Microburmyia veanalvena Grimaldi & Cumming

Grimaldi, David A., Arillo, Antonio, Cumming, Jeffrey M. & Hauser, Martin, 2011, Brachyceran Diptera (Insecta) in Cretaceous ambers, Part IV, Significant New Orthorrhaphous Taxa, ZooKeys 148, pp. 293-332 : 312-313

Microburmyia veanalvena Grimaldi & Cumming sp. n. Fig. 7c-e

Diagnosis.

cf. Microburmyia analvena (above), distinguished by the absence of an anal vein; posterior fringe of setae long, thick; basal flagellomere and style setulose, style with one article, oval.

Description.

A minute fly, wing length 0.85 mm. Head: Short, somewhat flattened anteroposteriad. Cervical region with connection anteroventrally on thorax; not visible dorsally. Eyes bare, large, well separated; no dorsoventral differentiation of facets [presence of emargination on posterior margin not visible]. Proboscis short [palps not visible]. Antenna with basal flagellomere ovoid, having dense setulae (longer apicad); apical style 0.6 × length of basal flagellomere, thick (nearly 0.5 × thickness of basal flagellomere), one articled, setulose. Three ocelli present. Postocciput expansive, concave. Thorax: Mesoscutum dorsally arched, devoid of setae or setulae; thorax deep in lateral view; mesoscutellum triangular in shape (nearly equilateral). Legs slender; devoid of setae, tibiae without apical spurs. Pretarsus with large pulvilli; empodium probably setiform. Halter with slender stem, large knob. Wing W/L = 0.43. Costa either without spinules or spinules minute; C reaching slightly beyond apex of R4+5. Posterior margin of wing with fringe of long, thick setae (visible only on left wing), but margin of alula bare. Vein Sc extremely faint, evanescent. R-R1 nearly straight; R2+3 2.0 × length of R1; R4+5 straight, ends at apex of wing; proximal portion of R4+5 joined to r-m to form distal margin of cell br. Cells br and bm large, br is 0.42 × length of wing, W/L cell br = 0.27; cell bm slightly narrower and shorter. Base of M straight, with short apical fork. Length crossvein bm-cu approximately equal to that of r-m, in line with each other. CuA1 and CuA2 short, straight and diverging. Vein A1 absent. Anal lobe differentiated, alula small. Abdomen: Very broad anteriorly, devoid of setae and setulae on tergites. Tergites I - V apparently without shallow, median keel [difficult to discern with preservation]; epandrium with 5-6 long, thick setae on posterior surface, length of setae approximately equal to length of epandrium.

Type.

Holotype, Male: Myanmar: Kachin (northern Myanmar), latest Albian to earliest Cenomanian. AMNH Bu1552. Specimen is displayed with wings and legs outspread, but body is only moderately well preserved, with some details obscured beneath layer of deep reddishness. Dorsal view is better than ventral view.

Etymology.

ve- (Latin prefix meaning without), anal vein (L., vena), in reference to this venational character.

Discussion.

It could be argued that these two species might warrant separate genera, based on the differences of antennae, wing fringe, epandrial setae, and proportions of the wing. However, other than the presence/absence of the anal vein, the wing venation is very similar between the two species.