Good-bye Scydmaenidae, or why the ant-like stone beetles should become megadiverse Staphylinidae sensu latissimo (Coleoptera)

Vasily V Grebennikov,Alfred F Newton

doi:10.14411/eje.2009.035

Abstract

Ant-like stone beetles (Coleoptera: Scydmaenidae) include more than 4,850 described species in about 90 genera main- tained as a separate cosmopolitan family since 1815. Recent authors have hypothesised that Scydmaenidae might be rooted deep inside rove-beetles (Staphylinidae). To test this hypothesis we analysed 206 parsimoniously informative larval and adult morpho- logical characters scored for 38 taxa. Strict consensus topologies from the shortest trees in all 12 analyses consistently placed Scyd- maenidae as sister to (Steninae + Euaesthetinae) in a monophyletic Staphylinine Group (with or without Oxyporinae). The single fully resolved and most consistently supported topology maintains a monophyletic Staphylinine Group consisting of Oxyporinae + (Megalopsidiinae + ((Scydmaenidae + (Steninae + Euaesthetinae)) + (Leptotyphlinae + (Pseudopsinae + (Paederinae + Staphylini- nae))))); Solierius lacks larval data and is ambiguously placed within the Group. Eight analyses of variably aligned 18S rDNA data for 93 members of Staphylinoidea under parsimony, neighbour-joining and Bayesian approaches were markedly inconsistent, although partly congruent with the Scydmaenidae + (Steninae + Euaesthetinae) hypothesis. Our results strongly suggest that ant-like stone beetles do not form an independent family, but are morphologically modified members of Staphylinidae and, consequently, should be treated as a 32nd recent subfamily within the megadiverse Staphylinidae sensu latissimo. Formal taxonomic acts are: Scydmaeninae Leach, 1815, status novus (= Scydmaenidae Leach, 1815); Scydmaenitae Leach, 1815, status novus (= Scydmaeninae Leach, 1815); Mastigitae Fleming, 1821, status novus (= Mastiginae Fleming, 1821); Hapsomelitae Poinar & Brown, 2004, status novus (= Hapsomelinae Poinar & Brown, 2004). The family Staphylinidae sensu latissimo becomes the largest in Coleoptera and in the whole of the Animal Kingdom, with 55,440 described species (extant plus extinct), thus surpassing Curculionidae with an esti- mated 51,000 described species.

Highlights

The beetle family Staphylinidae, or rove beetles, is one of the largest families of beetles and, of animals, passing the 50,000 described species mark in 2007 (Newton, 2007)
The purpose of the current study is to provide a new phylogenetic analysis based on a robust sample of all subfamily- and family-level taxa recently suggested as members of the Staphylinine Group, based mainly on adult and larval morphology but supplemented with inclusion of 18S rDNA molecular data available for a subset of taxa, with the intention of evaluating the monophyly of the Staphylinine Group and the relationships among the included subfamilies
We focus especially on two groups that have not been included in the more detailed recent studies within the Staphylinine Group mentioned in the second paragraph above: Solieriinae, suggested but not yet demonstrated as a member of the group, and Scydmaenidae, whose placement has varied wildly in recent studies that have included it

Summary

Introduction

The beetle family Staphylinidae, or rove beetles, is one of the largest families of beetles and, of animals, passing the 50,000 described species mark in 2007 (Newton, 2007). Lawrence & Newton (1982) summarized the classification at that time and proposed that the 22-odd staphylinid subfamilies recognized could be organized into four main lineages or informal groups, with several small allied families being probably or possibly related to one or another of these lineages (making Staphylinidae paraphyletic with respect to these other families). The largest such lineage, termed by them the “staphylinine group”, included the staphylinid subfamilies Oxyporinae, Megalopsidiinae, Steninae, Euaesthetinae, Leptotyphlinae, Paederinae, Staphylininae “and possibly Scydmaenidae and Silphidae”. The genus Solierius Bernhauer, 1921, was generally placed in the subfamily Omaliinae until Newton & Thayer (1992) established a subfamily for it and excluded it from the Omaliine Group, and subsequently (1995) placed it in the Staphylinine

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