Euodynerus sp. G

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

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36. Euodynerus sp. G

Figs B5.37, 39, 61; C36.1–4.

Rygchium boscii boscii sensu Bohart, 1939a, nec (Lepeletier, 1841) (partim)

Euodynerus auranus aquilus Bohart in Bohart & Menke, 1974 (partim, excluding type material)

Taxonomy. This undescribed species has previously been confused with its western sibling species E. auranus. Bohart (1939a) included in his concept of “E. boscii boscii” (misidentification) both Euodynerus sp. G as well as northeastern, southeastern and Mexican fringe populations of E. auranus (specimens from MI, TX and Coahuila, Mexico). After recognising the true identity of E. boscii (a valid species, see above) Bohart (in Bohart and Menke 1974) described the nameless entity as E. auranus aquilus Bohart. His concept of the subspecies remained more or less unchanged, i.e., he continued to include both eastern/southern E. auranus and Euodynerus sp. G under the new name. However, the holotype (examined, UCDC) and all 17 paratypes (8 examined, UCDC) pertain to southeastern populations of E. auranus, still leaving the eastern sibling species of E. auranus, Euodynerus sp. G, without a name.

Except in the south, the two species appear to be well separated geographically. There are no records of either of the two species between southwestern Ontario and Long Island, New York, or between the Appalachians and the Mississippi River. In Texas, however, both species occur in very close proximity even though a range overlap has not yet been detected.

Separate species status for the two species appears not only justified because of the subtle yet reliable morphological differences but also because of the strikingly different colour patterns in the southern contact zone. E. auranus occurs in a multitude of very divergent geographic colour forms throughout its extensive range, some of which (i.e., the northeastern form that occurs in Ontario and Michigan) are practically identical to the typical colour form of Euodynerus sp. G. The latter shows little variation except for a more extensively red-marked form from peninsular Florida. In Texas, where the ranges of the two species meet, E. auranus occurs in a form with abundant yellow and ferruginous markings (e.g., 1 ♂, Austin, UCDC), whereas Euodynerus sp. G maintains its largely black colour with restricted yellow and ferruginous markings (1 ♂, Lee Co., located just east of Austin; UCDC) that is typical for most of its range. The close proximity of such divergent colour forms can probably be taken as a good indicator for the genetic isolation between the two species.

Species recognition. See under E. auranus.

Variation. Fore wing length 7.5–8.5 mm (♂♂), 8.5–11.0 mm (♀♀). Punctation of tergum 1 somewhat variable, quite sparse. Apical reflex and punctation of apical fascia of tergum 2 also variable, on average stronger in male than in female. Female clypeus either with a pair of more or less separated basal yellow spots or a large basal crescent-shaped mark; apex narrowly reddish to yellowish, sometimes with small yellow spot(s). Interantennal spot of female entire, in male extending to clypeus but either narrowed or interrupted below prominence. Mandible largely reddish in female, with yellow basal spot. Spot on upper mesopleuron sometimes absent in male. Scutellum with a pair of yellow spots (sometimes suffused with ferruginous), occasionally absent in male. Metanotum black in specimens examined by us. Yellow propodeal spots usually large, sometimes smaller in male. Metasomal terga 1–3 with yellow apical fasciae in female; in male terga 1(–3)–4 fasciate. Tergum 1 usually with very restricted ferruginous markings, sometimes better developed on lateral forward extension of apical fascia. Sternum 2 with yellow apicolateral spots in female, other sterna black; in male fasciae usually complete on sternum 2 and sometimes 3.

Distribution. Not recorded from Canada. We have examined material from the following states in the U.S.: MA, NY (Long Island), NJ, VA, WV, GA, FL and TX (Lee Co.). Bohart’s (1939a) records (as E. “boscii boscii”, misidentification) pertain in part to E. auranus (records from MI, Austin, TX and Mexico), in part to this new species (NJ and MA).

Biology. Unrecorded. Based on the presence of rake setae on the female fore basitarsus and the close relationship with E. auranus (see above) there is little doubt that this species is ground-nesting. Very likely the nest is built in sandy soils as is the case in E. auranus (see also General Part – Morphology).

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ISSN 1911-2173

Canadian Journal of

ARTHROPOD IDENTIFICATION