Elateridae

Panspaeus guttatus, copyright Udo Schmidt.

Belongs within: Elateroidea.
Contains: Physodactylinae, Agrypninae, Denticollinae, Elaterinae, Thylacosterninae, Lissominae, Cardiophorinae, Negastriinae.

The Elateridae are the click beetles, so called for their ability to jump by rapidly bending the thorax (producing a clicking noise). This clicking ability is enabled by a long prosternal process entering a cavity on the mesosternum, causing a build-up of potential energy between the two segments. It has been lost in certain derived, softer-bodied subgroups, some of which have historically been treated as distinct families. Larvae of elaterids are liquid feeders on various foods by extraoral digestion. Some phytophagous species, known as wireworms, are pests of crops.

Members of the Elateridae have been divided between a large number of subfamilies though recent studies have lead to changes in classification (Kundrata & Bocak 2011). The Hemiopinae are found in southern and eastern Asia, and possess a pair of short longitudinal ridges near the base of the pronotum. Campyloxenus pyrothorax is a distinctive species from southern South America with bioluminescent organs on the pronotum (Bouchard 2014). The East Asian Subprotelater resembles the related family Eucnemidae in the presence of antennal grooves on the hypomeron, and has historically been included in that family, but is associated with other Elateridae by its sclerotised, exposed labrum and free ventrite 5 (Calder 1996). Panspaeus guttatus is a small, dorsally setose elaterid of uncertain affinities native to New Zealand. The Eudicronychinae are known from Africa and southern Asia, and have toothed or bifid tarsal claws and four connate abdominal ventrites. The Morostominae are a recently recognised lineage endemic to Madagascar.

Click! goes the beetle
Published 10 June 2016
The click beetle Athous haemorrhoidalis, copyright André Karwath.

There have been occasions when I’ve found myself complaining of the difficulty of recognising particular beetle families. It almost goes without saying, however, that this difficulty does not apply across the board. Whereas some beetle families may indeed be generically small and brown, there are others that are almost instantly recognisable. One such family, for the most part, is the click beetles of the Elateridae.

Click beetles are a cosmopolitan family with well over 900 known species. The majority of click beetles adhere to a consistent basic form: they have elongate, slender bodies, often with distinct longitudinal grooves running down the elytra. The front part of the body (the prothorax) is relatively large, and more or less acutely pointed at the back corners. Between the prothorax and the next part of the body (the mesothorax), the body is strongly constricted top to bottom so that the beetle can be flexibly bent. This distinguishes the Elateridae from most other beetle families (except for a few close relatives), and this is where the ‘click’ comes in. If the beetle finds itself lying on its back (or wishes to escape from a threat), it is able to arch itself so that the thoracic junction is lifted upwards. On the rear margin of the underside of the prothorax is a notched peg that sits against the front of the mesothorax, holding the two sections apart like the stick in a cartoon crocodile’s jaws. This builds up a lot of potential energy that the beetle is able to hold in place until it suddenly releases the peg, which then slams back into a ventral groove at the front of the mesothorax with an audible ‘click’. The effect of this sudden release of energy, followed by an equally sudden stop, is to cause the beetle to rapidly bend forwards, much in the manner of a person folding over as they receive a powerful punch to the gut. This self-inflicted gut punch results in the beetle being flung in the air, somersaulting to a hopeful landing on its feet. Evans (1972) conducted an analysis of the click-jumping of the elaterid Athous haemorrhoidalis, which is about a centimetre-and-a-half in length, and found that it could be lifted over a foot above the ground, tumbling several times over the course of a single jump. He calculated that during the jump it could be subjected to an acceleration of up to 3800 ms-2, equivalent to a force of 380 G, one of the highest acceleration forces known in the animal kingdom (a human subjected to a similar force would soon end up like a satchel of instant pudding). Ribak & Weihs (2011) subsequently found, however, that the beetle has no actual control over its movements once flung and is just as likely to end up flat on its back again as the right way up, requiring it to attempt a second jump.

Fire beetle Pyrophorus sp., copyright Andreas Kay.

