Scydmaenidae (Coleoptera), 1815

Fikáček, Martin, Skuhrovec, Jiří & Šípek, Petr, 2007, Abstracts of the Immature Beetles Meeting 2007, Acta Entomologica Musei Nationalis Pragae 47, pp. 287-306 : 299-300

Good-bye Scydmaenidae (Coleoptera) : larval morphology and 18S rDNA sequence suggest that rove beetles are paraphyletic with respect to ant-like stone beetles

Vasily V. GREBENNIKOV 1,2) & Alfred F. NEWTON 3)

1) Entomology Research Laboratory, Ontario Plant Laboratories, Canadian Food Inspection Agency, K.W. Neatby Bldg., 960 Carling Avenue, Ottawa, Ontario K1A 0C6, Canada; email: [e-mail] 2) Institut für Spezielle Zoologie und Evolutionbiologie, Friedrich-Schiller-Universität Jena, Erbertstrasse 1, D-07743 Jena, Germany 3) Zoology Department, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA; email: [e-mail]

Ant-like stone beetles ( Coleoptera : Scydmaenidae ) is a cosmopolitan group of more than 4600 described species in about 82 genera, although numerous new species remain to be named. These beetles are found in forest leaf litter and other relatively moist habiti where the adults or larvae prey on oribatid mites. The group has been maintained as a separate family since 1815. It appears increasingly convincing that Scydmaenidae , together with Silphidae and Staphylinidae , might form a monophyletic unit. It has even been hypothesised that the two former families might, in fact, be nested deep inside the Staphylinidae clade. This scenario, if true, would require synonymizing Scydmaenidae with Staphylinidae and treating the former as a subunit of the Staphylinidae .

To test the phylogenetic position of Scydmaenidae , a matrix of larval morphological characters was constructed to include 34 taxa and 90 parsimoniously informative characters. The following families/subfamilies were represented in the analysis, with the number of terminal taxa in parentheses: Leiodidae (1), Agyrtidae (1), Silphidae (3), Scydmaenidae (3), Omaliinae (1), Tachyporinae (1), Piestinae (1), Apateticinae (1), Trigonurinae (1), Oxyporinae (1), Megalopsidiinae (1), Leptotyphlinae (3), Steninae (2), Euaesthetinae (4), Pseudopsinae (3), Paederinae (3) and Staphylininae (4). The most parsimonious trees obtained were consistent in retaining monophyly of the Staphylinine Group of subfamilies (the latter seven subfamilies, either with or without Oxyporinae ) plus Scydmaenidae . Monophyly of this group was not affected by character ordering or character re-weighting using successive approximation. These results support the hypothesis of paraphyly of Staphylinidae with respect to Scydmaenidae .

A separate analysis was performed, for which a matrix of 18S rDNA sequences data was constructed to include 52 terminal taxa and about 2100 aligned nucleotide positions using ClusalX default settings. Neighbour joining, maximal parsimony, maximum likelihood, and Bayesian approximation were used as topology-building methods. Monophyly of the Staphylinine Group + Scydmaenidae was not retained, although Silphidae and Scydmaenidae were variably nested inside Staphylinidae on all unrooted dendrites, which also included representatives of Leiodidae and Agyrtidae . These results are consistent with the hypothesis that Staphylinidae are paraphyletic with respect to Scydmaenidae .

This study provides strong support for the hypothesis that ant-like stone beetles do not form an independent family, but are in fact rather modified members of Staphylinidae and, consequently, should logically be treated as a subfamily within the Staphylinine Group.