Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region
Matthias Buck, Stephen A. Marshall, and David K.B. Cheung
Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Taxonomic note. Previously published keys (e.g., Bequaert 1940a, Richards 1978) fail to separate this species from P. fuscatus. While the typical, extensively ferruginous, colour form from the southeast is easily distinguished from P. fuscatus, northern specimens (which are much darker) are extremely similar to certain sympatric colour forms of P. fuscatus. We have examined females of P. fuscatus with strikingly bellicosus-like colour patterns from as far north as Ontario. Based on the newly discovered character of male flagellum colour (see below) males of both species can now be separated without difficulty.
Discussion. The present definition of P. bellicosus significantly expands the previous concept of the species (e.g., Richards 1978) by including forms with predominantly black mesosoma, which were usually misidentified as P. fuscatus. The original description of P. bellicosus (based on specimens from Texas, see Cresson 1872) mentions a black median stripe of the propodeum as the only black colour element, and black markings are not mentioned at all in Richards’ (1978) subsequent diagnosis. Separation of dark males of P. bellicosus from P. fuscatus was possible through the discovery that all-dark apical flagellomeres are diagnostic for P. fuscatus. Cresson (1872) noted that the flagellum of male P. bellicosus was “pale beneath, dark above”, but subsequent authors did not realize the importance of this character.
Species recognition. Males of P. bellicosus and P. metricus can be distinguished from P. fuscatus males by the concolorous orange to ferruginous tyloids (in P. fuscatus tyloids of apical flagellomeres are considerably darker than the basal ones) and the yellowish to ferruginous anterior surface of apical flagellomeres (dark brown to black in P. fuscatus). The male of P. bellicosus possesses a yellow dorsal mesopleural spot (absent in P. metricus) and yellow apical fasciae on at least terga 1–3 (on tergum 1 at most in P. metricus). Females differ from most P. fuscatus females by the ferruginous hind trochanter and femur (lacking black or brown markings; see key), and the well-developed yellow markings (especially on clypeus). Polistes bellicosus can be distinguished from the largely ferruginous P. carolina and P. perplexus by its well-developed yellow markings.
Redescription. Fore wing length 13.0–17.5 mm (♀♀), 14.5–17.0 mm (♂♂). Female. Head ferruginous, with the following black markings: rectangular ocellar spot, in southern specimens often reduced to narrow area around ocelli, sometimes completely absent; small spots frequently above and below antennal sockets, the former rarely connected to ocellar spot. Dorsal surface of antenna including apex of scape usually more or less darkened. Mesosoma of northeastern specimens black, with the following ferruginous markings: at least dorsal half of pronotum, usually lateral areas in front of pronotal carina, usually small stripe bordering yellow dorsal mesopleural spot anteriorly, sometimes ventral mesopleural spot, usually stripes on scutum (often coalescent posteriorly), most of scutellum and metanotum, more or less extensive areas of propodeum, varying from small margins around yellow stripes to most of propodeum (propodeum rarely entirely black marked with yellow). Mesosoma of southern specimens (i.e., typical form) largely ferruginous with black markings reduced to sutures and median stripes of scutum and propodeum. Metasoma largely ferruginous, often with incomplete median stripe on tergum 1 and narrow basal bands on terga 2–4, often triangularly produced on tergum 2; sterna (especially 1 and 2) also often with black basal areas. Legs largely ferruginous; coxae usually with small to moderate-sized black spots on posterior surface, rarely with small spots on anterior surface (largest on fore coxa); fore and mid femora sometimes with small black posterobasal spots; hind tibia almost always with black or brownish posterodorsal apical spot, sometimes dorsal surface more or less brownish. Yellow markings usually well developed including at least half of surface of clypeal disc, mandibles, inner orbits, sometimes transverse supra-antennal stripes (if present often more or less suffused with ferruginous); gena along posterior eye margin at least in ventral half and usually most of malar space (rarely gena almost completely ferruginous); pronotal carina and pronotal hind margin; scutellum and metanotum anteriorly; upper mesopleural spot (exceptionally evanescent), often small subalar area of metanotum; paramedian propodeal stripes (exceptionally absent), rarely also lateral stripes (more common in specimens from southwestern part of range); coxae almost always with yellow markings; femora, tibiae and tarsi also marked with yellow; apical fasciae on metasomal terga 1 to 3, 4 or 5 (rarely well developed on terga 1 and 2 only and evanescent on 3), exceptionally discal spots on tergum 2; apical fasciae of sterna 2–(3)4, usually more or less broadly interrupted medially; exceptionally sterna without yellow markings. Male differs from female as follows: yellow markings better developed including most of face below top of ocular sinuses; ventral and anterior surface of mesopleuron, most of fore and mid coxa, and larger areas on femora and tibiae; often subbasal spot on sternum 2; yellow propodeal stripes sometimes absent. Black markings often better developed than in female, sometimes including entire propodeum; metasoma with black basal marks of terga 1–3 sometimes (almost) extending to yellow apical fascia.
Distribution. Canada: first recorded from Ontario, apparently adventitious (1 ♀, Chatham; CNCI). Eastern U.S.: newly recorded from NY, Long I. (1 ♂, USNM); NJ, Island Beach (3 ♀♀, USNM); DE, New Castle Co., Cedar Swamp Wildlife Area (1 ♀, DEBU); MD, Anne Arundel, Calvert, Talbot and Worcester Cos. (17 ♂♂, 21 ♀♀; DEBU, USNM); DC (1 ♂, 1 ♀, USNM); VA (all USNM), Tangier I. (1 ♂), Dyke (1 ♀), Cole’s Point (1 ♀), Cape Charles (2 ♀♀), and Norfolk (1 ♀); previously known from NC to FL and Gulf Coast states west to TX (Richards 1978). All new records are from coastal areas, except for the specimen from Dyke, VA.
Biology. Undescribed. One of us (S.A.M.) observed and photographed three different nests of this species on a pine branch, on a bare twig of a shrub and under an eave (Fig. 71.6) in Charleston Co., South Carolina.