Capa & Murray: Australian Megalomma sabellid polychaetes 
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Figure 4. Drawings to scale of thoracic and abdominal uncini. Megalomma phyllisae n.sp.: 
(A) thoracic uncinus; ( B ) abdominal uncinus. Megalomma cf. acrophthalmos : (C) thoracic 
uncinus; ( D ) abdominal uncinus. Megalomma interrupta n.sp.: (E) thoracic uncinus; (F) 
abdominal uncinus. Megalomma inflata n.sp.: (G) thoracic uncinus; ( H ) abdominal uncinus. 
Megalomma sp. 1: (7) thoracic uncinus; (7) abdominal uncinus. Megalomma suspiciens : (K) 
thoracic uncinus; (L) abdominal uncinus. Scale: 0.1 mm. 
Description. Largest specimen AM W35477, 30 mm long, 4 
mm wide with eight thoracic and 108 abdominal chaetigers 
(smallest has eight thoracic and 53 abdominal chaetigers). 
Crown longer than thorax, 9 mm long, with 25 pairs radioles 
(15 pairs in the small specimen). Outer surface of radioles 
quadrangular at the base (Fig. 6B) and rounded distally, with 
tips shorter than pinnules. Radiolar skeleton composed of 
15-20 cells in transverse section (Fig. 5B). Most radioles 
with subdistal eyes, dorsalmost four pairs appear spiral, 
and lateral ones large and becoming smaller more ventrally, 
lacking or missing in 1-2 pairs ventralmost radioles. Dorsal 
lips with radiolar appendages as long as two thoracic 
chaetigers, pinnular appendages absent. Caruncle absent. 
Low smooth keel (thickened and non-lamellate) projecting 
ventrally between dorsal lips, arising from raised triangular 
mound situated mid dorsal to dorsal lips. Ventral lips rounded 
and well developed; ventral parallel lamellae and sacs 
present. Posterior peristomial collar fused mediodorsally 
to the faecal groove; dorsal lappets present, elongate and 
spatulate-shaped distally, as long as lateral collar margins, 
and with dorsolateral U-shaped indentations on both sides 
forming pockets, reaching to level of second chaetiger (Fig. 
6A); lateral collar margins smooth (Fig. 6B), and ventrally 
forming overlapping lappets with rounded anterior margins, 
with a complete midventral incision (Fig. 6C). Ventral shields 
rectangular, all separate from the neuropodial tori (Fig. 6C), 
all similar in width. First ventral shield longer than the rest, 
with m-shaped anterior margin. First chaetiger with superior 
and inferior elongate narrowly hooded notochaetae; superior 
longer than inferior (Fig. 6D). Rest of thoracic chaetigers 
with two rows of superior elongate narrowly hooded and 
two rows of inferior broadly hooded notochaetae with 
progressively tapering tips (type B) (Fig. 6E); lamella-like 
lobe present between superior and inferior notochaetal 
fascicles. Uncini with around 7-10 rows of small, similarly 
sized teeth above main fang (Fig. 6F,G), well developed 
breast, handle long, three times the length of the distance 
from breast to main fang (Fig. 4C). Companion chaetae with 
asymmetrical membrane (Fig. 6H). Abdominal neuropodia 
with slender broadly hooded chaetae (Fig. 61). Abdominal 
uncini similar to thoracic uncini, with similarly-sized teeth 
over the main fang but covering more surface area (Fig. 6J) 
and with shorter handle (Fig. 4D). Pygidium with four small 
lobes, scattered eyespots laterally. 
Colour pattern. Three regular transverse pigment bands on 
branchial radioles plus other less regular pigment on pinnules 
distally. Brown pigment present on anterior dorsum of body 
and with dark regular patches dorsolaterally on anterior 
margins of first seven thoracic segments. 
Remarks. Of the species recorded in the Indo-Pacific, 
these described specimens most closely resemble M. 
multioculatum and M. phyllisae n.sp. in the presence of 
subdistal eyes on most radioles and with dorsal margins 
of collar fused to the faecal groove. However, M. cf. 
acrophthalmos has conspicuous elongated dorsal collar 
lappets which are absent in M. multioculatum and M. 
phyllisae n.sp. These three features (pattern of distribution of 
radiolar eyes, fusion and shape of collar dorsal margins), are 
shared with the type material described from the Philippines 
(Grube 1878) and restudied and drawn by Knight-Jones 
(1997). The chaetae and uncini of specimens from both 
