Ellipteroides (Ellipteroides) kishenehn De Jong, 2019

Dale E. Greenwalt, Daniel J. Bickel, Peter H. Kerr, Gregory R. Curler, Brian V. Brown, Herman de Jong, Scott J. Fitzgerald, Torsten Dikow, Michal Tkoč, Christian Kehlmaier & Dalton De Souza Amorim, 2019, Diptera of the middle Eocene Kishenehn Formation. I. Documenting of diversity at the family level, Paleontologia Electronica 22 (2), No. 50, pp. 1-56 : 8-9

Ellipteroides (Ellipteroides) kishenehn De Jong ,

sp. nov.

Figure 4 zoobank.org/ 8BD7F94B-69ED-43DE-8792-F2AA9196DFC3 Etymology. The specific epithet is regarded here to be a noun in apposition to the genus name Ellipteroides , which is masculine.

Holotype. USNM 621123 , deposited in the Department of Paleobiology , National Museum of Natural History (NMNH), Smithsonian Institution, Washington, District of Columbia, USA.

Type horizon. Middle Eocene Coal Creek Member, Kishenehn Formation .

Type locality. Park site, Middle Fork of the Flathead River (Pinnacle, Montana, USA).

Differential diagnosis. This species of the genus Ellipteroides is distinguished by the length of vein Sc, absence of vein R 2, wide cell r 3, absence of the discal cell and the shape of cell m 1.

Description

Adult male (Figure 4.1), body length about 5.0 mm, wing length about 5.1 mm. Specimen preserved in dorsal view.

Head. Head round. Eyes large covering most of sides of head, widely separated medially. Rostrum hardly visible but by inference very short. Antenna about 0.7 mm long, number of segments not distinguishable, basal segments short and somewhat bulbous, becoming more elongate and slender apically towards antennal tip; intermediate and apical flagellomeres with long verticils that exceed length of segments (Figure 4.4). Palp only vaguely indicated. Occiput dark brown.

Thorax. Hardly any distinguishing characters; metatergite distinct from remainder of thoracic dorsum. Thorax dark brown.

Wings. Both wings entirely preserved, right wing somewhat folded along M. Pterostigma not visible (Figure 4.2-3). Sc terminating in costa at level of first fork of Rs. The position of crossvein sc-r is uncertain, but it is possibly present at some distance proximad of apex of Sc. R 1 long, straight, terminating in costa near level of fork of R (2+)3 and R 4. Rs long, originating at level of apex of A 1, gradually curved. R (2+)3+4 with short petiole, free section of R 2 absent, R 3 slightly sinuous and subparallel to apex of R 1, R 4 long, slightly sinuous. R 5 long, evenly curved towards wing tip. Crossvein r-m rather long, a bit curved and oblique. Discal cell absent. M branches into M 1+2 and M 4 (M 3 absent). M 1+2 with short petiole before branching into M 1 and M 2. M 4 aligned with M. Crossvein m-cu touches M at its branching point, appearing somewhat curved possibly due to deformation of fossil. CuA almost straight, not upcurved at contact with crossvein m-cu, apical section of CuA aligned with preceding part of vein. False vein immediately posterior to CuA distinct from base of wing to level of crossvein m-cu. CuP gradually diverging from CuA from wing base to margin. A 1 long, gradually bowed to posterior wing margin. Anal area well developed, anal corner evenly rounded.

Legs. Missing.

Abdomen and genitalia. Abdomen entirely present, but covered by wings, dark-brown. Genitalia preserved in dorsolateral view, but no details discernible.

Allotype. Female unknown.

Syncompressions. None.

Remarks

The family Limoniidae currently includes 147 recent genera and 10,578 described species ( Oosterbroek, 2018). The genus Ellipteroides is divided into six subgenera, Ellipteroides sensu stricto (with 15 species), Progonomyia Alexander, 1920 (55), Protogonomyia Alexander, 1934 (38), Ptilostenodes Alexander, 1931b (9), Ramagonomyia Alexan- der, 1968 (2) and Sivagonomyia Alexander, 1968 (1). Ellipteroides is a taxonomic derivative of a huge clade that is dominated by the large genus Gonomyia Meigen, 1818 . The systematics of this group is based on venational characters as the length of Sc, presence or absence of R 2, depth of cell r 3, presence or absence of the discal cell, shape of cell m 1 and the structure of the male and female terminalia. The classification is in need of revision and given the present situation, the fossil is best filed under the subgenus Ellipteroides (Ellipteroides) . Placement in the genus Ellipteroides is based on the long Rs, the apically wide cell r 3, the very long R 4 (much longer than R (2+)3+4), the position of m-cu near the fork of M, branching of M into M 1+2 and M 4. Placement in the subgenus Ellipteroides s.s is based on the absence of a free section of R 2, the absence of a discal cell, and the petiole of M 1+2 being shorter than its fork. In the Nearctic region, the genus Ellipteroides is represented by only four recent species that are classified in the subgenus Progonomyia . No fossils of Ellipteroides s.l. have previously been described.

Figures

FIGURE 4. Ellipteroides (Ellipteroides) kishenehn sp. nov., USNM 621123. 1, Habitus; 2, Left wing; 3, Line drawing of left wing; 4, Antennae and palpus. Arrow points to palpus. Scale bars equal 2.0 mm (1), 1.0 mm (2) and 0.5 mm (3).