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female, body 3.5mm, found in a conservation area of mixed woods and meadows in an otherwise suburban area of Maryland

Keyed out to Chaetopleurophora using the Manual of the Nearctic Diptera phorid key. Brian Brown "revised this genus extensively" in 1992 (Memoirs of the Entomological Society of Canada, Volume 124 Supplement S164, 1992). His diagnosis retains the character state "Anepisternum setulose, and with long seta." used in the MND key. If I'm reading his monograph correctly, the "transverse rows of enlarged setulae on hind tibia" are characteristic of the Chaetopleurophora erythronota species group, of which 3 species are Holarctic/Nearctic: C. erythronota, C. multiseriata, and C. rufithorax. The taxonomy was further revised by Brown et al. who proposed moving C. multiseriata to a new genus, Hirotophora, in 2015 (Zoological Journal of the Linnean Society, 2015, 173, 424–485).

FWIW, the one photo I can find online (https://www.natur...rythronota) suggests that C. erythronota is much darker than this specimen. Photos of Hirotophora multiseriata (https://www.gbif..../142289801) seem to fit this one but I can't find photos of C. rufithorax.

If someone can point me in the right direction to resolve this ID, that would be great. Thanks in advance
Steve









dorsal view, right wing

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Update: I've found the original description of Chaetopleurophora rufithorax https://doi.org/1...1943/10520 but not any photos. Brues' text suggests that the present fly is not C. rufithorax based on the features of C. rufithorax described below. Although some of the distinctions are pretty subtle, the following seem fairly strong: "Length, 2.0mm" (vs. 3.5 for the present specimen); "hind legs pale, at the base, blackened beyond the basal third of the femora" (vs. as most reddish tan beyond basal half); "palpi fuscous" and "very small" (small is in the eyes of the beholder but the palps don't look small to me); "Front tibiae without any bristles before apex" (vs. a very strong bristle about 1/3 of the way down from the base.)