Oldest records of Bombyliidae: Phthiriinae and Mythicomyiidae: Glabellulinae from the Lowermost Eocene amber of France (Diptera: Bombylioidea)

Elektrophthiria magnifica gen. n., sp. n., oldest bee fly of the bombyliid subfamily Phthiriinae, is described from the Lowermost Eocene amber of Oise (France). It suggests at least a Late Cretaceous age for this group, coincident with the diversification of the flowering plants. Eurodoliopteryx inexpectatus gen. n., sp. n., oldest representative of the mythicomyiid subfamily Glabellulinae, is probably the sister genus of extant Doliopteryx, distributed in Africa and the Arabian peninsula, under very arid conditions. This discovery suggests a relatively humid forest close to a river with a drier surrounding area for the palaeoenvironment of the Oise


INTRODUCTION
Bombylioid flies are not rare in the fossil record (Evenhuis, 1991(Evenhuis, , 1994;;Nel & De Ploëg, 2004).Nevertheless, the known fossils are mainly from the late Eocene, Oligocene or Miocene.Cretaceous and Early Cenozoic bee flies are much less frequent.The Lowermost Eocene amber of Oise is of great interest for our knowledge of the early history of this family, as we have already described one new genus and species of Bombyliidae: Toxophorinae Schiner, 1868 and one Mythicomyiidae Melander, 1902 (Nel & De Ploëg, 2004).The present fossils are the third and fourth bee flies from this amber, representing the oldest records of the Bombyliidae: Phthiriinae Becker, 1913 and the Mythicomyiidae: Glabellulinae Cockerell, 1914.We follow the body and wing venation terminology of McAlpine (1981).
Diagnosis.Metapleuron covered with micropubescence; mesopleuron bare; male genitalia are rotated 180°, with gonocoxite in dorsal position; gonostylus rather strong, curved, and hook-like; epandrium with a small apical notch; costal vein ending at anal vein; stalk closing the anal cell shorter than cross-vein r-m; a ventral prong on its third antennal segment, of the same length as the dorsal prong; third antennal segment broader in its basal third than at apex and with only four rather long hairs in its basal third.curved, and hook-like; epandrium with a small apical notch.
Etymology.After the wonderful state of preservation of the holotype.
Discussion.Following the key to families of "Bombyliidae" s.l. of Zaitzev (1992), Elektrophthiria gen.n. would fall in the Phthiriinae Becker, 1913(= Crocidiinae Hull, 1973+ Mariobezziinae Becker, 1913+ Phthiriinae + Heterotropinae Becker, 1913)  even, without notch; antennae shorter than head; 1 st segment of antenna very short; vein M2 present and four postmarginal cells.If we follow the phylogenetic analysis of Yeates (1994), Elektrophthiria gen.n. falls in the "Usiinae: Phthiriini" (= Phthiriinae sensu Zaitzev, 1992) because of the following characters: postcranium flat; wing with R4+5 branched; palps present, long and slender, one-segmented; vein M2 present; flagellum with a very small apical sulcus containing a style (synapomorphy); clypeus reaching base of antennae (synapomorphy).Evenhuis (1990) proposed a revision of this group, as a subfamily Phthiriinae.Following this work, Elektrophthiria gen.n. also falls in this group because of its clypeus reaching the antennal bases and face absent; wing with four posterior cells; antennal sulcus apical.It is much more difficult to precisely ascertain the generic affinities of Elektrophthiria gen.n. within this group because some of the characters proposed by Evenhuis (1990) are difficult to see in the fossil specimens.Nevertheless, the metapleuron of Elektrophthiria gen.n. is covered with micropubescence, an apomorphy of the Phthiriini (sensu Evenhuis, 1990).Its epandrium has a small apical notch, which is plesiomorphic in this group and also in the poecilognathine genus Tmemophlebia Evenhuis, 1986.Its male genitalia are rotated 180°, with gonocoxite in dorsal position, which is also plesiomorphic.Its costal vein ending at anal vein is plesiomorphic.Elektrophthiria gen.n. has a ventral prong on its third antennal segment, which is present in many Phthiriinae.But it is of the same length as the dorsal prong, unlike in Acreotrichus Macquart, 1850.Its mesopleuron is bare, which is a plesiomorphy, while a bare mesopleuron is an apomorphy of the clade (Phthiria + (Acreotrichus & Pygocona & Australiphthiria)).Its third antennal segment is broader in its basal third than at apex and with only four rather long hairs in its basal third, very different from those of Acreophthriria Evenhuis, 1986 andNeacrotrichus Cockerell, 1917, sister . Also, the stalk closing the anal cell is shorter than cross-vein r-m, unlike in Acreophthiria.The gonostylus of Elektrophthiria gen.n. is rather strong, curved, and hook-like, unlike that of Neacrotrichus, but more similar to that of Acreophthiria.
