Aschizomyia, Grimaldi, 2018

Grimaldi, David A., 2018, Basal Cyclorrhapha In Amber From The Cretaceous And Tertiary (Insecta: Diptera), And Their Relationships: Brachycera In Cretaceous Amber Part Ix David A. Grimaldi, Bulletin of the American Museum of Natural History 2018 (423), pp. 1-97 : 1-97

Aschizomyia , new genus

DIAGNOSIS: Head lacking macrosetae, female frons pubescent; ptilinal suture absent; basal flagellomere large, tapered asymmetrically to apical point (which bears arista); scutum with numerous scattered setulae (none in rows); thorax with one pair of dorsocentral setae, one pair of of scutellars, three postalars, four notopleurals, no supraalars. Vein Sc long; apices of R 4+5 and M 1 converge closely at wing tip but do not meet; M forked, with very short stem; cells dm and cup very large. Metatibia with ventral pair short, stout apical spurs.

TYPE SPECIES: A. burmensis , n. sp.

ETYMOLOGY: Derived directly from Aschiza, and - myia (Greek, “fly”). The genus name is feminine.

COMMENTS: The phylogenetic position of the genus is equivocal (fig. 51), having features of Syrphidae and Pipunculidae but decidedly more primitive than the crown group of either. Syrphid features include a short sc-r crossvein, apex of CuA 1 incomplete, the exposed female frons being pubescent (the head lacking any macrosetae), and the alula is well developed. Aschizomyia plesiomorphically has a small cell bm; C ends at the apex of M 1 (instead of R 4+5); M is forked, and M 1 does not join R 4+5 preapically. The venation is very similar to that of Protonephrocerus , but Aschizomyia lacks all the features of the head, female terminalia, and pretarsi that characterize Pipunculidae . The large cup cell occurs in both Syrphidae and Pipunculidae , possibly convergently. It is difficult to discern whether the arista is dorsally or apically situated on the basal flagellomere, since it occurs at the apex of a narrow, pointed lobe and the flagellomere is asymmetrical, with an extensive, emarginate ventral margin. I have chosen to depict Aschizomyia , preliminarily, in a basal trichotomy with Syrphidae and Pipunculidae + Schizophora because of the equivocal morphological evidence. The lack of a ptilinum indicates that Aschizomyia is not a schizophoran, though the possibility remains that it is a stem-group one.