Synonyms and other taxonomic changes
Cresson, 1863 [Detailed original description
Pseudomasaris vespoides robertsoni
Cockerell, 1913 [Brief original description
A sharp transverse ridge right above the antennal sockets sets females of this species apart from all other Pseudomasaris.
Males can be separated from their congeners by the antennal club being longer than antennal segment III, and concave on the underside. Also, gastral tergite VII (almost always) has a pair of dorsal tubercles. Fore basitarsus with a long posterior fringe; hind basitarsus is curved and distally lobed.
(Above based on Richards, 1963, and 1966; see references)
Pale markings tend to be less extensive in individuals of northerly populations; they're also more whitish than yellowish. (Information from Roy Snelling, Natural History Museum of Los Angeles County; personal communication-HW)
Photos of males:
Western USA (AZ, CA, CO, ID, MT, NE, NM, NV, OR, SD, UT, WA, WY), to Baja California (Mexico).
Adults are found on or near various species of Penstemon, where they feed on nectar, and the females collect pollen for their larval brood cells.
Richards, O.W. The species of Pseudomasaris Ashmead (Hymenoptera, Masaridae). U.C. Press. 1963
Richards, O.W. New records of Pseudomasaris Ashmead (Hymenoptera: Vespoidea, Masaridae), with notes on P. phaceliae Rohwer and P. cazieri R.M. Bohart. Proc. Royal Ent. Soc. London (B), 35 (3-4), pp. 47-55. 1966
Torchio, Philip F. 1974. Mechanisms Involved in the Pollination of Penstemon Visited by the Masarid Wasp Pseudomasaris vespoides (Cresson). The Pan-Pacific Entomologist 50:226-234.