Chalcis Fabricius 1787

Chalcis Fabricius, 1787

Type species Sphex sispes Linnaeus, 1761, by subsequent designation of Westwood (1839: 65).

Chalcis Fabricius, 1787: 272.

Smiera Spinola, 1811: 147. Type species Sphex sispes Linnaeus, 1761, by subsequent designation of Curtis (1833: 472). Synonymy by Gahan & Fagan (1923: 31).

Smicra Spinola, 1837: 1. Unjustified emendation of Smiera.

Diagnosis. Both sexes. Mandibular formula 2:3 or 3:3, the upper tooth larger and longer than the others; mesocoxa with short pubescence dorsolaterally; mesotibial spur at most as long as apical width of mesotibia, occasionally absent. Female. Tarsal claws usually slightly curved (Figs 1e, 6a), sometimes falcate (Fig. 11f); hypopygium with median portion narrowly extended posteriorly with median portion distinct from the lateral areas (Figs 2c, 4c, 6d, 9d, 12c, 15e, 20a), or thickened but only slightly extended posteriorly beyond the adjacent margins (Fig. 21a). Male. Tarsal claws almost always bifid apically (Fig. 10c); hypopygium enlarged, flat or concave, with distal margin truncate (Fig. 13b) to notched (Figs 7d, 10d, 16c).

Biology. Few host records known, these as egg-pupal or larval-pupal parasitoids of Stratiomyidae (Diptera) (Hart 1895; M̹ller 1908; Schremmer 1960; Cowan 1979).

Distribution. Most species on Northern Hemisphere, but present on all continents except Antarctica (Noyes 2020).

Remarks. Chalcis can be distinguished from other genera of New Word Chalcididae using the key of Bouček (1992). Among Chalcidini, only females of Chalcis and Melanosmicra Ashmead have the posterior margin of the hypopygium medially setose and distinctly produced posteriorly (Figs 2d, 4c, 6d, 9d, 12c, 15e, 20a), usually reaching the apex of the gaster. Species of both genera also have mandibles that lack a ventral lamina, the upper tooth longer than the lower teeth (except a few Melanosmicra species in which the lower tooth is the longest), and a relatively long petiole and short gaster (Figs 3a, 5a). Species of Chalcis differ from those of Melanosmicra by the female hypopygium having the median portion extended posteriorly as a narrow projection (Figs 2d, 4c, 6d, 9d, 12c, 15e, 20a) or with the median portion distinct from the lateral areas, thickened but only slightly extended posteriorly beyond the level of adjacent margins (Fig. 21a) (posterior margin angled or bilobed in Melanosmicra); hypopygium of males comparatively large, flat or concave, and with distal margin truncate (Fig. 13b) to notched (Figs 7d, 10d, 16c) (hypopygium surface and distal margin convex in Melanosmicra); mesocoxa with short pubescence on dorsolateral surface (with few long, erect bristles in Melanosmicra); mesotibial spur absent or when present at most as long as the apical width of the mesotibia (longer than apical width of mesotibia in Melanosmicra); and metafemur usually without inner basal tooth ventrally or, if present, inner tooth short and triangular (Fig. 18a) (almost always spinelike and curved in females of Melanosmicra). The shape of tarsal claws has also been used to differentiate Chalcis species. In females, the claws have been most commonly described as slightly curved (Figs 1e, 6a, 8f, 9a, 14f, 15a) but in some species the claws are falcate (Figs 3f, 11f). In males, the tarsal claws are usually pectinate basally and almost always bifid apically (Figs 7c, 10c).

In addition to external morphology characters, Delvare (1992) lists the following features of the male genitalia as diagnostic to Chalcis: phallobase with dorsal expansion, emarginate apically, completely open ventrally, ventral frame most often present, median ventral lamina narrow, without incision on each side of the median ventral lamina; aedeagus with dorsal and sometimes ventral expansion. For comparison, in his diagnosis for Melanosmicra, he lists the phallobase closed ventrally at least along half length; ventral frame more or less obsolete or absent; median ventral lamina normal; phallobase emarginate or slightly incised near median ventral lamina; digiti normal, not narrow and not emarginate on outer edge; aedeagus short and rounded at apex.