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A REVIEW OF THE AUSTRALIAN MAJID SPIDER CRABS
(CRUSTACEA, BRACHYURA)
By D. J. G. Griffin
(Zooloey Department, University of Tasmania, Hobart)
(Plates XV-XVII & Text-figures 1-3)
SUMMARY
An historical account is given of taxonomic studies of spider or masking
crabs in Australia and overseas. The basis of the review is a key to all but
two of the species known to occur in Australia. The key includes information
on synonymies, geographic and bathymetric distribution and references to
descriptions and illustrations of the species. Characters which are important in
the classification are briefly reviewed. Zoogeographical relationships of the
fauna are discussed.
The family Majidae is currently divided into seven subfamilies mainly
on the basis of orbital configuration, form of the rostrum, abdomen and first
pleopod of the male. All but one of the subfamilies are represented in the
Australian fauna which is considered to comprise 95 species in 45 genera.
This is about twice the number of species and genera listed by Haswell (1882c)
in his "Catalogue." About one-third of the species have been recorded from
Australia on only a single occasion. Numerous genera and species are in need
of detailed reinvestigation.
The fauna is rather clearly partitioned into a tropical group with widespread
Indo-West Pacific relationships and a temperate group related to tropical
Australia and/or the Indo-West Pacific rather than to temperate regions outside
Australia. There are no clear boundaries between these two faunas but rather
quite broad transition areas. Thirty-seven species and five genera, most of
which are temperate, are restricted to Australia.
1. INTRODUCTION
One of the most characteristic features of spider crabs of the family Majidae
is the presence on the carapace and legs of special curled or "hooked" hairs
which aid in the attachment of various kinds of epifauna and flora, especially
seaweeds (for example see McNeill 1923). These organisms are placed in
position by the crab with the aid of the chelipeds which are able to reach up on
to the dorsal surface of the carapace. For this reason majid crabs are sometimes
called "masking crabs" or "seaweed crabs." Of special interest in these crabs
are the orbits which may be expanded in various ways and surrounded by
a seemingly complex array of spines. The legs are often long and slender and
the carapace usually triangular or pyriform. Spider crabs range in size from a
few millimetres to more than a metre in carapace length and are found in
almost all seas and oceans. They form a relatively important part of the benthos
and may be locally very abundant on the shelf although some species extend
considerable distances down the continental slope to depths as great as 1000
fathoms.
Substantial revisions of the family Majidae have been undertaken on a
world-wide scale by Dana (1851), Miers (1879c), Alcock (1895) and Balss
(1929). Sakai (1938), Stephensen (1945) and Garth (1958) have adapted
Balss's scheme to the faunas of Japan, the Iranian Gulf and America respectively.
In the course of these revisions the Majidae have been arranged in several very
different fashions (see historical reviews by Miers 1879c, and Garth 1958).
Early workers such as Dana and Miers grouped the species in several families
and a large number of subfamilies
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