Narcissomyia bella, 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 : 28-30

Narcissomyia bella , new species

Figures 6B , 10 , 42

DIAGNOSIS: As for genus, by monotypy.

DESCRIPTION: Male holotype, female paratype (respectively): antenna length 0.70, (not measured); body length 4.17, 4.83 mm; thorax length 1.68, 148 mm; wing length 3.49, 3.07 mm; abdomen length 2.09, 2.49 mm. Head: Large, significantly broader than thorax, with extensive dorsal surface, somewhat flattened dorsoventrally; occiput surfaces behind eyes bulging slightly, central half of occiput surrounding occipital foramen concave; occiput dark, with fine setulae only. Eye: Male: very large, holoptic, occupying nearly all of nonoccipital portion of head; facets with dorsoventral differentiation, dorsal ones ca. 2× diameter of ventral ones, a discrete transverse separation between the two. Eyes completely bare; medial/inner margins meeting from anterior end of ocellar triangle to just dorsal to antennal bases, strongly divergent just above antennae, slightly emarginate near antennal bases and with small, dark callosity within emargination; inner margins of eyes ventrally strongly divergent posteriad; very little cheek exposed laterally. Female: Eyes dichoptic, with significant amount of frons exposed, no differentiation of facets. Ocelli on raised tubercle, with anterior ocellus directed forward, posterior ocelli directed laterally. Antenna: Projecting forward, with 8 flagellomeres, submoniliform, evenly tapered in width apically; flagellomere 1 width 4.5× that of flagellomere 8; no apical stylus; all flagellomeres with sensillar foveae; scape and pedicel funnel shaped, latter with apical whorl of setae, length of antenna 0.60 mm; lengths of flagellomeres relative to flagellomere 1: 1.0 (1): 0.44 (2): 0.40 (3): 0.44 (4): 0.38 (5): 0.44 (6): 0.32 (7): 0.48 (8); antennal sockets very close, possibly touching medially. Mouthparts: Face fully ventral, steeply receded posteriad, moderately concave; clypeus and labrum not visible in either specimen, apparently quite small; palps light, 2-segmented, apical palpomere significantly broader than distal one in lateral view (laterally flattened). Labellum well developed, fleshy and membranous, exposed well beyond oral margin. Thorax: Scutum, scutellum, pleura apparently all dark; scutum and scutellum evenly, densely, and very finely pimplate; each pimple with fine setula; small sparse pimplate areas on katepisternum and anepisternum. Antepronotum very well developed, with very fine, stiff setae laterally; postpronotum well developed, pimplate, largely separate from lateral margins of antepronotum; postpronotal lobe narrow, triangular, posterior end slightly protuberant; anteroparamedian sulci not present on scutum. Transverse suture very well developed, deeply impressed, inner apices converging posteromedially; sutures forming pair of rounded lobelike portions of scutum posteriorly. Small proscutellum present, but well developed, discrete; scutellum narrow, length greater than width, no spines. Posterior portion of anepisternum large, protuberant portion pointed; katepisternum ventrally extended but not pendulous, ventral margin ending at middle of mesocoxa; medial margins of both katepisterna meeting ventrally. Postnotum a narrow tongue lying between lateral lobes of tergite 1. Wing: Relatively long and slender, linear, W/L 0.34. Sc complete, long, 0.47× wing length; C ends slightly past tip of R 5. R and R 1 close and parallel to Sc, diverging slightly at apices. Stem of Rs very short, 0.21× length of R 1; R 2+3 and R 1 of equal length, R 2+3 convergent with R 1 only at apex, apices of veins very close at C; fork of R 4 -R 5 long, base of fork slightly distal to level of cell d apex; R 4 not sinuous, curved primarily at base (not perpendicular to R 5), R 5 entirely straight, tip ending before wing tip. Faint pterostigma between Sc and R 1, and apices of R 1 and R 2+3, r-m crossvein slightly basal to middle of cell; base of M between cells br and bm very faint, not tubular or at all sclerotized. M 1 very faintly curved; apices of M 1, M 2, CuA 1 tapered and evanescent, barely meeting wing margin; bases of M 1 and M 2 meeting truncate apex of cell d separately (e.g., left wing of holotype), though width of cell apex varying significantly. Cell d fairly long, W/L 0.33; cell br longer than bm, both cells narrow. CuA 2 very arched, meeting A 1 well before wing margin. Anal lobe slender; A 2 not present/visible; alula small. Legs: Robust, covered with fine setulae, tibial spurs 0-1-0; mesotibial spur long, narrow, apically slightly hooked, length slightly greater than width of tibial apex, spur well sclerotized. Lengths of length segments: femur> tibia> basitarsomere> combined lengths of tarsomeres 2–5. Tarsomere 5 with dorsal apex extended into small lobe; empodium pulvilliform, slightly broader than pulvilli; empodium and pulvilli slightly shorter than pretarsal claws. Abdomen: Broad, flattened dorsoventrally. Tergites 2–5 each with transverse furrow impressed near posterior margins, furrows deepest on tergites 2–4, furrow lengths ca. 0.9× tergite width; 9 tergites exposed in male and female. Male Terminalia: Well developed, mostly exposed. Gonocoxa short, broad, fully articulating with gonostylus, having hooklike spine on mesal margin; gonostylus with three large spines, two distally and one medial. Epiproct narrow, tonguelike, lying between bases of cerci; cercus 1-segmented in male, ovoid, lateral to epiproct. Female Terminalia: Cercus 2-segmented, segments approximately equal in length, basal cercomere slightly thicker, apical cercomere with acute apex; terminalia not telescoping. Sternite 10 possibly present.

