Family HETEROCERIDAE

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Family HETEROCERIDAE

Compiler and date details

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

Introduction

The Australian Heteroceridae is a small family comprised of eight described species and two genera out of a world fauna of 14 genera and approximately 357 species (Pacheco 1964; recent literature). A majority of the Australian species is included in the cosmopolitan genus Heterocerus Fabricius. The only apparently endemic genus Elythomerus Waterhouse, is represented by a single Australian species that has not been recaptured since its original description. Heterocerids occur in most parts of the world but are apparently absent from the Tasmanian mainland. Pacheco (1964) has provided a phylogenetic analysis of the heterocerid genera of the world assigning them to five tribes. The last world catalogue of the Heteroceridae was that of Zaitzev (1910). The Australian species were revised by Charpentier (1968).

Heterocerus mastersii Macleay, 1871 was the first Australian heterocerid to be described. It was collected by George Masters from the Gayndah area of Queensland. Waterhouse (1874) described the next Australian Heterocerus, australasiae from Western Australia as well as the enigmatic Elythomerus elongatulus from central Queensland. Blackburn (1888, 1891, 1903) was responsible for describing another six species of Australian Heterocerus of which three are synonyms while Charpentier (1968) described another three species and a subspecies from Western Australia.

Adults and larvae occur in moist mud or sand at the edges of fresh and brackish watercourses, lakes and ponds. Larvae excavate subsurface tunnels in the substrate and feed on zooplankton, algae and other organic debris (Pacheco 1978; Lawrence 1991). Adults reside in their own tunnels with the entrances usually marked by 'sand chimneys' (Claycomb 1919; Pacheco 1978). Eggs are laid in small masses in breeding chambers (Pacheco 1978). Pupation takes place in a mud cell (Lawrence 1991). In Australia adults are readily attracted in large numbers to light near rivers, streams and ponds particularly in arid to semiarid inland regions.

Diagnosis

Adult heterocerids are robust, elongate, densely pubescent beetles with the pubescence forming a distinct variegated pattern. They are flattened beetles with legs well developed for burrowing and range from 2.2–5.3 mm in length. The head is prognathous, with strong mandibles visible from above with a strongly projecting incisor lobe, a large labrum and clypeus. The antennae are relatively short and thick, with an elongate, loosely formed, 7-segmented, serrate club. The pronotum is transverse with rounded lateral sides. The prosternum is well developed in front of the coxae and the intercoxal process is fairly narrow. The procoxae are transverse with the procoxal cavities open behind both internally and externally. The midcoxae are contiguous and the mid coxal cavity is partly closed by the mesepisternum. The elytra are subparallel. The hind wing has an open radial cell and no anal (wedge) cell. The abdomen has five visible sternites with the basal three connate. The first visible abdominal sternite possesses a stridulatory file on each side. Segment 8 bears functional spiracles. The tibiae are flattened and strongly spinose along the outer edge. The tarsi are 4-segmented with the first and fourth usually elongate (Charpentier 1965; Lawrence & Britton 1994).

The larvae are campodeiform, elongate, strongly setose, widest across the pronotal segments and tapering posteriorly. The frontoclypeal suture is present. The antennae are very short, 3-segmented, with a large sensorium on segment II. The head is prognathous and protracted and has five stemmata on each side. The mandibles are flattened, with an articulated prostheca and concave pseudomola and several teeth along the incisor lobe. The maxilla has a galea and lacinia. The abdominal apex has a soft fleshy unpaired lobe on the under-side known as a pygopod. The spiracles are cribriform (Lawrence 1991; Lawrence & Britton 1994).