Adult click-beetles feed on the juices from plants but larvae may be more diverse in habits, including phytophagous, saprophagous or predaceous forms. Some burrowing phytophagous larvae, known as wireworms, can be notable pests, feeding on the roots and buried seeds of crop plants. Predatory forms, on the other hand, can be quite beneficial: the eyed elater Alaus oculatus of North America, for instance, has larvae that feed on the larvae of other beetles burrowing in wood. The Elateridae also include the fire beetles of South and southern North America, belonging to the tribe Pyrophorini. These beetles have a pair of large bioluminescent spots on their back at the rear of the prothorax. The larvae and even the eggs of fire beetles are similarly bioluminescent, and my guess is that the bioluminescence provides some sort of defense against predation.

Larva of Drilus on a snail, copyright Cécile Bassaglia.

Not all elaterids match the family’s standard morphology, however. An analysis of elaterid phylogeny by Kundrata & Bocak (2011) found that a few groups that had previously been classified as separate families were in fact derived subgroups of the Elateridae. The ‘Cebrionidae’ (possibly a polyphyletic assemblage in the elaterid subfamily Elaterinae) are softer-bodied than other elaterids and lack the ability to click (presumably because their cuticle does not provide the resistance for a clicking mechanism to work). Female cebrionids may be flightless, with reduced wings and/or elytra. Even more dramatically altered are the females of the tribe Drilini (previously recognised as the Drilidae), the false firely beetles, which are larviform in appearance with only the head metamorphosing to an adult appearance. The larvae of Drilini feed on snails, and have a lifestyle that straddles the boundary between predator and parasite. Rather than killing and eating the prey snail immediately, they crawl into its shell and feed on it slowly; it may take several days for the larva’s victim to actually meet its demise.

Acritelater barbatus
Published 26 September 2023

Every week I assign myself a taxon to research and write about, selected semi-randomly, and this week I’ve drawn the click beetle Acritelater barbatus. This species is widespread in New Zealand (though I’ve not been able to find a habitus image for it), having been collected pretty much the entire length of both North and South Islands (Calder 1984).

Acritelater reversus, a closely related species, from Calder (1984). Scale bar = 5 mm. Acritelater barbatus would most obviously differ in being more strongly punctate.

Acritelater barbatus was first described by the Belgian entomologist Ernest Candèze in 1865 in the genus Chrosis (later changed to Elatichrosis after the original name proved to be preoccupied). Candèze was uncertain of the origin of the type specimen but thought that it probably came from Australia. However, this species has never since been found on that continent and it seems likely that Candèze was mistaken. Calder (1984) established the genus Acritelater for a group of New Zealand ‘Elatichrosis’ species including A. barbatus. Notable features of the genus include an incomplete frontal carina (fading away between the antennae), complete lateral carinae on the pronotum, and two setae at the base of each tarsal claw. The name of the genus roughly means ‘confused click beetle’, presumably a reference to its species’ confused taxonomic history.

(Left to right) prosternal spine in lateral view, aedeagus in dorsal view, and bursa copulatrix of Acritelater barbatus, from Calder (1984). Scale bars = 1 mm.

Acritelater barbatus grows to about 14 to 19 millimetres in length. It can be distinguished from other members of the genera by its more densely punctate prothorax, with the pronotum becoming more densely punctate laterally and the hypomeron (the ventro-lateral panels of the prothorax) densely and evenly punctate. The antennae are relatively short, failing to reach the hind corners of the pronotum. The body is dark reddish-brown in colour, with dirty yellowish-brown antennae and legs. The surface of the body is covered by a moderately dense, semi-decumbent, ashen-coloured vestiture.

Calder (1984) recorded this species as collected from a variety of habitats, ranging from coastal sand dunes to among alpine vegetation. Exemplars were recorded from most times of year except during winter. With its wide range and eclectic habits, this species should be a ready target for any enthusiast of New Zealand elaterids.

Systematics of Elateridae

Characters (from Lawrence & Britton 1991): Characteristic elongate form, with acute hind angles on prothorax and clicking mechanism enabling them to jump by forcing long prosternal process suddenly into cavity on mesosternum causing sudden movement of prothorax relative to hind body. Labrum always visible; frontal area usually with sharp transverse ridge between eyes; antennae almost always serrate; tarsi simple or provided with setal brushes or membranous appendages; fifth ventrite more or less free, membrane usually visible between it and ventrite 4. Larvae elongate and cylindrical to slightly flattened, either uniformly sclerotised and yellow to brown in colour, or more lightly sclerotised, except for head capsule, protergum and T9. Labrum and clypeus solidly fused to remainder of head capsule forming nasale, which is variously lobed or toothed; stemmata often reduced or absent; ventral mouthparts consolidated to form maxillolabial complex; tenth segment reduced and ventrally situated; T9 terminal.

