Gracilomyia, Grimaldi, 2016

Grimaldi, David A., 2016, Diverse Orthorrhaphan Flies (Insecta: Diptera: Brachycera) In Amber From The Cretaceous Of Myanmar: Brachycera In Cretaceous Amber, Part Vii David A. Grimaldi, Bulletin of the American Museum of Natural History 2016 (408), pp. 1-132 : 79

Gracilomyia , new genus

DIAGNOSIS: Body slender, wing slender (W/L 3.0) with narrow apex; antennal flagellum stylate, with four articles, middle two (2, 3) short and small; neck long, antepronotum large; thorax without macrosetae. Vein C circumambient; Sc, R 1, R 2+3 very long; sc-r crossvein lacking; R 4 -R 5 forked; M 3 absent; cell d large, cup cell open; anal lobe absent; tibial spurs 1-2-2; metacoxal peg present; cercus with two segments.

TYPE SPECIES: Gracilomyia wit , n. sp.

ETYMOLOGY: Combination taken directly from gracile (Latin, gracilis, “slender, thin”), and myia (Greek, “fly”), in reference to the body shape. The gender of the name is feminine.

COMMENTS: Placement of the genus is ambiguous, partly because the pretarsal structure is not obvious. If heterodactylan, a flagellum reduced to four articles would be consistent with placement in the Muscomorpha ( Nemestrinoidea + Asiloidea + Eremoneura). However, the tibial spurs and two cercal segments indicate that the genus, at best, is a stem group to Muscomorpha. Alternatively, if homeodactylan, the genus is possibly related to the Rhagionidae , some of which (i.e., Arthroteles , Atherimorpha ) have a 4-articled, stylate flagellum with apical setae. This placement would also be more consistent with the tibial spurs and cercal segmentation. Inconsistent with a placement in or near Rhagionidae are: anal lobe and alula narrow; apices of CuA 2 and A 1 distant (cell cup open); fork of R 4 -R 5 very short; and antepronotum large. Two M veins occur in both Rhagionidae (e.g., Austroleptis Hardy , Bolbomyia Loew , Spaniopsis White ) and various heterodactylans. Resolving the placement of Gracilomyia will require additional specimens.