Hirmoneura caudiprima, 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 : 50-52

Hirmoneura caudiprima , new species

Figures 17A , 18A–C , 49A–D

DIAGNOSIS: Very similar to modern Hirmoneura species in wing venation (including lack of cell cup) and by the female cerci modified into a long, sclerotized, swordlike oviscapt; differing from all modern species by body lacking pilosity and by having ocellar triangle unmodified (in living species the anterior ocellus is significantly anterior to the posterior ones and there are two separate mounds). Differs from the other two new species of Hirmoneura in Burmese amber by the longer oviscapt and venation differences (given in diagnoses below). Hirmoneura richterae Mostovski et al. and H. elenae Mostovski et al. , Early Cretaceous compression fossils from Spain and Siberia, respectively, possess cell cup.

DESCRIPTION: Based on female. Body length 9.98 mm (including cerci); thorax length 2.88 mm; wing length 8.77 mm; abdomen length 6.02 mm (including cerci). Head: Hemispherical in dorsal view, slightly flattened in lateral view, width equal to greatest width of thorax. Eyes very large, occupying virtually all of hemispherical anterior portion of head; occiput flat or slightly concave. Eye completely bare, no differentiation of facets, barely dichoptic. Frons present but extremely narrow, width at level of ocelli only 4–5× diameter of facets; inner margins of eyes gradually converging anteriad to width about equal to facet diameter. Ocelli present, small, forming equilateral triangle; anterior ocellus not on separate mound from posterior ones. Antenna: Distal portion slender and stylate, 6 antennal arti- cles present: cylindrical scape, shorter pedicel; drop-shaped flagellomere 1; and stylate portion comprised of short basal flagellomeres (2 and 3) and longer apical one (flagellomere 4). Lengths of antennal articles: apical article (f4)> scape = flagellomere 1> pedicel> f2 = f3. Mouthparts: Small, barely protruding beyond margins of oral cavity, elements mostly not observable. Thorax: Robust, dorsally flattened, with very short fine setae, slightly longer on scutellum. Body without long, dense, fine pilosity. Scutum with pair of very shallow, faint, paramedian grooves on anterior half, to level of transverse suture. Postalar wall protuberant, forming calli. Wing: Long, slender, W/L 0.29, anterior and posterior margins almost parallel; membrane entirely hyaline, microtrichia not visi- ble (either absent or microscopic). Sc 0.78× 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, R 5 slightly convergent apicad, diagonal vein well formed, running through distal third of wing; no apical radial-medial cells present. Cell br long, 1.56× length of cell bm, more slender. Cell cup absent (CuA 2 apices do not meet A 1 before wing margin). CuP well defined, anal lobe virtually absent; alula present but shallow. A 2 not extended beyond distal incision of alula. Legs: Long, slen- der. Mesocoxa much closer to ipsilateral metacoxa that to procoxa; coxae moderately pilose; hind coxa without knob on anterior surface. Femora slightly wider than respective tibiae; virtually bare; tibiae and tarsi with short, decumbent setae. Hind leg: femur 1.9 mm, tibia 3.1 mm, tarsus 2.3 mm. Basitarsus longer than respective tarsomeres 2–5 combined. Claws large, empodium pulvilliform, slightly larger than empodia. No tibial spurs. Abdomen: Dorsoventrally slightly compressed, relatively small, length 1.25× that of thorax; abdomen greatly tapered in width apicad, tergite 7 0.12× width of tergite 1. Tergites and sternites well developed, edges meeting laterally. Female cerci long, sclerotized, tapered into apical point, forming swordlike oviscapt. Distal margin of female sternite 9 medially emarginate, forming two small lateral lobes.

TYPE: Holotype, female, AMNH Bu-SE17.

ETYMOLOGY: From the Latin, meaning “first tail,” in reference to the long, ovipositor-like cerci of the species, the earliest occurrence of this feature in the genus.

COMMENTS: Bernardi (1974) demonstrated that substantial intraspecific variation in the venation occurs in Neorhynchocephalus species (which also exists in other nemestrinids), but most of this variation occurs in the branching patterns of the apical portions of the R and M veins. The venation differences diagnosed among the three species here involve basal veins.

The fly is in a piece of translucent amber that retains its natural outline, 30 × 20 mm, slabbed to 8 mm thickness and polished over surfaces that expose each side of the fly and a wing. The fly is missing only the distal half of the left wing and some leg segments. Syninclusions are a mite and small adult mayfly ( Ephemeroptera : Baetidae ).

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. 49. Hirmoneura spp. (Nemestrinidae). A–D. Hirmoneura caudiprima, new species, holotype female, AMNH Bu-SE17. E–G. Hirmoneura zigrasi, new species, holotype female, JZC Bu-169. A. Habitus, dorsolateral. B. Head, dorsolateral. C. Female terminalia, showing long cerci. D. Right wing. E. Habitus, dorsal. F. Habitus, left lateral. G. Habitus, ventral.