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Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region
CJAI 05, February 19, 2008
doi: 10.3752/cjai.2008.05

Matthias Buck, Stephen A. Marshall, and David K.B. Cheung

Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1

 

67. Zethus spinipes Say, 1837
Figs A4.5–6; B2.2, 4, 6, 31; C67.1–7.

Zethus spinipes
Zethus spinipes Zethus spinipes Zethus spinipes
Zethus spinipes Zethus spinipes Zethus spinipesZethus spinipes

Species recognition. Zethus and Eumenes are the only eumenine genera with a petiolate metasoma in the northeastern Nearctic. Besides characters already mentioned in the generic key Z. spinipes differs from the eastern Nearctic species of Eumenes as follows: distance between hind ocelli and occipital carina more than twice the distance between hind ocelli (distance between hind ocelli subequal to distance between ocelli and occipital carina in Eumenes); notauli present and almost extending to middle of scutum (absent in Eumenes); tegula elongate, ca. twice as long as broad (short, less ca. 1.5x as long as broad in Eumenes); omaulus present (absent in Eumenes); valvula of propodeum largely free dorsally (fused dorsally along its whole length to submarginal carina in Eumenes); outer surface of female mid and hind tibia with short, blunt, flattened spines (absent in Eumenes); male hind basitarsus wider than tarsomere 2 and with a dense brush of short hair on ventral surface (unmodified, its width subequal to tarsomere 2 in Eumenes).

Variation (partly after Bohart and Stange 1965). Fore wing length 9.5–11 mm (♂♂), 12–14 mm (♀♀). The extent of pale markings varies considerably. Southern populations (ssp. variegatus) have more extensive pale markings. Females of the nominate subspecies vary from being almost completely black (except a narrow apical fascia on tergum 1) to possessing small ivory markings on frons (a pair of interantennal spots), mandible, pronotum, upper mesopleuron, scutellum, metanotum, propodeum, tergum and sternum 2 (apical fascia). In the male, pale markings may or may not occur on the legs and one or more terga beyond tergum 2.

Distribution. Not recorded from Canada. Eastern U.S.: MA, NY (Westchester Co.), PA (Pike Co.), OH (Hocking Co.), IL and WI (new state record; 1 specimen, Cross Plains, Dane Co.; photographic record, Bugguide) south to FL, west to KS, OK and TX (Bohart and Stange 1965, Krombein 1979). The ssp. variegatus de Saussure, 1852 occurs from MD southward.

Biology. Poorly known. According to Ashmead (1894) the cells of Z. spinipes are attached to twigs. This observation is very likely due to confusion with Eumenes (see Grissell 1975). Other species build their nests in twigs and borings in wood. One species of Tortricidae (Olethreutinae) has been recorded as prey of ssp. variegatus (Krombein 1979).

 

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Zethus spinipes Zethus spinipes