Eocenotrichia magnifica, Garrouste, Romain, Azar, Dany & Nel, Andre, 2016

Garrouste, Romain, Azar, Dany & Nel, Andre, 2016, The oldest accurate record of Scenopinidae in the Lowermost Eocene amber of France (Diptera: Brachycera), Zootaxa 4093 (3), pp. 444-450 : 445-446

Eocenotrichia magnifica sp. nov.

Figs. 1–4

Material. Holotype PA 16841, stored in the Laboratory of Palaeontology, MNHN, Paris, France.

Etymology. Named after the excellent preservation of the type specimen.

Type horizon. Lowermost Eocene, Sparnacian, level MP7 of the mammal fauna of Dormaal.

Type locality. Le Quesnoy, Chevrière, region of Creil, Oise department, France.

Diagnosis. As for the genus (vide supra); vein R4 sigmoidal.

Description. Body length 7.6 mm [female]. Head 0.75 mm long, 0.96 mm high, higher than long, subspherical, female with broad, raised postocular ridge; antenna elongate, 0.46 mm long, cylindrical, length 0.6× head length; antennal style terminal, flagellum 0.3 mm long, notched; frons flat, not protruding anteriorly; mouthparts well developed, 0.42 mm long, distinctly shorter than head length; thorax 1.9 mm long, 1.7 mm high, scutum with dense pile of semi-appressed, very small setae; wing 4.2 mm long, ca. 1.3 mm wide; vein M1 joining with R5, cell r5 petiolate to wing margin, cell r5 large, 1.8 mm long, 0.4 mm wide; R5+M1 0.2 mm long, ending at wing apex; R4 sigmoidal, 0.6 mm long, emerging in distal third of cell [r5]; apex of R2+3 not far from level of base of R4; vein M2 absent; vein M4 originating on discal cell and fused with M3; costal margin ending at apex of vein R5+M1; cubital veins terminating before wing margin; abdomen elongate and broad, width equal to thorax; abdomen 3.8 mm long, 1.2 mm wide; female genitalia: tergite 10 narrow and band-like, acanthophorite spines present, well developed in a marginal row; sternite 8 slightly shorter than tergite 8, posteriorly rounded. Male unknown.

Discussion. Eocenotrichia gen. nov. is placed in the Scenopididae for the wing vein M4 originating on the discal cell and fused with M3; in the Scenopidinae for the cubital veins terminating before wing margin, vein M2 absent, cell [m1] wide, and in the Metatrichini Winterton & Ware, 2015 for the wing vein M1 fused to R5 (Winterton & Ware, 2015). Following the key to scenopinid genera of Winterton & Gharali (2011), within this tribe, Eocenotrichia runs to Propebrevitrichia Kelsey, 1969 in their couplet 25, for the following characters: mouthparts not atrophied; head shorter than high; relatively delicate flies with narrow tapered abdomen; antennal flagellum broad, notched apically; wing with vein R4 branching from R5 along distal half of cell [r5]; female acanthophorite spines present well developed. It shares with Propebrevitrichia , the sister group of all other Metatrichini, the presence of female acanthophorite spines developed in a marginal row (plesiomorphic state for character 28 in Winterton & Ware, 2015), However, Eocenotrichia differs from this genus in that tergite 8 is slightly longer than sternite 8, and the body size is greater than 7 mm instead of being less than 4 mm long (Kelsey, 1969, 1971, 1976; Winterton, 2005).

Remarks. As Propebrevitrichia is a South African genus that is the sister group of the clade that comprises all other modern Metatrichini, Winterton & Ware (2015: 23) proposed an African origin of the entire clade during the Late Cretaceous. The present discovery of a Metatrichini in the Earliest Eocene supports the age proposed by these author for this clade. However, the reduced contacts between the African plate and Europe during the period from the Late Cretaceous to the Eocene, questions their hypothesis of an African origin for the Metatrichini.

The modern Scenopinidae have predacious larvae associated with wood-boring larvae, termites, woodrat nests, bird’s nests, and carpet beetle larvae (Kelsey, 1981). Birds, termites and Dermestidae are recorded from the Oise amber, suggesting similar biology for Eocenotrichia (Nel & Bourguet, 2006; Kirejtshuk & Nel, 2013).

Figures

FIGURE 1. Eocenotrichia magnifica gen. et sp. nov., holotype PA 16841. A. general habitus; B. legs; C. antenna (scale bars represent 1 mm for A, B, 0.1 for C).

FIGURE 2. Eocenotrichia magnifica gen. et sp. nov., holotype PA 16841. A. mouthparts; B. ocelli (scale bars represent 0.1 mm).

FIGURE 3. Eocenotrichia magnifica gen. et sp. nov., holotype PA 16841, genitalia. A. right view (black arrow: acanthophorite spines, white arrow: sternite 8); B. right view (white arrow: sternite 8) (scale bars represents 0.5 mm).

FIGURE 4. Eocenotrichia magnifica gen. et sp. nov., holotype PA 16841, left wing. A. general view; B. detail of apex; C. reconstruction (scale bars represent 0.5 mm).