Eoconophorina delfineae, Maheu & Nel, 2020

Maheu, Aude & Nel, André, 2020, The oldest representative of the bombyliid bee fly in the earliest Eocene French amber, Acta Palaeontologica Polonica 65 (1), pp. 81-83 : 81-83

Eoconophorina delfineae sp. nov.

Fig. 1 .

Zoobank LSID: urn:lsid:zoobank.org:act:F8811EF3-6C33-4A77-8786-EB8AE5870605

Etymology: Named after Delphine Maheu, mother of first author.

Holotype: MNHN.F.A71306 (sex unknown, thorax, abdomen, legs and wings preserved but head missing).

Type locality: Farm Le Quesnoy, Chevrière, near Creil, Oise department, France.

Type horizon: Lowermost Eocene, in Oise amber, c. 53 Ma.

Diagnosis.—Mid tibial spurs present; R2+3 ending on C rather obliquely, not at right angle; R4 at right angle with R5 and strongly sigmoidal; cell r4+5 widely open with R5 and M1 slightly diverging; vein r-m at middle of cell dm; apex of R2+3 near apex of R1; cell cua open; abdomen cylindrical.

Description.—Medium-sized bombyliine (preserved part of body length ca. 5.0 mm). sex unknown; head not preserved; scutum and scutellum clothed in hairs and scales; two prealar bristles; haired anepimeron and laterotergite; no peg on hind coxa; femora slender; empodium setiform half as long as claws; claw shorter than distitarsus; wing 4.0 mm long, 1.4 mm wide; hyaline; base of R2+3 very oblique and close to base of Rs, opposite basal angle of cell dm; basal angle of dm very acute; dm narrow; R2+3 ending on C rather obliquely, not at right angle, apex of R2+3 very close to apex of R1; R4 at right angle with R5 and strongly sigmoidal; cell r4+5 open with R5 and M1 diverging; crossvein r-m situated slightly distal middle of cell dm; crossvein m-m slightly longer than crossvein r-m; cell r5 widely open; cell cua open with CuA2+A1 and A2 approximating near posterior wing margin; cell br broader and shorter than cell bm; alula rather well developed; abdomen 3.5 mm long, 0.9 mm wide, cylindrical, tergites 3–7 broader than long, covered with dense black scales; terminalia not preserved.

Remarks.—Following the key to fly families of Marshall et al. (2017), this fossil falls in the Bombyliidae because of the following characters: wing fully developed; body not strikingly modified; wing membrane without a pattern of folds between veins; cell cua very long; vein R4+5 forked; empodium bristlelike; no spurious vein; veins not conspicuously curved anteriorly before wing apex; basal median cell with veins arising from three corners; arculus present. Yeates (1994) proposed a series of synapomorphies for the Bombyliidae ; unfortunately, all concern characters that are not visible in our fossil. The absence of the head structures renders its attribution difficult. The absence of peg on the hind coxa excludes affinities with the Oligodraninae and Crocidiinae. But, after Yeates (1994) the presence of prealar bristles is a synapomorphy of the Bombyliinae . The absence of the mid tibial spurs is a character of the Bombyliinae , except the majority of the Conophorini , which could suggest an attribution to this tribe, but it is certainly a symplesiomorphy not sufficient for such an attribution. Nevertheless, its wing venation is very close to those of some Bombyliinae . The characters “three branches of Rs; R2+3 arises at an acute angle and in a proximal position; M2 present; cell r5open; dm-m present;costal vein circumambient” are also shared by Eoconophorina gen. nov. and the Bombyliinae . The open cell cua is shared by many Bombyliinae but also by representatives of some other subfamilies, e.g., some Lomatiinae . Some extant genera with wing venations similar to that of Eoconophorina gen. nov. belong to the Acrophthalmydini ( Acrophthalmyda Bigot, 1858 ), the Bombyliini ( Bombylisoma Rondani, 1856 , Laurella Hull, 1971 ), the Marmasomini ( Marmasoma White, 1917 , Paratoxophora Engel, 1936 ), and the Conophorini ( Conophorina Becker, 1920 ) ( Hull 1973). The haired anepimeron and laterotergite is a character shared by Eoconophorina gen. nov. and the Bombyliini sensu Yeates (1994) , while they are bare in Paratoxophora . Among these genera, only Conophorina shares with Eoconophorina gen. nov. the following venation characters: base of R2+3 very oblique; basal angle of dm very acute; R2+3 ending on C rather obliquely, not at right angle; cell r4+5 open with R5 and M1 diverging; cell cua open with CuA2+A1 and A2 approximate near posterior wing margin ( Hull 1973). The unique species of Conophorina , C. bicellaris Becker, 1920 , differs from Eoconophorina gen. nov. in the bare laterotergites ( Becker 1920; Greathead and Evenhuis 2001), the apex of R2+3 well distal of apex of R1, instead of being very close to it, as in Eoconophorina gen. nov., the abdomen of Eoconophorina gen. nov. is cylindrical elongate, while it is as broad as thorax at base and distally tapered in Conophorina ( Hull, 1973) . Eoconophorina gen. nov. differs from all the other genera of the tribe Conophorini sensu Li and Yeates (2019) in the wing venation.

After the key of Li and Yeates (2019), Eoconophorina gen. nov. would fall in the Conophorini because of the following characters: vein dm-m slightly curved; mid tibial spurs present (absent in Conophorina ). Eoconophorina gen. nov. has also the wing venation characters of the Conophorini as defined by Li and Yeates (2019), viz. cell br longer than cell bm; crossvein r-m located in basal part or at middle of cell dm; vein R5 nearly parallel to M1, cell r5 wide open.

Stratigraphic and geographic range.— Type locality and horizon only.

Figures

Fig. 1. Bombyliid bee fly Eoconophorina delfineae gen. et sp. nov., holotype MNHN.F.A71306; earliest Eocene, Oise amber, France. Habitus above A 1), left wing (A 2), mid tibia (A 3, arrow indicates spur). Abbreviations: bm, basal medial cell; br, basal radial cell; cua, cubital cell; dm discal cell; dm-m discal-medial crossvein; m-m medial crossvein; r-m radial-median crossvein; M1, first branch of median vein; R2+3, second + third branch of radial vein; R4, fourth branch; R5, fifth branch.