Microphorites erikai, Bramuzzo, Simone & Nel, André, 2017

Bramuzzo, Simone & Nel, André, 2017, Youngest representative of the extinct genus Microphorites in the Eocene amber of France (Diptera: Dolichopodidae: Microphorinae), Zootaxa 4231 (4), pp. 590-594 : 590-593

Microphorites erikai sp. nov. ( Figs 1– 4 )

Diagnosis. Head large, very long antenna, with prolonged postpedicel, broader at base, and tapered distally; postpedicel 1.2 times longer than basal and apical articles of arista-like stylus; thorax higher than longer, strongly arched; scutellum with a pair of long apical setae plus two pairs of shorter setae; no long prescutellar setae; one long seta in notopleuron; wing with costa ending at junction with R4+5; Sc weakened towards costa; distal half of subcostal cell darkened; dark pterostigma present at fusion of first radial vein and costa; crossvein dm-cu arched into cell dm; anal lobe of wing not developed, with long setae at base of anal margin.

Description. Female. Head rather large (0.42 mm long, 0.74 mm high), eyes bare, dichoptic; facets of equal size; ocellar triangle large, three ocelli well developed; anterior pair of ocellar setae long, followed by pair of minute postocellar setae; antennae situated near middle of head; antenna long (length 0.58 mm); scape and pedicel as long as wide, with ring of strong setae present on pedicel; postpedicel elongate, 0.28 mm long, broader at base, tapering distally and densely covered by rather long microtrichia; arista-like stylus 0.22 mm long, slightly shorter than postpedicel, composed of two articles, basal article very small and inconspicuous; stylus covered in short microtrichia; labellum and maxillary palpus visible, with setae; face not visible.

Thorax higher than longer (length 0.68 mm, height 0.94 mm), strongly arched; acrostichals tri- to biserial posteriorly, dorsocentrals uniserial, without two very long prescutellar setae; one long notopleural seta. Halter long (length 0.32 mm) and robust. Wing hyaline, 2.11 mm long, 0.97 mm wide, entirely covered with microtrichia. Pterostigma (Pt) long, occupying basal 1/3 of costal section between R1 and R2+3; alula not visible; costa (C) uniformly covered with smaller setae; subcosta (Sc) closely approximated with R1, with distal half very faint, ending at costal margin, veins R2+3 and R4+5 diverging in basal half, parallel in distal half, both simple; origin of radial veins basal, at level of humeral crossvein (h); crossvein r-m in basal fourth of wing; discal medial cell (dm) anteriorly tapered, emitting three veins, i.e. M1, M2 and CuA1 ending in wing margin; crossvein bm-cu complete; basal part of M2 straight, basal medial cell (bm) more or less triangular, anal (cup) cell rounded apically.

Legs long and slender, simple, covered uniformly with setae.

Abdomen cylindrical, 1.2 mm long, with long setae, other details not visible; female terminalia telescopic, relaxed, covered with setae, without acanthophorite spines.

Type locality. Farm Le Quesnoy, Chevrière, near Creil, Oise department (northern France).

Type horizon. Lowermost Eocene, Sparnacian (ca. - 53 Ma), level MP7 of the mammal fauna of Dormaal ( Nel et al. 1999).

Material examined. Holotype PA 979, stored in the Paleontological Department, MNHN, Paris , France; in the same piece of amber with a large wasp and a spider.

Etymology. Named after Erika Degasperi, girlfriend of the first author.

Discussion. The generic diagnosis by Grimaldi & Cumming (1999) based on Hennig (1971), with supplements by Nel et al. (2004), is followed. Our fossil has the typical characters for Microphorites , e.g., antennae located near the middle of anterior margins of the eyes; arista 2-articled; anal margin of wing not making a strong curvature; three radial veins; crossvein r-m in basal fourth of wing; crossvein bm-cu complete; cell dm present; two medial veins and vein CuA1 complete; absence of acanthophorite spines on tergite 10 of the female; female abdomen telescopic.

FIGURE 3. Microphorites erikai sp. nov., holotype PA 979, photograph of wing. Abbreviations: h, humeral vein; Pt, pterostigma; Sc, subcostal vein; R1, R2+3, R4+5, branches of radius; M1, M2, branches of media; CuA, anterior cubital. Scale bar = 0.5 mm.

Among the fossils currently attributed to the genus Microphor Macquart, 1827 , our fossil differs from the poorly known Microphor defunctus ( Handlirsch, 1910) in the smaller wings (2.11 mm long instead of 4.0 mm) ( Handlirsch 1910). Microphor eocenica ( Meunier, 1902) has a short postpedicel and wing length 0.75 mm, unlike in our fossil ( Meunier 1902: 402; 1908). Microphor rusticus ( Meunier, 1908) has an elongate postpedicel, but not pear-shaped unlike in our fossil ( Meunier 1908: pl. 6, fig. 12).

Within the genus Microphorites , the new fossil differs from all species except M. moravicus by the presence of a pterostigma. It differs from M. moravicus in few characters, viz. in the shape of the scape and pedicel. In M. moravicus the scape and pedicel are longer than broad, whereas in M. erikai sp. nov. they are broader than long. However, the distinctive shape of the scape and pedicel in M. moravicus could be due to taphonomic deformation in amber. The thorax of M. erikai is higher than longer, unlike M. moravicus . The head of M. erikai is larger than that of M. moravicus . Our fossil also has long setae at the base of the anal margin of the wing, apparently unlike M. moravicus .

There is some uncertainty concerning the age of the amber in which the type specimen of M. moravicus is embedded. The sediment from which it was found is Paleogene in age, but the amber itself is similar to some Late Cretaceous ambers ( Tkoč et al. 2016). With the present discovery, we can confirm the presence of the genus Microphorites in the Paleogene and consequently this taxon is present through the Cretaceous-Cenozoic crisis.

Figures

FIGURE 1. Microphorites erikai sp. nov., holotype PA 979, photograph of habitus. Scale bar = 1 mm.

FIGURE 2. Microphorites erikai sp. nov., holotype PA 979, photograph of head. Scale bar = 0.5 mm.

FIGURE 4. Microphorites erikai sp. nov., holotype PA 979, photograph of wing base, arrow indicate series of setae on posterior margin. Scale bar = 0.5 mm.