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Records of the Australian Museum (2009) Vol. 61 
satisfactorily resolved. The Kimberleys collection includes 
species of Spirobranchus that, due to lack of reliable 
characters for separating what appear to be more than a 
single species, have recently been referred to in publications 
as belonging to Spirobranchus “species groups” or “species 
complexes”, which need to be resolved in due course. With 
this end in view, the Kimberleys collections of Spirobranchus 
were compared with other Indo-West Pacific collections 
belonging to the genus available in the Natural History 
Museum, London, and the Australian Museum, Sydney. 
Although the scope of this study is not intended to be a 
revision of Spirobranchus and its species complexes, it has 
yielded interesting results, which are presented below. 
Ten Hove (1970a), in a revision of the genus Spiro¬ 
branchus Blainville, 1818, recognizes the following. 
Firstly, that there are two main groups of species: those 
in which the branchial radioles are spirally arranged 
and the opercular wings are fringeless, as in S. giganteus, 
and those in which they are arranged in a circle and the 
opercular wings are fringed, as in S. tetraceros. Secondly, 
that. Spirobranchus giganteus giganteus (Pallas, 1766) 
occurs in the tropical and subtropical coasts of America, 
while S. giganteus corniculatus (Grube, 1862), sensu ten 
Hove 1970, occurs from the Red Sea to the central Pacific. 
Thirdly, that S. tetraceros (Schmarda, 1861), S. giganteus 
giganteus (Pallas, 1766), S. polycerus (Schmarda, 1861) and 
S. polycerus (Schmarda, 1861) var. augeneri Hove 1970, 
are valid taxa from the Caribbean. Fourthly, that there are 
seven other valid taxa belonging to the genus Spirobranchus 
worldwide, namely, S. eitzeni Augener (1918), S. giganteus 
(Pallas, 1766) Blainville, 1818; S. latiscapus (Marenzeller, 
1885) (including S. maldivensis Pixell, 1913), S. lima, S. 
polycerus (Schmarda, 1861) Morch, 1863, S. polytrema and 
S. tetraceros (Schmarda, 1861). 
Furthermore, ten Hove (1994) recognizes S. paumotanus 
(Chamberlin, 1919), which he earlier (1970) synonymized 
with S. giganteus, and the following species from the 
Indo-West Pacific: S. coronatus Straughan, 1967, S. 
corrugatus Straughan, 1967 and S. gardineri Pixell, 1913, 
while expressing the possibility that the latter may consist 
of two species. Ten Hove & Nishi (1996), while providing 
a very good re-description of Spirobranchus corrugatus 
Straughan, 1967, show that it has an Indo-West Pacific 
distribution, although originally described from Australia. 
According to Smith (1985, unpublished thesis) what had 
been identified in the past as S. giganteus and S. tetraceros 
are each a group of closely related species, the limits of which 
are as yet unclear, and arrives at the following conclusions. 
1. Tube colour, besides its form need to be given more 
importance than in the past. 2. There are three main species 
complexes in the Australian material studied by him, namely, 
those of S. giganteus, S. tetraceros and S. latiscapus. 3. 
The Spirobranchus giganteus (Pallas, \166)-complex can 
be assigned to four species, and that the Spirobranchus 
tetraceros (Schmarda, 1861) complex can be assigned to 
three species. 4. Spirobranchus decoratus Imajima, 1982 
and S. gardineri Pixell, 1913 are valid taxa, with two variant 
types of the latter. Fifthly, that Spirobranchus giganteus 
giganteus, and S. polycerus among the Caribbean species 
identified by ten Hove (1970), the seven species worldwide 
listed by the latter, and S. spinosus Moore 1923 from the 
Californian region are valid taxa. 
Frank and ten Hove (1992) and ten Hove (1994) agree with 
Smith (1985), and believe that the Spirobranchus giganteus 
and S. tetraceros categories are in need of further revision. 
This includes species that had been incorrectly synonymized 
with others by ten Hove (1970). Under the Spirobranchus 
tetraceros- complex, for instance, ten Hove (1994:113) states: 
“in 1970,1 united various nominal taxa from circumtropical 
origin in a single species: S. tetraceros. Nowadays I realize 
that this has been an oversimplification, the taxon tetraceros 
probably contains a number of species... ” 
An important character pointed out by ten Hove (1994) 
between the Spirobranchus giganteus and S. tetraceros 
categories relates to the opercular plate. It is oval, and 
arises obliquely from the peduncle in the former, whereas 
it is circular and arises at right angles to the peduncle in the 
latter. Moreover, the arrangement of the branchial radioles is 
whorled in the Spirobranchus giganteus category but circular 
in S. tetraceros category, Ten Hove (1994) also refers to his 
earlier (1970) S. giganteus corniculatus complex as the S. 
corniculatus complex. 
For a recent view on this see Kupriyanova et al. (2001: 
74-75). The present study shows that not only certain 
“species complexes” of the genus Spirobranchus described 
in recent years consist of more than one species, but also 
that certain species previously synonymized with others 
are distinct species. 
Spirobranchus is mainly a tropical to sub-tropical genus. 
However, its distribution will now extend to temperate waters 
with, for example, Spirobranchus triqueter (Philippi, 1844) 
(= Pomatoceros triqueter) in the Mediterranean, Northwest 
Atlantic and North Sea, to the Tasmanian Sea from where 
a new species Spirobranchus tenhovi, is described below. 
Synonymy of the genera Spirobranchus, 
Pomatoceros and Pomatoleios 
Zibrowius (1968: 161) discusses the close similarities 
between Pomatoceros, Spirobranchus, and Pomatoleios and 
points out the following: the only difference between them 
is in their collar chaetae, which are reduced or sometimes 
even absent in Pomatoceros. There is no reason to retain 
the genus Pomatoleios, based solely on the absence of 
collar chaetae, since there is a tendency towards their 
reduction and disappearance. Even if there are populations 
of Pomatoleios in which all the individuals lack collar 
chaetae there is no justification for retaining this genus. 
The tendency towards reduction of collar chaetae is equally 
present in the genus Spirobranchus, as exemplified by S. 
eitzeni Augener 1918. Special collar chaetae occasionally 
are absent in Pomatoceros and Spirobranchus, and present in 
some juvenile Pomatoleios. The distinction between hooded 
chaetae and “ Spirobranchus-chaetae ” sometimes is very 
hard to make. However, a (needed) revision of the complex 
of genera falls outside the scope of this paper.” 
The operculum in all three genera is a calcareous plate 
at the end of a winged peduncle. In Spirobranchus, it may 
lack processes, as in S. maldivensis Pixell 1913, or may bear 
processes, as in its various species, including “complexes”. In 
Pomatoceros triqueter (Linnaeus, 1767), the opercular plate 
bears processes similar to those of species of Spirobranchus or 
may be devoid of processes, as in S. maldivensis (Fig. 52C-E). 
As remarked earlier, the shape of the opercular plate is oval 
in the S. giganteus and corniculatus category, but circular in 
