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Syrphid - Polybiomyia macquarti - female

Syrphid - Polybiomyia macquarti - Female
Resaca De La Palma State Park, Cameron County, Texas, USA
August 9, 2017
Polybiomyia macquarti?

Great find & photo, Jeff!
Thanks for posting this...good to have an exemplar of a female (from "eyes separated"), to complement the single previous BugGuide post of a male.

Williston, in his original description of a single female (under the preoccupied name Ceria scutellata), had seemed to imply that his type specimen had a single, large, prescutellar spot of trapezoidal shape. Shannon(1925) indicated that he had: "Two males; one female, the type, at hand. The males have the prescutellar spot divided." It seems both your female here (from dichoptic eyes) and that seen in this iNat post also have the trapezoidal presutellar spot "divided" (at least partially). So, contrary to the sugesstion in Shannon(1925), it appears the character of prescutellar spot "entire vs. divided" is not a consistent sexual dimorphism for the species.

BTW, your find is from very near Brownsville and the Mexican border, at the southern tip of TX...where Shannon(1925) gave a record for P. macquarti from June 5, 1904. The previous BugGuide post is from Victoria, TX...about 190 miles to the north.


Thanks much for the wonderful and thorough commentary. Great info to have in the guide.

Moved from Cerioidini.