104 
Records of the Australian Museum (2009) Vol. 61 
Description 
Measurements. External tube diameters: 0.5 mm in 
juveniles to 2.0 mm in older specimens. Total lengths 
of worms: 3.2 mm in a juvenile to 13.7 mm in a larger 
specimen; their thoracic widths: 0.7 mm to 0.2 mm, 
respectively. Lengths of operculum and peduncle range 
from 3.8 mm in an older specimen to 1.0 mm in smallest 
juvenile; length of abdomen up to about 7.5 mm, possibly 
longer in specimens not contracted in alcohol. 
Tube. Shape: sinuous (Figs 5A, 6B,K) to loosely coiled 
(Figs 5C, 61, 71). Maximum number of longitudinal ridges 
observed 5 (Figs 5A,C). When sinuous, outermost ridge 
on each side, especially on concave side, extends laterally 
rather than vertically. Earlier formed posterior parts of tubes 
may have a smaller number of longitudinal ridges, e.g., 4 
(Fig. 6B). Texture: mostly more or less pitted in longitudinal 
rows between ridges; may occasionally be quite smooth and 
shiny, with smooth ridges and hardly any pitting (Fig. 71); 
or somewhat smooth-ridged and regularly pitted (Fig. 5C); 
older tubes roughly trapezoidal in cross-section, with a wide 
lateral flange along the substratum on each side, as seen in 
two latter specimens; a light brown inner tube lining often 
present. An unattached tube fragment, circular in cross- 
section, occurring in collection has peristome-like transverse 
ridges and some faint transverse ridges between latter (Fig. 
7B). Further studies are necessary to confirm whether such 
an unattached portion occurs in this species. 
Worm. Radioles semicircularly arranged; maximum number 
observed per side: 10 in an older specimen, 3 in smallest 
juvenile; pinnule-free tips Vs to V 9 the total length of the 
radioles, usually slightly thicker than the pinnules (Figs 
5A,B,D,E, 6J-L, 7C-E,G,N); up to about thrice as thick as 
pinnules in some specimens. Determination of opercular 
insertion difficult in adult worms; ontogenetically, however, 
it occurs in position of first, as seen in juveniles (Fig. 
7D,E,M,N); may occur on the left or right side; rudimentary 
operculum absent. In older specimens, consists of a 
bulbous transparent to translucent basal part, and a conical 
transversely partitioned distal cap of chitin-like material 
(Figs 5A,B, 6C-E,I-L, 7A,C-E,G,H); latter translucent 
to semi-translucent, light to somewhat darker-brown in 
colour. Number of partitions ranges from none in the 
smallest juvenile (Fig. 7D,K,M,N), to 9 in one of the older 
specimens (Fig. 5A); however, maximum number could be 
much higher, 16, (Fig. 7A). Variations in opercular shape 
in alcohol-preserved material: as follows. Ter min al cap in 
early juveniles frequently collapsed into a concavity with a 
small convex peak at its centre (Fig. 7C-E,K,M,N). Likely, 
however, to be dome-shaped in live condition, as seen in less 
contracted juvenile operculum (Fig. 7G,H); may be relatively 
unaffected (Fig. 5A,B), or collapsed to various extents in 
older specimens too (Figs 5D,E, 6J-L). Basal bulb-shaped 
part of operculum may also may retain its original form 
(Figs 6K,L, 7K,M,N), or be affected to various extents (Figs 
5A,B,D, 6C-E,7A,C,D,G,H,J). Peduncle bears up to about 
5 annuli distally, most distal one conspicuously large; may 
be relatively unaffected in alcohol preservation (Figs 6J,L, 
7A,E,G,H,M,N); or, frequently, assume a very characteristic 
ventrally directed projection (Figs 5E, 6C,D). 
Thorax bears 7 pairs of chaetal fascicles and 6 pairs of 
uncinal tori (Figs 5B,E, 6D,J,L, 7J). Thoracic membranes 
extend to fourth or fifth chaetiger only (Figs 5D, 6D,J,L, 
7C-E,G); apron absent. Total number of abdominal segments 
varies from 32 in the smallest specimen available to 66 in 
an older specimen; capillaries in latter specimens start from 
segments 23 and 51, respectively; pygidial gland absent. 
Chaetae. Chaetal composition of one side of thorax in 
longest worm as follows. Collar fascicle bears about 6 simple 
chaetae with curved serrated blades (Fig. 6F) and a similar 
number of capillaries; 2nd and 3rd fascicles, bear curved 
serrated blades only; 4th to 7th bear serrated blades chaetae 
and sickle-shaped chaetae, the latter numbering 2, 5, 3 and 
3, respectively. Thoracic uncini: saw-shaped (Fig. 6G); bear 
about 12 teeth and a simple anterior; anterior and posterior 
abdominal uncini rasp-shaped (Fig. 6H). Anterior abdominal 
neuropodia frequently bear a single geniculate chaeta each, 
with a serrated blade; posterior ones bear 2 such chaetae. 
Ontogenetic observations. The small juveniles in 
collection provide data on early development of tube, 
besides derivation and later development of the operculum 
and number of branchial radioles. The circular juvenile tube 
condition is shown in Fig. 7K, which then develops a MLR 
(Fig. 7L). A LLR is then added on, e.g., as seen toward the 
posterior end of the tube in Fig. 7F Then, an OLR is added 
on each side, bringing the total to 5 as shown in Fig. 7F,I. 
Their form and number may or may not be distinct along 
parts of the tube (Fig. 6K). 
As seen in the earliest available juvenile, the operculum 
is shaped like an inverted bell, terminating in a transparent to 
translucent chitinous plate (Fig. 7K,M,N). A faint constriction 
is discernible distally, between the vesicular part and the 
chitinous plate. At the centre of the latter is a tiny transparent 
to translucent swelling or peak. The first peduncular annulus 
is developed just beneath the vesicle (Fig. 7M). Two such 
annuli are seen in a later juvenile (Fig. 7C,D). It also bears a 
somewhat more prominent peak at the centre of the latter. In 
the next stage (Figs 6C-E, 7G,H), the operculum has changed 
shape, its chitinous part becoming somewhat conical, and 
its distal plate more like a cap, and its peduncle developing 
more annuli, most of them partially formed. An additional 
partition is noticeable in the cap (Fig. 7H). 
The early juvenile operculum of V. glandigera as 
described above goes through stages similar to those 
described for V. cylindrica (Figs 3J, 4B,C), and it appears 
difficult to distinguish between the two species at this stage. 
Remarks. The differences between V. cylindrica n.sp., 
and V. glandigera can be summarized as follows. In V. 
cylindrica, worms attain a larger size, as observed, up to 
a total length of about 25.3 mm, and possess a maximum 
number of 22 branchial radioles, which is about double that 
in V. glandigera. The chitinous distal part of the operculum 
in older specimens of V. cylindrica is cylindrical, its 
diameter greater than its height, which gives it a cylindrical 
pillbox shape transparent and may bear from 1 to about 5 
light-brown bands encircling it.. In V. glandigera, on the 
other hand, it is conical in shape, and the maximum number 
of transverse partitions encountered is much higher, up 
to 16 observed in the Kimberleys collection (Fig. 7A). 
Thoracic uncini in V. cylindrica bear about 14-15 teeth 
and a truncated anterior process (Fig. 3H), whereas the 
number in V. glandigera is somewhat lower, about 12, and 
its anterior process is pointed (Fig. 6G). 