<==Elateridae (see below for synonymy)
|--+--Panspaeus guttatusKB11
| `--+--+--AgrypninaeKB11
| | `--DenticollinaeKB11
| `--+--ElaterinaeKB11
| `--+--ThylacosterninaeKB11
| `--LissominaeKB11
`--+--CardiophorinaeKB11
`--NegastriinaeKB11

Elateridae incertae sedis:
Acritelater Calder 1984C84
|--*A. reversus (Sharp 1877) (see below for synonymy)C84
|--A. barbatus (Candèze 1865)C96 (see below for synonymy)
|--A. elongatus (Sharp 1877) [=Chrosis elongata, Elatichrosis elongata]C84
`--A. setiger (Broun 1881) (see below for synonymy)C84
ThoramusWH02
Codemus teresP02
AmychusWH02
|--A. candezei Pascoe 1876E02
`--A. granulatusWH02
Pectocera Hope 1842H42 [PectoceriniPS07]
|--P. babai Kishii 1990PS07
|--P. cantori Hope 1842H42
|--P. formosana Kishii 1990PS07
|--P. mellii Hope 1842H42
`--P. yaeyamana Suzuki 1976PS07
Camptosternus fulgensB66
AgonischiusM86
|--A. breviusculusFl89
|--A. delauneyi Fleut. 1887Fl89
|--A. mirusFl89
|--A. obscuripesB66
|--A. speculifer Cand. in Fairmaire 1889Fa89
`--A. thoracicus Fleutiaux 1889Fl89
EopenthesO94
Poecilonata masudai Kano 1929TYM08
Archontas murinusC01
Betarmon picipennisC01
CampyloxenusB14 [CampyloxeninaeKB11]
`--C. pyrothorax Fairmaire & Germain 1860B14
HemiopinaeKB11
|--Parhemiops dubius Fleutiaux 1889B14, Fl89
|--PlectrosternumB14
`--HemiopsPS07
|--H. flava Castelnau 1838PS07
|--H. ireiiB14
`--H. substriataB14
EudicronychinaeKB11
MorostominaeKB11
Subprotelater [Subprotelaterinae]C96
Psephus quadraticollis Schwarz 1906C96
PhotophorusB70
|--P. bakewelliB70
`--P. jansoniB70
Cryptochile melanopteraB35
Elaterophanes regius Whalley 1985RJ93
CrioraphesP92
DiaraphesP92
ElatronP92
HolopleurusP92
IdolusP92
MecynocanthusP92
OrthoraphesP92
PlagioraphesP92
PorthmidiusP92
SternopesP92
TetraraphesP92
Mionelater Becker 1963P92
`--M. planatus Becker 1963P92
DiploconusFl89
|--D. coracinusFl89
`--D. melanopterusFl89
AphanobiusFl89
|--A. cylindricusFl89
`--A. malaccensisFl89
Crepidius Cand. 1859FS90
|--C. brunneus Fleutiaux & Sallé 1890FS90
`--C. rhipiphorus Cand. 1859FS90
PhysodactylinaeKB11

Acritelater barbatus (Candèze 1865)C96 [=Chrosis barbataC96, Elatichrosis barbataC96; incl. C. valida Broun 1881C84, E. validaC84]

*Acritelater reversus (Sharp 1877) [=Chrosis reversa, Elatichrosis reversa; incl. C. dubitans Broun 1912, E. dubitans, C. eximia Broun 1893, E. eximia, C. impressa Broun 1893, E. impressa]C84

Acritelater setiger (Broun 1881) [=Chrosis setigera, Elatichrosis setigera; incl. C. brevicollis Broun 1881, E. brevicollis]C84

Elateridae [Adrastites, Agriotites, Agrypnides, Alaites, Athoites, Cardiophorites, Cardiorhinites, Cavicoxumidae, Cebrionates, Chalcolepidiides, Crepidomenites, Dicrepidiites, Dimites, Elaterides, Hemicrepidiini, Hemirhipides, Hypodesites, Ludiides, Melanactides, Melanotites, Monocrepidiites, Octocryptites, Oxynopterides, Pangauridae, Physodactylides, Physorhinites, Pomachilites, Pyrophorites, Semiotina, Serricornes, Tetralobites]

*Type species of generic name indicated

References

[B66] Bates, H. W. 1866. On a collection of Coleoptera from Formosa sent home by R. Swinhoe, Esq., H. B. M. Consul, Formosa. Proceedings of the Zoological Society of London 1866: 339–355.

