Oligopipiza Nidergas, Hadrava, and Nel

Nidergas, Valentin, Hadrava, Jiří, Garrouste, Romain, Prokop, Jakub, Schubnel, Thomas & Nel, André, 2018, The first pipizine hoverfly from the Oligocene of Céreste, France, Acta Palaeontologica Polonica 63 (3), pp. 539-548 : 540-543

Genus Oligopipiza Nidergas, Hadrava, and Nel nov.

Etymology: Combination of Oligo in reference to Oligocene and Pipiza , the type genus of the subfamily.

Type species: Oligopipiza quadriguttata sp. nov., by monotypy, see below.

Diagnosis.—Same as for the type species. Oligopipiza quadriguttata Nidergas, Hadrava, and Nel sp. nov.

Figs. 1–7 .

Etymology: Combination of Latin quadric, four and guttata , drop; in reference to the shape of the yellow maculae on tergites II and III.

Type material: Holotype: RNGL-S01 (male) . Paratypes: RNGL-S10 (female allotype) , RNGL-S03 , RNGL-S07 , RNGL-S08 (males) , RNGL-S02 , RNGL-S04–06 , RNGL-S09–15 (females) . Nearly complete specimens with wings and legs preserved as imprint and counter-imprint; all from the type locality; coll. AN.

Type locality: Céreste, Lubéron, South-East France.

Type horizon: Middle Oligocene.

Material.— Type material only.

Diagnosis.—Medium-sized species, ca. 6–8 mm long; face simple, flat; basoflagellomere rounded; hind femora 4× longer than wide; abdomen ovoid, 1.5× longer than wide, dark; tergites II and III with two yellow maculae on each.

Head without frontal prominence; face simple, not protruding, and apparently concave below antennal fossa; antenna shorter than head, arista bare; no pronounced gibbosity above antennal bases; eyes pilose ( Fig. 3B ), holoptic in male, dichoptic in female; anterior mesopleuron possibly pilose; posterior anepisternum and anterior anepimeron hairy; metanotum (subscutellum) bare; no bristles on posterior margin of scutellum; no spurs on mid and hind coxae and hind trochanters; crossvein r-m slightly curved and ending before middle of cell dm; R 2+3 perpendicular to costa; R 4+5 making a strong curve basal of r-m, straight distal of r-m, and slightly curved just before crossvein M 1 insertion; cell R 4+5 acute apically because M 1 is making an acute angle with the vein R 4+5; R 4+5 pedicel straight and short; abdomen emarginated, not petiolate, oval; four visible abdominal tergites in male, five in female; tergites II to IV entirely pilose; male genitalia very large, about 0.4× abdomen length; surstylus without tooth, shorter than epandrium, epandrium long, with a very deep and narrow median theca, from cerci to basal 3/10 of theca.

Description.—The abdominal ornamentation pattern on tergites II and III is subject to variations in size and shape ( Fig. 7 ), but the general pattern is the same, viz. two ovoid to sub-rectangular yellow maculae on tergite II and two “water drop-shaped” to sub-triangular maculae on tergite III. The asymmetry of these spots is probably due to taphonomical artefacts.

Holotype (male RNGL-S01 ): Head: face simple, not protruding, apparently concave below antennal fossa; frons rounded; eyes holoptic, suture 0.15× tergite III length, anterior angle about 100–110°, size of omatidia uniform all over eyes, size 22.5 μm, about 0.45 × maximum width of epandrium theca indentation; antenna very short, less than 1/5 as long as head length, scape and basoflagellomere rounded, arista at basal third of basoflagellomere, apparently bare.

Thorax: mesoscutum and scutellum apparently completely dark; at least posterior anepisternum and anterior anepimeron hairy.

Legs: covered with pale short bristles; hind femora 4× as long as wide, locally covered with long hairs between apical 1/5 and apical 3/5, about 2× longer than hind tibia basal width; apex of hind tibia 1.8× as large as base; length of hind metatarsus about 0.56× hind tibia length; hind tarsomeres II, III, IV, and V of equal lengths; claws basally pale and black in its apical third.

