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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

 

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13. Ancistrocerus sp. A
Figs B3.15, 43; C13.1–5.

Ancistrocerus sp. A Ancistrocerus sp. A Ancistrocerus sp. A
Ancistrocerus sp. A Ancistrocerus sp. A Ancistrocerus sp. A Ancistrocerus sp. A

Taxonomy. See notes on the taxonomy of A. catskill and related species.

Species recognition
. At present the males of this species cannot be separated with confidence from A. catskill. The female is similar to A. albophaleratus and A. catskill. From the former it differs by the following characters (besides those mentioned in the key): pale spot on tergum 6 present (tergum 6 and often 5 completely black in A. albophaleratus), sternum 5 often with a pair of apicolateral pale spots (absent in A. albophaleratus), clypeus with a pair of spots in ventral half (usually absent in A. albophaleratus).

Variation (females only). Fore wing length 7.5–10.0 mm. Pale markings of body ivory, those of head and scape rarely distinctly yellowish. Clypeus with a pair of dorsal and a pair of ventral spots, the spots fairly often coalescent ventrally less commonly laterally, rarely both laterally and ventrally. Scape usually with an anterobasal and/or a ventrodistal spot (often confluent), when confluent and well-developed, always with a fairly abrupt narrowing near middle; sometimes scape nearly completely black. Pedicel usually dark beneath, sometimes more or less yellowish. Pronotal band rarely interrupted laterally, in western specimens lateral portions rarely absent. Spot on upper mesopleuron rarely absent. Pair of pale scutellar spots usually large, rarely small (especially in western specimens). Metanotal band usually at least narrowly interrupted medially, sometimes reduced to small, irregular evanescent spots or completely black (the latter only seen in western specimens). Propodeum usually black, rarely with a pair of small, pale spots at (and sometimes below) propodeal angle. Metasomal terga 1–5 fasciate, tergum 6 with a well-developed pale spot. Sternum 1 usually without fascia, if present often indistinct; fascia of sternum 2 usually complete; sternum 3 with apicolateral spots, sometimes with incomplete fascia, rarely with complete fascia; sternum 4 always and 5 sometimes with apicolateral spots, sternum 4 rarely also with apicomedian markings. A rare melanic variety lacks the spot on tergum 6 (1 ♀, QC, Kazabazua, CNCI) and sometimes also pale markings of tergum 5 and sternum 4 (1 ♀, ON, Pukaskwa Natl. Pk., DEBU). It is not clear whether these specimens are conspecific with Ancistrocerus sp. A.

Distribution. Canada: all provinces and territories except LB, NU. Eastern and northern U.S.: NY, AK, ID and CO (identification of specimens from CO tentative).

Biology. A series of specimens from Nyack, NY (AMNH) is labelled “ex Amphibolips confluentus”. This Cynipidae species causes oak apple galls from which the specimens were apparently reared. One female (NS[?], “N Sawler East”, CNCI) is pinned with an unidentified caterpillar.

 

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