Eoacridophagus azari, Myskowiak, Justine, Garrouste, Romain & Nel, Andre, 2016

Myskowiak, Justine, Garrouste, Romain & Nel, Andre, 2016, A new genus and species of micro bee fly from the Earliest Eocene French amber (Diptera: Mythicomyiidae: Psiloderoidinae), Zootaxa 4114 (5), pp. 583-586 : 583-586

Eoacridophagus azari sp. nov.

( Figs. 1–2 )

Material. Holotype MNHN.F. A57338 , stored in the Laboratory of Palaeontology, MNHN, Paris, France. Diagnosis. That of the genus. Very small fly, wing 1.3 mm long.

Etymology. Named after our friend Dr Dany Azar (Lebanese University), specialist on fossil insects. Type horizon. Lowermost Eocene, Sparnacian, level MP7 of the mammal fauna of Dormaal. Type locality. Le Quesnoy, Chevrière, region of Creil, Oise department, France. Description. Head 0.3 mm long and 0.25 mm wide, 0.4 mm high; eyes large but dichoptic, well separated; three ocelli placed in triangle on posterior margin of vertex; antennae shorter than head, 0.2 mm long; flagellum broader in its basal third than at apex; proboscis shortened, not surpassing the mouthpart cavity.

Thorax 0.45 mm long and 0.55 mm high; mesonotum covered with a short pilosity; lateral sides bare.

Wing 1.3 mm long, 0.5 mm wide; cell r1 not a small triangle distally opened; apex of vein R1 0.7 mm from wing base; Rs 0.1 mm long; R2+3 ending in costa well separated from R1, 0.4 mm long; vein R4+5 0.75 mm long, ending in costa at a level clearly well beyond end of vein M2, not reaching wing apex; r-m at 0.55 mm from wing base, approximately in middle of wing; vein M2 present; cell cup closed just before posterior wing margin.

Legs long and slender, fore femur 0.4 mm long, tibia + tarsus 0.6 mm; mid leg 0.95 mm long; hind femur 0.45 mm long, tibia + tarsus 0.5 mm long; femora bare; tibia covered with short bristles; no tibial spur.

Abdomen deformed, 0.6 mm long, 0.4 mm wide, covered with short hairs. Genitalia not clearly visible.

Discussion. Following the key to families of Bombyliidae s.l. of Greathead & Evenhuis (2001), our fossil can be included in the Mythicomyiidae because of the following characters: wing with R4+5 not branched; vein MA absent; palpi absent; abdominal spiracles located in terga; very small insect (wing 1.3 mm long). Eoacridophagus gen. nov. falls in the Psiloderoidinae because of the following characters: wing vein R4+5 ending in costa at a level clearly well beyond end of vein M2; R2+3 present and ending in costa well separated from R1; cell r1 large, not a small triangle; antennal style placed apically on second flagellomere; vein R2+3 short, much shorter than R4+5. The Platypyginae have their vein R2+3 long, similar in length to R4+5, unlike Eoacridophagus .

Following the key to the modern genera of Psiloderoidinae presented by Lamas et al. (2015), Eoacridophagus differs from Psiloderoides Hesse, 1967 for the proboscis probably functional even if it is very short. Acridophagus Evenhuis, 1983 (replacement name for Cyrtomorpha White, 1916 ) has a proboscis half then length of the head, and projecting forward, longer than in Eoacridophagus . Their wing venations are very similar ( White, 1916). Amydrostylus Lamas, Falaschi & Evenhuis, 2015 has a very long proboscis but its venation is very similar to that of Eoacridophagus . Eoacridophagus also differs from Onchopelma Hesse, 1938 in the narrower anal area, cell cup closed before the wing margin by a stalk ( Hesse, 1938; Evenhuis, 2002). Eoacridophagus differs from Psiloderoides in the absence of the discal cell, r-m situated well basal of level of apex of R1, and R2+3 longer ( Hesse, 1967).

In addition, our fossil differs from all the fossils of the Psiloderoidinae: the genera Proplatypygus Hennig, 1969 (Eocene Baltic amber) and Borissovia Evenhuis, 2002 (Cretaceous amber of Siberia) can easily be separated from Eoacridophagus by the different antennal shape, the presence of a discal cell and the well-developed mouthparts ( Hennig, 1969; Zaitzev, 1986; Evenhuis, 2002). Carmenelectra Evenhuis, 2002 (Eocene Baltic amber) differs from Eoacridophagus in the well-developed proboscis ( Evenhuis, 2002). Procyrtosia Zaitzev, 1986 (Cretaceous amber of Siberia) differs from Eoacridophagus in the presence of a discal cell, CuA2 and A1 not fused, and a long vein R2+3. The proportions between the lengths of R2+3 and R4+ 5 in Procyrtosia are similar to the situation in Platypygus (Platypyginae) , suggesting a position in this last subfamily. Eoacridophagus differs from Palaeoplatypygus Kovalev, 1985 (Cretaceous amber of Siberia) in the absence of discoidal cell, shorter R1 and CuA2-A1 fusion on the ventral margin of wing ( Kovalev, 1985; Zaitzev, 1986). Zarzia Zaitzev, 1986 (Cretaceous amber of Siberia) has a vein R2+3 sigmoidal, and a discal cell unlike our fossil.

Remark. The recent Psiloderoidinae are known to be parasitoids on the eggs of Acridoidea. Grasshoppers are really not frequent in the Oise amber, which in no way means that they were not present in the corresponding palaeoenvironment because these insects are quite able to escape the embedment in the fresh resin. The recent Psiloderoidinae are distributed in the Neotropical, Afrotropical and Australian areas, in warm environments, which is in accordance with the current reconstruction of the palaeoenvironment of the Oise amber and the presence of other insects also living in such biota (viz. Isoptera Mastotermitidae ) ( Nel & Bourguet, 2006; Nel & Brasero, 2010).

Figures

FIGURE 1. Eoacridophagus azari gen. et sp. nov., holotype MNHN. F. A 57338. A, habitus; B, wing. Scale bars represent 0.2 mm.

FIGURE 2. Eoacridophagus azari gen. et sp. nov., holotype MNHN. F. A 57338. Head, ventral view (arrow proboscis). Scale bar represents 0.2 mm.