[B35] Boisduval, J. B. 1835. Voyage de Découvertes de l’Astrolabe. Exécuté par ordre du Roi, pendant les années 1826–1827–1828–1829, sous le commandement de M. J. Dumont d’Urville. Faune entomologique de l’océan Pacifique, avec l’illustration des insectes nouveaux recueillis pendant le voyage vol. 2. Coléoptères et autres ordres. J. Tastu: Paris.

[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature’s gems. Ivy Press: Lewes (United Kingdom).

[B70] Britton, E. B. 1970. Coleoptera (beetles). In: CSIRO. The Insects of Australia: A textbook for students and research workers pp. 495–621. Melbourne University Press.

[C84] Calder, A. A. 1984. Acritelater (Coleoptera: Elateridae), a new genus of click beetle from New Zealand. New Zealand Journal of Zoology 11 (1): 35–42.

[C96] Calder, A. A. 1996. Click beetles: genera of the Australian Elateridae (Coleoptera). CSIRO Australia: Collingwood.

[C01] Csiki, E. 1901. Bogarak [Coleopteren]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 75–120. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.

[E02] Emberson, R. M. 2002. The beetle (Coleoptera) fauna of the Chatham Islands: additions and corrections. New Zealand Entomologist 25: 69–77.

Evans, M. E. G. 1972. The jump of the click beetle (Coleoptera, Elateridae)—a preliminary study. Journal of Zoology 167: 319–336.

[Fa89] Fairmaire, L. 1889. Coléoptères de l’intérieur de la Chine. 5e partie. Annales de la Société Entomologique de France, 6e série 9: 5–84.

[Fl89] Fleutiaux, E. 1889. Contributions a la faune Indo-Chinoise. Cicindelidae et Elateridae. 1er mémoire. Annales de la Société Entomologique de France, 6e série 9: 137–146.

[FS90] Fleutiaux, E., & A. Sallé. 1890. Liste des coléoptères de la Guadeloupe et descriptions d’espèces nouvelles. Annales de la Société Entomologique de France, 6e série 9: 351–484.

[H42] Hope, F. W. 1842. Monograph on the coleopterous family Phyllophoridae. Proceedings of the Zoological Society of London 10: 73–79.

[KB11] Kundrata, R., & L. Bocak. 2011. The phylogeny and limits of Elateridae (Insecta, Coleoptera): is there a common tendency of click beetles to soft-bodiedness and neoteny? Zoologica Scripta 40: 364–378.

[M86] Masters, G. 1886. Catalogue of the described Coleoptera of Australia. Part IV. Proceedings of the Linnean Society of New South Wales, series 2, 1 (2): 259–380.

[O94] Otte, D. 1994. The Crickets of Hawaii: origin, systematics and evolution. The Orthopterists’ Society: The Academy of Natural Sciences of Philadelphia.

[PS07] Platia, G., & R. Schimmel. 2007. Click beetles of Taiwan collected by the expeditions of the Hungarian Natural History Museum in the years 1995 to 2003 (Coleoptera: Elateridae). Annales Historico-Naturales Musei Nationalis Hungarici 99: 49–91.

[P92] Poinar, G. O., Jr. 1992. Life in Amber. Stanford University Press: Stanford.

[P02] Ponomarenko, A. G. 2002. Superorder Scarabaeidea Laicharting, 1781. Order Coleoptera Linné, 1758. The beetles. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 164–176. Kluwer Academic Publishers: Dordrecht.

Ribak, G., & D. Weihs. 2011. Jumping without using legs: the jump of the click-beetles (Elateridae) is morphologically constrained. PLoS ONE 6 (6): e20871. doi:10.1371/journal.pone.0020871.

[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.

[TYM08] Tennent, W. J., M. Yasuda & K. Morimoto. 2008. Lansania Journal of arachnology and zoology—a rare and obscure Japanese natural history journal. Archives of Natural History 35 (2): 252–280.

[WH02] Worthy, T. H., & R. N. Holdaway. 2002. The Lost World of the Moa: Prehistoric life of New Zealand. Indiana University Press: Bloomington (Indiana).

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