Symphoromyia eocenica, Nel, Andre, Perreau, Ziann & Doitteau, Gaelle, 2016

Nel, Andre, Perreau, Ziann & Doitteau, Gaelle, 2016, The oldest representative of the modern snipe fly genus Symphoromyia (Diptera: Rhagionidae), Zootaxa 4196 (1), pp. 144-150 : 145

Symphoromyia eocenica sp. nov.

( Figs. 1–3 )

Etymology. Named after the Eocene period.

Material. Holotype MNHN.F. A57537 (PA 2496, sex unknown), stored in the laboratory of palaeontology, MNHN, Paris.

Type locality. Farm Le Quesnoy, 49°19'31" N, 2°40'22" E, Chevrière , Region of Creil, Oise Department (northern France).

Type horizon. Lowermost Eocene amber, Sparnacian (53 Ma), level MP7 of the mammal fauna of Dormaal ( Brasero et al. 2009).

Diagnosis. Clypeus bulbous; postspiracular sclerite smooth and flat; hind tibial spur one; R2+3 well separated from R1 at apices; M3 present, reaching wing margin; laterotergite setose; macrochaetae of hind tibia absent; palpus two-segmented; scale-like thoracic setae absent; first antennal flagellomere kidney-shaped, convex below arista, arista subterminal and anterodorsal; mandibles present; wing ca. 4.2 mm long; body ca. 5.1 mm long.

Description. Body ca. 5.1 mm long. Head 0.71 mm long, ca. 1.0 mm high. Clypeus bulbous. Face bare between eyes. Scape 0.07 mm long, 0.08 mm high, clearly larger than pedicel. First flagellomere of antenna kidney-shaped, convex below arista, laterally compressed, enlarged, bearing a long subterminal anterodorsal arista. Eyes large, without visible setae; distinctly separated. Labella ca. 0.79 mm long, slightly shorter than height of head. Palpus two-segmented, distal segment setose, 0.24 mm long, longer than proximal segment, ca. 0.2 mm long. Lacinia longer than palpus, with serrated tip. Mandibles long and acute.

Thorax 1.6 mm long. Dorsocentral bristles of mesonotum absent; all dorsal setae of equal length. Anepisternum setulose throughout posterior half. Laterotergite setose. Postspiracular sclerite smooth and flat. Prescutellum present. Subscutellum inconspicuous. Wing apparently hyaline, without markings or membrane lightly to moderately infuscate, brownish. Lower calypter reduced. Upper calypter well developed, with broad curvature, lobe-like. Wing ca. 4.2 mm long, 1.6 mm wide. Apex of costa not preserved. Humeral crossvein well developed. Crossvein sc-r weakly developed, positioned distal to h a little less than length of h. R1 and R2+3 separated at wing margin. Dorsal side of R1 setulose, ventral side bare. All other wing veins without setulae. Apical third of R2+3 ultimately bends anteriorly slightly, toward leading edge of wing margin. Length of R2+3 probably shorter than R5. Base of R4+5 fork proximal distal end of cell dm. R4 nearly straight apically. R5 probably posterior to wing tip, clearly longer than R4+5. Crossvein r-m at proximal one-third of discal cell. M3 present. Crossvein m-cu present. Origin of CuA1 at cell bm near discal cell. M3 cell at margin convergent. CuA2 length ca. 2/3 the length of posterior vein of cell bm. Alula with broad, evenly rounded curvature. Anal lobe well developed. Cell cup open. Halter knob approximately 3/5 length of stem. Tibial spur formula 0:2:1. Hind tibial macrochaetae absent.

Abdomen ca. 2.4 mm long, 1.2 mm high. Abdominal segments evenly tapered. Segmentation not clearly visible, last 3 abdominal segments telescoped; genitalia not visible.

Figures

FIGURE 1. Symphoromyia eocenica sp. nov., holotype MNHN. F. A 57537. Habitus. A, left side; B, right side.

FIGURE 2. Symphoromyia eocenica sp. nov., holotype MNHN. F. A 57537. A, head, white arrow first flagellomere; black arrows palpomeres; B, thorax, abdomen, and wing.

FIGURE 3. Symphoromyia eocenica sp. nov., holotype MNHN. F. A 57537. Wing.