Family LUCANIDAE

<I>Syndesus cornutus</I> (Fabricius, 1801)

Syndesus cornutus (Fabricius, 1801)

Lucanidae, male. Rowville, Victoria

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Family LUCANIDAE

Compiler and date details

1 December 2002 - Barry P. Moore & Gerasimos Cassis; updated by Andrew A. Calder, CSIRO Entomology, Canberra, Australia

Introduction

The Lucanidae are one of the smaller families of Scarabaeoidea but with a worldwide distribution. Currently some 95 genera are recognised and there are about 1,250 valid species. The Australian fauna comprises 17 genera and 97 species and these include both old 'Gondwanian' stocks and more recent Oriental immigrants (Moore 1978). Several fossil genera and species have also been described but their relationships with existing taxa are poorly understood.

Lucanids are remarkable principally for their marked sexual dimorphism, often coupled with pronounced allometry (and sometimes polymorphism) in the males. This dimorphism, however, is minimal in a few groups and the sexes are externally indistinguishable in Figulus W.S. Macleay and related genera. This pronounced variation has led to much confusion in the taxonomy at all levels. The development of a higher classification within the family has been greatly retarded by the proliferation of taxa without adequate description and differentiation.

Pioneering studies by Holloway (1960, 1968, 1969), based largely on the morphology of the ocular canthus and of the male genitalia, led to a substantial refinement of the higher classification. Howden & Lawrence (1974) established the existence of five recognisable subfamilies (Syndesinae, Aesalinae, Lampriminae, Nicaginae and Lucaninae), four of which occur in the Australian fauna. Further research, however, may well indicate the need to subdivide the Lucaninae. Two species were newly described and new records for established species given by Bartolozzi (2003).

Larval taxonomy in the family was pioneered by van Emden (1935, 1951) and has since been developed by Lawrence (1981b). Major characters involved include mandibular dentition and the form of the stridulatory apparatus. In general, there is fair concordance with the accepted higher classification of adult Lucanidae, but again much more research is needed. The most recent world catalogue of the family is that of Benesh (1960).

BIOLOGY
Lucanids are largely dependent on fallen timber, in which (or beneath which) the larvae feed, and are therefore concentrated in wetter forest habitats. A few species, notably those of the South African genus Colophon Gray, manage to subsist in the roots of shrubby vegetation. Many of the adults are flightless and probably do not feed, but some winged species feed on blossom, young foliage or sappy exudatess.

Diagnosis

Lucanid larvae are typically scarabaeiform but may be distinguished from others principally by their prominent tenth segment, which bears a vertical anal slit. They feed mostly within very soft, fungus-infested wood. Members of a few genera (in Australia, notably Cacostomus Newman and Lissotes Westwood) are found in humus beneath fallen timber in a less advanced state of decay. Isolated cases of infestation of structural timbers have been reported (Lawrence 1981a). All known larvae possess stridulatory organs, which comprise a field of granules (the pars stridens) on the posterior surface of each mesocoxa, together with a plectrum on the anterior surface of the corresponding metatrochanters. The precise role of stridulation in the biology of these larvae has not been established.