Thread subject: Diptera.info :: Gymnosoma from Virginia ID Help

Posted by Mabuva2021 on 05-10-2023 00:52
#1

Location: Central Virginia
Date: October 4th, 2023

Posted by Mabuva2021 on 05-10-2023 00:53
#2

photo 2/2

Posted by John Carr on 05-10-2023 02:04
#3

I am unable to separate the American species of Gymnosoma. I think I can rule out G. occidentalis and G. amplifrons. On average females of the remaining species can be ordered from lightest to darkest abdomen:

G. filiola "red with small, isolated black spots"
G. fuliginosum "abdominal spots small, separated or only narrowly connected"
G. par "abdominal spots broadly triangular and widely connected"
G. canadense "abdomen black with at most the narrow lateral edges reddish"

(Brooks, 1946)

Brooks writes, using an old genus name, "Rhodogyne par shows a maximum amount of color variation on the abdomen and specimens of either sex may be wholly black, largely black or largely red with small black spots. The species is similar to fuligionsa but smaller and darker."

Is it an average par or a dark fuliginosum or a light canadense?

Posted by Mabuva2021 on 05-10-2023 03:30
#4

Hello John, thank you for the explanation for each species! I wasn't aware just how variable this genus was.