XYLOMYIDAE

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 : 11

FAMILY XYLOMYIDAE

This is a relatively small family of approximately 143 species as of 2016, comprising four living genera. Two of the living genera of Xylomyidae are nearly cosmopolitan, Xylomya Rondani and Solva Walker. Arthropeina Lindner contains six neotropical species (Fachin and Amorim, 2014); the monotypic genus Coenomyiodes Brunetti is from India and very poorly known. Macroceromyx Bigot is now synonymized with Xylomya and Formosolva James with Solva ( Woodley, 2011) . The world species were cataloged by Woodley (2011), who also discussed relationships of the genera. Solva and Arthropeina both hold the abdomen elevated and have extensive membrane on tergite 1, and are closely related ( Papavero and Artigas, 1991; Woodley, 2011). Coenomyiodes is possibly a derived species of Xylomya or a sister group to Xylomya ( Woodley, 2011) . The fossil record of the family is sparse, including a species in Early Cretaceous Lebanese amber, Cretoxyla azari Grimaldi and Arillo , and an undescribed species possibly in this family preserved in Early Cretaceous Spanish amber ( Grimaldi et al., 2011). Xylomyia ? (sic: Xylomya ) shcherbakovi Mostovski, from the Late Jurassic of Kazakhstan, is just a fragment of a wing whose identity is impossible to assess. Otherwise, all other fossils are from the Eocene: Solva inornata Melander and Xylomya moratula Cockerell from Florissant, and Solva nana Loew in Baltic amber. Thus, the finding of three xylomyids in Burmese amber (described below) significantly adds to the fossil record. The two new genera differ from modern ones by possessing obvious tergal sulci and no thickened node or weak area on the short stem of vein Rs. In all Solva I have examined Rs is weakened only; Arthropeina has this stem weakened and with a thickened node; Xylomya has the membrane surrounding the apex of Rs thickened and yellowed. Unfortunately, none of the fossils are males, so certain genitalic features could not be assessed (e.g., enlarged male cerci, and epandrium with large lateral processes, as is found in Xylomya ). Other differences are noted in the diagnoses, below.