Elateridae  Leach, 1815   Cebrionates Latreille, 1802; Elateridae Leach, 1815

 Recognition: Click beetles are generally recognized by possessing a combination of an elongate, narrow body form, with a large and freely articulating prothorax. Most species produce an audible clicking or snapping noise and will flip themselves by rapidly moving the prosternal intercoxal process from a locked position into a deep mesosternal cavity.

 Habitus: Body form short ovoid to narrowly elongate, depressed to strongly convex; length 1.5-60 mm; color usually somber browns and blacks, sometimes iridescent, many brightly marked with red and yellow; pubescence usually hair like, moderately long, decumbent, to appressed and scale like. Head hypognathous or prognathous, usually narrower than prothorax. Eyes lateral, moderate to large, hemispherical. Antenna serrate to pectinate; insertion beneath strong, often carinate ridge. Frons convex, depressed, to concave; frontal margin smooth and flat to strongly and transversely carinate. Clypeus absent. Labrum visible, freely articulating. Mandible shallowly to strongly arched, apex beveled to emarginate, incisor usually strongly dentate. Maxilla densely setose medially; palpus 4-segmented. Labium with small quadrate mentum, ligula reduced; palpus 3-segmented. Thorax freely articulating between prothorax and mesothorax. Prothorax subcylindrical to dorsoventrally compressed. Pronotum with lateral edges deplanate and strongly carinate, to rounded and ecarinate; pronotal hind angles usually extended, dorsally ecarinate, unicarinate, or bicarinate. Hypomeron large, subtriangular, often with antennal or crural cavities or impressions. Prosternum with anterior margin truncate or extended and deflexed to form a lobe, or chin piece, covering ventral mouthparts; posterior intercoxal portion extended and fitting into a mesosternal fossa. Mesosternum reduced, with deep median fossa to receive prosternal intercoxal process. Scutellum triangular, pentagonal, cordate, ovoid, to elongate. Elytra elongate, narrow, separately or conjointly rounded at apices, sometimes attenuate and spinose , or emarginate and bispinose; striae 9, rarely with short stria 10, each stria serially punctate to sulciform, often obsolescent, subparallel or apically coalescent. Mesocoxae globular, narrowly to moderately separated. Metasternum large, subquadrate. Metacoxae nearly approximate, transverse, excavate posteriorly, usually with a ventral plate or lamina. Metathorax usually alate and wings functional, frequently brachypterus to micropterus, rarely apterus; venation variable; radial cell large, elongate; medial field usually with wedge cell; apical field with 0-3 sclerotized patches. Legs long and slender, often received in crural depression or fossa; femur subfusiform, flattened ventrally; tibia slender, often spinose, usually with two apical spurs; tarsal formula 5-5-5, segments filiform to broadened or emarginate, usually with spiniform setae, often with ventral setose pads or membranous lobes. Abdomen with 5 ventrites, 1-4 connate. Male aedeagus trilobed; penis usually simple, attenuate; parameres slender, attenuate, to sagittate or hooked apically, variously setiferous. Female gonocoxites dorsoventrally compressed; styli reduced, peg like; bacculum slender, short to long, narrow to spatulate.

 Larvae are elongate, narrow, subcylindrical to flattened; mature length approximately 10-60 mm. Integument darkly sclerotized to desclerotized and nearly membranous; usually sparsely setose. Head wedge shaped, prognathous, darkly sclerotized; cranial sutures lyriform. Clypeus and labrum obsolete; frontal margin usually a projecting 1 or 3 dentate nasale. Antenna 3-segmented; 1-6 apical sensoria on segment 2. Stemmata 0-6 each side. Mandible robust, apically dentate, usually with retinaculum, without mola (mandible elongate, deeply cleft, and strongly toothed dorsally in Cardiophorinae). Maxilla and labium well developed; palpi 3-4 segmented. Legs long, 5-segmented, tarsungulus elongate. Abdomen 10-segmented; segments 1-8 similar, often with patches of longitudinal striations anterolaterally; tergite 9 variously modified, entire to emarginate, often with tubercules, spines, pits, simple or tuberculate urogomphi, or depressed; sternite 9 sometimes transversely carinate, or with lateral hooks. Spiracles biforous, on mesothorax and abdominal segments 1-8; ecdysial scar adnate to or separate from atrium margin; lacking closing apparatus.

