#404 Rove Beetle – Devil’s Coach Horse (Ocypus sp.)

13 April 2021

A genus of rove beetles in the subfamily Staphylininae primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the group is currently recognized as the largest extant family of organisms. It is an ancient group, with fossilized rove beetles known from the Triassic, 200 million years ago, and possibly even earlier if the genus Leehermania proves to be a member of this family. They are an ecologically and morphologically diverse group of beetles, and commonly encountered in terrestrial ecosystems.

Most rove beetles are predators of insects and other invertebrates, living in forest leaf litter and similar decaying plant matter. They are also commonly found under stones, and around freshwater margins.

Note: The possible identification to species level is supported by contributions from beetle specialists vis iNaturalist

There is an interesting discussion about this species at [https://www.gbif.org/species/7448446]

For a period of more than fifty years (1944-2000), the adventive species Ocypus nitens was known only from a small area in New England. The expansion of its range westward (Ontario and New York) and northward (Maine) appears to have been recent and rapid, though the reasons for this remain unknown. reported non-brachypterous individuals in North America, which may be expected to fly, at least occasionally. Their presence on several islands in New England supports this, though they could have been transported there with soil or other organic debris. There is a possibility that Ocypus nitens remained undetected in Ontario and New York for much of this fifty year period due to a lack of sampling. However, this scenario is considered unlikely, especially for southern Ontario, which has had a long history of collecting by professionals and students in rural and urban habitats. Furthermore, many adventive staphylinid species that now occur broadly in eastern North America were first detected in southern Canada during this period (). Ocypus nitens is large (12-20 mm, ()) and typically found in human disturbed habitats including woodlots and backyards, making it likely to be encountered by homeowners, naturalists and entomologists alike. Indeed, this is reflected in the number of recent photographic records available on BugGuide. This online, community-based resource continues to be an important source of first detections of adventive species in Canada, the United States, or the entire Western Hemisphere (, ). demonstrated that a rapid range expansion of an adventive bee species was captured by digital insect collections, including BugGuide, and emphasized their effectiveness when coupled with adequate identification resources or taxonomic expertise. Citizen science-based observation data, especially when verified, have become a cost and time-effective option to answer large-scale questions about insect distributions for certain groups that are taxonomically well-known and conspicuous, such as lady beetles (Coccinellidae) ().

Ocypus nitens joins Ocypus aeneocephalus (DeGeer), Tasgius ater (Gravenhorst), T. melanarius (Heer) and T. winkleri (Bernhauer) as the largest adventive staphylinids established in Canada and can be expected to eventually occur in Quebec and the Maritime Provinces. The even larger adventive species Ocypus olens (Müller) has become established in western North America but is still restricted to the western United States (Washington, Oregon, California and Arizona) and unknown from Canada (, BugGuide). This is another staphylinid that would be easily monitored by citizen science. The impact of these large species on related, native edaphic rove beetles (Platydracus and Dinothenarus) occupying similar microhabitats is unknown but several Platydracus species appear to be less abundant than they were at the beginning of the 20th century

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