Among the fossil taxa, Zaitzev (1992) listed two Oligocene species in the genus Phthiria.First, P. fossa Lewis, 1975 from the Ruby River Basin (USA) is described on a 111 well preserved impression on sediments (Lewis, 1975), but the delicate structures of the third antennal segment, thorax pilosity and genitalia are not visible, thus it is not possible to determine with accuracy its exact relationships within the Phthiriinae sensu Evenhuis (1990).Thus its attribution to the genus Phthiria sensu stricto is questionable.After the photograph and drawing of Lewis (1975), P. fossa has no or a very short stalk of anal cell, distinctly shorter than in Elektrophthiria gen.n., its wings are dark, unlike the hyaline wings of Elektrophthiria gen.n.Second, P. oligocenica Timon-David, 1943 from the Early Oligocene of Camoins-les-Bains (Marseille Basin, Bouches-du-Rhône, France) is described on a more poorly preserved impression but with the wing venation, some legs, and one antenna in better state.The type specimen is now preserved in the collection of the Musée Longchamp (Marseille).Evenhuis (1994) transferred this fossil to the genus Geron Meigen, 1820, under the incorrect spelling "Geron oligocaenica", without explanation or reexamination of the type material.Numerous characters crucial for a correct classification at subfamily level are not preserved, viz.closure of anal cell, posterior margin of eye, relative lengths of head and antennae, presence of palps, structure of the antennal flagellum, and relative positions of the clypeus and the base of antennae.Nevertheless, its wing venation is very similar to that of Phthiria (see Hull, 1973), especially in the presence of the vein M2.Thus, we prefer to consider it as a Bombyliidae subfamily and genus undetermined, probably related to the Phthiriinae.It differs from Elektrophthiria gen.n. in its longer wings (length about 4.5 mm).Other fossil taxa that have been originally placed in the Phthiriinae are now attributed to different bombyliid subfamilies (Evenhuis, 1984(Evenhuis, , 1990;;Zaitzev, 1992).
The Recent Phthiriini are found worldwide (Evenhuis, 1990).Thus, little can be inferred about palaeoenvironmental or palaeoclimatology from the present discovery.Recent Phthiriinae are strongly attracted to flowers (Hull, 1973), and their long proboscis, also present in Elektrophthiria, "could have developed as a result of parallel coevolution with the flowering plants" (Zaitzev, 1992).The present discovery supports the presence of Phthiriinae in the very Early Cenozoic and a probable origin of this group during the Late Cretaceous, contemporaneous and maybe in relation with the diversification of the Angiosperms.Eurodoliopteryx inexpectatus sp.n.Diagnosis.As for the genus.Description.Head 0.28 mm long, 0.44 mm high; eyes dichoptic but very large; inner eye margin straight; ommatidia of equal size; ocellar tubercle flat; lateral ocelli farther from each other than from anterior ocellus; occiput slightly rounded; frons poorly visible; face not wider than frons; proboscis short, 0.16 mm long, but only partly visible because of an air bubble; antennal socket situated at middle of inner eye margin; antennal scape very small; pedicel cup-shaped; first flagellomere elongate-lanceolate, about 3× longer than wide; second flagellomere very long, 0.06 mm long, with a short apical sensillum.

