Arachnospila (Ammosphex) altaica Loktionov, sp. nov.

(Figs 1–13, 20)

Diagnosis. MALE. Sternum 8 (hypopygium) in ventral view spear-shaped, with well developed lateral lobes, long bristles regularly radiating along the margin in apical part, and very dense long somewhat curved bristles in baso-lateral part (Fig. 12). FEMALE. Unknown.

Description. MALE. Length of body 7.5–10.0 mm. Length of fore wing 5.8–7.4 mm. Width of head in frontal view 1.15–1.18 × its height. Ocelli small, ratio POD/OOD 1.0–1.1 ×. Width of gena medially 0.48–0.52 × width of eye medially (head in lateral view) (Fig. 7). Clypeus slightly convex, anterior border hardly emarginate with very narrow smooth rim (Fig. 3). Labrum hardly convex, anterior border straight. Malar space hardly developed (Fig. 7). Length of flagellomere 1 2.1–2.25 × its width. Relation of scape, pedicel and two first flagellomeres length 20: 8: 18: 20. Apical flagellomere pointed on the apex. Pronotum slightly broadened posterad, its posterior border distinctly angulate (Fig. 4). Length of metanotum medially 1.5 × length of metapostnotum. Metanotum posteriorly slightly overhanging anterior portion of metapostnotum (Fig. 6). Metapostnotum matt, with delicate transverse striae anteriorly, its posterior border with median smooth shiny impressed triangle. Length of propodeum medially 0.75 × its maximum width. Wings slightly infuscated; fore wing with darker apical part (Figs 1, 2); hind wing as in Fig. 1. Posterior border of sternum 6 arcuately emarginated. Sternum 7 as in Fig. 13. Sternum 8 (hypopygium) in ventral view spear-shaped, with well developed lateral lobes, long bristles along margin in apical portion, and dense long somewhat curved bristles in baso-lateral part (Fig. 12); with preapical tuft of long bristles ventrally (Fig. 11). Genitalia as in Figs 8–10.

Frons and gena with scattered erect pale rather long setae. Mandible with few strong curved setae. Fore coxae posterior face with several long erect setae. Other body parts lacking setae, except single erect setae on pronotum posteriorly and propodeum postero-laterally. Low frons with iridescent brownish pubescence (Fig. 3), sometimes covering lateral sides of clypeus. Body and legs with brownish micropubescence. Body regularly micropunctate. Body and legs black except following: mandible brownish preapically; tergum 1 posterior half, tergum 2 (except apical portion) ferruginous-red (Fig. 1).

Type material. Holotype, ♂, RUSSIA, Altai Republic, Tydtuyaryk River valley, 50°04’N, 88°25’E, altitude 1800 m, 18.VI.2022 (MP) [FSCV] . Paratypes, 2 ♂, RUSSIA, the same locality, 14, 22.VI.2022 (MP) [FSCV] .

Distribution. Russia: Western Siberia (Altai Republic).

Etymology. Named after Altai, the mountain region of Western Siberia (Russia), where this species was discovered.