Oxypoda opaca, copyright Udo Schmidt.

Belongs within: Oxypodini.
Contains: Calodera.

Rove by the riverside
Published 5 September 2020

The Staphylinidae, commonly known as the rove beetles, are one of the most diverse of the recognised beetle families. Indeed, thanks to their habit in recent years of glomming up lineages previously treated as distinct families like the pselaphids and scydmaenids, they now rival the weevils of the Curculionidae for the position of largest of all recognised animal families. But for their diversity and ubiquity, staphylinids are comparatively poorly studied, owing to a not-unwarranted reputation for taxonomic recalcitrance (the relatively soft bodies of many staphylinids mean they often do not handle well with standard methods for examining beetles). Perhaps the most neglected of all staphylinid subgroups is the subfamily Aleocharinae. Aleocharines are often minute (the average aleocharine is only a couple of millimetres in length) and their identification often requires resolving features that lie at the very limit of what can be seen with a standard dissecting microscope. Nevertheless, aleocharines are remarkably diverse and among their representatives are the representatives of the genus Parocyusa.

Parocyusa americana, from Brunke et al. (2012); scale bar = 1 mm.

Typical aleocharines have what is thought of as the ‘standard’ body form for staphylinids, with short, square elytra that do not cover the long, flexible abdomen (though I should mention that, with the aforementioned assimilation of the pselaphids and scydmaenids, I suspect there may now be more ‘non-standard’ staphylinid species than ‘standard’ ones). For the most part, they can be distinguished from other staphylinid subfamilies by the position of the antennae, with their insertions placed behind the level of the front of the eyes. Aleocharines are divided between numerous tribes; Parocyusa is included in the tribe Oxypodini, a heterogenous group of relatively unspecialised aleocharines. Notable features distinguishing Parocyusa from other aleocharine genera include legs with five segments to each tarsus, a frontal suture between the antennal insertions, the median segments of the antennae being longer than wide, the head not having a well defined ‘neck’, the sides of the pronotum not being strongly deflexed downwards (so the hypomeron, the lateral section of the pronotum, is clearly visible in side view), and deep transverse impressions across the third to fifth abdominal tergite but not across the sixth tergite or across the sternites (Newton et al. 2001). Members of the genus are a bit over three millimetres in length.

Species of Parocyusa are found widely in the Holarctic realm; I’ve found reference to species from Europe, Korea, and northeastern North America (I should also note that I’ve also encountered dark allusions to recent rearrangements of the generic status of some of these species but without access to such revisions I’m going to stick with what I can find). I haven’t found any reference to their specific diet but I suspect that they would be micropredators, a common lifestyle for staphylinids of their kind. Parocyusa species are associated with running water, living among the gravel and sand alongside stream beds (e.g. Brunke et al. 2012). As such, these and other aleocharines have received attention in ecological studies: the higher the diversity of staphylinids present, the more healthy the ecosystem is likely to be.

Systematics of Oxypodina
|--+--Crataraea Thomson 1858LC20, NT01
| | `--C. suturalis (Mannerheim 1830)NT01
| `--Haploglossa Kraatz 1856LC20, NT01 [incl. Microglossa Stein 1868NT01, Microglotta Kraatz 1862NT01]
| |--‘Microglotta’ barberi Fenyes 1921F21
| `--H. villosulaLC20
`--+--+--Phloeopora Erichson 1837LC20, NT01
| | |--P. gratiosa Fauvel 1878O86
| | `--P. laeviuscula Fauvel 1878O86
| `--PlacusiniLC20
| |--Euvira Sharp 1883 [incl. Crimalia Casey 1911]NT01
| | |--E. diazbatresaeNT01
| | `--E. quadriceps (Casey 1911)NT01
| `--Placusa Erichson 1837 [incl. Calpusa Mulsant & Rey 1871]NT01
| |--P. pinearumLC20
| |--P. tachyporoidesNT01
| |--P. tenuicornis Fauvel 1878O86
| `--P. tridens Fauvel 1878O86
`--+--+--Oxypoda Mannerheim 1830LC20, NT01 (see below for synonymy)
| | |--O. binodosa Seever 1971P92
| | |--O. exiguaO86
| | |--O. lividipennisO86
| | |--O. opacaLC20
| | |--O. termitophila Bernhauer 1901S57
| | |--O. variegata Fauvel 1878O86
| | `--O. vincta Fauvel 1878O86
| `--+--Myrmobiota Casey 1893LC20, NT01 [incl. Soliusa Casey 1900NT01]
| `--+--Neothetalia canadianaLC20
| `--+--Ocalea Erichson 1837LC20, NT01 [incl. Rheobioma Casey 1906NT01]
| | `--O. corsicanaLC20
| `--+--Isoglossa Casey 1893LC20, NT01
| | `--I. agnitaLC20
| `--Mniusa Mulsant & Rey 1875LC20, NT01
| `--M. incrassataLC20
`--+--+--Ocyustiba Lohse & Smetana 1988LC20, NT01
| | `--O. appalachiana Lohse & Smetana 1988NT01
| `--‘Oxypoda’ alternansLC20
`--+--‘Oxypoda’ longipesLC20
`--+--+--Oreuryalea watanabeiLC20
| `--Devia Blackwelder 1952LC20, NT01 [incl. Dasyglossa Kraatz 1856 non Illiger 1807NT01]
| |--D. congruens (Casey 1893)NT01
| `--D. prosperaNT01
`--+--Ocyusa Kraatz 1856LC20, NT01 [incl. Cousya Mulsant & Rey 1875NT01, EurylophusF21]
| `--O. picinaLC20
`--+--Ilyobates Kraatz 1856LC20, NT01 [incl. Gennadota Casey 1906NT01]
| |--I. bennettiLC20
| `--I. nigricollisLC20
`--+--Tetralaucopora Bernhauer 1928LC20, NT01
| `--T. rubicundaLC20
`--Tectusa longitarsisLC20

