Females of Osmia calaminthae are most similar to Osmia (Melanosmia) albiventris Cresson and Osmia (Melanosmia) cordata Robertson, sharing with those species the white hairs of the body (including scopa) and four-toothed mandible with the outer and condylar ridges parallel (Figs 13, 14). Unlike those species, Osmia calaminthae has specialized hairs on the face (including clypeus and frons) that are extremely short, evenly spaced, simple, and stout (Figs 5, 6; longer and finer in Osmia albiventris and Osmia cordata). In addition, the punctures of the head and mesosoma are large and deeply impressed in Osmia calaminthae, the hairs on the posterior surface of the foretarsal segments are relatively long, the wings are heavily infuscate, the rugose sculpturing of the dorsal propodeal triangle is strongly impressed and well differentiated from the ventral area of shagreened integument (Fig. 15), and the hairs on the lateral dorsal surface of T1 are dense and long, much more so than on remaining metasomal terga (Figs 9, 10; T1 hairs not conspicuously longer and denser than those on other metasomal terga in Osmia albiventris and Osmia cordata). Osmia (Melanosmia) sandhouseae Mitchell is a superficially similar species found sympatrically in Florida and is known to visit Calamintha in March (Deyrup et al. 2002); however, in that species the outer and condylar ridges of the mandible converge apically (parallel in Osmia calaminthae) and the hairs of the clypeus and frons are long and fine.

Males of Osmia calaminthae are distinguished from many other Osmia by the relatively slender, pointed teeth of T7 (basally about one-fourth the width of the midapical emargination; Fig. 22). Among the Osmia with such slender teeth on T7, Osmia calaminthae is extremely similar to Osmia cordata due to the white hairs on the metasomal terga (including laterally on T6) and S4 (Fig. 24), and by the hairs on the apical margin of S4 that are longer medially than laterally. Osmia calaminthae can be separated from Osmia cordata by the deep and large punctures on the frons and vertex. Males of Osmia sandhouseae Mitchell are superficially similar; however, in that species the punctures on the upper gena are extremely large and deep, much more so than on the vertex, while in Osmia calaminthae the punctures of the upper gena and vertex are subequal in size.

Female. Figs 5–7, 9–16. Total length: ca. 11 mm (10–11 mm); Forewing length: 7 mm (6–7 mm); distance between lateral ocellus and preoccipital margin 0.6 mm (0.5–0.6 mm); distance of lateral ocellus to compound eye 0.6 mm.

Color: Dark blue (mesosoma sometimes with integument slightly paler blue), except with brown integument on mouthparts, labrum, mandible, apical edge of clypeus, antenna, legs distal to trochanters, apical margins of metasomal terga, and metasomal sterna. Wings strongly infuscate.

Pubescence: Hairs entirely white to pale golden except darker golden on mouthparts and distally on legs, brown on wings; hairs conspicuous on mesosoma and T1 so as to obscure underlying blue integument, but inconspicuous on distal terga. Galea and basal two labial palpal segments with hairs on lateral margins straight, 0.2–0.5 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and at approximate midpoint (hairs slightly more scattered along row at midpoint), with additional fringe of shorter hairs at apical margin. Clypeus below apical margin with lateral tuft of pale golden, medially directed hairs (often hidden by clypeal margin). Head with short, stout, simple, erect hairs evenly spaced on face (Figs 5, 6), scape, and pedicel, these hairs denser and appressed on outer surface of mandible, longer and relatively sparse on ventral margin of mandible, vertex, and posteriorly on gena. Hypostomal area with straight, minutely branched hairs evenly distributed across area, 2.0–3.0 OD in length. Mesosoma (excluding legs and wings) and laterally on T1 covered with dense, long, minutely branched, white hairs (Figs 9, 10); remainder of metasomal terga with hairs conspicuously shorter and sparser than hairs on mesosoma and T1. Legs with hairs on outer surfaces white, on forefemur and foretibia relatively slender and minutely branched, on foretarsal segments long (ca. 3.0 OD in length), slightly stouter, and simple; on midleg outer surface entirely minutely branched; on hindleg outer surface mostly minutely branched except basitarsus with hairs appressed, simple, and relatively stout. Legs with hairs on inner surfaces of fore- and midfemora and fore- and midtibiae white, minutely branched, and relatively sparse, with some shining areas lacking hairs; inner surface of hindfemur with denser, minutely branched white hairs, of hind tibia with very dense, short, white, subappressed hairs; inner surfaces of all tarsal segments with hairs dense, golden, stout, and simple. Wing membranes with short, dense, evenly distributed, simple hairs. Scopa white to pale golden.

Punctation: Head and mesosoma with punctures nearly contiguous, round, and strongly impressed except as follows: labrum mostly impunctate; clypeus with impunctate midapical truncation about half length of F1; clypeus immediately adjacent to apical impunctate truncation and next to compound eye with punctures relatively small and dense (Fig. 12); paraocular area with punctures separated by up to two puncture diameters; clypeus, vertex, and mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to one puncture diameter; mesepisternum in upper anterior corner with punctures relatively small, ventrally with punctures separated by up to one puncture diameter; hypostomal area, pronotum, propodeum, and legs with punctures shallowly impressed, sometimes elongated into oval shape; tegula with punctures minute, dense at margins and sparse medially (separated by up to four or five puncture diameters); metanotum, metepisternum, and lateral and posterior surfaces of propodeum with background integument moderately granulose and relatively dull; propodeal triangle with dorsal third strongly, deeply areolate to lineate, lower two thirds granulose grading to shining, glabrous area along lower lateral margin (Fig. 15). T1 anterior and dorsal surfaces, and T2–T3 shining, T4–T6 moderately shagreened, T1 medially on disc with small punctures separated by up to a puncture diameter, grading to slightly larger and denser punctures on more posterior terga, T1–T5 apical impunctate bands relatively narrow laterally, ca. one puncture diameter in length, medially with impunctate bands widened, up to four puncture diameters in length (or even longer at exact midpoint).

