Family CANTHARIDAE

Chauliognathus lugubris

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Family CANTHARIDAE

Cantharids, Soldier Beetles

Compiler and date details

30 November, 1996 - Andrew A. Calder, CSIRO Entomology, Canberra, Australian Capital Territory, Australia

Introduction

The Cantharidae are commonly referred to as soldier beetles, and comprise about 135 genera and 5000 species worldwide (Lawrence 1982). They are arranged in five subfamilies (Brancucci 1980): Cantharinae, Silinae, Dysmorphocerinae, Malthininae and Chauliognathinae. Miskimin (1961) raised the Chauliognathinae to the status of a separate family, however this has been disputed by Crowson (1972) and Magis & Wittmer (1974). The present concept of the Cantharidae recognises the Chauliognathinae merely as a subfamily. The Australian fauna is small and not diverse, consisting of only 119 described species in three genera and Cantharis australis Boisduval which cannot be placed at present (CALDER 1998). Heteromastix Boheman is by far the largest genus represented by 77 described species followed by Chauliognathus Hentz with 34 and Sphaerarthrum Waterhouse with eight. A pictorial key to the South Australian cantharid genera is provided by Matthews (1985). Delkeskamp (1977) has provided the most recent catalogue to the world fauna.

The first Australian cantharid to be described was Cantharis lugubris Fabricius, 1801, now included in the genus Chauliognathus. W.S. Macleay (1826) described Telephorus pulchellus, which was collected on Captain P.P. King's voyage along the northern and western coasts of Australia; it is now synonymised with Chauliognathus lugubris (Fabricius) (see Witmer 1953). Boisduval (1835) described Cantharis australis from Australia, however it is unrecognisable until the type specimens can be located and studied. Castelnau (1840) described Telephorus pictus and Telephorus tricolor from Nouvelle Hollande and Erichson (1842) described Cantharis nobilitata from Tasmania. Boheman (1858) described Heteromastix bicolor and Telephorus pusillus (a junior primary homonym of pusillus LeConte, 1851) collected on the voyage of the Eugenies and Redtenbacher (1867) described Telephorus imperialis from Sydney, NSW. Macleay (1872, 1887) described 12 new species from Gayndah and the vicinity of Cairns, Queensland. Fairmaire (1877) described a new genus Selenurus, and new species Selenurus luteopictus, from Peak Downs, Queensland. This genus is now synonymised with Chauliognathus. Olliff (1889) described the apterous cantharid Telephorus apterus (now included in Chauliognathus) from Lord Howe Island. Most of the Australian species have been described by two workers: Blackburn (1888, 1889, 1892a, 1892b, 1900) and Lea (1895, 1908, 1909, 1915, 1921a, 1921b, 1921c, 1922, 1929). Between them they have described 107 species (10 of which are synonyms) and this represents some 80% of the total Australian fauna described to date. Pic (1912, 1927, 1930) the most recent worker on the Australian fauna has described four new species and a variety which is a junior synonym. A modern revision of the Australian species is badly needed, in light of recent systematic theory and new generic concepts.

Brancucci (1980), primarily on the basis of wing venation and female genitalia, recognised five cantharid subfamilies: Cantharinae, Silinae, Dysmorphocerinae, Malthinae and Chauliognathinae. The Australian fauna comprises three genera in three subfamilies: Silinae (Sphaerarthrum), Dysmorphocerinae (Heteromastix) and Chauliognathinae (Chauliognathus). The Dysmorphocerinae is primarily a Southern Hemisphere group, Chauliognathinae has a disjunct distribution between North and South America and Australia-New Guinea and Silinae is predominantly Palaearctic extending into the Oriental-Australian Regions. None of the Australian genera is endemic and all are shared with New Guinea.

