Elateroidea is a morphologically diverse group, including hard-bodied beetles with 5 abdominal ventrites, soft-bodied beetles with 7-8 ventrites connected with membranes (formerly known ascantharoids), and beetles with intermediate forms.[2] They have a range of sizes and colours, but in terms of shape, they are usually narrow and parallel-sided as adults.[3]
Many of the sclerotised elateroids (Cerophytidae,Eucnemidae,Throscidae, Elateridae) have a clicking mechanism.[4] This is a peg on the prothorax which fits into a cavity in the mesothorax. When a click beetle bends its body, the peg snaps into the cavity, causing the beetle's body to straighten so suddenly that it jumps into the air.[5]
Most beetles capable ofbioluminescence are in the Elateroidea, in the families Lampyridae (~2000 species),Phengodidae (~200 species),Rhagophthalmidae (100 species) and Elateridae (>100 species).[4]
Females in several lineages, includingLycidae, Lampyridae, Phengogidae and Rhagophthalmidae, do not pupate andremain in a larval form. This trait is estimated to have evolved independently at least three times within the superfamily.[6]
Some Elateroidea, including species of Cantharidae[7] and Lycidae,[8] have brightaposematic colours to signal to predators that they are poisonous and so should not be eaten.
The validity and relationships of some families, such asPodabrocephalidae are not fully resolved. The familyRhinorhipidae has recently been removed to its own superfamily, with evidence that it is a basal taxon withinElateriformia dating to an Upper Triassic/Lower Jurassic split from other extant beetle lineages.[9]
Some morphological and molecular phylogenetic analyses find thatByrrhoidea is either a monophyletic or paraphyletic group closely related to Elateroidea.[11]
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