Histerinae

Introduction

The Histerinae is very diverse in form and numbers of species, containing probably around one-half of all histerid species. The group includes some of the most commonly encountered species, particularly those associated with dung. However, habits of Histerinae are extremely diverse, including others associated with dead wood and other rotting vegetation, fungus, vertebrate nests, and the colonies of social insects. The inclusion of the exclusively myrmecophilous and termitophilous Hetaeriinae in this group has long been suspected, but has only recently been demonstrated conclusively (Caterino & Vogler, 2002).

Characteristics

Histerinae are very diverse in form. Body shapes range from oval and convex (most Histerini) to strongly cylindrical (some Exosternini and Platysomatini) or flattened (some Platysomatini and most Hololeptini). The most consistent characters across the subfamily include lack of labral setae and the presence of a well developed prosternal lobe, which usually extends laterally to shield the antennae from beneath. However, many exceptions, particularly in the more unusually shaped groups (Hetaeriinae, Hololeptini) are known.

Discussion of Phylogenetic Relationships

The relationships shown above result from the recent work of Caterino & Vogler (2002). However, their taxon sampling was insufficient to provide significant confidence for most of these branches. The sister group relationship of Histerini and Hetaeriinae, although one of the more surprising results of the analysis was, in fact, relatively well supported by 18S rDNA data. The monophyly of all of these taxa is still questionable. Until tribal limits can be confidently established, no trees at this level will be very meaningful.

Hetaeriinae and Chlamydopsinae (both largely myrmecophilous) have often been considered sister groups, and the two share many unusual characters. However, many of these characters may well be convergences related to myrmecophily (Slipinski & Mazur, 1999; Caterino & Vogler, 2002). Recent higher level studies instead place Hetaeriinae within Histerinae, although without a clear sister group therein. Exosternini presents many possible sister groups, and many Neotropical Exosternini are also myrmecophilous. However, 18S data suggest that Hetaeriinae are closer to Histerini (Caterino & Vogler, 2002). Additional sampling for 18S will likely answer this question, but the relevant taxa have proven difficult to obtain.

References

Caterino, M. S., and A. P. Vogler. 2002. The phylogeny of the Histeroidea. Cladistics 18(4):394-415.

Slipinski, S. A., and S. Mazur. 1999. Epuraeosoma, a new genus of Histerinae and phylogeny of the family Histeridae. Annales Zoologici (Warszawa) 49:209-230.

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