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Records of the Australian Museum (2009) Vol. 61 
localities also show similarities: the inferior thoracic chaetae 
are broadly hooded but with a progressively-tapering hood 
(type B) and the thoracic uncini have long handles, exceeding 
twice the distance of main fang to breast. The only specimen 
available from the type locality (most probably the holotype 
according to Knight-Jones [1997]) is not in good condition. 
Because of this reason, identification should be confirmed 
with additional material from the type locality. However, 
it is quite possible that the species has a southeast Asian 
distribution. This species has also been recorded in Sri 
Lanka (Willey, 1905) as Branchiomma acrophthalmos but 
this identification has not been confirmed. 
Other species in the genus described as possessing well 
developed dorsal lappets are M. fauchaldi (Giangrande et 
al., 2007) from Belize, M. vesiculosum from England, and 
M. mushaense and M. nechamae from the Red Sea, all of 
which also possess radiolar eyes on most radioles, collar 
fused to the faecal groove and pockets present, although 
this last feature was not interpreted as such by Knight- 
Jones (1997). The shape and size of the lappets and the 
margin of the collar of M. acrophthalmos are all different in 
shape and size to these four species, and their geographical 
distributions are discrete and separated widely enough to 
also separate them as different species. 
Megalomma interrupta n.sp. 
Figs 2J-L, 4E-F, 5B, 7, 8 
Material examined. Queensland. Holotype AM W35478, One Tree 
Island, 23°30'S 152°05’E, Stn 10.4, coll. P.A. Hutchings, Oct. 1972. 
Paratypes: AM W35479, (6spec., 1 onSEM stub AM 501), same locality 
as holotype; AM W35480 (1 spec.), Stn 11.2, same locality and date; AM 
W35481 (1 spec.), Stn 1.1, same locality and date; AM W35482 (1 spec.), 
Stn 5.4, same locality and date; AM W35483 (2 spec.), Stn 14.3, same 
locality and date; AM W35484 (1 spec.), Stn 2.4, same locality and date; 
AM W35485 (2 spec.), Stn 10.2, same locality and date; AM W35486 (1 
spec.), Stn 15.1, same locality and date; AM W35487 (1 spec.), Stn5.1, same 
locality and date; AM W35488 (5 spec., 2 on SEM stubs MI090-91), Stn 
10.3, same locality and date; AM W35489 (1 spec.), Stn 7.1, same locality 
and date; AM W35490 (1 spec.), off Station Beach, Lizard Island, 14°41'S 
145°27'E, 75 LIZ 1-8, coll. P.B. Berents & P. Hutchings, 6 Jan. 1975, from 
dead Pocillopora, 3 m; AM W35491 (3 spec., one on SEM stub), south 
headland of Turtle Beach, Lizard Island, 14°39'S 145°27’E, 76 LIZ 21-1, 
coll. P. Berents & P. Hutchings, 27 Aug. 1976, dead branching coral, 3 m; 
AMW35492 (1 spec.) off Granite Bluff, Lizard Island, 14°39'S 145°27'E, 
76 LIZ 27-1, coll. P. Berents & P. Hutchings, 31 Aug. 1976, thin plates 
dead coral, 6 m; AM W35493 (2 spec.), off Coconut Beach, Lizard Island, 
14°41'S 145°28'27"E, QLD1185, coll. K.B. Attwood & P.A. Hutchings, 29 
Mar. 1995, dead coral at foot of reef, covered in Lithothamnion , 12 m; AM 
W35494 (1 spec.), reef front between Bird & South Islands, Lizard Island, 
14°41'53"S 145°27'51"E, QLD1187, coll. P.A. Hutchings, 30 Marl995, 
dead coral, 13 m; AM W35495 (1 spec.), off North Point Lizard Island, 
14°38'51"S 145°27'12"E, QLD1183, coll. P.A. Hutchings, 28 Mar. 1995, 
dead coral with heavy coralline algal growth, 20 m. Western Australia. 
AM W35496 (2 spec.), Kendrew Island, Dampier Archipelago, 20°28'42"S 
116°32'E, coll. P.A. Hutchings, 3 Apr. 1987, crevice fauna, 10 m; AM 
W35497 (1 spec.), 2 km west of Angel Island, Dampier Archipelago, 
20°29'46"S 116°47'29"E, WA 639, coll. P.A. Hutchings & L. Avery, 
4 Aug. 2000, pinnacle, dead coral substrate & large bivalves heavily 
encrusted and bored, 10 m; AM W35498 (3 spec., 2 on SEM stub MI089 
andMI090), west of Angel Island, 20°29'03"S 116°47'50"E, WA619, coll. 
