Diptera of the middle Eocene Kishenehn Formation. I. Documentation of diversity at the family level

Abstract

The Coal Creek Member of the Kishenehn Formation in northwestern Montana, USA, is an emerging middle Eocene Lagerstätte. While fish, plant, mammal and molluscan fossils are present, the most numerous and well-preserved fossils are those of insects. In this study, we initiate an effort to enumerate, at the family level, the diversity of flies (Insecta: Diptera) at this locality. Seventeen specimens from 17 different families (15 families with Limoniinae and Cylindrotominae within Tipulidae s.l.), 15 new species and three new genera are described. These include Tipula fji sp. nov. (Tipulidae), Ellipteroides kishenehn sp. nov. (Limoniidae), Cyttaromyia lynnae sp. nov. (Cylindrotomidae), Sylvicola silibrarius sp. nov. (Anisopodidae), Efcookella nigra sp. nov. (first fossil known in the genus) (Scatopsidae), Bibiodes kishenehnensis sp. nov. (Bibionidae), Eosciarites hermes gen. et sp. nov. (Sciaridae), Rymosia hypnolithica sp. nov. (Mycetophilidae), Litoleptis araeostylus sp. nov. (Rhagionidae), Kishenehnoasilus bhl gen. et sp. nov. (Asilidae), Drapetis adelomedos sp. nov. (Hybotidae), Salishomyia eocenica gen. et sp. nov. (Dolichopodidae), Agathomyia eocenica sp. nov. (first known fossil in genus) (Platypezidae), Lonchoptera eocenica sp. nov. (Lonchopteridae) and Aenigmatias kishenehnensis sp. nov. (Phoridae). Two specimens in the families Psychodidae and Pipunculidae are described but not assigned to a genus. In addition, we revise several related fossil species housed at the NMNH. Asilopsis fusculus Cockerell, 1921, formerly described in Asilidae, is transferred to Cyttaromyia (Cylindrotomidae) as C. fuscula, Sciara florissantensis Cockerell, 1917 is assigned to Sciaroidea incertae sedis, and Sciara gurnetensis Cockerell, 1916, Sciara lacoei Cockerell, 1915 and Sciara protoberidis Cockerell, 1915, are assigned to Sciaridae incertae sedis. Given their diversity and high degree of preservation, continued characterization of the Coal Creek Member fossils may help elucidate the Eocene radiation of Diptera in North America.

Phylogeny and biogeography of the enigmatic ghost lineage Cylindrotomidae (Diptera, Nematocera)

“…Number of character given above circles, states of characters below circles; ( B ) Wing venation of fossil Cylindrotominae with chronostratigraphic distribution view; ( C ) Wing venations of representatives of genera: Cylindrotoma , Cyttaromyia , Diogma , represented in fossil record. Wing venation redrawing 24 , 25 , 27 – 29 , 31 , 34 , 42 , 50 . Stratigraphic chart according to International Stratigraphic Chart, International Commission of Stratigraphy (v. 2021/05) https://stratigraphy.org/chart .…”

“…The study was based on material from the collection of the Muséum national d'Histoire naturelle (MNHN), Paris (five specimens) and American Museum National History (AMNH) (one specimen). The imprints from sediments of Green River Formation USA (age 50.3–46.2 Ma 42 ) were studied using a Nikon SMZ 1500 stereomicroscope equipped with a Nikon DS–Fi1 camera in University of Rzeszów. The microphotographs and measurements were taken with NIS–Elements D 3.0 software.…”

Phylogeny and Biogeography of the Enigmatic Ghost Lineage Cylindrotomidae (Diptera: Nematocera)

“…(one specimen). The imprints from sediments of Green River Formation USA (age: 50.3 -46.2 Ma [38] ) were studied using a Nikon SMZ 1500 stereomicroscope equipped with a Nikon DS-Fi1 camera in University of Rzeszów. The microphotographs and measurements were taken with NIS-Elements D 3.0 software.…”

“…Cyttaromyia princetoniana [22] 7. [38] - . Cyttaromyia fuscula [23] 12 [27] Cyttaromyia obdurescens [25] ( Comparison.…”

“…-Vein r-r (R2) terminating at level of r`-m`, behind level of m-m ……………………………………….................................... Cyttaromyia fenestrata [22] 10. [38] -M3+4 bifurcation on M3 and M4 before level of m-m; d-cell 1.5x as long as M4; m-m approximately at level of tip of r-r (R2) …………….…………….….. …………………….…………………………………….....….. Cyttaromyia fuscula [23] 12.…”