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Records of the Australian Museum (2009) Vol. 61 
vestigial horns. Its tube is reddish in colour, triangular 
in cross-section, and possesses a prominent ridge, which 
projects over the aperture. However, S. elatensis differs from 
the latter and S. tetraceros reported from the Indo-Pacific 
with regard to the following characters. Its tube is white, 
trapezoidal in cross-section and bears a high, thick, wavy 
median longitudinal ridge, the latter with fin-like sections 
at intervals and projecting forwards over the aperture. It also 
bears a pair of lateral longitudinal ridges, each along the edge 
of a flattened part of the tube on either side of the median 
longitudinal ridge. Furthermore, the special collar chaetae of 
S. elatensis are quite characteristic, in possessing a square, 
papillate boss, and the distal part of its chaetal shaft being 
conspicuously serrated all round (Fig. 50E,F). Indeed, they 
are quite unlike those of the other species of Spirobranchus 
dealt with in this account as well as in the specimen from 
Bahrein described by ten Hove (1970: fig. 18). 
Spirobranchus tetraceros differs from S. elatensis as 
follows. Its tube is white to cream or bluish, its adult tubes 
are obtusely triangular in cross-section and its thin, low 
median longitudinal ridge is comparatively inconspicuous 
(Fig. 44A). Its opercular horns are comparatively long and 
well developed. The boss of its special collar chaetae is 
not as square and papillate all around the distal part of the 
chaetal shaft, as in S. elatensis, but serrated only ventrally 
and ventrolaterally (Fig. 45C,D). 
Etymology. Named after the type locality, Elat, Gulf of 
Aqaba, Red Sea. 
Spirobranchus kraussii (Baird, 1865) 
Fig. 49E-G 
Placostegus cariniferus var. kraussii Baird, 1865: 14. 
Pomatoleios crosslandi .—Pixell (1913: 85-86, fig. lOa-d). 
Pomatoleios crossland Pixell .—Hartman (1959: 587). 
Pomatoleios crosslandi .—Pillai (1960: 15, fig. 6A-D). 
Pomatoleios kraussii .—Uchida (1978: 33), Pillai (1971: 98), 
Mohammad (1971: 300), Straughan (1967: 235), Ishaq 
& Mustaquim (1996: 172-174, fig. 7). 
Pomatoleios kraussii var. manilensis .—Pillai (1965: 169, 
fig. 22H). 
Material examined. Pomatoleios kraussii collected from Dhafra Beach, 
Jebel Dhanna, Abu Dhabi in 1996 by Dr J. David George, Natural History 
Museum London. Registration No: NHM ANEA 2009.23. 
Description 
Measurements. Total lengths of larger worms up to about 
23.0 mm. One juvenile worm has a total length of 4.0 mm. 
Tube. White, with a pair of longitudinal ridges, a tongue¬ 
shaped extension over the aperture and several growth 
markings. 
Worm. Colour of anterior part of body, especially operc¬ 
ulum, radioles and thorax, blue in in alcohol-preserved 
material. Opercular insertion: in position of second radiole 
of left side; opercular plate circular, with a non-transparent 
rim, and lacks processes (Fig. 49E,F). Radioles arranged 
in a circle on each side; inter-radiolar membranes present; 
apron present. 
Chaetae. Collar chaetal fascicles: absent in adults. A juvenile 
specimen has 7 thoracic chaetigers on the left (Fig. 49E), 
and 6 on the right (Fig. 49F). Collar chaetae of juvenile lack 
a boss; consist of shaft and blade (Fig. 49G). Abdominal 
chaetae with long shafts present throughout abdomen (Fig. 
49E,F); their flattened, trumpet-shaped, distal ends have one 
side drawn out into a tapering process. 
Remarks. The total lengths of Ishaq and Mustaquim’s 
specimens (1996: 174) from Manora, Karachi Coast, Paki¬ 
stan, ranged from 5.0-25.0 mm. 
For a discussion on the synonymy of Pomatoleios and 
Spirobranchus see earlier discussion in the present paper. 
As regards special collar chaetae their reduction is more 
than in the preceding species to to the extent of their lacking 
even a trace of a boss, consisting merely of a shaft and blade 
(Fig. 49G), and being indistinguishable from the bladed 
notochaetae of the remaining thoracic chaetigers. 
Spirobranchus sp. 4 
Fig. 51A-G 
Spirobranchus semperi. —Mohammad (1971: 300); non 
Morch, 1861. 
Type material. Four specimens, without tubes, Kuwait, Arabian Gulf, 
BMNH 1969.256, coll, and determined by M.B.M. Mohammad as S. 
semperi Morch, 1861; as S. tetraceros (Schmarda, 1861) sensu ten Hove, 
1970, according to a note in the jar by H. Zibrowius in 1972. 
Description 
Measurements. Total lengths of the four specimens range 
from 11.6-23.6 mm; thoracic widths, from 1.9-2.5 mm; total 
lengths of opercula, including opercular spines, opercular 
plate, and peduncle: 1.9-3.6 mm; diameters of opercular 
plates: 1.5-2.5 mm. abdominal lengths, 7.3-16.0 mm. 
Numbers of branchial radioles range from 11 plus operculum 
on left and 12 on right, to 23 plus operculum on left and 22 
on right; number of abdominal segments, 5-80. 
Ttibe. Missing in all specimens. Mohammad (1971: 300) 
does not describe them, and provides only a note on 
occurrence of the in Kuwait and the world distribution. 
Worm. An easily removable epizoic bryozoan was found 
on the bases of opercular processes of the three specimens 
(Fig. 51 A). Colour of opercular processes translucent 
white, their spines transparent white. Operculum on left 
side, no rudimentary operculum; opercular plate circular, 
slightly dorsoventrally oval; bears three main processes, 
each with two dichotomies in 3 specimens (Fig. 51B-D); 
in one specimen, however, dorsolateral spines are branched 
thrice. A single medial spine is located at or below the 
second dichotomy, followed distally by one, two, or three 
along each branch (Fig. 51C). Peduncular wings fringed, 
with a double row of papillae (Fig. 51A,C,E). Radioles 
transparent and colourless, conspicuously transversely 
wrinkled (Fig. 51B,D), end in pinnule-free tips, Vs to IVi 
times as long as longest pinnules. Maximum number of 
radioles observed on each side 23, arranged in a circle; 
inter-radiolar membranes fringed (Figs 51B,D). Thorax 
consists of 7 chaetigers; apron present. 
