Family CLAMBIDAE

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Family CLAMBIDAE

Compiler and date details

31 December 1999 - Andrew A. Calder, CSIRO Entomology, Canberra, Australian Capital Territory, Australia

Introduction

The Clambidae is a small family of 5 genera and about 144 species worldwide which has been revised by Endrödy-Younga in a series of papers (1959, 1960a, 1960b, 1961a, 1961b, 1961c, 1965, 1974, 1978, 1981, 1990). These beetles are very rounded and convex with a characteristic ability to roll their bodies into a globose shape by reflexing the head and prothorax against the underside of their bodies. The family was previously associated with Leiodidae in the Staphylinoidea until Crowson (1960, 1979) pointed out the non-staphylinoid characters of clambids and united them with Eucinetidae and Helodidae (=Scirtidae) in a superfamily Eucinetoidea (Scirtoidea is an earlier available name for the superfamily). The Australian fauna consists of 3 genera and 21 described species. Crowson (1979) divided the family into three subfamilies: the monotypic Acalyptomerinae, with a widespread species in warmer regions not yet recorded from Australia; Calyptomerinae with two species in central and southern Europe of which one species appears to have been introduced into both South Africa and Australia; and Clambinae with the three genera Loricaster Mulsant & Rey, Clambus Fischer von Waldheim and Sphaerothorax Endrödy-Younga. In the Australian fauna Clambus is represented by 13 species while Sphaerothorax contains 7 species.

The first Australian species were described by Blackburn (1902, 1903) who described 4 species and Lea (1910) who described a species thought to be an ant inquiline. Lea (1912) reviewed the Australian species describing 5 new species of which one is synonymous with the European Calyptomerus dubius (Marsham) and another two with Blackburn species. Endödy-Younga (1974) reviewed the Australian and New Zealand faunas noting six species in the Australian fauna and later completely revising the Australian fauna (Endödy-Younga 1990) describing three new species in Sphaerothorax and nine in Clambus bringing the total for the Australian fauna to 21 species.

Clambids are found in decaying vegetation such as leaf litter, grass and manure heaps, silage, rotting hay, haystack bottoms and flood refuse, in moss and on damp twigs (Johnson 1966). Both adults and larvae feed on hyphae and spores of moulds (Crowson & Crowson 1955).

Diagnosis

Adult clambids are small species not exceeding 1.8 mm and can be recognised by the combination of excavate hind coxae forming a large, broad femoral plate that covers the retracted hind leg, and a body that can be rolled up into a ball in all Australian genera. The head is broad and strongly concave beneath. The antennae have 8- to 10-segments and have a 2-segmented club. The frontoclypeal region is ridged and conceals the mouthparts and often divides the eyes. The procoxae are projecting and transverse with exposed trochantins and the procoxal cavities are open behind both internally and externally. The prosternal process is not received in the mesosternum and the metasternum is without a transverse suture. The metendosternite is of the helodid-type. The elytra completely cover the abdomen and are never striate. The venation of the hindwing is reduced and has a marginal fringe of setae. The tarsi are 3- or 4-segmented and not lobed beneath. The abdomen has 5 or 6 visible sternites with functional spiracles on segments 1-5 and sometimes 8. The aedeagus is of the trilobe type with a distinct basal piece (Crowson 1979; Endrödy-Younga 1990; Johnson 1966).

Clambid larvae are similar to eucinetid larvae and are cylindrical to fusiform in shape, with a plagiognathous head with 0, 5 or 6 stemmata each side and without urogomphi. The frontoclypeal suture is absent. The labrum is free and the antennae usually have a very long third segment. The mandibles have a mola and an articulated prostheca while the maxillae are sometimes divided into a distinct galea and lacinia. The spiracles are annular (Lawrence 1982; Lawrence & Britton 1994).