This relatively common, southwestern species of Belandrena is distinctive in having the third and fourth labial palpal segments meeting the preceding segment before the tip of that segment. The third segment meets the second segment near the middle of the second segment, and the fourth segment meets the third segment about one-fourth the length of the third from its apex. In addition, both sexes of palpalis are distinctive in having bright metallic blue integument.
FEMALE. Measurements and Ratios. — N = 20; length, 9-10 mm; width, 2.5-3.0 mm; wing length, M=3.36±0.116 mm; FL/FW, M= 1.03± 0.004; FOVL/FOVW, M= 3.21 ±0.035.
Integumental Color. — Bright metallic blue except as follows: mandible black with apex rufescent; labrum black; clypeus black except extreme base; scape black; flagellum dark reddish brown below; tegula brown; wing membranes hyaline, veins dark brown; terga 5 and 6 dark brown to black; sterna and legs piceous; tibial spurs testaceous.
Structure. — Antennal scape as long as first three flagellar segments; flagellar segment 1 about as long as segment 2 plus 3, which are subequal in length and about as long as broad; median flagellar segments distinctly longer than broad. Eyes each about four times as long as broad or slightly less, inner margins parallel. Malar space short, linear. Outer mandible when closed extends beyond middle of labrum by one-fourth its length, bidentate apically. Galea narrow, spear shaped, outer margin straight, sharply pointed; dulled by fine shagreening in apical half or less, shiny basally. Maxillary palpus longer than galea by last two segments; segmental ratio about 0.8:1.0:0.9:1.0:0.8:0.9. Labial palpus with first segment long, curved, flattened, especially apically; third segment meets second segment near outer half of second segment; fourth segment meets third subapically; segmental ratio about 0.9:1.0:0.8:0.8. Labral process bidentate, depressed at base; labrum apical to process with median crista, not sulcate. Clypeus bowed outward, with large round punctures separated mostly by half to one puncture width, sparser apicomedially, smaller " near base and at extreme sides; surface shagreened, especially in basal third, often shiny apicomedially, occasionally shagreened throughout with weak transverse rugulae apicomedially. Supraclypeal area opaque, dulled by dense fine tessellation. Face above antennal fossae dulled by small punctures, fine longitudinal rugulae, and tessellation. Facial fovea broad, separated from lateral ocellus by three-fourths ocellar diameter, extending below to a line at lower margins antennal fossae. Vertex above lateral ocellus equal to about half an ocellar diameter or slightly more, finely punctate, irregularly tessellate. Genal area broad, in profile distinctly broader than eye; punctures minute, separated by two or more puncture widths, surface shiny, unshagreened or sparsely so.
Pronotum with angle and dorsoventral ridge extremely weak to absent, surface dulled by fine tessellation. Mesoscutum with small round punctures separated largely by one puncture width medially and obscured by coarse tessellation. Scutellum similar but frequently shiny or moderately so. Propodeum with dorsal enclosure coarsely and evenly tessellate; dorsolateral and posterior surfaces with finer tessellation and small sparse punctures. Mesepisterna with minute sparse punctures and fine tessellation moderately dulling surface.
Metasomal terga with small round shallow punctures separated mostly by one to two puncture widths, surfaces shiny or moderately shiny medially to dulled by fin( reticular shagreening, especially basally and apically. Sterna densely punctate except in narrow apical areas, finely shagreened, moderately shiny. Pygidial plate V-shaped with narrow, rounded apex and distinct raised internal triangular area.
Vestiture. — White except as follows: facial foveae with tomentum brown especially in upper half; vertex usually with sparse dark brown hairs; tarsi and tibiae with outer surfaces with brown hairs in part; scopal hairs hind tibiae below basitibial plate washed with light brown to posterior half or three-fourths dark brown; basitibial plate and apex of femur dark brown; terga 5 and 6 with brown hairs except laterally on tergum 5. Propodeal corbiculum incomplete anteriorly, with abundant long simple internal hairs; tibial scopal hairs long, simple; terga 1-5 with narrow apical pale pubescent fasciae, but weak on tergum 1; tergum 1 and tergum 2 basomedially with long white hairs.
MALE. Measurements and Ratios. — N = 20; length, 7-10 mm; width, 1.25-2.50 mm; wing length, M=3.06± 0.426 mm; FL/FW, M= 1.06± 0.007; FS1/FS2, M=1.65±0.031.
Integumental Color. — As in female except as follows: Clypeus pale yellow except narrow marginal area and two small maculae below anterior tentorial pits.
Structure. — Antennal scape as long as first two flagellar segments or slightly shorter; flagellar segment 1 equals one and one-half times segment 2 or more, segment 2 about as long as broad and shorter than segment 3. Malar space, galea, maxillary and labial palpi as in female. Labral process shiny, strongly reflexed, bidentate. Clypeus as in female but usually shiny, unshagreened. Supraclypeal area and face above antennal fossae as in female. Vertex above lateral ocellus usually equals about three-fourths ocellar diameter, dull, finely punctate, tessellate. Genal area in profile about one and one-half times as broad as eye, with rounded, knob-like angle posteromedially; surface minutely punctate, moderately shiny to shiny, lightly shagreened.
Pronotum with low humeral angle and weak dorsoventral ridge, ridge rounded but with distinct depressed area between it and posterior margin (below humeral angle); surface as in female. Thoracic sculpturing as in female. Terga 2-4 with apical areas impunctate, basal areas with shallow punctures separated mostly by one or more puncture widths; surface moderately shiny, with coarse shagreening. Sternum 6 flat, apex broadly and shallowly emarginate. Terminalia as in figures 69-73.
Vestiture. — White except as follows: upper half of face, vertex, and along inner margins compound eyes to level of antennal fossae usually with dark brown hairs; inner surfaces tarsi pale yellow. Terga 1-5 with thin but complete apical pale fasciae. Terga 1-3 with basal hairs long to moderately so. Sterna 2-4 with subapical fimbriae of long pale hairs, but fimbriae weak with hairs barely differentiated from more basal hairs.