Molecular phylogeny of the tribe Oxypodini

Molecular phylogeny of the aleocharine tribe Oxypodini Thomson, 1859
(Coleoptera: Staphylinidae: Aleocharinae)

The beetle tribe Oxypodini belongs to the subfamily Aleocharinae of the family Staphylinidae.  Staphylinidae, or Rove Beetles, is one of the two largest families of beetles and includes more than 3000 genera and about 50,000 species (with about 400 new added annually), distributed worldwide and common in most terrestrial habitats (Newton et al. 2000).  Within Staphylinidae, the subfamily Aleocharinae is the largest and the least known.  It includes more than 1000 genera and over 12,000 species (Newton et al. 2000).  Monophyly of Aleocharinae is firmly established.  The most convincing synapomorphy for Aleocharinae is large and complex parameres of the male genitalia (Hammond 1975, Ashe 1994).  More than 50 tribes are recognized within Aleocharinae.

As far as phylogeny at the tribe level is concerned, only relationships at the basis of the aleocharine tree have been resolved with good support (Ashe 2005).  Most of the aleocharine tribes (including Oxypodini) belong to a monophyletic group of so called “higher” Aleocharinae which share two important synapomorphies:  a unique defensive gland on abdominal tergite VII (adults) or tergum VIII (larvae) (Frank & Thomas 1984, Steidle & Dettner 1993).  Phylogenetic analyses have been done only within a few tribes, e.g., Aleocharini (Maus, Peschke & Dobler 2001, Hoplandriini (Hanley 2002), Gymnusini and Deinopsini (Klimaszewski 1979, Ashe 2005).  The phylogeny of Athetini is currently a focus of another project (click here for details).  Relations between most of the larger tribes, such as Athetini, Oxypodini, Aleocharini, Homalotini, etc. have never been analyzed.  Further, some of these tribes may not be monophyletic.

The tribe Oxypodini includes about 150 genera and 2000 species worldwide (Newton & Thayer 2005a).  In terms of number of species this tribe of beetles is comparable to the class of mammals, but is still very poorly known.  Meanwhile, since Oxypodini is one of dominating groups of arthropod predators in many terrestrial habitats (e.g., forest litter, river and lake banks), dramatic improvement in our knowledge of this tribe is crucial for understanding of the processes in these ecosystems.  The tribe is particularly well represented in the Northern and Southern Temperate zones.  Ashe (Newton et al. 2000) considers this tribe to be poorly defined.  The main diagnostic characters for the tribe are plesiomorphic within Aleocharinae:  the 5-5-5 tarsal segmentation (within some lineages of Oxypodini occasionally transformed in 4-5-5, or 4-4-4), the lack of the additional (4^th ) segment in the maxillar palpus (present in Aleocharini and Hoplandriini), and the lack of the “athetine bridge” in the male genitalia (present in Athetini, Falagriini and Lomechusini).  The following are major unresolved problems in systematics of Aleocharinae:  monophyly of Oxypodini has not been tested by modern analyses, synapomorphies for the tribe are not known, and relationships between Oxypodini and other tribes of “higher” Aleocharinae have never been examined.

Currently, the most widely accepted classification (e.g., Newton et al. 2000, Smetana 2004) recognizes 5 subtribes within the tribe Oxypodini:  Blepharhymenina, Dinardina, Meoticina, Oxypodina and Tachyusina.  This classification was first proposed by Seevers (1978) and was based mostly on easily observable morphological characters, traditionally used in staphylinid taxonomy.  Seevers further subdivided subtribe Oxypodina into 6 groups of genera but did not name them (in the sense of the Code).  Some of the subtribes recognized by Seevers are based on characters which appear to be unique and are likely to be confirmed as apomorphies, once phylogeny has been analyzed.  Examples of probable monophyletic subtribes include Blepharhymenina with their very narrow neck and Meoticina with their curved tarsal claws (Seevers 1978) and distinct structure of the internal sac of the male genitalia (Muona 1991).  Other groupings, such as Oxypodina, may be based more on superficial similarity, and/or plesiomorphies.  Since no phylogenetic analysis within Oxypodini has ever been done, the currently recognized subtribes can be considered only as preliminary hypotheses which need to be tested.

