Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1972. A revision of the bees of the genus Andrena of the Western Hemisphere. Part V: Gonandrena, Geissandrena, Parandrena, Pelicandrena. Transactions of the American Entomological Society 98: 271-358.
Please report text errors to: leah at discoverlife dot org.
This poorly known small bee has distinctive morphological features in both sexes. The forewings of atypica have two submarginal cells, for which reason Cockerell considered it to be a Parandrena and Lanham placed it provisionally in Diandrena. The pronotum, however, lacks a humeral angle and ridge, unlike all of the Parandrena and most of the Diandrena. The female of atypica has a propodeal corbicula which is incomplete anteriorly and provided with numerous internal simple hairs. The male has a yellow clypeus and the first flagellar segment strongly excavated on the under surface so that in repose it fits closely over the lateral ocellus.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-8 mm; width, 1.5-2.0 mm; wing length, M = 2.59 ± 0.103 mm; FL/FW, M = 0.98 ± 0.005; FOVL/FOVW, M = 3.46 ± 0.056.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third to half rufescent; flagella dark brown below; wing membranes hyaline, slightly infumate, brownish-yellow, veins dark reddish-brown; terga and sterna narrowly hyaline apically; distitarsi rufescent; tibial spurs testaceous.
STRUCTURE. — Antennal scape length equals about first four flagellar segments; flagellar segment 1 as long as following two and one-half segments; segment 2 about as long as 3, each broader than long; segments 4-9 quadrate. Eyes each about three and three-fourths times as long as broad, inner margins parallel. Mandible short, in repose extending beyond midline of labrum by one-sixth mandibular length or less. Galea broad at base, evenly tapered to point; surface moderately shiny, delicately shagreened. Labial palpus short, segment 1 only slightly curved, broad, segmental ratio about as 1.0:0.6:0.6:0.7. Maxillary palpus extends beyond tip of galea by more than last two segments, last segment slender, attenuate, segmental ratio about as 1.0:1.0:0.8:0.8:0.8:0.8. Labral process short, broad (about as 1:2.5 or 3), distinctly but shallowly emarginate apically; labrum apical to process shiny, impunctate except for narrow zone just below process. Clypeus evenly rounded from side to side but often flattened slightly medially; punctures round, sparse, separated mostly by two to four puncture widths or more; surface dulled by regular reticular shagreening. Supraclypeal area with abundant minute shallow punctures and delicate reticular shagreening. Face above antennal fossae with small longitudinal rugulae and coarse tessellation dulling surface. Facial fovea broad, extending down to level of antennal fossae, shallow, separated from lateral ocellus by one ocellar diameter. Vertex short, above lateral ocellus height equals slightly more than half an ocellar diameter; surface dull, finely tessellate and punctate especially above ocelli. Genal area in profile about as broad as eye, surface moderately shiny, with coarse reticular shagreening and scattered minute punctures.
Pronotum dulled by fine shagreening, impunctate. Mesoscutum with small round punctures separated mostly by two to four puncture widths (denser laterad of parapsidal line and anteriorly), surface opaque, dulled by fine dense tessellation. Scutellum similar but shinier. Propodeum with dorsal enclosure opaque, densely tessellate; dorsolateral, posterior and lateral surfaces slightly shinier, tessellation finer, with minute scattered punctures. Mesepisternum with punctures minute, sparse, obscured by fine, dense tessellation. Wing venation as in Parandrena. Posterior hind tibial spur strongly curved inwards and broad, anterior spur straight, slender, about two-thirds as long and half as broad as hind spur.
Metasomal terga dull, minute sparse punctures obscured by dense, regular, fine tessellation. Pygidial plate V-shaped with rounded apex; without raised internal triangular area. Sternum 2 basal area with small punctures mostly separated by two puncture widths; sterna 3-5 with basal areas almost impunctate in basal halves or more, similar to sternum 2 apically; sterna 2-5 with apical areas impunctate; surfaces shiny to moderately so, shagreening delicate.
VESTITURE. — White except as follows: vertex and face (especially along eye margins and surrounding foveae) often brown; facial foveae usually with short inner hairs brown at least in upper half; thoracic dorsum with hairs short, but erect and plumose, sparse; terga 2-4 with basal areas with short, relatively simple, sparse, brown hairs, apical pale fasciae narrow, broadly interrupted on tergum 2 and narrowly on tergum 3; basitibial plate and scopal hairs immediately below plate brown.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 5-7 mm; width, 1.0-1.5 mm; wing length, M = 2.49 ± 0.131 mm; FL/FW, M = 1.06 ± 0.008; FS1/FS2, M = 2.09 ± 0.028.
INTEGUMENTAL COLOR. — Generally as in female except as follows: clypeus yellow except anterior margin and spots below tentorial pits, occasionally posterior margin irregularly brown; flagella dark brown below.
STRUCTURE. — Antenna long, in repose reaching posterior margin of scutellum; scape length almost as long as first three flagellar segments; flagellar segment 1 twice as long as segment 2 or longer, strongly excavated on lower surface (to fit over lateral ocellus in repose); segment 2 shorter than 3, broader than long; segments 3-11 longer than broad. Eyes each about three times as long as broad, inner margins converging towards mandibles. Galea as in female. Labial palpus as in female but segmental ratio about as 1.0:0.7:0.6:0.6. Maxillary palpus as in female but ratio about as 1.0:1.0:0.8:0.8:0.8:1.0. Labral process as in female but slightly longer; labrum below process as in female. Clypeus as in female but punctures sparser, shagreening more delicate, shiny to moderately shiny. Supraclypeal area as in female. Face above antennal fossae as in female but longitudinal rugulae often incomplete or absent. Vertex as in female. Genal area slightly broader than eye, dull, reticularly shagreened.
Thoracic sculpturing as in female but dorsal enclosure of propodeum slightly roughened at extreme base medially.
Metasomal terga 1-5 sculptured as in female terga 1-4. Sterna 2-5 as in female sterna 3-5 but basal area punctures sparser. Sternum 6 not reflexed apically, shallowly emarginate. Terminalia as figured (Figs. 71-76); note the following: penis valves with acute apices, long, narrow, not much bent downwards, without dorsal or ventral lateral lamellae; gonobase small. Sternum 1 with apicomedian lobe much elongated, as long as lateral lobes. Sternum 8 with hairy apical lobe set-off by a sharply constricted, extremely narrow neck region.
VESTITURE. — Generally white except as follows: vertex, face and antennal scapes with hairs often brown; terga with basal area hairs short, sparse, suberect, brown. Tergal apical pale fasciae much as in female but even narrower (often worn and thus absent); sterna lacking subapical fimbriae.