Species account taken from "A Revision of Perdita (Xerophasma) Timberlake (Hymenoptera: Andrenidae) Author(s): TERRY GRISWOLD & WENSDAE MILLER Source: Zootaxa, Vol. 2517, (June 24, 2010), pp. 1-14"
Female. Length: 6.5–8.0 mm. Forewing length: 4.5–5.0 mm. Head, mesosoma dark brown except: cream-colored on mandible basally, lateral margin of clypeus, paraocular area below level of antennal socket, flagellum ventrally, pronotum dorsally, pronotal lobe, tegula, sometimes scutellum; dark reddish brown on labrum, mandible apically; greenish metallic reflections on dark areas of head and mesosoma except barely visible on mesoscutum medially; scutellum sometimes caramel-colored. Legs cream-colored except: light brown on coxae, fore and midfemora basoventrally, midtibia dorsally, mid tarsi except midbasitarsus ventrally, hindtibia; dark brown on hind tarsi. Costal vein, prestigma dark. Stigma with brown margins, center clear. Brown apical bands on T2-T4 or T5. Frons reticulate but shiny. Mesoscutum, scutellum dull, very sparsely, indistinctly punctate. Hair on mesoscutum sparse, except for dense, short hair anterior to scuto-scutellar suture.
Mandible with preapical tooth. Labrum with apical margin scarcely convex. Clypeal width dorsally 1.5–2X as wide as subantennal area. Frontal line slightly raised halfway to median ocellus then slightly depressed to median ocellus. Facial fovea dull, linear, densely pubescent, extending from middle of antennal socket 2/3 or more of distance to median ocellus. Ocellar area not inflated. Median ocellar diameter equal to 1/5 width of frons. Length of vertex behind lateral ocellus less than ocellar diameter. Forecoxa, mesepisternum ventrally with long, simple, erect, apically bent hair. Length of marginal cell on wing margin less than or equal to 1.5 apical width. Pygidial plate acutely angled.
Male. Length: 5.5 mm. Forewing length: 4 mm. Head, mesosoma black except: cream-colored on clypeus, paraocular area below level of fovea, spot medially on supraclypeal area, subantennal area, flagellum dorsally and basally, sometimes along dorsal margin of eye, pronotum except dark spot anterior to pronotal lobe, mesepisternum ventrally near forecoxal cavity. Slight metallic green reflections on dark integument of head, almost no metallic reflection on mesoscutum or mesepisternum. Foreleg, midleg entirely caramel colored except tibiae with brown posterior longitudinal stripe, faint on foreleg. Hindleg caramel-colored except hindfemur dark distally and dorsally, hindtibia, hindbasitarsus and hindtarsi brown dorsally. Brown bands apically on otherwise cream colored terga. T2 lateral fovea forming fine dark line. Sculpture, punctation, pubescence as in female except mesoscutum, scutellum polished.
Clypeal width dorsally greater than width of subantennal area. Supraclypeal area not protuberant, without tuft of hair. Facial fovea appearing glabrous, indistinct, barely visible as small, slight oval indentation where light and dark markings meet. Frontal line, ocellar diameter, forewing as in female. T7 with pygidial plate ill-defined, without apical tuft of hair protruding from beneath apical margin. S8 as in Fig. 16. Genitalia as in Figs. 6, 11.
Type material. Holotype female: USA NEVADA, Clark County, St. Thomas Gap, 36°24.35' N 114°5.62' W, 8 Jun 1998, Camissonia, T. Griswold. Paratypes: NEVADA, Clark County: 1 male, 6 females, same label data as holotype; 1 female, Grand Gulch Road, 22 air mi S Mesquite, 11–21 May 1983, F. D. & J. H. Parker; 4 females, Mesquite, 25 May 1973, Oenothera, G. Bohart; 3 females, same except 8 May 1994, Oenothera, P. Torchio, D. Veirs; 4 females, Toquap Wash, W Mesquite, 36°46'34"N 114°11'10"W, 24 May 2003, Camissonia, D. Yanega; 3 females, Toquap Wash, 1 mi N Hwy I-15, 485 m, N36°46'39" W114°11'10", 25 May 2003, Camissonia, D. Yanega. Holotype deposited in the U.S. National Pollinating Insects Collection, Logan, Utah; paratypes in Logan and Riverside.
Diagnosis. Perdita celadona differs from other Xerophasma by the darker body and truncate rather than rounded or angled apical margin of the labrum. The female pygidial plate is pointed, rather than rounded or truncate as in other Xerophasma, and the mandible has a preapical tooth whereas other species lack a preapical tooth.
Range. Apparently endemic to the eastern Mojave Desert in Clark County, Nevada (Fig. 26) where it was active at dusk. Known only from the Virgin River drainage ranging from Mesquite south to St. Thomas Gap. Specimens labeled as collected on Oenothera are actually on plants now assigned to Camissonia (F. D. Parker, personal communication).
Variation. A single female from Mesquite has the dark clypeus interrupted by a pale longitudinal line. The size of the intercalated second submarginal cell varies among individuals. In three (14%) of the females it is missing on one wing. The female from Grand Gulch Road and all the females from St. Thomas Gap have the scutellum dark, while those from Mesquite have the scutellum pale in contrast to the dark metanotum. T5 may be all brown except for two oval light spots.
Etymology. From the French “celadon” meaning a sea green color, in reference to the metallic green reflections on most areas of dark integument.