The Wharton Lab

Rhaestes Foerster, 1869: 198.
Type species: Grypocentrus rufipes Holmgren, 1857. Included in Rhaestus by Thomson (1883).

Rhaestus Thomson, 1883: 924. Unjustified emendation but available as replacement name for Rhaestes Foerster, 1869 not Rhaestus Gistel, 1856

The following 6 valid species were included by Yu et al. (2012):

Rhaestus femoralis Thomson, 1894
Rhaestus grandis (Teunissen, 1953)
Rhaestus lativentris (Holmgren, 1858)
Rhaestus ophthalmicus (Holmgren, 1857)
Rhaestus rufipes (Holmgren, 1857)
Rhaestus testaceipes (Brischke, 1892)

According to Townes (1970), this genus is very similar to Glyptorhaestus except for the absence of a glymma. However, there is a species from Sweden with weakly converging eyes that has wing venation and enlarged hind tibia resembling the species of Syntactus. Nevertheless, the combination of basal depression on the mandible (which Syntactus lacks), absence of a glymma, short S1, and strongly converging eyes in females are sufficient for recognition of all other species of Rhaestus.

Female with inner eye margins strongly converging ventrally (Fig. 3); male only weakly so. Clypeus sparsely setose along midline, often nearly bare elsewhere; ventral margin weakly, evenly convex to nearly truncate, depending on angle of view, blunt but not broadly rounded (Fig. 3); epistomal sulcus distinctly impressed throughout; clypeus in profile weakly protruding. Face densely, usually finely punctate, not granular; frons and vertex finely punctate, sometimes nearly smooth, densely setose. Malar space very short in female, much shorter than half basal width of mandible; distinct in male, about half basal width of mandible. Mandible (Figs 3, 4) relatively short, outer surface distinctly convex, bulging, with strong basal transverse depression; ventral margin rounded, not strongly carinate; ventral tooth slightly longer than dorsal tooth or the two teeth of equal length, ventral tooth slightly narrower than dorsal tooth. Maxillary palp distinctly shorter than height of head; antenna shorter than body in female, nearly equal to length of body in male. Hypostomal carina meeting occipital carina distinctly dorsad base of mandible; occipital carina complete. Epicnemial carina reaching anterior margin of mesopleuron (Fig. 1). Notaulus distinctly impressed, usually extending posteriorly at least to level of tegula. Groove between propodeum and metapleuron broadly u-shaped, readily visible in lateral view; broad, u-shaped groove mid-dorsally between propodeum and metanotum also readily visible in lateral view; pleural carina well-developed, complete; median and lateral longitudinal carinae usually well developed as is lateral portion of posterior transverse carina, more rarely lateral longitudinal carina absent or obscured by sculpture; anterior transverse carina absent, areola not distinct, entire median field often flask-shaped; propodeal surface varying from smooth and polished to finely granular to rugulose as in Fig. 7. Hind femur usually slender; apical margin of mid tibia expanded into a tooth weaker than but similar to that of fore leg; apical comb on posterior side of hind tibia nearly absent; posterior hind tibial spur about 7x longer than maximum width at base, hind tibial spurs almost equal in length; all tarsal claws pectinate, at least in the type species. Fore wing (Fig 5) with areolet usually present, rarely absent; stigma usually short and broad, with Rs+2r arising near midpoint of stigma. Hind wing (Fig. 6) with first abscissa of CU1 longer than 1cu-a. T1 (Fig. 8) evenly broadening, either weakly or strongly, from base to apex; dorsal carinae well-developed to level of spiracle, weaker posteriorly, absent over posterior 0.2-0.3; basal depression at dorsal tendon attachment small; dorsal-lateral carina complete between spiracle and apex of T1; glymma absent. S1 not extending to level of spiracle. T2 thyridium absent. Ovipositor (Figs 1, 9) upcurved, strongly narrowed from moderately large basal swelling, slender throughout; without dorsal, subapical notch.

This description is expanded from that given by Townes (1970), who also included Rhaestus in a key to genera of Pionini.

The genus is Palearctic, recorded from the UK to far eastern Russia.

The following hosts and references for those host records are listed by Yu et al. (2012).

Empria tridens (Hinz 1961)

This page was assembled by Bob Wharton as part of a larger collaborative effort on the genera of Ctenopelmatinae.

This work would not have been possible without the groundwork provided by Ian Gauld’s study of the Australian and Costa Rican faunas, and we are particularly grateful for his assistance in many aspects of this study. We also thank David Wahl of the American Entomological Institute and Andy Bennett of the Canadian National Collection for extended loans of the material used for this study and particularly Dave Karlsson for sending valuable material from the Swedish Malaise Trap Survey (trap 37, collecting event 831). Matt Yoder provided considerable assistance with databasing issues, and our use of PURLs (http://purl.oclc.org) in this regard follows the example of their use in publications by Norm Johnson. Heather Cummins, Andrea Walker, Patricia Mullins, Caitlin Nessner, Amanda Ladigo, and Cheryl Hyde graciously assisted with image processing, formatting, and literature retrieval. This study was supported by the National Science Foundation’s PEET program under Grant No. DEB 0328922 and associated REU supplement #s DEB 0723663, 0923134, and 1026618. Page last updated Jan, 2015.

This material is based upon work supported by the National Science Foundation under Grant Number DEB 0328922 with REU supplements DEB 0723663, 0923134, and 1026618. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.