Eodromyia pumilio Myskowiak, Garrouste, and Nel 2018
- Dataset
- Eodromyia pumilio gen. et sp. nov., a new empidoid fly from the Earliest Eocene amber of France (Diptera: Hybotidae: Tachydromiinae)
- Rank
- SPECIES
- Published in
- Myskowiak, J., Garrouste, R., Nel, A. (2018): Eodromyia pumilio gen. et sp. nov., a new empidoid fly from the Earliest Eocene amber of France (Diptera: Hybotidae: Tachydromiinae). Zootaxa 4379 (2): 279-286, DOI: 10.11646/zootaxa.4379.2.8
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Insecta
- order
- Diptera
- family
- Hybotidae
- genus
- Eodromyia
- species
- Eodromyia pumilio
description
Description. Male. Head triangular in shape from above, 0.2 mm long and 0.15 mm wide; eyes 0.15 mm long and 0.05 mm wide, dichoptic with deep ocular notch (Fig. 1 A); eyes well separated on frons and linearly approximate on face, with ommatrichia; ocellar triangle broad and shallow, with 2 pairs of ocellar setae, anterior pair just behind anterior ocellus, convergent, posterior pair divergent; postocellar setae minute and proclinate; inner vertical long and divergent; a series of four rather long pairs of setae on occiput; gena very shallow. Antenna with very small, bare scape, pedicel setose with row of short setae surrounding apex, wider than postpedicel, subequal in length with suboval postpedicel; length of postpedicel ca. 0.05 mm; flagellum aristate, apex of flagellum with bristle-like style; flagellum 0.15 mm long. Mouthparts well developed, distinctly shorter than head; maxillary palpus not visible; sclerotized sharp and dark structure (hypopharynx?). Thorax 0.3 mm long, 0.25 mm wide; scutum as broad as long; 6 pairs of presutural acrostichal setae and 6 presutural dorsocentral setae; lateral portion of thorax poorly visible, but mesopleuron with some setulae; scutellum with single apical pair of setae. Wing 0.9 mm long and 0.4 mm wide, slender, W / L = 0.44 (Figs 1 B, 2 B); membrane microtrichia arranged in oblique rows and longitudinal rows; vein C reaching apex of M; Sc short, very faint [best seen when tilting specimen]; base of vein R thick; R 1 short, 0.35 mm long; Rs originating well distal to level of crossvein h, rather long, 0.2 mm long, weaker than R 2 + 3 and R 4 + 5; R 2 + 3 unbranched, slightly curved anteriorly, meeting C 0.4 mm from wing base; R 4 + 5 slightly curved anteriorly, meeting C 0.6 mm from wing base; distance between apices of R 2 + 3 and R 4 + 5 twice that between R 2 + 3 and R 1; first sector oblique; crossvein r-m short, perpendicular to R 4 + 5 and M; vein M simple, complete, unbranched, nearly straight, extended to tip of wing; CuA simple (CuA 2 lost, no cells bm and cup), weakly curved posteriorly, reaching wing margin; M and CuA strongly divergent; bm-cu, dm-cu and A 1 veins lost; anal lobe present but narrow; alula not developed. Halter not visible. Legs of moderate length, setulose, without distinctive spines / spurs; femora, especially fore femur, very broad compared to tibiae, fore femur 0.25 mm long, 0.15 mm wide; median femur 0.25 mm long, 0.05 mm wide; hind femur 0.35 mm long, 0. 0 5 mm wide, without subapical strong setae; fore tibia appressed to femur, gland not viewable; median tibia 0.35 mm long; hind tibia 0.5 mm, bearing anterodorsal setae; pretarsus with claws well developed, empodia setiform, pulvilli present. Abdomen 0.8 mm long, 0.25 mm wide, relatively short compared to wings, with sparse vestiture of short, stiff setae; male genitalia visible, asymmetrical, only epandrium and surstyli discernable (Fig. 4 C). Female. Unknown.
description
The Oligocene genus Archaeodrapetiops Martins-Neto et al. 1992, considered by the authors to be related to Drapetis and Elaphropeza, strongly differs from Eodromyia gen. nov. in the presence of a long crossvein bm-cu very far from r-m. The absence of head characters for this genus, based on incomplete compression fossils renders its family attribution uncertain (Martins-Neto et al. 1992). It should be noted that Solórzano-Kraemer et al. (2005) listed the Oligocene genus Taubatempis Martins-Neto 1999 among the fossil Tachydromiinae, but Martins-Neto (1999) considered it in the Empididae. This genus is based on very poor compression fossils for which even the attribution to this family is weakly supported. Concluding remarks. Except for Archaeodrapetiops, all the other fossil taxa currently included in the Drapetini belong to extant genera (Solórzano-Kraemer et al. 2005). The tribe is known from the mid Eocene Baltic amber, and the Miocene Mexican and Dominican amber. Eodromyia gen. nov. is the oldest representative of the tribe, even if it is only a few million years older than Baltic amber. This fossil strongly suggests that the diversification of this group is certainly more ancient.
diagnosis
Diagnosis. As for the genus. Very small fly, wing 0.9 mm long, 0.4 mm wide.
discussion
Discussion. Eodromyia gen. nov. can be attributed to the Empidoidea on the basis of the following characters: ptilinal fissure absent; empodia setiform; three flagellomeres; CuA 2 absent; flagellum elongate; wing rounded at apex; A 1 not reaching wing margin; Sc incomplete (Buck et al. 2009). Eodromyia gen. nov. is similar in wing venation to the Cretaceous empidoid atelestid genus Cretodromia Grimaldi & Cumming, 1999 and the genus Myanmyia Grimaldi et al., 2011 (Diptera: unplaced family) due to the complete reduction of CuA 2, no cell bm, and all longitudinal veins simple (Grimaldi & Cumming 1999; Grimaldi et al. 2011). Despite the somewhat similar venation of these two Cretaceous fossils, Eodromyia gen. nov. belongs to the tribe Drapetini [= Drapetidini] Collin, 1961 (Hybotidae Tachydromiinae) as defined by Sinclair & Cumming (2006) by sharing the following synapomorphies: apex of antenna with long, slender seta-like receptor; R 4 + 5 unbranched; loss of M 2; loss of cell dm, due to loss of dm-cu; eyes with ommatrichia (even if some other Empidoidea also have ommatrichia); loss of CuA 2. Chillcott & Teskey (1983) added that the Drapetini are recognized by the scutum being as broad as or broader than long, which is also the case in Eodromyia gen. nov.
etymology
Etymology. Named after its very small size.
materials_examined
Type material. HOLOTYPE male, labeled: MNHN. F. A 57316; stored in the Laboratory of Palaeontology, MNHN, Paris, France.
materials_examined
Type strata. Lowermost Eocene, Sparnacian, level MP 7 of the mammal fauna of Dormaal. Type locality. Le Quesnoy, Chevrière, region of Creil, Oise department, France.