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Records of the Australian Museum (2009) Vol. 61 
Figure 16. A-F, Hydroides minax (Grube, 1878), 
from AM W202951. A,B from specimen in Fig. 
15I,J: (A) thoracic uncini; (B) anterior abdominal 
uncini; (C) anterior end of another worm from 
the same collection having two opercula; ( D-F ) 
bayonet-shaped special collar chaetae. 
centre of crown (Fig. 17B-D); remaining coronal spines 
much shorter and end in simple outwardly curved pointed 
tips. Infundibular processes number 21; ending distally in 
swollen to somewhat T-shaped tips (Fig. 17B-D). Brownish 
clusters of prostomial ocelli present. 
Chaetae. Special collar chaetae bayonet-shaped and possess 
two elongated conical teeth at the base of the blade (Fig. 
17E-I), originating way down along the boss.further down 
along the boss than in other species of Hydroides, as shown 
by dotted lines in Fig. 17E,F, and Fig. 17G-I. As also shown 
in latter figures, the unserrated notch is very long, about one 
third of total length of blade; tip of latter smooth (Fig. 171). 
Thoracic uncini saw-shaped with 5 or 6 teeth (Fig. 17J); 
anterior abdominal uncini similar with 4 or 5 teeth (Fig. 
17K); posterior abdominal uncini are rasp-shaped. Anterior 
abdominal uncinal tori almost meet along the mid-dorsal 
line from about the 2nd to the 10th pair, after which the gap 
between them gradually increases. (Fig. 17B); capillaries 
commence from about the 85th. 
Remarks. Although the operculum of H. pseudexaltatus 
is superficially similar to that of H. exaltatus (Marenzeller, 
1885), the infundibular marginal processes are tapered 
and pointed in H. exaltatus (Figs 12C,E,F, 13A,B,L), 
whereas they end in swollen, somewhat T-shaped tips in H. 
pseudexaltatus (Fig. 17B-D). Moreover the coronal spines 
of H. pseudexaltatus lack medial processes (Fig. 17D), 
whereas in H. exaltatus, each coronal spine, including the 
enlarged one, bears a short pointed medial accessory process 
at about the level at which each main spine originates from its 
swollen base (Figs 12F, 13A,B). The bayonet collar chaetae 
of H. pseudexaltatus are characteristic in having a very long 
unserrated notch, which is about one third of the length of 
the blade (Fig. 17E-I); as also seen in the latter figures, the 
two teeth at the base of the blade originate way down along 
the boss compared to that in H. exaltatus. 
Etymology. Named after the superficial similarity of its 
operculum to that of H. exaltatus (Marenzeller, 1884). 
Hydroides simplidentatus n.sp. 
Fig. 18A-J 
Material examined. Holotype, AM W21415, Kimberleys, Western 
Australia, reef north-west of Buffon Island, 14°55'S 124°48'E, 20 m, coll. 
P.A. Hutchings, 23 Jul. 1988, st 85. 
Description 
Measurements. Worm incomplete posteriorly; width of 
thorax 0.5 mm; length of operculum and peduncle 2.5 mm, 
of operculum alone 1.0 mm. 
Tfibe. Missing. 
Worm. Thorax has dark brown pigmentation both dorsally 
and ventrally, and anterior to the thoracic tori; modified 
coronal spine translucent and off white, remaining coronal 
spines translucent and light brown. Modified dorsal spine 
vesicular, shaped like a swollen beak, curved towards the 
centre of the crown (Fig. 18A,B-F); remaining coronal 
spines number 6, highly reduced, pressed against base of the 
modified spine; their bases broad, but their short, simple, and 
