Atherhagiox ambiguum, 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 : 36-38

Atherhagiox ambiguum , new species

Figures 12B, C, D ; 44

DIAGNOSIS: Very similar to A. simulans , n. sp. (also known only as a female), except that A. ambigua has: smaller body size (3.5 mm, vs. 4.0); basal flagellomere more narrow; wing with vein Sc shorter; base of R 4 perpendicular (vs. acute) to stem of R 4-5; cells br and bm shorter (in A. ambigua cell bm is 0.24× length of wing, in A. simulans it is 0.34×); cell cup closed; CuA 2 and A 1 meeting just before wing margin (vs. at wing margin); R 4-5 more sinuous than in A. simulans .

DESCRIPTION: Based on female. Body length 3.52 mm; thorax length 0.90 mm; abdomen length 2.15 mm; wing length 2.81 mm. Head: Eyes large, dichoptic, bare, no dorsal-ventral differentiation of facets; dorsal margins of eyes extending above margin of head vertex; in lateral view eye occupying entire lateral surface (occiput not visible). Inner margins of eyes dorsally convergent toward level of antennae, then divergent ventrally. Ocelli on large, well-defined tubercle. Frons bare, no setae/setulae. Face with bulging clypeus, laterally bordered by deep sulci between clypeus and parafacial plates. Antenna: Aristate. Base membranous; scape and pedicel lengths approximately equal, dorsal portion of scape longer than ventral portion, without bristlelike setae; pedicel bean shaped, attachment slightly dorsal, with 2–3 stiff setae on ventrodistal margin; basal flagellomere reniform, its attachment to pedicel dorsal; apical portion of flagellum aristate, length 3× that of basal flagellomere, with microscopic pubescence, no minute apical style apparent. Mouthparts: Proboscis length ca. 1.5× that of head; labellum long, 0.7× length of theca, with fine setae on ventral surface. Labrum long, same length as lacinia + mandibles; tip of mandible with several minute teeth/serrations. Palps long, slender, gently curved (dorsally convex); 2-segmented, basal segment 0.3× length of distal segment; apical segment tapered distad. In frontal view palps closely flanking proboscis. Thorax: Dorsum and portion of pleura (anepisternum, anepimeron, katatergite, meron) dark brown. Scutum dorsally with fine, short, erect setae; longer, thicker setae at middle of scutum, along margins and on disk of scutellum, 9–10 on notopleural area. Postpronotal lobe with fine, light setae. No pubescence or setae on pleurites. Proscutellum present, very narrow. No post-metathoracic spiracular scale or suprametacoxal pit present. Wing: Short, broad, hyaline except for small pterostigmatic area over distal half of R 2+3. Minute setulae on dorsal surface at base of R-R 1. Vein C with very small, fine spinules to wing tip; basicosta well developed; tip of Sc reaches to 0.4× length of wing; R 1 runs very close to Sc, length 0.6× that of wing; R 2+3 sinuous, apex not converging with apex of R 1; cells br and bm of nearly equal length; cell d long, narrow, slightly arched; apices of R 4 and R 5 barely encompass wing tip; R 4 branches from stem of R 4-5 very proximal to apex of cell d. Veins M 1, M 2, M 3 present, first two slightly sinuous. Veins M 3 and CuA 1 virtually parallel; cell cup closed, elongate, and narrow, CuP and A 1 meeting just before wing margin; vein A 2 present, nearly complete. Anal lobe well developed; alula well developed, approximately same size as upper calypter. Halter knob evenly drop shaped, symmetrical; dorsal and ventral portions brown with color pattern having discrete margins. Legs: Long, slender; largely yellowish grading to brown on tarsi. Pro- and mesofemur without macrosetae; metafemur with ventral row of very fine setae. Tibial spurs 0-2-1, middle spurs of equal length. All tarsi with ventral row of short, black, spinulelike setae; metatibia with dense dorsal row of spinules. Pretarsal structures small, empodium pulvilliform. Mesocoxa with dense setae; metacoxa without anterior knob. Abdomen (female): Not dorsoventrally flattened, terminal segments tapering and telescoping; pleural membrane between tergites and sternites 2–4 broad; spiracles in membrane, one for each of segments 2–4. Tergite 1 obscured (cannot determine if medially divided); tergites 2–4 large, 5–10 appear to be telescoping, significantly narrower than preceding segments. Tergites dark brown, heavily setulose; sternites light brown, well developed, with fine, sparse setulae. Dorsal portion of tergite 10 obscured (medial division not observable). Cerci 2-segmented, basal segment cordate in lateral view, ventral lobe slightly more extended; apical cercomere with small emargination on posterior margin.

TYPES: Holotype, female, AMNH Bu-SE2/3.

ETYMOLOGY: The species name is from the Latin (“ambiguous”), and refers to the apparent relationships of Atherhagiox to Rhagionidae and/ or Athericidae .

COMMENTS: See above, under Tabanomorpha and genus. The fly is in a thin slab 3 mm thick, with two large, flat, parallel surfaces 12 × 13 mm, optimizing views of wings and sides of body. The fly is complete and the amber has superb clarity. The piece also contains some plant trichomes and bubbles.

Figures

FIG. 12. Atherhagiox, new genus (stem-group Tabanomorpha). A, E, F: A. simulans, new species, JZC Bu-288, holotype. B, C, D: A. ambiguum, new species, AMNH Bu-SE2/3, holotype. A. Lateral view of mouthparts, anterior part of head, and antenna. B. Antenna. C. Posteroventral portion of thorax, lateral view. D. Female terminalia, lateral view. E. Female cercus. F. Wing, upper surface.

FIG. 44. Atherhagiox ambiguum, new genus and species (stem-group Tabanomorpha), holotype AMNH Bu-SE2/3. A. Habitus, dorsolateral view. B. Head, right lateral. C. Head, frontal. D. Female terminalia, dorsolateral.