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Reprinted with permission from: Rightmyer, M.G. A Review of the Cleptoparasitic Bee Genus Triepeolus (Hymenoptera: Apidae) TRIEPEOLUS MICROPYGIUS ROBERTSON
(Figs. 129, 130)
Triepeolus micropygius Robertson 1903: 286 [Lectotype: Illinois Natural History Survey No. 23531; female, Carlinville, Macoupin Co., Illinois; 29 September 1902]; Webb 1980: 110 [lectotype designation (by W. E. LaBerge)].
Triepeolus micropygius micropygius; Mitchell 1962: 474–475.
Description.—Length ca. 10–12 mm (rarely as small as 8 mm); ITW 1.9–2.4 mm (rarely as small as 1.4 mm). Integument black, with red apical half of mandible; sometimes with orange labrum and clypeus, usually with orange F1, tegula, and legs (black in specimen from Mississippi); dorsum of mesosoma and metasoma with bands of pale yellow setae. Clypeus with faint midline (stronger dorsally) and faint larger punctures, clypeus sparsely covered with white setae (sometimes asetose in more eastern specimens). Paramedian band narrow, clearly separated from other pale setae on mesoscutum (lectotype specimen and a few others) or joined laterally to appressed setae on anterior margin of mesoscutum. Scutellum weakly bigibbous; axillar spine triangular, reaching midpoint of scutellum. Mesepisternum with relatively short, erect, simple setae (ca. 0.25 OD); usually mostly covered with pale yellow, appressed, branched setae, this setae sparser ventrally (lectotype specimen mostly lacking appressed setae ventrally); punctures dense and small, ventrally nearly contiguous to separated by one puncture diameter (up to three puncture diameters in lectotype). T1 discal patch transversely ovate to widely subrectangular; T2 with LLB forming weakly to strongly acute angle with ATB, this angle correlated with overall width of tergal bands [some specimens’ banding enlarged by diffuse pale setae, and others (including lectotype) with banding rather narrow (reminiscent of T. helianthi)]. Female: Pseudopygidial area (and T5 in general) narrowed apically, basally with dense, silvery, pilose setae, this silvery setae extending laterally towards apical margin, partially enclosing small, rounded apical region of sparse, coarse setae (apical margin straight in specimen from Mississippi); S2–S4 with apical bands white setae (rarely only on S2–S3 or S3–S4); S5 distinctly downturned, also narrowed apically. Male: Unknown.
Comments.—This species resembles T. fraserae due to the small, rounded pseudopygidial area with the distinct basal region of silvery shining setae; however the S5 and T5 of T. micropygius are conspicuously narrowed distally, S5 is much more strongly downcurved, the pseudopygidial area is even more distinctly rounded, and the erect, simple setae of the mesepisternum are much shorter in T. micropygius (0.25 OD vs. greater than 0.5 OD in T. fraserae). The rounded pseudopygidial area and the downcurved S5 resemble those of the T. verbesinae species group; however the small size of the pseudopygidial area and the general banding pattern of the metasoma (i.e., often the T1 transverse bands of pale setae are medially interrupted, and the T2 LLB forms only a weakly acute angle with the ATB—although in some exceptionally setose specimens this angle is strongly acute) differentiate this species from the T. verbesinae group.
The distribution of this species is largely in the Western U. S., with only one known specimen from Illinois (the lectotype specimen). The lectotype specimen is less setose than many, but not all, of the other examined specimens. In addition, I have seen one specimen from Mississippi (repository: Starkville); this specimen agrees with T. micropygius in most characters, except it has black legs and tegula, and is also quite sparsely setose.
Distribution.—USA: Arizona, California (Mono Co.), Colorado, Idaho, Illinois (Macoupin Co.), Mississippi (Oktibbeha Co.), Montana, Nebraska, Nevada, New Mexico, Oregon, Utah.