 Ecology: Most species of click beetle are relatively common, with adults often collected in various traps, on vegetation, or at lights; most fly well. Diurnal species are often found on foliage, at flowers, or flying along woodland edges, trails, forest roadways, and through forest openings. Many species are active in late morning and late afternoon, though most neotropical species are crepuscular and nocturnal. In all areas there are seasonal or phenologically related diversity shifts. Some species are predaceous on soft bodied sternorrhynchous insects and their "honey dew" exudates, but many feed on nectar, pollen, floral parts, and at extra floral nectaries.

Larvae are found in soil, forest duff, or decaying plant materials, especially fibrous stems and wood. Generally, most species are opportunistic predators. Wood inhabiting larvae are predaceous on small and immature invertebrates or saprophagous on decay organisms, while soil dwelling species are generally predaceous or omnivorous. Some soil dwelling species are phytophagous on sprouting seeds and roots of grass seedlings, and occasionally on roots and tubers of vegetables. Larvae are liquid feeders and practice extra oral digestion. There are generally 3-5 larval instars taking 1-3 years for development, depending on food quality and availability. The pupal stage typically lasts 10-30 days, depending on ambient temperatures. Larvae of pest species are called wireworms.

Most members of the tribe Pyrophorini are bioluminescent. Adults of these beetles have paired light organs on the thorax and usually an additional median spot that is visible in flight on abdominal segment 3. Embryos and larvae of these species are luminous through intersegmental membranes.

 Status of the Classification: Elateridae is the largest family of the series Elateriformia and superfamily Elateroidea. It was recently enlarged by inclusion of Lissomidae, Cebrionidae, Dicronychidae, Anischiinae (ex Cerophytidae), and Subprotelaterinae and Thylacosterninae (ex Eucnemidae) (Lawrence & Newton 1995). No recent published world catalog is available. Taxonomically, the Elateridae is the ninth most diverse family of beetles. The Costa Rican click beetles have never received faunistic treatment since Champion’s (1894-1896) fascicles in the Biologia Centrali-Americana. Except for the taxa containing bioluminescent species, most of the genera remain in need of revisionary study. Taxonomic and phylogenetic concepts in Elateridae are in flux.

 Diversity and Distribution: There are nearly 10,000 species worldwide. However, only 61 species are formally reported from Costa Rica. Ten (10) of these species are apparently endemic to Costa Rica, in that they are only known from their type localities, and seven (7) of these species were described from Volcan de Irazu. Another 218 described species are known, but not recorded, or are predicted to occur in Costa Rica based on their occurrences in Nicaragua and Panama. No fewer than 25 undescribed species are known from recent limited sampling. Recorded species represent 33 genera, with unrecorded or predicted species representing an additional 36 genera. From the latter group, two additional subfamilies and at least six additional tribes may be added to the Costa Rica elaterid fauna. Predictively, the Costa Rican click beetle fauna could reach 350 or more species, representing at least 7 subfamilies, 19 tribes, and 72 genera, following appropriate study.

Click beetles are found throughout Central America and are found in all but aquatic and the highest montane habitats. Forest, savanna, and ecotonal areas harbor the greatest local diversities of these beetles. Historically, most Costa Rican specimen records are from the Pacific slope mid-elevational mesic forests, cloudforests, or the northwestern dry forests. Relatively few samples are from southern Pacific or Caribbean slope regions, or lowland coastal areas of either coast. However, it is these latter regions that produced the majority of new records and undescribed species in recent sampling efforts. The Pacific slope and Caribbean slope elaterid faunas appear significantly different at all taxonomic levels and species associations seem to correlate with mid scale biogeographic patterns, such as vegetation communities.
 
 

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