Family ELATERIDAE Leach, 1815

Conoderus leluti

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Family ELATERIDAE Leach, 1815

Blacksmith, Click Beetles, Clicker, Skip-jack, Spring Beetle

Compiler and date details

31 December 1996 - Andrew A. Calder, CSIRO Entomology, Canberra, Australian Capital Territory, Australia

Elaterides Leach, W.E. 1815. Entomology. pp. 57-172 in Brewster (ed.). The Edinburgh Encyclopedia. Edinburgh : William Blackburn Vol. 9(1) 764 pp. [reprint 1830].
Type genus:
Elater Linnaeus, 1758.

Introduction

The Elateridae are common and abundant throughout the world. Adults are well known for their ability to click which has led to several common names in the English speaking world: Click beetle, Skip-jack, Spring beetle, Clicker or Blacksmith. It is the largest family in the Elateroidea with some 400 genera and 9000 species worldwide (Lawrence 1982), which have been arranged in as many as 23 subfamilies. Masters (1886) provided the first catalogue of Australian species listing 37 genera and 258 species. The world fauna was catalogued by Schenkling (1925, 1927) and various authors have since provided separate catalogues of regional faunas. Neboiss (1956, 1961) produced the first checklist of Australian species since 1950 and Calder (1996) gave an overview and list of described species for each genus.

The classification of the family is in a state of change and no one system is followed in this Catalogue. Schwarz (1906b, 1906c, 1907a) in Genera Insectorum lists 28 tribes which were largely based upon the classification first proposed by Candèze (1857, 1859, 1860, 1863). Succeeding classifications have resulted in these tribes being arranged in a smaller number of subfamilies. Hyslop (1917) proposed a radical system of only four subfamilies Agrypninae (as Pyrophorinae which also included many Denticollinae), Elaterinae, Cardiophorinae and Physodactylinae. These groups corresponded to three larval types while larvae were unknown for the fourth group. More recently Crowson (1961) recognised six subfamilies based upon wing and larval characters. Gur'yeva (1974) listed 10 subfamiles based on adult thoracic characters and Dolin (1975) proposed the same 10 subfamilies using instead characters derived from the hind wing venation together with structural features of the larval forms.

Stibick (1979) was the last author to attempt a classification of the Elateridae dividing the family into 12 subfamilies. Some of these subfamilies have not been accepted and are accorded tribal status only by contemporary workers. The classification followed here is that of Calder (1996) which recognises eight subfamilies and is based upon that of Dolin and Gur'yeva. The tribal arrangement, particularly within the larger subfamilies Denticollinae and Elaterinae, is not fixed and is open to interpretation and must await the study of the family on a worldwide basis. The only published phylogeny of the family based upon cladistic principles is that of Calder et al. (1993). However, the authors were only considering the relationship of the aberrant group Lissominae to the rest of the elaterid subfamilies rather than attempting to provide a definitive suprageneric classification of the Elateridae.

Several taxa previously associated with other elateroid families are listed as elaterids in this Catalogue. The Thylacosterninae (= Balginae) with Cussolenis resemble eucnemids and were once included in that family. Emden (1932) and Gardner (1936) suggested that this group was better accommodated in the Elateridae on the basis of the larvae of Pterotarsus Guérin-Méneville and Cussolenis Fleutiaux. The Lissominae in its original sense, including Lissomus, Paradrapetes Fleutiaux and Drapetes Dejean previously associated with the Throscidae, also includes the genera Austrelater Calder & Lawrence and Osslimus Calder as well (Calder et al. 1993). Böving & Craighead (1931) also proposed the transfer of the throscid genus Drapetes to the elaterid "subfamily" Oestodinae based upon its larva. Crowson (1961) supported this move based upon both adult and larval characters, but interestingly left Lissomus in the Throscidae. However, Burakowski (1975) and Costa et al. (1988) consider both Drapetes and Lissomus to form a separate family with links to both the Elateridae and Throscidae. Calder et al. (1993) considered the Lissominae, Oestodinae and Protelaterinae to form a monophyletic group within the Elateridae. This has been disputed by Muona (1996) who claims the Lissominae as well as the Thylacosterninae form a monophyletic group with the Throscinae as Throscidae.

