Pillai: Serpulid polychaetes from the Australian Kimberleys 
199 
38 Opercular processes consist of 3 main horns, of two located 
dorsolaterally and the third ventrally; up to 2 dichotomies present 
in each horn; accessory spines along and end of horns, acutely 
triangular, elongated, tapering, mainly single; fissures present 
along main branches, even extending along dichotomies; opercular 
plate circular. Tube white, quadrilateral in cross-section, bears 
a low, more or less smooth MLR; area on either side of latter 
flattened, edge of latter forming a lateral ridge; tube chambered 
ventrolaterally, the chambers transversely elongated. 
. Spirobranchus sp. 5 
-Operculum has other forms. 
. 39 
39 Opercular processes consist of a single, dorsally located column, 
the end of which bears 3 bifid horns, 2 of them dorsolateral, 
the 3rd ventral; each dorsolateral has, close to its tip, 2 short 
pointed spines, and another shorter spine almost at its tip; lower 
branch of bifid lateral horns, in turn, ends in a bifid spine, with 
their tips pointing away from the opercular plate; ventral horn 
ends in 2 spines, their tips pointing anteriorly, i.e., away from 
opercular plate rather than towards it. Tube white, bears a 
very simple, low MLR. 
. Spirobranchus sp. 6 
-Operculum has other forms. 
. 40 
40 Opercular processes of up to about 4 stacked plates with a thin 
rim along its edge; peduncle conspicuously elongated. Tube 
quite characteristic; its colour yellowish-orange to orange and 
white; a light caramel to yellowish-brown longitudinal band 
present along base of MLR; shape of latter quite unlike that of 
hitherto known species of the genus; where MLR is highest, 
at its anterior end, it is 2¥z times as high as wide, and consists 
of sinuous, fin-shaped forwardly directed processes of varying 
lengths; 2 very low, thin, LLRs present on each side, one very 
close to base of MLR, and the other flank; along either side of 
base of MLR is a row of oblique, forwardly directed foramina; 
likewise, along either side of base of each LLR, is a row of 
similar foramina. 
... Spirobranchus tenhovi n.sp. 
-Opercular processes consist of 1 to a few obliquely superimposed, 
eccentrically attached plates; most dorsal plate may occur at end 
of a short, oblique column. Tube white to faintly bluish, with faint 
to darker grey along flanks, much lighter to white along flanges ; 
triangular in cross-section, with a wide flange on each side; MLR 
high, sinuous, projects conspicuously over aperture; a very low 
LLR present on either side of MLR; on either side at the bases 
of MLR, and each LLR, is a row oval to obliquely foramina; 
furthermore, there is a row of foramina along each flank. Although 
4 longitudinal rows of foramina is typical, variations may occur, 
e.g., where an LLR may be reduced, and only foramina may be 
irregularly present. 
.. Spirobranchus zibrowii n.sp. 