Family Mythicomyiidae
Thorax 0.64 mm long, strongly humped when viewed laterally, with microscopic pubescence; scutellum small.Legs normal in size and shape, with microscopic vestiture.
Discussion.Following the key to families of "Bombyliidae" s.l. of Zaitzev (1992), Eurodoliopteryx gen.n. falls in the "Mythicomyiidae" because of the following characters: simple R4+5, head distinctly smaller than large mesothorax, abdominal spiracles on tergites.It also falls in the "Mythicomyiinae" sensu Yeates (1994) because of postcranium flat, R4+5 simple, palps absent, abdominal spiracles on tergites, costal vein ending between apices of R4+5 and M1.Following the key to mythicomyiid subfamilies of Greathead & Evenhuis (2001), Eurodoliopteryx falls in the Glabellulinae because of the following characters: R4+5 ending in costa at a level slightly beyond end of vein M2, R4+5 and M1 diverging at wing margin, costa ending nearer to M1 than to R4+5.Evenhuis (2002a) listed four world genera in this subfamily and Greathead & Evenhuis (2001) keyed them.Eurodoliopteryx would fall near the Recent genus Doliopteryx Hesse, 1956 because: vein R2+3 forming a small triangular cell r1, clypeus normal, not strongly developed (unlike in genus Mnemomyia Bowden, 1975), and all cells between M2 and CuA2 confluent (apomorphy).The vein M between cells br and bm of Eurodoliopteryx is strongly evanescent, evanescent, imperceptible, unlike the strong vein M in Glabellula (Hull, 1973: Fig. 351).We can add that Eurodoliopteryx shares with Doliopteryx the first antennal flagellomere about 3× longer than wide, and a complete sclerotization of the first abdominal tergite (clearly visible in all specimens), both unlike Glabellula Bezzi, 1902 (Evenhuis, 2000(Evenhuis, : 120, 2002b: Figs 1-4).Eurodoliopteryx differs from Doliopteryx in its longer vein R4+5, broader cell br (+ bm) and fork of M1+2 and basal portion of M1 present, not evanescent.The vein CuA1 of Eurodoliopteryx is still connected to postero-distal margin of cell br (+ bm), unlike in Doliopteryx.In the Recent D. crocea Hesse, 1956, it is  strongly approximate (Evenhuis, 2000: Fig. 26).Eurodoliopteryx shares with Doliopteryx its vein CuA2 separating from M + Cu near the very base of the wing (unique character in all Bombylioidea), suggesting a sister genus relationships between the two taxa.
Doliopteryx is distributed in Egypt, Israel, Namibia, Oman, Southern Africa, and Zimbabwe, apparently living in extremely arid regions (Evenhuis, 2000).The probable sister-genus relationships between Doliopteryx and Eurodoliopteryx suggests a similar palaeoenvironment for the Oise amber forest.There is some evidence of a dry season, with forest fires, but there is also strong evidence for the presence of a great quantity of water (rivers, crocodiles, aquatic tortoises) in the same palaeoenvironment.The present discovery suggests a possible reconstruction of the palaeoenvironment of a relatively humid forest along a river, in a surrounding arid area.
The discovery of Eurodoliopteryx in the Early Eocene of Western Europe suggests that the Doliopteryx lineage was not strictly confined to the Arabian and African area in the Tertiary.The subfamily Glabellulinae is widespread, with species in Africa, Western Palaearctic, Nearctic, Neotropical, and Australasian regions.The present discovery is the oldest representative of this subfamily, previously known from Middle to Late Eocene, Oligocene, and Miocene (Evenhuis, 2002a,b).
Etymology.After Europe and the Recent African genus Doliopteryx.