Revision of Hemiquedius Casey (Staphylinidae, Staphylininae) and a review of beetles dependent on beavers and muskrats in North America


Brunke, A., Smetana, A., Carruthers-Lay, D., Buffam, J. (2017). Revision of Hemiquedius Casey (Staphylinidae, Staphylininae) and a review of beetles dependent on beavers and muskrats in North America, 2017(702), 27-43.

Plain language summary

Previously, the predatory rove beetle genus Hemiquedius is considered to have a single species, found only in eastern North America. A population of this species has been observed to live in the lodges of beavers and muskrats and was suspected to be a separate species. The authors examined specimens from across its distribution and used evidence from external body measurements, male genitalia, DNA and ecological data to conclude that a pair of new (unnamed) species occur in northeastern North America. This pair cannot be separated by DNA barcoding but possess clear differences in morphology and their microhabitat preferences. One of these species develops only within the lodges of beavers and muskrats, and is named in honor of Canada’s 150th birthday. The authors also reviewed the entire assemblage of beetles that are known to depend on the structures created by beavers. In their dedication, they draw an analogy between Canada and its national animal that recognizes their promotion of diversity. This work also provides an example of how very recent speciation may not be recognized by DNA-barcoding.


Based on newly discovered characters on the male genitalia, external morphology and an accumulation of ecological data, we revise the single member of the genus Hemiquedius. Two new species, H. infinitus Brunke & Smetana, sp. n. and H. castoris Brunke & Smetana, sp. n., from eastern North America are described, and H. ferox (LeConte), restricted to peninsular Florida, is re-described. Hemiquedius castoris is strongly associated with the microhabitats provided by nest materials of the North American beaver and muskrat. A key to the three species of Hemiquedius is provided and diagnostic characters are illustrated. We also review the beetles known to be obligate associates of beavers and muskrats, and discuss the potential role of these keystone vertebrates in beetle evolution and distribution. Based on nest-associated beetles and their closest living relatives, beaver and muskrat lodges may extend distributions northward by moderating winters, promote sympatric speciation and act as refugia against extinction of lineages on a broader time­scale. Further research into these potential impacts by ecologists and evolutionary biologists is encouraged.

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