Besides the five subtribes currently recognized within Oxypodini, there are seven additional available family-group names (Newton & Thayer 1992), which were rarely used and are now treated as synonyms of the five valid subtribal names.  If properly formed as subtribe names, these additional available names are:  Ocyusina, Phloeoporina, Ocaleina, Caloderina, Microglottina, Homaeusina and Decusina.  Unless the type genera of all twelve (5 valid + 7 invalid) available family-group names are included in analysis, new additional names for any lineage within Oxypodini cannot be proposed, even if phylogenetic analysis reveals previously unrecognized monophyletic lineages deserving a name.

Position of some taxa in relation to Oxypodini has been controversial.  Sometimes these taxa are included in Oxypodini, sometimes in a different tribe.  Examples include Halobrecta (often placed in Athetini, based on tarsal formula (4-5-5) (e.g., Benick & Lohse 1974), despite lacking important apomorphies of that tribe), subtribe Tachyusina (historically placed in Falagriini (e.g., Lohse 1974), based on tarsal formula and overall body shape, but shown to lack important apomorphies of that tribe (e.g., split velum of the parameres) (Seevers 1978).  Position of such groups in the phylogenetic tree of Aleocharinae needs to be clarified and classification stabilized.

Another major problem in oxypodine systematics is that many non-Palaearctic species have been placed in genera originally described from Europe.  Such placement is usually based on overall similarity, body shape and other superficial characters (e.g., 38 Southern Temperate species placed in Calodera, 10 in Ocalea, 22 in Oxypoda (Newton & Thayer 2005b).  Reexamination, use of previously neglected characters and phylogenetic analysis will result in correct placement of these taxa.  To some extent this happened when Patagonian Oxypodini were studied by Pace (1988, 1999).  Resolving phylogenetic relationships between taxa with extratropical or Southern Temperate distributions is very important for understanding the biogeography of these areas.

The large genus Oxypoda presents a particular problem, because it includes morphologically diverse species, partially distributed among multiple subgenera (Palaearctic species), and partially unassigned to any subgenus.  Phylogeny of Oxypoda should be analyzed in detail, aiming to test monophyly of the genus and its subgenera.  Such analysis has never been done.

The project includes the following goals:

• testing monophyly of the tribe Oxypodini
• identifying phylogenetic relations between Oxypodini and other tribes of so called "higher" Aleocharines (Aleocharini, Athetini, Falagriini, Homalotini, Hoplandriini, Lomechusini, Myllaenini and Placusini)
• testing monophyly of the subtribes currently recognized within Oxypodini
• identifiying phylogenetic relations between the main lineages within Oxypodini
• testing monophyly of the large genus Oxypoda Mannerheim, 1830 and its subgenera
• assessment of generic placement of Southern Temperate oxypodines, identifying monophyletic lineages and analyses of their distribution patterns
• testing the hypotheses that particular taxa with uncertain taxonomic position (e.g., Halobrecta) are indeed members of Oxypodini

As this stage we are assembling a collection of specimens, with preserved DNA, to be used in our analyses. The material available at the moment is very limited, and any help in obtaining additional specimens preserved in 96% ethanol will be greatly appreciated. If you are willing to help, please see instructions on how to handle specimens to ensure that their DNA is not degraded.

Below, we provide a list of taxa already available and an additional list of species particularly important for our project

A list of available genera and species of Oxypodini

Some additional species not yet on the above list were obtained recently during our own field work and provided by our colleagues. The above list will be periodically updated. The list below includes taxa we are particularly desperate to get. Any help will be greatly appreciated.

A list of genera and species of Oxypodini particularly needed for future studies

References

Ashe, J. S. (1994) Evolution of aedeagal parameres of aleocharine staphylinids (Coleoptera: Staphylinidae: Aleocharinae). The Canadian Entomologist, 126, 475–491.

Ashe, J. S. (2005) Phylogeny of the tachyporine group of subfamilies and ‘basal’ lineages of the Aleocharinae (Coleoptera: Staphylinidae) based on larval and adult characteristics. Systematic Entomology, 30(1), 3–37.

