Hirmoneura aff. richterae Mostovski and Delclòs

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 : 53-54

Hirmoneura aff. richterae Mostovski and Delclòs

Figures 17C , 18D , 50

EMENDED DIAGNOSIS: A very small species, body length 6.01 mm, wing length 6.02 mm. Venation essentially identical to that of H. richterae (Early Cretaceous, Montsec, Catalonia, Spain) in vein branching patterns and proportions. Both species have female cerci slightly elongate (length ca. 3.3× basal width) and tapered to apical point. The only difference between the two species is size, richterae being larger (10.3 mm wing length), which by itself I do not consider diagnostic.

DESCRIPTION (based on present, amber specimen): Based on female. Among smallest known nemestrinids, head length 0.91 mm; head width 1.73 mm; body length 6.01 mm; thorax length 1.69 mm; wing length 6.02 mm; abdomen length 3.12 mm. Head: Hemispherical in dorsoventral views, slightly flattened in lateral view, width slightly larger than greatest width of thorax. Eyes very large, occupying virtually all of hemispherical anterior portion of head; occiput slightly concave. Eye completely bare, no pilosity; no differentiation of facets. Dorsum of head barely observable, inner margins of eyes almost meeting in middle of frons; ocellar area not visible. Clypeus bulbous, black, slightly oval in shape; laterally flanked by deep paraclypeal pits. Genae are black, setose, rounded lobes facing mediad, forming deep notch posterior to labellum. Antenna: Portion distal to basal flagellomere lost; scape short, slightly shorter than pedicel; flagellomere 1 incompletely preserved but seemingly drop shaped. Mouthparts: Well preserved, though portion of labellum lost at surface. Proboscis short, apex barely extending past ventral surfaces of eyes. Palps long, slender, digitiform, not tapered apicad; projecting forward over paraclypeal sulci; basal palpal segment slightly longer than distal segment; tips dark, most of palp yellowish; palp with fine, erect setae. Proboscis very short, only labellar lobes visible at oral cavity; color light. Thorax: Robust, dorsally flattened, length 2.4 mm, with very short fine setae. Body without long, dense, fine pilosity; small tufts of short pilosity on subalar area. Postalar walls protuberant, forming calli. Wing: Slender, W/L 0.33, anterior and posterior margins almost parallel; membrane entirely hyaline, microtrichia very fine, covering entire membrane of wing. Sc 0.80× length of wing, gradually meets C, apex not upturned. Vein h opposite MA. R 1 very close and parallel to Sc, virtually straight; apices of veins R 1, R 2, R 3+4, and R 5 virtually parallel. Diagonal vein well formed, running through middle of wing in straight line (no crossveins); no apical radial-medial cells present. Cell br 1.41× length of cell bm, more slender. Cell cup almost closed, apices of CuA 2 and A 1 virtually meeting before wing margin. CuP well defined; anal lobe virtually absent; alula present but shallow. A 2 extended beyond distal incision of alula, apex evanescent. Legs: Prolegs and distal portions of mesothoracic legs lost; metathoracic legs slender. Mesocoxa much closer to ipsilateral metacoxa than to procoxa; metacoxa with short, sparse pilosity on mesal surface, no knob on anterior surface. Metafemur with sparse, short pilosity on ventral surface, slightly wider than metatibia; tibia and tarsi with short, dense, decumbent setae; metabasitarsus longer than respective tarsomeres 2–5 combined. Claws large, empodium pulvilliform. No meso- or metatibial spurs. Abdomen: Dorsoventrally compressed, relatively short and broad, width 0.65× the length; abdomen suboval in dorsolateral views, not tapered in width apicad. Tergites and sternites well developed, edges meeting laterally. Female cerci relatively short, length ca. 3.3× basal width, not heavily sclerotized, tapered into apical point but not forming oviscapt. Distal margin of female sternite 9 not visible.

SPECIMEN: Female, HP-B-6084, in collection of Di-Ying Huang, Institute of Geology and Palaeontology, Nanjing, China.

COMMENTS: The unique specimen lies within a dark piece of amber 18 × 14 × 3 mm, which also contains two phlebotomine psychodids, a cecidomyiid, and a mite. The fly is missing only portions of the legs and apices of antennae; the dorsum is obscured by several layers of particles, debris, and sand grains.

Figures

FIG. 17. Wings of three species of Hirmoneura Meigen (Nemestrinidae) in Burmese amber. A. Hirmoneura caudiprima new species, holotype, AMNH Bu-SE17. B. Hirmoneura zigrasi, new species, holotype, JZC Bu-169. C. Hirmoneura aff. richterae Mostovski and Martínez-Delclòs, HP-B-6084.

FIG. 18. Details of Hirmoneura spp. in Burmese amber. A–C. Hirmoneura caudiprima, holotype AMNH Bu-SE17. D. Hirmoneura aff. richterae, HP-B-6084. A. Head, oblique dorsal view. B. Antenna, dorsolateral view (as preserved). C. Female terminalia, left lateral view. D. Face and mouthparts, ventral view.

FIG. 50. Hirmoneura aff. richterae Mostovksi et al. (Nemestrinidae), HP-B-6084. A. Habitus, ventral view. B. Head, ventral. C. Left wing. D. Terminalia, ventral.