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Records of the Australian Museum (2009) Vol. 61 
33 Operculum lacks processes; opercular plate circular, flat to 
somewhat concave, bears circular concentric markings which 
decrease in diameter towards centre (not scars of left over from 
broken off spines). Tube caramel brownish or faintly pinkish in 
colour, with slightly darker pink along MLR; latter prominent, 
somewhat sinuous, with conspicuous forwardly directed 
projections, low anteriorly, may be triangular along middle of tube, 
or end in laterally flattened, stumpy tips, as if they were, apparently, 
broken off. Spirobranchus maldivensis Pixell, 1913 
-Operculum has other forms. 34 
34 Operculum 1 to at least 3 stacked circular plates; latter plus 
peduncle about as long as long as abdomen in preserved 
material; peduncle and wings transparent, triangular; peduncular 
wings unfringed . Spirobranchus murrayi n.sp. 
-Operculum has other forms. 35 
35 Opercular processes consist of 3 horns arising from a short, stout 
stem, 2 of them dorsolateral, and the 3rd ventral; dorsolateral horns 
horn shaped, curved outwards and ventrally; each dorsolateral horn 
bears along its lateral edge, a groove covered by a chitinous layer, 
may also bear a small knob dorsomedially, at its base; ventral 
horn tallest of three, projects conspicuously anteroventrally, 
then curved anteriorly, and ending in two outwardly curved 
branches; each of latter may, in turn, be dichotomously branched 
once or twice to give rise to short outwardly curved processes. 
Tubes white, mutually boded, their shape quite characteristic 
when unhindered by competing individuals in same clump; 
obtusely triangular in cross-section; initially a low MLR, 
which abruptly develops 1 to about 5 massive teeth, the most 
anterior of which projects over tube aperture; depending on 
competing individuals, most anterior process may be pointed, 
somewhat flattened, or like a cobra’s hood directed anteriorly or 
laterally . Spirobranchus paumotanus (Chamberlin, 1919) 
Operculum has other forms 
36 
36 Operculum conical, its peak usually dorsally curved, sometimes 
a short, cylindrical stump. Tube triangular in cross-section, wide 
anteriorly, but rapidly narrows posteriorly; bears a smooth, 
irregularly formed MLR, which ends anteriorly as a small, low, 
tooth over aperture; an irregularly formed row of foramina 
present at the base on either side of MLR; an irregularly formed, 
low, narrow LLR present on either side of MLR; a row of 
irregularly formed foramina present on both sides of base of 
each LLR. Spirobranchus pseudopolytremus n.sp. 
-Operculum has other forms. 37 
37 Opercular processes consist of 4 stiff horns, of which 2 are 
dorsal and 2 ventral; dorsal pair longer than ventral pair; each 
dorsal horn bears only a short dorsomedial branch, ventral horns 
unbranched; very short, stiff spines occur along branches, simple 
medially, mostly bifid dorsally; opercular plate circular, more or 
less flat. Tube has an overall pink colour, in parches on a white 
background; bears a prominent, thick, raised, wavy MLR, which 
projects as a small tooth over aperture; a very faint, smooth 
MLR may be discernible in places; a wide lateral flange present 
in places . Spirobranchus semperi Morch, 1861 
38 
Operculum has other forms 
