Extracted from: Timberlake P.H., (1962). 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 V. University of California Publications in Entomology Editors, Volume 28, No. 1, pp. 1-124.|
This species and fulvicauda differ from others of the group in having the face depressed, the frons and mesonotum closely punctured and unusually hairy, and the mesonotum entirely green and polished. The female of erythropyga collects pollen from Dalea.
Female.—Head and thorax dark green; labrum and clypeus blackish. Usually a small spot at anterior end of lateral plates of face adjacent to clypeus, rarely a short median streak on upper part of clypeus, and basal half of mandibles, white; mandibles shading into red at apex. Thorax entirely dark. Abdomen, including venter, dark fuscous or blackish; apex of tergite 6, tergite 7, and last two segments of venter, reddish ferruginous; a rather narrow enclosed white band at base of tergites 2 to 4, often medially notched or slightly interrupted. Legs black, or tinged with brown; middle tibiae brown; anterior side of front tibiae yellow; sometimes middle tibiae more or less, and front tarsi, yellowish tinged above with brown. Antennae blackish, flagellum brownish bneath. Proboscis dark. Tegulae subhyaline, with a basal brown mark margined with yellowish white. Wings hyaline, nervures testaceous, subcosta and margins of stigma brown.
Head as broad as long; face unusually depressed, especially above level of antennae. Clypeus moderately convex, disk much broader than high, and broadly truncate apically, the lateral extensions strongly reflexed. Facial f oveae twice as wide as space between them and eyes and reaching from level of middle of antennal sockets about two-thirds of distance to level of anterior ocellus. Proboscis moderately long, apex of galeae reaching base of stipites in repose. Mandibles moderately stout, with a well-developed inner tooth, and reaching far margin of proboscidial fossa. Pterostigma about three times as long as wide, three-fourths as wide as first submarginal cell; parts of marginal cell beneath and beyond it about equal. Inner tooth oftarsal claws about half as long as outer tooth. Pygidial plate as broad as long and broadly rounded at apex. Head and thorax polished, with frons and vertex tessellate and somewhat dullish, base of propodeum weakly tessellate. Puncturation strong but fine, rather dense on frons, moderately close on face below antennae and on mesonotum. Pubescence white, short, erect, and rather dense on frons, sparser on mesonotum, considerably longer on cheeks, front coxae, mesopectus, and ridges of propodeum. Length: 5-6 mm.; anterior wing, 3-3.6 mm.
Male.—Head and thorax dark green. Narrow line on posterior orbits nearly reaching middle of eye, mandibles except red tips, labrum, and most of face below level of antennae, yellow. Lateral marks of face much narrowed above and going somewhat above level of antennae; the green of frons descending on each side in a sharp point to middle of outer margin of subantennal plates. Upper middle of disk of clypeus sometimes with two fuscous marks. Tergites 1 to 4 blackish (sometimes with a distinct greenish luster) and with whitish or testaceous apical depressions; an interrupted yellow band often present on tergites 2 to 4, or only on 2; venter and tergites 5 to 7 fulvous, tergite 5 sometimes more or less infuscated. Legs fuscous, anterior side of front and middle legs except middle coxae, underside of hind tibiae, and small spot on anterior side of hind femora at apex, yellow. Antennae brown above, becoming darker toward base, scape broadly clear yellow, flagellum brownish yellow beneath. Tegulae and wings as in female, except subcosta and margins of stigma darker brown.
Head as broad as long, rotund and not enlarged; cheeks as broad as eyes. Disk of clypeus somewhat less than twice as broad as high, and lateral extensions broad and moderately reflexed. Facial foveae faint, close to margin of eyes, and about three times as long as high. Mandibles tapering from base to acute apex and reaching far margin of proboscidial fossa. Antennae about normal length, but rather incrassate, with joints of flagellum except first and last broader than long. Flanks of pronotum normal. Tarsal claws much larger than in female; inner tooth almost as long as outer tooth, becoming wider toward its base. Sculpture and pubescence about as in female. Tergite 7 produced apically into a broad ogival lobe, convex above. Subgenital plate distinctively quadrate at base with long acuminate median lobe, pubescence of disk extremely fine and short. Aedeagus rather large, with dorsal lobes of caulis divergent, rather short and obtuse at apex in both dorsal and lateral views; volsellae large, well exposed, and armed with numerous fine tubercles, those on inferior pair running in several rows on outer surface of plate, instead of on dorsal margin, and some bearing an extremely fine short seta; parameral lobes almost hairless, about as long as caulis, slenderly subfusiform as seen from above and tapering in lateral view; sagittae stout, expanding in apical half, where the rods spread apart, apex of rods acute in both dorsal and lateral views. Length: 3.5-5 mm.; anterior wing, 2.9-3.6 mm.