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Records of the Australian Museum (2009) Vol. 61 
Fitzhugh, 2003; Tovar-Hernandez & Salazar-Vallejo, 2006, 
2008). However, these Groups have not yet been tested for 
evolutionary meaning and therefore should be treated as 
operational only. 
Some features that have been traditionally included 
in the description of species and used to characterize the 
abovementioned Groups (Knight-Jones, 1997) are difficult 
to interpret and/or to classify into discrete character states. 
The most obvious case is the form and development of the 
dorsal margins of collar. In some species, a low membrane 
or ridge appears to be a continuation of the dorsal collar 
margin, making difficult the interpretation of whether or not 
the collar is fused into the faecal groove, and therefore also 
whether pockets are present or absent. See for example the 
discussion about placement of M. neapolitanum (Claparede, 
1868) into either Knight-Jones’ Group 2A or 1A (Giangrande 
& Licciano, 2008). Some other species with the dorsal 
collar margins fused to the faecal groove (Group 1A and 
IB in Knight-Jones’ categories), show an enlargement of 
the collar on its dorsal margins forming dorsal lappets or 
flaps on both sides of the faecal groove. This is the case for 
M. acrophthalmos (Grube, 1878), M. fauchaldi Giangrande 
et al. , 2007 and M. vesiculosum (Montagu, 1815) (Knight- 
Jones, 1997; Giangrande et al., 2007). But other similar 
species with these well-developed collar dorsal lappets such 
as M. mushaense (Gravier, 1908) and M. nechamae (Knight- 
Jones, 1997) were considered to have the collar not fused 
to the faecal groove, and these lappets were interpreted as a 
development of the dorsum or peristomium and not of the 
collar (Knight-Jones, 1997). 
It has also been observed that some of these “diagnostic 
features” can be misinterpreted when the number of 
specimens examined is small, as some species show variation 
in the number and development of subdistal compound eyes 
(Fitzhugh, 2003) which may not necessarily be related to 
size of the specimens (Nishi, 1998). 
A worldwide review of the genus is currently being 
undertaken (Tovar-Hernandez pers. comm.) in which the 
groups proposed by Knight-Jones (1997) will hopefully 
be reassessed. 
Nine species of Megalomma have been reported from 
the Indo-Pacific: M. acrophthalmos from Philippines, M. 
miyukiae Nishi, 1998 and M. multioculatum Fitzhugh, 
2002 from Thailand, M. pacificum Johansson, 1927 from 
Gilbert Islands, M. suspiciens (Ehlers, 1904) and M. 
kaikourense Knight-Jones, 1997 from New Zealand, M. 
trioculatum Reish, 1968 from Marshall Islands, and M. 
cinctum Fitzhugh, 2003 from Taiwan. Only one species, 
M. vesiculosum, was reported from Australian coasts, in an 
Australian polychaetes interactive key (Wilson et al., 2003). 
However, no material identified as such has been found in 
any Australian museum collections, leading to the conclusion 
that this was a mistake (Wilson, pers. comm.). The only 
other recorded presence of Megalomma in Australia, was 
Megalomma monophthalma from Queensland by Augener 
in 1922, as Sabella monophthalma Augener, 1922, but this 
species has subsequently been synonymized with Stylomma 
palmatum (de Quatrefages, 1866) by Knight-Jones (1997). 
Therefore, the present paper is the first valid record of the 
genus in Australia. 
One of the aims of this study is to document the presence 
of Megalomma, its diversity along the Australian coastline 
and to record the species’ distribution. Some features 
traditionally used to separate species into groups as well as 
others proposed herein, have been tested for potential value 
for taxonomic and systematic accounts. 
Materials and methods 
Material examined. Specimens from Australian coasts were 
studied from collections housed in the Australian Museum 
(AM), Sydney; Museum and Art Gallery of the Northern 
Territory (MAGNT), Darwin, and Museum Victoria (MV), 
Melbourne. This included material collected in several 
surveys and projects around the Australian coast. Some 
specimens were also collected for live examination and 
then fixed in 10% seawater formalin and preserved in 80% 
ethanol or in 95% ethanol for further molecular studies. Other 
specimens belonging to other collections were also studied 
for comparison: Zoologisches Museum Hamburg, Germany 
(ZMUH) and Smithsonian Institution, National Museum of 
Natural History, United States of America (USNM). 
Some parapodia (usually from first and seventh thoracic 
chaetigers and some from the abdominal region) were 
removed and mounted on slides to examine chaetae. The 
internal structure of the radioles were examined by cutting 
thin transverse sections of these structures at base level and 
mid-length with a surgical blade and mounting them on 
slides. Line drawings were made to scale with a drawing tube 
attached to either a stereo or compound microscope. Some 
specimens were dehydrated in ethanol, critical point dried 
and covered with 20 nm of gold and examined under a Zeiss 
Evo LSI5 scanning electron microscopy, using Robinson 
backscattered and ET secondary electron detectors. 
Cladistic analysis 
Taxa considered for the analyses. A total of 20 species of 
Megalomma were included as the ingroup, including the 
type species, two species of each of the groups proposed 
by Knight-Jones (1997) and used in subsequent studies 
(e.g., Nishi, 1998; Fitzhugh, 2003; Tovar-Hernandez & 
Salazar-Vallejo, 2008), as well as all the Australian species 
described herein. The data were obtained from direct study 
of specimens, when these were available, and descriptions 
in the literature. Demonax leucaspis Kinberg 1867, was 
Figure 1 (facing). SEM. (A-D) Types of collar dorsal margins: (A) separated and with no pockets as in Megalomma sp. 2; ( B) fused to the 
faecal groove and forming vestigial pockets on each side, as in Megalomma interrupta n.sp.; (C) fused to the faecal grove and with short 
dorsal lappets as in M. phyllisae n.sp.; (D) fused to the faecal groove and with spatulate dorsal lappets as in M. cf. acrophthalmos. (E,F) 
Types of inferior thoracic chaetae: ( E ) Megalomma phyllisae n.sp. with broadly hooded chaetae type A and (F) M. cf. acrophthalmos 
with broadly hooded chaetae type B. (G,H) Shape of radioles: (G) M. cf. acrophthalmos with quadrangular external margins at the base; 
(FT) M. inflate n.sp. with quadrangular distal margins of radioles. (I,J) Parallel lamellae and ventral sacs, smaller in (/) Megalomma cf. 
miyukiae and, more developed in (7) M. interrupta n.sp. (K,L) Abdominal chaetae: (K) narrowly hooded and (L) broadly hooded. (M) 
Companion chaetae of M. cf. miyukiae showing the asymmetrical and dentate membrane. 
