Epicharmeropsis Huang, Ren & Shih

Huang, Jiandong, Ren, Dong & Shih, Chungkun, 2007, New genus and species of Hexagenitidae (Insecta: Ephemeroptera) from Yixian Formation, China, Zootaxa 1629, pp. 39-50 : 40

Genus Epicharmeropsis Huang, Ren & Shih , gen. nov.

Type species. Epicharmeropsis hexavenulosus Huang, Ren & Shih , sp. nov.

Etymology. Greek prefix Epichar- (beautiful) and meropsis (a suffix taken from genus Ephemeropsis ).

Diagnosis. Imago. Moderate to good-sized species; mesonotal suture (MNs) in anterior part of mesonotum strongly stretched backwards medially, not transverse; paired medioparapsidal sutures (MPs) anastomosed at middle area of mesonotum, not parallel; lateroparapsidal suture (LPs) curved laterally; metanotum relatively long. Forewing about 2.4 times as long as its width; membrane thickened at distal part of the field between C and RA; RS forking about 10mm from base of forewing, RSa formed two triads, RSp nonbranched; distinct intercalary veins existing between MP2 and CuA1; CuA1 with 4–6 triads (loop-shaped veinlets) leading to wing margin; numerous crossveins and intercalary veins between longitudinal veins. Hindwing more or less than half as long as forewing, broad, about 1.6 times as long as its width with fairly obtuse tip.

Composition. The type species and Epicharmeropsis quadrivenulosus .

Comparison. Epicharmeropsis gen. nov. is very similar to Ephemeropsis Eichwald from the Early Cretaceous of Transbaikalia and Mongolia in the shape and venation of fore and hind wings; but it differs from Ephemeropsis by membrane thickened at distal part of the field between C and RA, unforked RSp, and the distinct intercalary veins existing between MP2 and CuA1 of forewing. The later two features of wing venation are present in Late Jurassic genus Hexagenites Scudder, 1880 and Lower Cretaceous genus Cratogenites Martins-Neto, 1996 , but in contrast to them, hind wing of Epicharmeropsis is more or less than half as long as forewing.

Remark. The combined characters of this new genus allow an allocation of it to the family Hexagenitidae : moderate to large size; vein CuA of forewing forked, one of its branches with a series of triads (loopshaped veinlets) leading to wing margin.

Epicharmeropsis gen. nov. possesses a peculiar combination of characters: mesonotal suture (MNs) in anterior part of mesonotum strongly stretched backwards medially, not transverse; paired medioparapsidal sutures (MPs) jointed at middle area of mesonotum, not parallel; forewing less than 2.5 times as long as its width; RSp non-branched; the presence of intercalary veins between MP2 and CuA1; hindwing broad, about 1.6 time as long as its width, with fairly obtuse tip. These characters allow formal separation of this new genus from other known genera of the Hexagenitidae established by mayfly adults, extant or in fossil records.