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
Taxonomy. This newly discovered species is very similar to, and has been confused with the closely related P. fuscatus and P. metricus. Females key to either P. fuscatus pallipes (dark specimens) or P. metricus (couplet 15; specimens with well-developed ferruginous markings) in Richards’ (1978) key.
Species recognition. Females differ from all other species of the P. fuscatus-group by the sparser punctation of central areas of sterna 3–5. Females of P. metricus, which rarely also show somewhat sparser punctation on these sterna differ from sp. B. by the more bulging sternum 2. Males differ from other species by the following characters: anterior surface of flagellum dark reddish brown, usually becoming gradually darker brown to black on distal flagellomeres (neither uniformly yellowish as in P. metricus nor yellow with contrasting black apical flagellomeres as in P. fuscatus); rows of ventral teeth of aedeagus not extending basally almost to apex of median expansion of aedeagus (as in P. fuscatus), aedeagal teeth distinctly smaller than in P. fuscatus, slightly smaller than in P. metricus. The colour pattern of females differs from dark varieties of P. fuscatus (“pallipes”) by the entirely ferruginous clypeal disk (lacking black or yellow markings), the presence of a ferruginous dorsal mesopleural spot (spot yellow or absent in “pallipes”), absence of yellow propodeal stripes (often present in “pallipes”). Females (with few exceptions) differ from P. metricus in possessing a large black frontal spot which broadly connects the ocellar area to the antennal bases (interrupted by transverse ferruginous band in P. metricus).
Description. Fore wing length 14.0–17.0 mm (♀♀), 14.0–16.0 mm (♂♂). Female head ferruginous with the following black areas: large frontal spot extending to from ocellar area to antennal bases, sometimes including small ferruginous spots dorsomedially of antennal base (rarely interrupted above antennal bases by transverse ferruginous band), spots connecting antennal base to dorsal margin of clypeus, most of occiput, dorsal surface of antenna; head without yellow markings. Mesosoma black with the following ferruginous markings: pronotal carina often, small to very large spots on pronotum behind carina, dorsal and often ventral mesopleural spot, small ventral metapleural spot rarely, scutal stripes frequently, scutellum and metanotum partly to entirely (scutellum rarely all black), propodeal stripes usually (one or two pairs, rarely stripes on each side coalescent); pale yellow markings very restricted, usually present pronotal carina medially and propodeal valves. Metasoma largely black, ferruginous markings sometimes present on tergum and sternum 1, rarely basolaterally on tergum 2; pale yellow apical fascia usually present on tergum 1, usually interrupted, sometimes evanescent. Legs with coxae black, often marked with ferruginous; femora black, fore femur with ferruginous anterior surface, mid and hind femur with ferruginous dorsal stripes; fore tibia ferruginous, sometimes with black dorsal stripe, mid tibia ferruginous and black, sometimes with yellow base, hind tibia often largely black, usually with more or less yellow base; tarsi yellow to reddish yellow. Male similar to female except following: face yellow, sometimes partly suffused with reddish between and below antennal bases including dorsobasal part of clypeus; small black spots often present above and below antennal bases and on median part of frontoclypeal suture. Mesosoma with ferruginous markings on average less developed: dorsal mesopleural spot sometimes, ventral spot usually absent, scutal and propodeal markings rarely present; yellow mesosomal markings present on venter of mesopleuron (pair of spots behind fore coxae, sometimes coalescent); one specimen with evanescent yellow spots on propodeum. Metasoma usually lacking ferruginous markings; if present including small spot on tergum 1 and in one specimen small discal spots on tergum 2; whitish apical fascia present and well-developed on tergum 1, rarely also on terga 2 and 3 (evanescent on latter); metasomal venter with pale yellow spot at base of sternum 2 (size small to moderate, rarely absent) and pale yellow apical fasciae of sterna 2–5 (often wide on sternum 3; darkest specimens with sternal fasciae absent except for tiny apical spots on sternum 3). Pale yellow spots on fore and mid coxae well developed, small or absent on hind coxa; yellow anterior stripes present on fore and mid femur (sometimes reduced to apical half on latter), usually absent or represented by small basal spot on hind femur; anterior surface of fore, mid and basal half of hind tibiae sometimes yellow, often more or less suffused with ferruginous.
Distribution. Insufficiently known. Not known from Canada. We have examined 9 ♂♂ and 10 ♀♀ from MD, VA and WV.