Seventy genera and 667 valid species are listed by Calder (1998) for the Australian fauna. However, much of the Australian fauna still remains undescribed and at least one genus new to Australia has come to light since the publication of Calder (1996). The two most speciose genera, Agrypnus and Conoderus Eschscholtz, are in need of modern revisionary work as many new species are recognised in collections and numerous synonymies are suspected. The limits of the Denticollinae-Pityobiinae-Elaterinae also need to be studied as it is still difficult to place some genera in one nominal subfamily or another on the basis of adults, even though the three groups hold up when the larval stages are examined. A majority of the species (550 species) were described in the Westwoodian-Macleayian Period of Australian entomology which extended from 1830 to 1929 as defined by Musgrave (1930). The more recent Musgravian Period (Whitley 1961) has seen only 165 new species described. Candèze, Schwarz and W.J. Macleay account for 386 names or 53% of the fauna so far described.

The biology of this family varies considerably with the larvae being found in a variety of habitats. Larval stages can be found under the bark of trees, in rotten wood or in the soil. Pseudotetralobus larvae live in or adjacent to termite nests and feed upon their inhabitants. Lanelater larvae live in the soil where they prey upon melolonthine and ruteline scarab larvae. Several species of Paracalais live in partially rotten wood, feeding upon cerambycid larvae. Species of Agrypnus, Conoderus and Heteroderes Latreille live either in the soil or in rotten wood. Since the natural habitat of the larval stage of numerous elaterid species is either grassland or pasture it is not surprising that some are also agricultural pests (Calder 1996). Recorded pest species belong to the genera Agrypnus, Conoderus, Heteroderes, Arachnodima Candèze and Hapatesus Candèze. Several Australian species of Agrypnus are known to evert a pair of repugnatorial glands that open on the intersegmental membrane between abdominal segments 7 and 8 rather than employing the clicking mechanism to startle predators (Calder 1996). More information on the biology of particular species can be obtained from the introductory section for each of the recognised subfamilies. The biology of most Australian species is totally unknown and further work is essential for a full understanding of this family.

Excluded Taxa

Other Excluded: PITYOBIINAE [the Australian genera in this subfamily were reclassified into the subfamily Parablacinae by Kundrata et al., 2015; consequently this subfamily no longer has any Australian taxa] — Kundrata, R., Gunter, N.L., Douglas, H. & Bocak, L. 2016. Next step toward a molecular phylogeny of click-beetles (Coleoptera: Elateridae): redefinition of Pityobiinae, with a description of a new subfamily Parablacinae from the Australasian Region. Austral Entomology 55(3): 291–302 [299]

Diagnosis

Most elaterids cannot be confused with any other family. All elaterids have the following combination of characters: an exposed labrum, projecting hind pronotal angles, a long prosternum elongated to form a spine, mesosternum with well-developed cavity, globular procoxae with highly reduced and concealed trochantins, well-developed hind coxal plates and abdomen with five ventrites, the first four ventrites (abdominal sternites 3–6) connate (Lawrence & Britton 1994). Sexual dimorphism occurs occasionally, but is mostly confined to the females being larger and having shorter antennae. Four genera, Macromalocera Hope, Pseudotetralobus Schwarz, Dicteniophorus Candèze and Agrypnus display marked sexual dimorphism. The male of Macromalocera has elongate antennae that exceed the apex of the elytra in a way reminiscent of longicorn (longhorn) beetles (Cerambycidae). The female on the other hand is usually brachypterous, sometimes apterous, and has very short, moniliform antennae that do not exceed the apices of the pronotum. Males of several species of Pseudotetralobus have pectinate antennae of 12 segments, while the corresponding females have serrate or subpectinate antennae of 11 segments. Female Dicteniophorus are much larger and more robust than the males as well as having extremely reduced hind wings incapable of flight. In several Australian female Agrypnus species, ventrite 4 or both ventrites 3 and 4 have a modified area consisting of either one large distinctly raised area with several punctures, or one large puncture from which several narrow short scales arise (see Calder 1996).

Elaterid larvae are characteristic and the cylindrical body form with heavily sclerotised cuticle of many soil-dwelling species has led to the common name of wireworms. Larvae are elongate, cylindrical to flattened, evenly sclerotised dorsally and ventrally, with or without an apically forked ninth abdominal segment and have a heavily scleorised head. The head has strong mandibles, well developed maxillae and a densely setose oral filter. They range in colour from yellow, to brownish yellow or dark brown to black (Becker 1991). Larvae are omnivorous, extraoral feeders, feeding on insect larvae and other invertebrates as well as feeding upon organic and other vegetable matter.