Triassodotes rasnitsyni, SINITSHENKOVA, 2021

SINITSHENKOVA, NINA D., 2021, A new mayfly species Triassodotes rasnitsyni sp. nov. of the family Misthodotidae Tillyard, 1932 (Insecta; Ephemerida, Permoplectoptera) from the Triassic deposits of Kuzbass, Russia, Palaeoentomology 4 (5), pp. 429-432 : 429-430

Triassodotes rasnitsyni sp. nov.

( Fig. 1 )

Holotype. PIN 4887 /140, part and counterpart of mayfly imago with four superimposed wings without head and poorly preserved abdomen without cerci. The holotype is stored at the A.A. Borissiak Paleontological Institute RAS, Moscow.

Etymology. Named for the outstanding paleoentomologist Alexandr P. Rasnitsyn.

Diagnosis. Imago. On the fore wing SC does not reach the apex of the wing, flows into C slightly proximal to the middle of the wing; the first RS fork is in the basal third of the wing. Two intercalary veins depart from the posterior branch of RS, the second of them forms a triad, and one intercalary vein departs from the anterior branch. The transverse veins are numerous. The apex of the hind wing is narrowed; the ratio of the length of the fore wing to the length of the hind wing is 1.4.

Type locality and horizon. The specimen was found in the locality Babiy Kamen in the basal Malsevo Group at the Tom’ River of Kemerovo Region, Keznetsk Basin, Russia. The age of the deposits is considered to be Early Triassic.

Description. The described specimen 4887/140 is a remnant of an imago with superimposed fore and hind wings, the abdomen is partially preserved, the head is absent, the thoracic region is severely damaged, only some sclerites are preserved. The end of the abdomen with cerci is absent, so determination of the sex of the mayfly is impossible. The basalmost part of the forewing of T. rasnitsyni sp. nov. has not been preserved, therefore, it is impossible to speak with certainty about the presence or absence of costal brace. The cubital and anal parts of wings are also absent. On the hind wing, the first fork of RS is located in the basal third of the wing, an intercalary vein departs from its anterior branch and forms a triad, and one intercalary vein departs from its posterior branch. MA with short fork near the wing margin. The length of the fore wing is 4.6 mm, its width is about 1.5 mm, hind wing length 3.3 mm, its width 1.2 mm.

The new species differs from T. vogesiacus in smaller size (the length of T. vogesiacus fore wing is 5.5 mm) and the character of RS branching on the fore wing; in T. vogesiacus , its posterior branch is simple, all intercalary branches are separated from the anterior RS branch.

Figures

FIGURE 1. Triassodotes rasnitsyni sp. nov. Holotype, part PIN N 4887/140. A, Photograph. B, Fore wing. C, Hind wing.