Benick, G. & Lohse, G. A. (1974) 14. Tribus: Callicerini (Athetae). In:  Freude, H., Harde, K. W. & Lohse, G. A. (Ed.) Die Käfer Mitteleuropas. Band 5. Staphylinidae II (Hypocyphtinae und Aleocharinae). Pselaphidae. Kreferld, Goecke & Evers, p. 72–220.

Frank, J. H. & Thomas, M. C. (1984) Cocoon-spinning and the defensive function of the median gland in larvae of Aleocharinae (Coleoptera, Staphylinidae): a review. Quaestiones Entomologicae, 20, 7–23.

Hammond, P. (1975) The phylogeny of a remarkable new genus and species of gymnusine staphylinid (Coleoptera) from the Auckland Islands. Journal of Entomology (B), 44(2), 153–173.

Hanley, R. S. (2002) Phylogeny and higher classification of Hoplandriini (Coleoptera: Staphylinidae: Aleocharinae). Systematic Entomology, 27, 301–321.

Klimaszewski, J. (1979) A revision of the Gymnusini and Deinopsini of the world (Coleoptera: Staphylinidae, Aleocharinae). Agriculture Canada Monograph, 25, 11–69.

Lohse, G. A. (1974) 13. Tribus: Falagriini. In:  Freude, H., Harde, K. W. & Lohse, G. A. (Ed.) Die Käfer Mitteleuropas. Band 5. Staphylinidae II (Hypocyphtinae und Aleocharinae). Pselaphidae. Kreferld, Goecke & Evers, p. 64–72.

Maus, C., Peschke, K. & Dobler, S. (2001) Phylogeny of the genus Aleochara inferred from mitochondrial cytochrome oxidase sequences (Coleoptera: Staphylinidae). Molecular Phylogenetics and Evolution, 18, 202–216.

Muona, J. (1991) The North European and British species of the genus Meotica Mulsant & Rey (Coeloptera, Staphylinidae). Deutsche Entomologische Zeitschrift (N. F.), 38, 225–246.

Newton, A. F. & Thayer, M. K. (1992) Current classification and family-group names in Staphyliniformia (Coleoptera). Fieldiana: Zoology. New Series. 67, iv + 92 pp.

Newton, A. F. & Thayer, M. K. (2005a) Catalog of higher taxa, genera and subgenera of Staphyliniformia [online]. Chicago: Field Museum of Natural History [last updated November 3, 2005; accessed May 30, 2007].

Newton, A. F. & Thayer, M. K. (2005b) Catalog of austral species of Staphylinidae and other Staphylinoidea [online]. Chicago: Field Museum of Natural History [last updated November 3, 2005; accessed May 30, 2007].

Newton, A. F. et al. (2000) 22. Staphylinidae Latreille, 1802. In: Arnett, R. H. & Thomas, M. C. American beetles. Volume 1. Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia. CRC Press, Boca Raton, Florida, pp. 272–418.

Pace, R. (1988) Aleocharinae del Cile meridionale (Coleoptera, Staphylinidae). Lavori, Società Veneziana di Scienze Naturali, 70, 85–99.

Pace, R. (1999) Aleocharinae del Cile (Coleoptera, Staphylinidae). Bollettino del Museo Civico di Storia Naturale di Verona, 23, 119–210.

Seevers, C. H. (1978) A generic and tribal revision of the North American Aleocharinae (Coleoptera: Staphylinidae). With additions and annotations by Lee H. Herman. Fieldiana: Zoology, 71, vi + 289 pp.

Smetana, A. (2004) Subfamily Aleocharinae Fleming, 1821. In: Löbl, I. & Smetana, I. Catalogue of Palaearctic Coleoptera. Volume 2. Hydrophyloidea–Histeroidea–Staphylinoidea. Apollo Books, Stenstrup, pp. 353–494.

Steidle, J. L. M. & Dettner, K. (1993) Chemistry and morphology of the tergal gland of freeliving adult Aleocharinae (Coleoptera: Staphylinidae) and its phylogenetic significance. Systematic Entomology, 18, 149–168.

Last updated: July 12, 2010