Hylaeus (Nesoprosopis) pectoralis Förster, 1871

Hylaeus pectoralis Förster, 1871: 972, ♀ (type locality: unknown, MNHN Paris). Hylaeus kriechbaumeri Förster 1871: 973, ♀, Ƌ (type locality: München, Germany). Prosopis palustris Perkins 1900: 49, ♀, Ƌ (type locality: England).

Material examined. Mongolia. Dornod Aimag: 1 ♀, 13 km W Dash-Balbar, Uldzy River, 24.VIII.1975, EN (ZISP).

Distribution in Mongolia. * Dornod Aimag (Fig. 3 h).

General distribution. Transpalaearctic, from the Pyrenees to Japan; missing in southern Europe, north to 61° in Finland. This species nests in abandoned reed galls of Lipara flies ( Diptera: Chloropidae), and because of this specific ecological requirement it is only locally recorded. New to * Mongolia.