Family CHELONARIIDAE

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Family CHELONARIIDAE

Compiler and date details

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

Introduction

The Chelonariidae is a small family of three genera and 300 species known mostly from the tropical areas of the Oriental, Australian and Neotropical Regions (Spangler 1991; recent literature). Chelonarium Fabricius is found mostly in Central and South America with species known to occur in America north of Mexico and northern Australia, Pseudochelonarium Pic is known from south-east Asia and Indonesia, and Brounia Sharp is an unusual New Zealand representative of the family (Méquignon 1934; Lawrence 1982; Klimaszewski & Watt 1997). The family is represented in Australia by a single species of Chelonarium from north Queensland.

Nothing is known regarding the biology of the Australian species. However, Spangler (1980) has recorded that American Chelonarium species are terrestrial being associated with packing material around the roots of several species of orchids, in termite galleries in branches and under the bark of a dead tree. Chelonariid larvae are known from nests of ants in epiphytic plants and mound-building ant nests (Spangler 1991). That the larvae are truly myrmecophilous is based on the observation of Lenko (1967) who found live chelonariid adults, larvae and pupae in ant nests. This was subsequently confirmed by Janzen (1974). Larval chelonariids are thus definitely terrestrial and not aquatic as was assumed by Böving & Craighead (1931).

Diagnosis

Adult chelonariids are highly compact, oval beetles resembling seeds and range in length from 5 to 6 mm. The head is small and strongly deflexed and not visible from above. The antennae are 11-segmented, weakly serrate, with the second and third segments enlarged. The mandibles are reduced and lack both a mola and a prostheca. The pronotum is small and transverse with well developed, sharp lateral carinae. The prosternum is reduced and has a deep median cavity that receives the head in repose. The procoxae are transverse with exposed trochantins and the procoxal cavities are open behind both internally and externally. The mesosternum has a large cavity for the reception of the prosternal process. The elytra have narrow epipleural grooves that interlock with the thorax and abdomen. The hind wing has an obliquely closed radial cell and no anal (wedge) cell. The legs are flattened and are capable of being retracted into ventral depressions. The fore tibiae are spinose along the outer edge. The tarsal formula is 5-5-5 with segment 3 bearing a ventral membranous appendage and segment 4 minute. The tarsal claws are toothed (Lawrence & Britton 1994).

The larvae are elongate, tapered posteriorly and are clothed with tubercles and long pubescent setae. The head is small and globular, prognathous and bears a single large stemmata each side. The ventral mouthparts are retracted. The mandibles have three or four apical teeth that are perpendicular to the plane of movement and lack a mola. The labrum is free. Abdominal segment 9 has an operculum that is ventrally hinged and lacks both anal hooks and gills. Urogomphi are absent. There are nine pairs of biforous spiracles that are borne on lateral tubercles and are of the modified undulating type (Spangler 1991).