P.A. Hutchings & L. Avery, 25 Jul. 2000, dead coral, 6 m; AM W35499 
(2 spec.), East Montlivet Island, Kimberley region, 15°06'S 125°18'E, 
Stn 50, coll. P.A. Hutchings, 16 Jul. 1988, 6 m; AM W35500 (1 spec.), 
south side of Long Reef, Kimberley region, 14°01'S 125°44'E, Stn 60, 
coll. P.A. Hutchings, 18 Jul. 1988, 20 m. Indonesia. MAGNT W5975 
(lspec., Bay of Maumere, Pasir Sari, 8 o 37'00"N 122 0 13'59"E, 24-27 m, 
rubble E, coll. B.C. Russell, 6 Nov. 1991. 
Additional material. Queensland (identification is tentative due to poor 
preservation): AM W198006 (2 specimens, 1 on SEM stub MI086), Calliope 
River, Gladstone, 23°51'S 151°10'E, coarse sand, 3.9 m, coll. P. Saenger, 
Aug. 1982; AM W198007 (1 spec.), same locality and date, silty sand, 5.6 m. 
Diagnosis. This species is characterized by a combination 
of features: radiolar eyes present in dorsalmost and lateral 
radioles only, with approximately four radioles in between 
without eyes; radiolar skeleton with approximately 10 cells 
in cross section; collar margins not fused to the faecal groove, 
shallow inconspicuous pockets present, caruncle absent, and 
inferior thoracic broadly hooded chaetae with distal end 
narrowing abruptly (type A). 
Description. Holotype 22 mm long and 2.5 mm wide with 
body flattened dorsoventrally, thorax wider than abdomen 
and abdominal segments diminishing in size posteriorly. 
Eight thoracic and 78 abdominal chaetigers. Crown longer 
than thorax, with 15 radioles in each lobe semicircular lobe. 
External margin of radioles quadrangular at the base (Figs 
21,7C) and rounded towards the tips, without lateral flanges 
but with two longitudinal bands of cilia. Tips of radioles 
tapering, shorter than pinnules (Fig. 2J). Basal membrane 
absent. Radiolar skeleton with about 10 cells in transverse 
section at the base of radioles (Fig. 5C). Dorsalmost pair 
of radioles longer than the rest, each with a large subdistal 
compound eye almost surrounding the whole radiole, and 
with visible ommatidia (Figs 2J, 7K), adjacent next five pairs 
of radioles without eyes, next two pairs of lateral radioles 
with small, similarly-sized subdistal eyes. Dorsal lips with 
radiolar appendages as long as two thoracic chaetigers, with 
lateral lamellae almost reaching the tip of appendage; three 
dorsal pinnular appendages each. Caruncle absent. Ventral 
lips rounded and well developed. Ventral sacs and parallel 
lamellae present (Fig. 7A). Collar with pointed ventral 
lappets (Figs 21, 7A); lateral margins of collar smooth with 
dorsolateral FT-shaped indentations on both sides forming 
inconspicuous pockets and continuing as ridges to the 
middorsal faecal groove (Figs 21, 7B-C). Ventral shields 
quadrangular with parallel lateral margins, not in contact 
with the neuropodial tori (Figs 2K, 7A). First ventral shield 
longer than the rest, with a midanterior incision (m-shaped 
anterior margin). First chaetiger with superior and inferior 
elongate narrowly hooded notochaetae; superior row longer 
than the inferior one (Fig. 7D). Rest of thoracic chaetigers 
with superior elongate narrowly hooded and inferior 
broadly hooded notochaetae (about 20, type A) arranged 
in two rows (Fig. 7H). Notopodia of thoracic chaetigers 
with elongated lobe between superior and inferior chaetae 
(Fig. 7B). Neuropodial tori becoming slightly shorter more 
posteriorly. Thoracic uncini with several rows of small teeth, 
all similar in size above main fang (Fig. 7F,G); uncinus with 
well developed breast and handle about twice the length of 
the distance from breast to main fang (Fig. 4E). Companion 
chaetae with asymmetrical membrane covered proximally 
with rows of small teeth (Fig. 7E). Abdominal neuropodia 
with elongate, broadly hooded chaetae arranged in two rows 
(Fig. 71). Notopodial abdominal uncini similar to the thoracic 
(Fig. 7J) but with shorter handle (Fig. 4F). Pygidium as a 
rounded papilla without pygidial eyes. 
Variation. There is some variability in the number of 
thoracic chaetigers, with some paratypes having nine or ten. 
The number of radioles varies between 10 and 18 pairs and 
