Pillai: Serpulid polychaetes from the Australian Kimberleys 
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distal part of the operculum leads into a hollowed cavity with 
its bulbous proximal part (Figs 32D,E,K,N). Highest number 
of radioles amongst the three specimens, 20 plus operculum 
on left and 18 plus rudimentary operculum on right; smallest 
number 12 plus operculum on right, and radiolar crown 
missing on left; pinnule-free tips longer and thicker than 
pinnules (Fig. 32N). Prostomial ocelli and apertures for 
thoracic glands absent; apron present. Number of abdominal 
segments in a complete specimen about 79; capillaries start 
from about segment 45. 
Juvenile worm: operculum bell-shaped (Fig. 33K,M), 
bears 23 marginal lobes; latter nearly triangular, with smooth 
tips; uncertain whether a hollow is present within operculum 
in the early juvenile condition (Fig. 33M). Radioles number 4 
on each side; a short filamentous rudimentary operculum on 
left, operculum on right; pinnule-free tips short and slender. 
Number of thoracic chaetigers 7; an apron is present. Number 
of abdominal segments 32 abdominal segments, capillaries 
start from the twenty-third. 
Chaetae. Bayonet-shaped special collar chaetae (Fig. 
33A-G) usually possess two, sometimes three teeth at base 
of blade; in fully formed bayonets, boss as well teeth directed 
away from blade (Fig. 33A-F); in newly formed bayonets 
from within collar fascicle, teeth directed parallel to or 
slightly towards the blade (Fig. 33G). Unserrated notch short 
to moderately long in the older bayonets (Fig. 33A,E), yet to 
be developed and not evident those within collar fascicle (Fig. 
33G);. Thoracic uncini saw-shaped (Fig. 33H) and bear 5 or 
6 teeth; anterior abdominal uncini similar (Fig. 33H) with a 
similar number of teeth. Abdominal neuropodia with about 
13 flattened trumpet-shaped chaetae in each chaetal fascicle. 
Corresponding pairs of anterior abdominal uncinal tori are 
lateral separated dorsally by a very wide gap (Fig. 32G). 
The juvenile possesses 4 bayonet-shaped special collar 
chaetae per fascicle, each bearing 2-4 teeth at base of blade, 
of which 2 may be larger than the rest; similar to the number 
described for adult specimens. Thoracic uncini bear 5 or 6 
teeth in a single row. 
Remarks. Serpula watsoni Willey is similar to S. ampli- 
lobata and Serpula nudiradiata described earlier in that 
the proximal part of its operculum is bulbous and a sharp 
constriction occurs between the operculum and the peduncle. 
However, unlike in both the latter species, S. watsoni 
possesses a cavity extending from the funnel-shaped distal 
part to into the bulbous proximal part of the operculum. 
Serpula watsoni possesses tubercles along its radii, whereas 
they are absent in both S. nudiradiata and S. amplilobata. 
The spirally coiled tube with mutually bonded coils of S. 
amplilobata (Fig. 27 A) distinguishes it from tube of Serpula 
watsoni (Figs 32A,B,H-J). For differences between their 
collar chaetae see relevant descriptions. Straughan’s figure 
(1967a, fig. 3b) of S. watsoni does not show the bulbous 
proximal part of the operculum that observed by Willey 
(1905: pi. VIII, fig. 6) and in the present account (Fig. 
32C,D,F,K,M). Straughan’s figure (1967a, fig. 3a) of S. 
vermicularis appears to be that of a juvenile S. watsoni (vide 
Fig. 33J-M in the present account). 
The tube of the juvenile specimen, with its two 
longitudinal ridges along its crest (Fig. 33J), is similar 
to that of older specimens of S. watsoni (Fig. 32A,B,I). 
Bayonet-shape collar chaetae are also similar. It is uncertain 
whether a hollow is present in the bulbous proximal part of 
the operculum in the early juvenile condition. 
Genus Spiraserpula Regenhardt, 1961 
Type species. Spiraserpula spiraserpula Regenhardt, 1961. 
Diagnosis. Operculum chitinous; funnel-shaped, usually 
bearing dichotomous radii ending in marginal lobes, only 
a few or lacking in certain species; inserted in position of 
second branchial radiole; peduncle non-pinnulate; inter- 
radiolar membranes absent. Number of thoracic chaetigers: 
seven or more. Apron: absent. Special collar chaetae usually 
bayonet shaped, bearing two to a number of teeth on boss. 
Most anterior uncinal tooth: larger than the rest. Distal ends 
of abdominal neurochaetae shaped like asymmetrically 
‘flattened trumpets’, with one side longer than other, and 
bear numerous serrations or denticulations. Apron absent, as 
an adaptation to presence of internal tube structures. Tube: 
internal tube structures present. 
Remarks. The genus Spiraserpula was first known from 
Cretaceous fossils (vide Regenhardt [1961], Jager [1983] 
and Pillai [1993]). For descriptions of the type species S. 
spiraserpula Regenhardt 1961, S. versipellis Regenhardt 
1961 and other fossil species of Spiraserpula, see Regenhardt 
(1961:41^44) and Pillai (1993:71-82). For 18 extant species 
of Spiraserpula see Pillai & ten Hove (1994) and ten Hove 
& Kupriyanova (2009). 
Spiraserpula snellii 
Pillai and ten Hove, 1994 
Figs 34A-E, 35A-J 
Spiraserpula snellii Pillai & ten Hove, 1994: 39-104. 
Spiraserpula sp.—ten Hove (1994: 112). 
Material examined. Kimberleys, Western Australia, 1 specimen, AM 
W21475, south west corner of Lucas Island, 15°13'S 124°31'E, 30 m, on a 
dead oyster shell, 24 Jul. 1988, st 101; coll. P.A. Hutchings. 
Description 
Measurements. Maximum external diameter of tube 1.5 mm 
in places, elsewhere about 1.2 mm. Worm (radioles missing): 
length of thorax and abdomen 18.0 mm, width of thorax 0.5 
mm; length of abdomen 16.8 mm. 
Tube. Has an overall brownish mustard colour, with a lateral 
longitudinal pigment band on each side and a less distinct 
and narrower median longitudinal band. In addition to the 
mustard colour, a pinkish tinge present dorsally. A granular 
overlay is present (Fig. 34A,B), granules being larger along 
the lateral borders. Forwardly directed peristomes may 
be present (Fig. 34A,E). Internal tube structures present, 
consisting only of a ventral longitudinal ridge; it is somewhat 
T-shaped in cross-section posteriorly (Fig. 34C). More 
anteriorly, as the ventral ridge decreases in height, it develops 
a shallow longitudinal groove, which gives it a somewhat 
Y-shaped appearance (Fig. 34E) and, still more anteriorly, 
becomes wedge-shaped and skewed (Fig. 34D), then tapers 
to a simple low ridge. 