Oxypodina incertae sedis:
Parocalea Bernhauer 1901NT01
Stichoglossa Fairmaire & Laboulbène 1856NT01
Acrimea Casey 1911NT01
`--A. fimbriataNT01
Longipeltina Bernhauer 1912NT01
`--L. bakeri Bernhauer 1912NT01
Melanalia Casey 1911NT01
`--M. tabida Casey 1911NT01
Moluciba Casey 1911NT01
`--M. grandipennis Casey 1911NT01
Pachycerota Casey 1906NT01
`--P. duryi Casey 1906NT01
Parocyusa Bernhauer 1902 [incl. Chilopora Kraatz 1856 non Haime 1854, Chiloporata Strand 1935]NT01
|--P. longitarsisLC20
`--P. rubicundaNT01
Pentanota Bernhauer 1905NT01
`--P. meuseli Bernhauer 1905NT01
Athetalia Casey 1910NT01
|--A. metlakatlana (Bernhauer 1909)NT01
`--A. oregonensis (Bernhauer 1909)NT01
Gnathusa Fenyes 1909NT01
|--*G. evaF21
`--G. tenuicornis Fenyes 1921F21
Neodemosoma Pace 1989NT01
|--N. exposita (Casey 1911) [=Leptusa exposita]NT01
`--N. semirufa (Casey 1906) [=Leptusa semirufa]NT01

Oxypoda Mannerheim 1830LC20, NT01 [incl. Baeoglena Thomson 1867NT01, Bessopora Thomson 1859NT01, Demosoma Thomson 1859NT01, Disochara Thomson 1858NT01, Hylota Casey 1906NT01, Paroxypoda Ganglbauer 1895NT01, Podoxya Mulsant & Rey 1874NT01, Sphenoma Mannerheim 1830NT01]

*Type species of generic name indicated


Brunke, A. J., J. Klimaszewski, J.-A. Dorval, C. Bourdon, S. M. Paiero & S. A. Marshall. 2012. New species and distributional records of Aleocharinae (Coleoptera, Staphylinidae) from Ontario, Canada, with a checklist of recorded species. ZooKeys 186: 119–206.

[F21] Fenyes, A. 1921. New genera and species of Aleocharinae with a polytomic synopsis of the tribes. Bulletin of the Museum of Comparative Zoology 65 (2): 15–36.

[LC20] Lü, L., C.-Y. Cai, X. Zhang, A. F. Newton, M. K. Thayer & H.-Z. Zhou. 2020. Linking evolutionary mode to palaeoclimate change reveals rapid radiations of staphylinoid beetles in low-energy conditions. Current Zoology 66 (4): 435–444.

[NT01] Newton, A. F., M. K. Thayer, J. S. Ashe & D. S. Chandler. 2001. Staphylinidae Latreille, 1802. In: Arnett, R. H., Jr & M. C. Thomas (eds) American Beetles vol. 1. Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia pp. 272–418. CRC Press: Boca Raton.

[O86] Olliff, A. S. 1886. A revision of the Staphylinidae of Australia. Part I. Proceedings of the Linnean Society of New South Wales, series 2, 1 (2): 403–473, pl. 7.

[P92] Poinar, G. O., Jr. 1992. Life in Amber. Stanford University Press: Stanford.

[S57] Seevers, C. H. 1957. A monograph on the termitophilous Staphylinidae (Coleoptera). Fieldiana Zoology 40: 1–334.

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