© The Authors, 2009. Journal compilation © Australian Museum, Sydney, 2009 
Records of the Australian Museum (2009) Vol. 61: 201-224. ISSN 0067-1975 
doi:10.3853/j.0067-1975.61.2009.1529 
Review of the Genus Megalomma (Polychaeta: Sabellidae) 
in Australia with Description of Three New Species, 
New Records and Notes on Certain Features with 
Phylogenetic Implications 
Maria Capa* and Anna Murray 
Marine Invertebrates, Australian Museum, Sydney NSW 2010, Australia 
maria.capa@austmus.gov.au 
Abstract. The aim of this paper is to document the presence, diversity and distribution of Megalomma in 
Australia. This could be considered the first valid record of the genus in this continent as the only species 
previously recorded was transferred to another genus (Knight-Jones, 1997). The species diversity found 
during this study indicates that the occurrence of Megalomma in Australia has been overlooked, as the 
genus is well represented with at least seven species, living in a range of habitats and depths, and three 
of which are herein described as new, M. phyllisae n.sp, M. inflata n.sp. and M. interrupta n.sp. Cladistic 
analyses have been performed after the generation of a matrix of morphological features including those 
of some well documented species, in order to find informative characters for grouping species and to test 
the validity of previous artificial classifications. According to the phylogenetic hypothesis presented herein, 
the fusion of dorsal collar margins to the faecal groove and the presence of collar “pockets” characterizes 
the apomorphic clade of Megalomma species but the number of radiolar eyes is a homoplastic character, 
varying substantially in the Megalomma radiation, meaning that the traditional groups should be reviewed. 
A dichotomous key is provided to facilitate Australian species identification. 
Capa, Maria & Anna Murray, 2009. Review of the genus Megalomma (Polychaeta: Sabellidae) in Australia with 
description of three new species, new records and notes on certain features with phylogenetic implications. Records 
of the Australian Museum 61(2): 201-224. 
The genus Megalomma Johansson, 1925 is characterized 
by the presence of subdistal, unpaired, sessile, compound 
eyes with distinct ommatidia in at least dorsal-most radioles, 
a unique feature among sabellid polychaetes (Fitzhugh, 
1989; Fitzhugh & Rouse, 1999), but to date no phylogenetic 
analysis of the genus has been performed for assessing the 
relationships among the species. 
The number of species included in this genus has 
increased in the last decade especially after detailed 
taxonomic studies in Thailand (Nishi, 1998; Fitzhugh, 
2002), the Grand Caribbean (Tovar-Hernandez & Salazar- 
Vallejo, 2006; Giangrande et al., 2007), the Eastern Tropical 
Pacific (Tovar-Hernandez & Salazar-Vallejo, 2008) and the 
Mediterranean Sea (Giangrande & Licciano, 2008), bringing 
the number of species to 31 (see Table 2). 
Most of the taxonomic accounts are based primarily on 
three morphological characters proposed by Knight-Jones 
(1997): fusion of dorsal collar margins with the faecal 
groove, presence of collar “pockets” and distribution of 
subdistal radiolar eyes. Based on the combination of these 
characters she produced a table of species’ groups that 
has been used by subsequent authors (e.g., Nishi, 1998; 
* author for correspondence 