Watt (1975) noted that the Cantharidae of Latreille (1802) and most 19th Century authors are based upon the misidentified type genus Cantharis Müller, 1764 not Linnaeus, 1758, which is equivalent to Lytta Fabricius in the Meloidae. Lawrence & Newton (1995) recorded that Imhoff (1856) was the first to use Cantharidae correctly for the present family and a case should be referred to the ICZN for a decision. The next family-group name to have priority is Telephoridae based on Telephorus Schaeffer, 1766, but since Telephorus has been treated as a junior synonym of Cantharis for a long time, retention of Cantharidae, which has gained wide acceptance, can be justified under ICZN Article 40(b).

Relatively little is known about the biology of this family. Adults are diurnal and frequently aggregate in large numbers on the flowers of various native and exotic trees and shrubs as well as various prominent objects. The nature of swarms of Chauliognathus lugubris (Fabricius), commonly known as the Plague Soldier Beetle, was unknown to Zeck (1919). However, Webb (1986) suggested that such aggregations are presumably for the purpose of breeding, since 92% of animals in the aggregation are paired and in copulation. Such large mating aggregations have led to studies of mating strategies in cantharids elsewhere in the world (e.g. McLain 1982). Adults are predacious but also feed on pollen, nectar and fresh foliage (Lawrence & Britton 1994). Larvae are common in the soil and leaf litter where they are general predators on small arthropods. Larvae pupate in earthen cells in moist soil below the surface emerging in spring-summer (LeSage 1991).

In southern Tasmania, Shohet & Clarke (1997) have shown that C. lugubris is univoltine, with a mid to late spring emergence of adults, the adult population declining over summer. The larvae are predacious, have seven instars and may be active over autumn and winter in the field.

Adult cantharids are known to produce defensive secretions and belong to mimicry complexes. Moore & Brown (1978) have shown that the common Chauliognathus lugubris when roughly handled produces small drops of a milky secretion from the orifices of their thoracic and abdominal defensive glands. The active components of this secretion were shown to be the alkaloids precoccinelline (II), hippodamine (III) and propyleine (IV) previously known only from Coccinellidae, and (Z)-8-dihydromatricaria acid (I) which has also been reported from the American Chauliognathus lecontei Champion by Meinwald et al. (1968).

Diagnosis

Adult Cantharidae are elongate, parallel-sided, soft-bodied beetles ranging in length from 2.5 to 15 mm in length. They are usually aposematically coloured in various combinations of yellow and black or bluish black. The head is relatively large and deflexed; labrum membranous and often inconspicuous; the frons lacks well-developed tentorial pits, and the mandibles are strongly curved and acute at the apex. The antennae are filiform, 11-segmented and the antennal insertions are widely separated. Many males of the genus Heteromastix have strange modifications to one or more antennal segments. The pronotum is oval or subquadrate and flattened, without acute hind angles. The fore coxae project below the prosternum, the trochantin is exposed, and the mid coxae are contiguous. No basal ventrites are connate. The elytra are usually complete, smooth and without distinct epipleura but are very abbreviated in Chauliognathus apterus Olliff from Lord Howe Island. The hind wing has a reduced number of anal veins and no closed anal cell. The tarsi have a membranous lobe on the fourth segment. The abdominal tergites have paired gland openings and luminous organs are absent. Females are usually fully winged, lack an ovipositor or spiculum gastrale. The male genitalia are usually large, asymmetrical and exposed (Lawrence & Britton 1994).

The larvae are elongate and narrow. The body is lightly sclerotised, lacking distinct tergites or lateral projections and is usually clothed with fine, velvety pile. The integument is often darkly pigmented or patterned. The head is more or less quadrate with well-developed stemmata. The mandibles are falcate, usually grooved and lack a molar part. The gular region is well developed and the maxillae have articulated galea. The spiracles are biforous without a closing apparatus. All thoracic segments and abdominal segments 1–8 or 9 have paired glandular openings and segment 10 is reduced and terminal; articulated urogomphi are absent (Lawrence 1982; LeSage 1991; Lawrence & Britton 1994) .