Sciency Thoughts: Protoplecid Flies from the Middle Jurassic Daohugou Biota of Inner Mongolia.

Tuesday, 5 May 2015

Protoplecid Flies from the Middle Jurassic Daohugou Biota of Inner Mongolia.

Protoplecid Flies are a group of True Flies, Diptera, known from Jurassic deposits across Eurasia. They are thought to be ancestral to the modern Bibionidae (March Flies and Love Bugs) and the group is therefore considered paraphyletic (i.e. not everything descended from the earliest common ancestor of the group is included in the group). The first Protoplecid specimens were described from Karatau in southern Kazakhstan in 1938, and members of the group have subsequently been described from Germany, Kyrgyzstan and a number of sites from China. The earliest specimens known come from the Blue Lias in Germany.

In a paper published in the journal ZooKeys on 30 March 2015,Xiuqin Lin, Chungkun Shih and Dong Ren of the Key Lab of Insect Evolution and Environmental Change at Capital Normal University describe five new species of Protoplecid Flies from the latest Middle Jurassic Jiulongshan Formation of Inner Mongolia (the ‘Daohugou Biota’). All are placed in the genus Epimesoplecia, which previously contained two species, both described from the Daohugou Biota in 2007.

The first new species described is named Epimesoplecia plethora, where ‘plethora’ means ‘fullness’ in reference to the dense fur on the body. The species is described from two specimens, a well preserved female plus a partial fossil of indeterminate sex. The female is 10 mm in length with crescent shaped compound eyes, thin and slender forelegs and longer, hindlegs and long, narrow wings.

Epimesoplecia plethora, female specimen. Scale bar is 1 mm. Lin et al. (2015).

The second new species described is named Epimesoplecia prosoneura, where ‘prosoneura’ means ‘before the sinew’, in reference to the venation of the wings. The species is described from one male and one female specimens. The male is 9.3 mm in length, the female 8.2 mm. The male has more protrusive eyes than the female, both have long antennae with thick bases, becoming more slender towards the tips, slender fore- and middle legs, with slightly thicker and longer hindlegs and long, narrow wings.

Epimesoplecia prosoneura, male specimen. Scale bar is 1 mm. Lin et al. (2015).

The third new species described is named Epimesoplecia stana, where ‘stana’ is ‘an arbitrary combination of letters’. The species is described from a single female specimen. This is 10.2 mm in length with slender forelegs, intermediate midlegs and thicker hindlegs and long, narrow wings.

Epimesoplecia stana, female specimen. Scale bar is 1 mm. Lin et al. (2015).

The fourth new species described is named Epimesoplecia macrostrena, where ‘macrostrena’ means ‘large and strong’, in reference to the large wings and apparently strong body of this species. The species is described from two specimens of indeterminate sex and a female. These are 7-11.3 mm in length with small heads, thick legs and long, narrow wings.

Epimesoplecia macrostrena, specimen of indeterminate sex. Scale bar is 1 mm. Lin et al. (2015).

The fifth new species is named Epimesoplecia ambloneura, where ‘ambloneura’ means ‘obtuse sinew’, in reference to the venation of the wings. The species is described from one female specimen and one partial specimen of indeterminate sex (in their description Lin et al. describe the first specimen as ‘male’, but then go on to describe its anatomy as female, including illustrations of female genitalia, so ‘male’ is presumably a typing error). The complete specimen is 12.7 mm long. Both have small oval heads with long antennae, thick legs and long narrow wings.