 411 for holotype; Fig. 43H for 
another specimen) are smaller but bear similar number of 
teeth. Abdominal neurochaetae with long shafts present 
throughout the abdomen (Fig. 42B,H). 
Two specimens in the collection appear to be aberrant. 
Although similar to the above in having a circular opercular 
plate and three horns arising from a long central column, the 
horns themselves differ, as follows: In the smaller one (Fig. 
43A), the dorsolateral pair of horns are blunt and appear 
abraded, while all horns are blunt in the other (Fig. 43B-D). 
However, bayonet-shaped special collar chaetae (Fig. 43E) 
are similar to those described earlier. Thoracic uncini similar, 
but bear a lower number, about 15 teeth in a single row, and 
an anterior gouged process (Fig. 43F); anterior and posterior 
abdominal uncini similar and bear about 10 and 9 teeth, 
respectively (Fig. 43G,H). 
In the juvenile specimens from AM W21442: tube 
white, bears traces of two longitudinal ridges and faint 
transverse ridges (Fig. 431). Operculum on left side, no 
rudimentary operculum on right; opercular plate circular, 
flat (Fig. 43 J,K), bears a central column at the end of which 
are three rudiments of soft, unbranched, tapering horns; 
peduncle winged; wings unfringed. Radioles number 6 per 
side, arranged in a circle on either side, as to be expected in 
early juveniles; inter-radiolar membranes present; number 
of thoracic chaetigers 7; abdomen consists of 25 segments; 
neurochaetae with long shafts protruding conspicuously 
from the abdominal wall present from about segment 15; 
abdominal uncinal tori short and lateral. 
Remarks. Spirobranchus richardsmithi n.sp., is superficially 
similar to S. gardineri Pixell, 1913 with regard to the circular 
opercular plate and column arising from it bearing three 
processes distally. However, unlike in the present species, 
the three distal processes in S. gardineri are not bifurcated, 
and are directed anteriorly S. gardineri as described by 
Pixell (1913:81, plate 8, fig. 7a-c), and as confirmed by ten 
Hove (1994) in material from the Seychelles and Amirantes, 
directed “away from the opercular plate”. According to 
the latter, “forms with re-curving ventral spines occur in 
the Indo-West Pacific too; may be the taxon gardineri 
contains two species.” Pixell (1913) also mentions that the 
three anteriorly directed processes “sometimes give rise 
to short secondary branches”. A very important character 
of S. gardineri relates to the size and proportions of its 
thoracic uncini. As stated and figured by Pixell (1913: 81, 
plate 7, fig. 7c), they are very large. It is confirmed after 
examination of Pixell’s slides (types) in the Natural History 
Museum during the present study that they are indeed quite 
unlike those of the other species dealt with in this account, 
in being extraordinarily long and bearing at least 25 teeth 
plus the anterior gouge. 
Bailey-Brock (1985) describes material from the Fijian 
coral reefs similar to S. richardsmithi from the Kimberleys, 
but assigned them to S. giganteus corniculatus {sensu ten 
Hove, 1970). Smith ( unpublished thesis, 1985) describes 
similar forms from Queensland, in which the most ventral of 
the three processes at the end of the common column is bifid, 
which he refers to Spirobranchus gardineri, Pixell, 1913 
(sensu stricto ), with two variant types. However, specimens 
from the Seychelles and Amirantes studied by ten Hove 
(1994) agree with those described by Pixell (1913) in that 
all the spines at the distal end of the common column are 
directed anteriorly, i.e., away from the opercular plate. The 
single very large specimen described above and identified by 
by Bailey-Brock (1985: fig. 6a-c) therefore appears to belong 
to the new species, S. richardsmithi. Its opercular plate is 
circular, unlike in S. corniculatus, described earlier in this 
account, in which it is oval, and, as in S. richardsmithi, the 
two dorsolateral processes arising from the central column 
are curved anteroventrally, while and tips of its bifid ventral 
process are curved towards the opercular plate. 
Another synonymy is that of S. gardineri Pixell, 1913, 
described from Hainan, South China Sea by Fiege & Sun, 
(1999: 126). The number of teeth in the thoracic uncini, in 
addition to the gouged process, in the Kimberleys material 
of S. richardsmithi is about 15-20, while it is 20-21 in the 
specimens from Hainan. As shown above, it is much higher, 
about 26, in S. gardineri (Pixell, 1913). Fiege & Sun also 
state that although the tubes are embedded in coral, with only 
their openings visible, they have a purplish interior, which is 
similar to the mauve tube colour of S. richardsmithi from the 
