Unturella truncata Shcherbakov 2022, sp.n.

Figs 1–8.

Unturella truncata Shcherb.: Kazakov et al., 2002: 160 (nomen nudum)

Unturella truncata Shcherb.: Varganov et al., 2015: 127 (nomen nudum)

MATERIAL. Holotype PIN 2989 /1±, complete tegmen (clavus separated; M-CuA area crumpled, so that apical margin seems oblique), Untuun-2, left bank of Untuun R. (left tributary of Kochechumo R.) against mouth of Khoktokon R., Evenkiysky District, Krasnoyarsk Krai; Bugarikta, Nidym or lower Kochechumo Formation (Agitkan Horizon), terminal Permian (Changhsingian) or basal Triassic; paratypes PIN 5382 /98±, 100±, 101±, 104±, incomplete tegmina (clavus missing), Khungtukun-2, right bank of Nizhnyaya Tunguska R. 4.9 km ESE from mouth of Khungtukun R., Evenkiysky District, Krasnoyarsk Krai; Bugarikta Formation (Khungtukun Horizon [Sadovnikov, 2015]), terminal Permian (Changhsingian).

DESCRIPTION. Tegmen 12.0– 13.5 mm long, elongate (2.7:1), transversely truncate apically, with distinct apex and tornus (posterior apical angle). Costal margin convex near base, nearly straight (not concave) distally; precostal carina narrow except near base; CP long, strong; bSc long, low arched. R stem arched forwards proximally, as long as RA to dSc. dSc very long, slanting, continuing proximal RA. RA with 2–3 postnodal branches less oblique than dSc; prenodal branches barely visible or absent. RP with small fork. M forked distal to CuA, pectinate backwards, with 3 main branches, M1 with small fork. Basal cell long, closed with arculus. CuA fork long, CuA1 arched forwards, CuA2 joining margin distant from claval apex. Three crossveins. Claval veins widely separated, nearer to sides of clavus; Pcu gently curved, joining margin about 2/3 clavus length. Tegmen entirely covered with fine punctures on upperside (coarser on clavus) and stub-like microtrichia on underside (apparently forming plastron). In costal area near base these microtrichia merge into closely packed microscopic ridges covering elongate oval fingerprint-like area (strigil) about 1.3 x 0.6 mm; ridges more dense in proximal part of strigil (10 per 100 µm) than in its distal part (6.5 per 100 µm) Ambient vein not corrugated; marginal membrane narrow. Tegmen brownish, more so towards base, especially in costal area and on clavus; precostal carina dark brown.

ETYMOLOGY. Latin truncatus (truncated).