Procrocidium, 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 : 69-70

Procrocidium , new genus

DIAGNOSIS: Small bodied, without long pilosity; antenna with one flagellomere, plus minute subapical style. Three notopleural, one supraalar seta present. Wing short, relatively broad, apex rounded; fork of R 4 -R 5 nearly symmetrical, vein R 4 only slightly sinuous; cells br and bm nearly equal in length (vs. br much longer), crossvein sc-r present, r-m crossvein near base of cell d (vs. distal); CuA 2 very long, converging with but not meeting CuA 1 toward wing margin, A 1 apparently lost. Mesotibia with long apical spur; metacoxa with well-developed anterior peg; acanthophorite spines present; thick brush of fine setae on tergites 7 and 8, but sand chamber not well developed.

TYPE SPECIES: Procrocidium minutum , new species.

ETYMOLOGY: In reference to the apparent relationships of the fossil to the subfamily Crocidiinae , with the prefix denoting some generalized features as well. The gender of the name is neuter.

COMMENTS: The genus is phylogenetically intermediate among subfamilies of Bombyliidae, sensu Yeates (1994) , probably close to Crocidiinae . On the one hand, it possesses acanthophorite spines (node 41 in Yeates, 1994), which are not found in the basal grade of subfamilies Mythicomyiinae , Oligodraninae , Usiinae , Toxophorinae , and Lordotinae . Also, tergites 9 and 10 are separate, unlike the fused condition in the first three of these subfamilies. The new genus has a dense brush of fine setae on tergite 8, but sternite 8 is not invaginated into a sand chamber (node 42 in Yeates, 1994), which partly defines the “higher beeflies,” the larger, more typical, pilose species. The dense brush of fine setae on the apical tergites of female bombyliids is, according to Yeates (1994) closely associated with the development of a sand chamber, a pouch formed from the invagination of sternite 8 and tergite 8 in which eggs are coated with sand grains. The brush occurs in Nealimyia , Pseudorhagio , and Procrodium (apex of the female abdomen is not preserved in the unique specimen of Pioneeria , but I predict this genus has the brush).

Plesiomorphic features of Procrodium include cells br and bm nearly equal in length (vs. br much longer); vein R 4 not strongly sinuous (generally S-shaped in higher beeflies); crossvein r-m connected to cell d near its base (instead of in distal half of cell d). These features, plus a virtual lack of pilosity, a flagellum structure similar to that of Oligodranes and Usia , and a sinuous dm-cu crossvein like that in Pseudamictus, indicate that the new genus is an amalgam of plesiomorphic and apomorphic features that will need a quantitative analysis. Probably most revealing is that the genus has a long mesotibial spur and well-developed metacoxal peg, like the subfamily Crocidiinae ( Yeates, 1994) . Crocidium also have a small sc-r crossvein.