Extracted from: Timberlake P.H., (1958). A Revisional Study of The Bees of the Genus Perdita F. Smith, with Special Reference to the Fauna of the Pacific Coast (Hymenoptera, Apoidea) Part III. University of Caifornia Press Berkeley and Los Angeles 1958, Volume 14, No. 5, pp. 303-410, plates 4-15.|
In Cockerell's key to Perdita (1896) crassula runs out at couplet 11 containing chamaesarachae and semicrocea, which are only distantly related to this species
Male.—Head and thorax dark green, the mandibles except red tips, labrum, face below level of antennae except the supraclypeal area, and the tubercles white. Abdomen uniformly and somewhat dusky ferruginous. Antennae brown, the flagellum paler beneath, and the scape broadly pale yellow beneath. Legs fuscous, the knees of all legs, front tibiae almost entirely, middle tibiae except a broad mark at middle beneath and behind, and front and middle tarsi pale yellow, the hind tarsi more dusky yellow. Tegulae pale yellow at base and broadly hyaline on outer margin. Wings dusky hyaline, the nervures brown, the subcosta and margins of stigma fuscous.
Head distinctly broader than long, the cheeks not broadened. Mandibles reaching far margin of proboscidial fossa, tapering to acute apex, and with a small inner tooth. Facial foveae very obscure and not certainly detectable. Proboscis not exceeding the proboscidial fossa, the galeae falling far short of base of the stipites when folded in repose. Pterostigma narrow, not more than half as wide as the submarginal cells. Marginal cell with the parts beneath and beyond stigma nearly equal. Abdomen subdepressed and broader than thorax. Frons finely tessellate, dullish, with fine close punctures, the vertex nearly impunctate. Thorax rather shiny, but finely tessellate, the mesoscutum with minute, evenly spaced, and moderately close punctures. Pubescence white, mosslike, that on face subappressed and rather short, the upper part of frons and the vertex nearly nude; hair of mesoscutum moderately short and erect and that of the pleura not much longer. Subgenital plate and aedeagus very similar to same parts in euphorMae and polycarpae but the parameral lobes are more attenunate and a little twisted beyond the middle and extremely fine at apex, and the sagittae lack the group of hairs on the underside near apex.