Aschizomyia burmensis, 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 burmensis , new species

Figures 20 , 53

DIAGNOSIS: As for genus, by monotypy.

DESCRIPTION: (female only). Head: Hemispherical. Eye large, bare of setulae (portion of

right eye missing); occupying all of lateral surface of head (cheek not exposed), margins flanking frons are parallel. Frons well developed, width slightly less than face; with fine, short pubescence only; no macrosetae on head (e.g., no interfrontals, ocellars, orbitals, verticals, or vibrissae). Occiput densely setose, with thick, short setae overall; occiput slightly swollen laterally, centrally deeply recessed. Oral margin slightly protruding dorsally. Ptilinum lacking.

Antenna: Scape hidden (probably minute); pedicel asymmetrical, with ventral lobe; dorsoapical portion with stiff setae, having rounded condylelike “conus” inserted into base of flagellomere 1 (cuticle is cleared). Basal flagellomere large, laterally flattened, apex tapered and pointed; asymmetrically drop shaped in lateral view; arista attached to pointed apex. Arista with 2 minute basal articles; apical article long, fine, flagellate, bare (no micropubescence visible).

Mouthparts: Clypeus protruding; narrow U-shaped, articulating with but not fused to oral margin. Palp relatively large, apex pointed, slightly longer than labellum; labellum flat, as preserved largely recessed into oral cavity and between palps; labrum not observable.

Thorax: Relatively flattened dorsally, not particularly deep. Prosternum (very exposed) cordate, entirely free, unconnected to surrounding sclerites. Scutum and scutellum covered in dense, short setulae (these thicker and longer on scutellum, especially lateral margins) (rows of acrostichals absent). Transverse suture very short, far anterior, just above notopleural setae. Thorax with following large macrosetae: 1 pair of large, prescutellar dorsocentrals; row of 3 postalar setae (posteriormost one very thick); row of 4 notopleural setae (posterior 2 largest, thickest; anterior one ~0.5× size of others); anepisternum with dense, fine pilosity; katepisternum bare. Prescutellum absent; scutellum triangular in dorsal view, apex pointed, with pair of large, thick scutellar setae. Wing: Relatively slender, length 2.5× the width, apex narrow (not broadly rounded); no infuscation or darkening of membrane, even between Sc and R 1; membrane with fine microtrichia over entire surface. Row of 5 prehumeral costal setae; vein C with fine setulae (without thick/coarse spinules), C ends at tip of M 1. Sc relatively long, slightly greater than 0.5× length of wing; R 1 close and parallel to Sc, ends closer to apex of R 2+3; crossvein sc-r present, close to level of crossvein h. Apex R 2+3 slightly divergent from apex of R 4+5; apices of R 4+5 and M 1 converge closely at wing tip but do not meet. Cell dm very large; cell br long, slender, with small, incomplete, spurlike crossvein near base of CuA 1. Crossvein dr-m weakened in middle; no trace of spurious vein present; cell dm very large, crossvein dm-cu very close to wing margin. M 1 -M 2 fork present, with very short stem attached to apex of cell dm. Apex CuA 1 incomplete (not reaching wing margin); cell cup large, with short apical vein; anal lobe present, small; A 2 present, complete; alula well developed. Halter relatively small.

Legs: Of moderate length and width. Pro- and mesocoxae short, mostly integrated into pleura; metacoxa slightly longer, suspended and largely free from pleura; pro- and mesocoxae with setae on distal margin. All podomeres setulose, with longer setae on some portions; profemur with irregular, ventral row 10–12 longer, fine setae; mesofemur with longer setulae on distal half. Tibial spurs 0-2-0, mesotibial spurs ventroapical, short, stout; apex of metatibia slightly swollen; basitarsomere length equal to length of tarsomeres 2+3 on all legs; claws large, pulivilli relatively small (≤0.5 length of claws); empodium setiform.

Abdomen: As preserved, dorsoventrally flattened; 6 tergites exposed, 1–4 large, all covered with dense, short, decumbent setulae (as on scutum); 6 sternites present, 1–4 large, well developed, width ~0.7× width of abdomen. Pleural membrane exposed between lateral margins of sternites and ventral margins of tergites. Spiracles in membrane, close to margin of tergite.

Male Terminalia: Unknown. Female Terminalia: Very simple; terminal segments apparently not telescoping; cercus small, oval, simple, 1-segmented.

SPECIMENS EXAMINED: Holotype, female, AMNH Bu-SA1. The specimen is very well preserved, missing only the right eye and the tips of the left wing and metatarsi.

ETYMOLOGY: In reference to the country of origin.

Figures

FIG. 20. Aschizomyia burmensis, n. gen., n. sp. (Syrphoidea), female holotype in Burmese amber, AMNH Bu-SA1 A. Habitus, dorsal lateral. B. Head, right lateral. C. Head, dorsolateral. D. Scutellum and portions of thorax. E. Basal half of wing.

FIG. 53. Aschizomyia burmensis, n. gen., n. sp. (Syrphoidea), female holotype in Burmese amber, AMNH Bu-SA1 A. Head, lateral view as preserved, showing internal structures. B. Antenna, lateral view. C. Thorax, dorsolateral view. D. Wing.