Wing: hyaline, with pale veins; R 4+5 and R 2+3 straight, crossvein r-m before middle of cell dm, spurious vein sv distinct.

A 2

B

Abdomen entirely covered with hairs, as long as basal width of hind tibia, apparently erected as it is visible for those situated on the sides of tergites; tergite I dark; tergites II and III dark, each with two pale maculae, probably originally yellow; tergite IV completely dark.

Genitalia: theca of epandrium about 0.5× as long as tergite III, about 1.1× as long as wide, with a deep and narrow indentation opened from cerci to basal 3/10, 7.1× as long as wide; cerci about 3× times as long as maximum width of epandrium indentation; surstyli short without tooth; hypandrium not visible.

Allotype (female RNGL-S10 ): It completes the description as follows: frons pilose; wing 4.5 mm long; crossvein r-m ending at basal fourth of cell dm, cell R 4 +5 acute apically, upper crossvein M 1 curved at its center; tergite I with posterior margin wave-shaped. Terminalia not visible. Sexual dimorphism: eyes dichoptic; tergite V visible; absence of hairs on hind femur (but this character could be a fossilization artefact).

Dimensions (taken on all specimens): body lengths vary between 6.8–8.1 mm (average value 7.4 mm); abdomen lengths vary between 2.7–4.5 mm (average value 3.6 mm); widths vary between 2.1–3.1 mm (average value 2.5 mm).

Stratigraphic and geographic range.— Rupelian (33.9–28.4 MYR BP), middle Oligocene; Céreste, at the boundary between the Vaucluse and the Alpes-de-Haute-Provence (43.9°N, 5.6°E), France .

Figures

Fig. 1. Pipizine hoverfly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., holotype RNGL-S01; Rupelian, Céreste, France. Imprint of male habitus. Normal light photograph (A), ESEM photograph (B).

Fig. 2. Pipizine hoverfly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., Rupelian, Céreste, France. Wing venations. A. Holotype RNGL-S01, normal light photograph (A1), reconstruction (A2). B. Allotype RNGL-S10, reconstruction. Abbreviations: dm-cu, distal median-cubital crossvein; M1, first branch of median vein; R1, R2+3, R4+5, branches of radius; r-m, radial median crossvein; Sc, subcostal vein; sv, supplementary pseudovein.

Fig. 3. Pipizine hoverfly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., holotype RNGL-S01, Rupelian, Céreste, France. A. Head, ESEM photograph. B. Eye’s omatidia, arrows point to microtrichia.

Fig. 4. Dorso-lateral pilosity of thoracic pleura of pipizine hoverflies. A. Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., holotype RNGL-S01, Rupelian, Céreste, France. B. Extant Pipiza festiva Meigen, 1822. Red, posterior anepisternal setae; green, anepimeral setae; blue, calypter setae.

Fig. 5. Pipizine hoverfly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., allotype RNGL-S10, Rupelian, Céreste, France. A. Wing. B. Wing apex, normal light photograph (B1), treated to better show veins (B2).

Fig. 6. Pipizine hovefly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., holotype RNGL-S01, Rupelian, Céreste. Male epandrium. ESEM photograph (A), reconstruction (B).

Fig. 7. Pipizine hoverfly Oligopipiza quadriguttata Nidergras, Hadrava, and Nel gen. et sp. nov., Rupélian, Céreste, France. Reconstructions of abdomens of all type specimens. A. RNGL-S1 (holotype, male). B. RNGL-S2 (female).C. RNGL-S3 (male). D. RNGL-S4 (female). E. RNGL-S5 (female). F. RNGL-S6 (female). G. RNGL-S7 (male). H. RNGL- RNGL-S8 (male). I. RNGL-S9 (female). J. RNGL-S10 (female). K. RNGL-S11 (female). L. RNGL-S12 (female).M. RNGL-S13 (female). N. RNGL-S14 (female). O. RNGL-S15 (female).