Floral Records.—Aster tanacetifolius [= Machaeranthera tanacetifolia (H.B.K.) Nees], Chrysothamnus sp., Grindelia squarrosa (Pursh) Dunal, Melilotus sp., Oligoneuron rigidum (L.) Small, Solidago sp.
Seasonal Records.—19 August to 23 October.
Specimens examined.—45 female (BOULDER, CORVALLIS, DAVIS, LAWRENCE, LOGAN, NEW YORK, SAN FRANCISCO, STARKVILLE, URBANA, WASHINGTON D.C.).
Reprinted with permission from: Mitchell, T.B. 1962 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152.
FEMALE—Length 10 mm.; entirely black, including antennae, tubercles, tegulae, legs and spurs; space between margin of vertex and lateral ocelli considerably less than their diameter; basal segment of flagellum considerably shorter than segment 2, median segments considerably longer than broad; cheeks very narrow, little more than one-third width of eye, somewhat more narrowed below, posterior margin carinate; median length of labrum nearly two-thirds the breadth, apical margin with a pair of minute, submedian denticles; posterior margin of scutellum quite strongly outcurved, broadly impressed medially, free part of axillae extending considerably from sides of scutellum, reaching somewhat beyond mid transverse line (fig. 112); wings lightly infuscated, with the usual three submarginal cells, veins piceous; face with a small amount of silvery tomentum between bases of antennae and eyes, pubescence otherwise rather short, thin and erect, but practically absent from lower part of face; margin of pronotum with rather dense whitish tomentum, and tubercles with a similar fringe; pleura with a narrow, transverse patch of white tomentum above; scutum with a pair of narrow, longitudinal lines of white tomentum toward anterior margin medially, lateral margins narrowly fringed, and scutello-mesothoracic suture with some very short, inconspicuous, whitish hairs; metanotum and adjacent margin of scutellum rather densely whitish fasciate, with a tuft of elongate, white hairs on each end behind wing bases; propodeum rather thinly white fasciate along margins of basal triangle and at extreme sides above; basal abdominal tergum with a median, transverse patch of black tomentum, this bordered basally by whitish tomentum, and apical margin with a whitish fascia which is slightly interrupted medially and narrowly joined to the basal tomentum on each extreme side; terga 2-4 with apical, transverse, tomentose fasciae, and tergum 2 with a quadrangular patch of pale tomentum on each extreme side, joining the apical fascia which is sub- interrupted medially; tergum 5 with a triangular patch of short pale tomentum on each side of pseudopygidium; tegulae minutely and closely punctate on inner margins, becoming impunctate along outer rim; punctures of face above antennae quite deep and distinct but rather fine and close, becoming somewhat finer and quite regular on cheeks below, face below antennae very densely and minutely rugoso-punctate, clypeus with an indefinite, median, shining line; scutum rather coarsely rugoso-punctate, with only scattered, indefinite, shining interspaces evident between punctures, scutellum and axillae somewhat more rugose; pleura below shining between rather coarse, deep and distinct punctures which are slightly but not widely separated, becoming quite densely rugoso-punctate above; discs of abdominal terga very finely, closely and regularly punctate beneath the black tomentum; median length of pseudopygidium about equal to the width, very broadly rounded or subtruncate apically, apical half covered with short, erect bristles, basal half with dense, pale yellowish tomentum, the two areas in sharp contrast; sternum 5 broadly convex as seen from beneath.
MALE—Resembles female in most details; venter of thorax with considerable dense, appressed, whitish tomentum; outer surface of tibiae quite densely white tomentose; segments of flagellum somewhat shorter, not much longer than broad; abdominal terga 5 and 6 with dense, whitish, apical fasciae; sterna 4 and 5 with subapical fringes of long, curved setae; pygidial plate strongly elevated above disc of tergum 7, apical part beyond transverse ridge somewhat triangular, with narrowly rounded apex, margin subcarinate, surface with a few shallow, obscure pits, the more basal area densely fine tomentose.
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