Thyreosthenius parasiticus Westring 1851

Thyreosthenius parasiticus (Westring 1851)

(Figs 37–40)

Material examined.— Canada: Québec: Brome­Missisquoi, Saint­Armand [45°02’N, 73°03’W] 04.ix.2000, hand collecting under bark of dead tree, 1Ψ, N. Dupérré & P. Paquin (CPAD); Longueuil, Boucherville [45°36’N, 73°27’W] 01.x.2000, hand collecting under bark, 1Ψ, C. Chantal (CPAD); Brome­Missisquoi, Saint­Armand [45°02’N, 73°03’W] 19.ix.2004, hand collecting under wood beams, 1ɗ 2Ψ, P. Paquin & N. Dupérré (CPAD); Gatineau, Aylmer [45°23’N, 75°49’W] 20.x.1989, hand collecting in wood chips, 2Ψ, L. LeSage (CPAD); Parc de la Gatineau, Lac Brown [45°36’N, 75°55’W] 21.xi.1991, leaf litter on margin of the lake, 1ɗ 1Ψ, R. Hutchinson & L. LeSage (CNC).

Diagnosis.— The males are recognised by the long curved embolus (E) (Fig. 37), the pointed anterior radical process (ARP) (Fig. 37), and the shape of the palpal tibia (Fig. 39). Females are recognised by the presence of a cusp­shaped knob (arrow) on the anterior portion of the epigynal plate (Fig. 40), and the oblique slit­like copulatory openings (CO) (Fig. 40).

Distribution.— Palearctic. In North America, the species is found on the eastern side of the continent from Newfoundland to Wisconsin, south to Ohio. An isolated record is known from Washington (Crawford 1988).

Remark.— The occurrence of the species in Québec was suspected by Hutchinson & Bélanger (1994) who reported its occurrence from habitats related to forest and decaying wood, which is supported by the records given here. Interestingly, all the above specimens were collected in late summer–early fall.