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

Abstract

Abstract. Ant-like stone beetles (Coleoptera: Scydmaenidae) include more than 4,850 described species in about 90 genera maintained 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 morphological characters scored for 38 taxa. Strict consensus topologies from the shortest trees in all 12 analyses consistently placed Scydmaenidae 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 + Staphylininae))))); 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);

Larval morphology of Scydmaenus tarsatus and S. hellwigii, with notes on feeding behaviour and a review of the bibliography on the preimaginal stages of ant-like stone beetles (Coleoptera: Staphylinidae: Scydmaeninae)

“…Scydmaeninae is a large subfamily of Staphylinidae, comprising nearly 4900 species in about 90 genera and ten tribes (Grebennikov & Newton, 2009). Larval morphology of ant-like stone beetles, however, is very poorly known.…”

“…All larval stages and the pupa are described only for a single species (De Marzo, 1984) and only for one species are the details of the chaetotaxy illustrated and described using modern methods (Wheeler & Pakaluk, 1983). Although larval characters of Scydmaeninae were recently used in an extensive phylogenetic analysis (Grebennikov & Newton, 2009) and may be crucial for clarifying suprageneric relationships within this subfamily, such data is scarce, which hampers further taxonomic study.…”

“…In addition to Cephennium, in the tribe Cephenniini there are only illustrations of the general habitus and a few morphological details of Cephennodes Reitter (as an unidentified genus by Morimoto &Hayashi, 1986 andas Coatesia Scott by Newton, 1991). In Eutheiini, some details are described and illustrated for larvae of Eutheia Stephens and Veraphis Casey (Brown & Crowson, 1980;Newton, 1991); in Cyrtoscydmini for Stenichnus Thomson, Scydmoraphes Reitter, Neuraphes Thomson and Euconnus (Paulian, 1941;Franz, 1965;Brown & Crowson, 1980;Wheeler & Pakaluk, 1983;Schmid, 1988a;Newton, 1991); in Scydmaenini for Scydmaenus Latreille only (Meinert, 1888;Böving & Craighead, 1931;Jeannel & Paulian, 1945;Brown & Crowson, 1980;Newton, 1991;Beutel & Molenda, 1997); and in Mastigini, Clidicini and Leptomastacini larvae of one genus in each tribe are known, respectively Palaeostigus Newton, Clidicus Laporte and Leptomastax Pirazzoli (De Marzo, 1983, 1984Vit & De Marzo, 1989;O'Keefe & Monteith, 2000;Grebennikov & Newton, 2009). Data from the above-listed literature were used by several authors in identification keys, reviews and summaries (e.g., Ghilarov, 1964;Kasule, 1966;Klausnitzer, 1978Klausnitzer, , 1997Newton & Franz, 1998, O'Keefe, 2005.…”

Feeding of two species of Scydmaeninae "hole scrapers", Cephennium majus and C. ruthenum (Coleoptera: Staphylinidae), on oribatid mites

“…However, some Scydmaeninae will eat or even prefer soft-bodied mites and springtails (Leleup, 1968;O'Keefe & Monteith, 2001;Jałoszyński, 2012a;Jałoszyński & Kilian, 2012), scavenge on dead arthropods (Molleman & Walter, 2001;Jałoszyński, 2012b) and in the peculiar case of the fi rst-instar larvae of Palaeostigus Newton, the only source of food is the secretion deposited by a female together with her eggs (De Marzo, 1983). As the biology of about 5,000 currently known species of Scydmaeninae (Newton & Franz, 1998;Grebennikov & Newton, 2009;Jałoszyński, 2016) is still poorly known, the current picture of their feeding preferences, techniques and adaptations is without doubt far from complete.…”

Specialized feeding of Euconnus pubicollis (Coleoptera: Staphylinidae: Scydmaeninae) on oribatid mites: Prey preferences and hunting behaviour

“…The subfamily Scydmaeninae (ant-like stone beetles) is a large lineage within the Staphylinidae, currently comprising nearly 4,900 species (Newton & Franz, 1998;Grebennikov & Newton, 2009). After two hundred years of study, the biology of Scydmaeninae is still exceptionally poorly known compared to many other subfamilies of rove beetles.…”