Pillai: Serpulid polychaetes from the Australian Kimberleys 
115 
Hydroides exaltatus (Marenzeller, 1885) 
Figs 12A-F, 13A-L 
Eupomatus exaltatus Marenzeller, 1885: 217, fig. IV a. 
Eupomatus exaltatus .—Willey (1905: 312, pi. VII, fig. 182) 
Hydroides exaltata .—Pillai (1960: 10, fig. 4A-E), Imajima 
(1976: 127, fig. 4A-J), Imajima, (1977: 94), Imajima 
(1979: 168), Imajima & ten Hove (1984: 48), Imajima 
& Hove (1986: 4), Fiege & Sun (1999: 186, fig. 5D-F). 
Material examined. Kimberleys, Western Australia: 1 specimen, AM 
W202941, south side of Slate Island, 15°32'S 124°24'E, lower intertidal, 
rocks, 9 Jul. 1988, st 5; 7 specimens, AM W21456, south west comer of 
Lucas Island, 15°13'S 124°31'E, 30 m, 24 Jul. 1988, st 101. 1 incomplete 
specimen with tube, AM W202931, east side of Fenelon Island, 14°07'S 
125°43E, 6 m, 18 Jul. 1988, st 64; lspecimen without tube, incomplete 
posteriorly, AM W202945, south west comer of Lucas Island, 15°13’S 
124 ° 3 i>e, 30 m, 24 Jul. 1988, st 101. 1 incomplete specimen without tube, 
AMW21413, sand cay on Port George IV, 15°205'S 124°39E, 12 Jul. 1988, 
st 26; all coll, by P.A. Hutchings. 
BMNH 1959.12.16.19, determined by Pillai (1960) as H. exaltata (Maren¬ 
zeller), from the Pearl Banks, Sri Lanka. 
Description 
Measurements. A maximum external diameter of 1.6 mm 
occurs in specimen from AM W202941. Longest available 
specimen has a total length of 16.8 mm and thoracic width of 
1.0 mm; length of operculum and peduncle 4.2 mm, operculum 
alone, 2.0 mm; abdomen 10.4 mm. Smallest specimen is a 
juvenile only 3.8 mm long with a thoracic width of 0.5 mm. 
Tube. White, quadrilateral cross-sectional appearance 
and lacks a granular overlay (Fig. 12A,B,D); a pair of 
dorsolateral longitudinal ridges present, discontinuous in 
places; a thinner, more discontinuous, less developed median 
longitudinal ridge may or may not be present; transverse 
ridges present. 
Worm. A brown transverse pigment band present anterior to 
each thoracic uncinal torus. Coronal and infundibular spines 
end in transparent light-brown tips. A juvenile specimen in 
collection has two opercula (Fig. 13L). Corona heterospinous; 
total number of coronal spines 6 to 10 in available specimens; 
in older specimens most dorsal spine enlarged, sub-terminally 
expanded laterally before ending in a ventrally curved hook 
(Figs 12E,F, 13A,B), narrower in younger specimens (Fig. 
12C). A dimple may be present externally, on the sub¬ 
terminal enlargement (Fig. 12E,F). Remaining coronal spines 
curved outwards and tapered to a point. A short medial 
spine occurs halfway along each coronal spine, including 
the enlarged one (Figs 12F, 13A,B); may not be developed 
in juveniles. Infundibular radii end in simple pointed spine¬ 
like processes; number 22 in four juveniles. Infundibular 
radii end in simple pointed spine-like processes; number 22 
in four out of the seven specimens, 23 in two, and only 14 
in one of the two opercula of the juvenile described above. 
Each infundibular spine appears jointed to the marginal 
lobe from which it arises, curved outwards, and tapers to a 
simple pointed tip in older specimens (Figs 12E,F, 13A,B); 
less obvious in juveniles. Radioles range from 7 per side in 
juvenile described above, to 14 on left and 13 on right in an 
older specimen; their pinnule-free tips very short, as slender as 
or thinner than pinnules. A pair of prostomial ocellar clusters 
present, purplish brown in colour, lighter in juveniles. 
Chaetae. Special collar chaetae bayonet-shaped (Fig. 
13C-I), total number of teeth at base of blade 2-6; of which 
2 may be large and the rest one to few smaller accessory 
teeth (up to 4 observed) at base of blade; two large worn 
out teeth seen in an older chaeta (Fig. 13C). A newly formed 
bayonet-shaped chaeta from within fascicle has 3 main teeth 
and a slightly smaller fourth one (Fig. 13E); another, 1 main 
tooth and 4 smaller teeth (Fig. 131). Unserrated notch in 
newly formed chaetae: moderately long, about one sixth 
of total length of blade (Fig. 13E); may be indistinct (Fig. 
131); blade long and tapered. Thoracic uncini saw-shaped: 
bear 7 teeth (Fig. 13J); anterior abdominal uncini similar, 
with 5 teeth in single row (Fig. 13K); posterior abdominal 
uncini rasp-shaped. 
Remarks. The tube of Hydroides exaltatus (Marenzeller, 
1885) according to Imajima’s figure and description (1976: 
128, fig. 4J), is “white, thick; it is subtrapezoidal in cross- 
section with three low longitudinal ridges and many growth 
rings (fig. j).” Fiege & Sun (1999: 116) give a similar 
description. Marenzeller’s (1885: 217) type material of 
Hydroides exaltatus came from Eno-shima, Japan, but his 
original species description does not mention the short 
medial spine on each coronal spine. Willey (1905: 312, plate 
VII, fig. 182) and Pillai (1960: 110, fig. 4A-E) describe the 
coronal spines as being plain and devoid of accessory spines. 
Fiege & Sun (1999: 116, fig. 5D-F) also do not describe the 
presence of an accessory spine on each coronal spine, but 
the operculum is similar to that described by Willey (1905) 
and Pillai (1960). 
However, according to Imajima’s description (1976:127, 
fig. 4a-j), which does not include material from Eno-shima, 
each coronal spine, including the enlarged one, has a short 
medial spine close to its base. The Kimberleys specimens 
(Figs 12F, 13A,B) agree with Imajima’s (1976) description. 
It appears, therefore, that there are two apparently si mil ar 
species. The infundibular processes in both are simple, and 
the coronal spines are similar in that the enlarged pointed 
main spine is curved towards the centre of the crown, while 
the remaining ones are shorter, end in simple tapered tips, 
and are curved outwards. 
Other collections identified as H. exaltatus were examined 
with a view to seeking an explanation for the above 
differences. A specimen, BMNH 1992.382, collected by 
Pillai in 1971 from Biak, West Irian, Indonesia, determined 
as H. exaltatus (Marenz) by ten Hove in 1988, is also similar 
to the older specimens from the Kimberleys with regard to 
this character. BMNH 1959.10.19.3-4, from Bougainville, 
Solomon Islands identified as H. exaltatus according to the 
label, contains 2 detached opercula and a detached corona. In 
the specimens from West Irian and Bougainville the enlarged 
coronal spine lacks the medial spine, while the unmodified 
coronal spines bear a short medial spine each. 
Pillai’s specimen from Sri Fanka, BMNH 1959.12.16.19, 
its identity confirmed by ten Hove in 1969, was re-examined 
during this study. Its enlarged coronal spine does not possess 
a medial spine, as in the above specimens from Bougainville. 
However, careful re-examination revealed that, of the 
remaining 7 coronal spines, the one next to the enlarged 
one lacks the short medial spine, another possesses only 
an insignificant stub, and each of the rest possesses a short 
medial spine. They are quite transparent and located close 
to the base of enlarged spine. Moreover, the adjacent medial 