TYPES: Holotype, male AMNH Bu-SE3/1. Paratype female AMNH Bu-Pk1.

ETYMOLOGY: From the feminine form of the Latin adjective, bellus (“beautiful”), for the beautiful preservation of the holotype.

COMMENTS: The holotype is in a thin piece slabbed to 5 mm thickness (14 × 8 mm dimensions), surfaces parallel to the lateral sides and wing of the fly. The amber has superb clarity and contains only some plant trichomes. The fly is complete and preservation excellent. Paratype female is in a cabochen 12 × 10 × 5 mm with some small bubbles; a flattened surface was made over the left side of the fly, the right side is close to surface of the cabochen (so could not be flattened). The fly is complete, though slightly crumpled; scutum has metallic-reflective highlights.

Figures

FIG. 6. Lateral views of thoraces of Burmese amber Stratiomyomorpha. A, B. Stratiomyidae. C, D. Xylomyidae. A. Normyia longistyla, new genus and species. B. Narcissomyia bella, new genus and species. View is slightly ventral. C. Archosolva biceps, holotype (note inflated metacoxa). D. Archosolva sulcata, holotype (note fossa, for apparently receiving the raised mesofemur).

FIG. 10. Narcissomyia bella, new genus and species (Stratiomyidae). A–F: AMNH Bu-SE3/1, holotype male. G: AMNH Bu-Pk01, paratype female. A. Wing. B. Antenna. C. Mesotibial apex, showing spur. D. Tarsomeres 4, 5, dorsal view, with pretarsal structures. E. Male terminalia, dorsolateral view. F. Male terminalia, ventrolateral view. G. Female terminalia, left lateral view. Panels C, D to same scale.

FIG. 42. Narcissomyia bella, new genus and species (Stratiomyidae). Holotype male AMNH Bu-SE3/1 (A–D), paratype female AMNH Bu-Pk1 (E). A. Habitus, right lateral view. B. Thorax and head, dorsal view (head is turned to expose ventral view). C. Male genitalia, oblique ventral view. D. Head, dorsal view. E. Habitus of female, left lateral.