Structure: Labial palpus four-segmented, second labial palpal segment ca. one-fourth longer than basal-most segment. Mandible with outer and condylar ridges of subequal thickness or with condylar ridge slightly thicker, parallel along length (Fig. 14); apical margin with four teeth, third separated from second and fourth by carina, margin of third tooth forming distinct V-shape with adjacent margin of second and weakly curved U-shape with adjacent margin of fourth, third tooth weakly set back from second and fourth (Fig. 13); inner, ventral margin of mandible lacking distinct tooth, very weakly diverging away from condylar ridge basally; mandible apically widened (1.5 times wider than median width), first tooth length subequal to that of other teeth or very slightly longer, second tooth located about half way between first and fourth teeth (Fig. 13). Clypeus with apical margin forming anteriorly produced truncation, linear or weakly concave along truncation and forming ca. 130 degree angle with lateral apical margin of clypeus. F1 one-third longer than F2 length or slightly more, remaining apical flagellar segments gradually increasing in length such that F10 ca. one-fourth longer than F1 length. Vertex behind lateral ocellus 2.5–3.0 OD in length. Genal width subequal to that of compound eye in lateral view. Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, highest at about midpoint of hypostomal area posterior to angle, not forming triangular projection at this point but forming distinct, semicircular projection, tapering to low carina or near obsolescence at angle. Malus forming pointed apical spine, this spine more or less a narrowed continuation of nearby edge of velum. Foretarsal segments excluding basitarsal and apical-most segments with lobes moderately swollen, anterior lobes slightly longer than posterior. Midtarsal segments with anterior and posterior lobes of equal width, weakly swollen; hind tarsal segments not swollen. Hind tibial spurs more or less straight on basal three-fourths, with outer spur moderately curved at apical tip and inner spur slightly less strongly curved apically, outer spur about a fifth to a sixth shorter than inner. Hind basitarsus with lateral margins of outer surface parallel.

Male. Figs 17–26. Total length: ca. 10 mm; Forewing length: 6 mm; length of lateral ocellus to preoccipital margin 0.4 mm; length of lateral ocellus to compound eye 0.5 mm.

Color: Head and mesosoma pale blue, metasoma dark blue, except with brown integument on mouthparts, labrum, mandible, apical edge of clypeus, antenna, legs distal to trochanters, S5–S8, and apical margins of all metasomal terga and S1–S4. Wings moderately infuscate, except along leading edge of forewing more strongly infuscate.

Pubescence: White, minutely branched hairs on body except golden to pale golden, stouter hairs on inner surfaces of tarsi. Labrum sparsely covered with hairs on apical half and with hairs forming short fringe at apical margin. S2 with hairs at apical third relatively long (ca. 3.0 OD). S3 with dense, posteriorly directed hairs forming semicircular fringe along entire emargination (hairs ca. 1.5 OD in length throughout) (Fig. 23). S4 sparsely covered with white, medio-posteriorly directed, distally wavy hairs, these hairs not interrupted medially on S4, distinctly longer at midapical truncation than laterally on apical margin of disc. S6 midapical truncation sparsely covered with short, white hairs.

Punctation: Head with punctures ovate to circular, contiguous or nearly so and deeply impressed except as follows: labrum mostly impunctate on basal half; clypeus with impunctate area immediately next to anterior tentorial pit and impunctate band along apical margin about one-fourth length of F1 and slightly swollen on median third (Fig. 20); disc of clypeus and interantennal area with punctures small and ovate; hypostomal area anteriorly near angle with punctures weakly, shallowly impressed. Mesosoma with punctures round, nearly contiguous and deeply impressed except as follows: tegula with punctures minute, sparser medially, separated by up to eight puncture diameters; metepisternum with punctures more irregular and with impunctate area near anterior margin and sometimes medially across sclerite; pronotum and lateral and posterior surfaces of propodeum strongly shagreened, with very weakly, shallowly impressed punctures; metanotum with punctures distinct but smaller than on mesoscutum and separated by about a puncture diameter; propodeal triangle strongly lineolate to reticulate on dorsal half and shagreened on lower half, sometimes with weakly shining areas laterally near ventral margin (Fig. 21); legs with inner surfaces of trochanters, femora, and tibiae (except hind tibia) shining, with scattered smaller punctures. T1 with anterior surface weakly shagreened, shining; metasomal terga with dorsal surfaces very weakly shagreened, shining. Metasomal terga with punctures small and well impressed (slightly less impressed on T5–T7). T1–T4 dorsal surfaces with punctures separated between 0.5 and 2.0 puncture diameters; apical impunctate margins medially ca. 3.0–4.0 puncture diameters in length, laterally as little as 1.0 puncture diameter. T5–T6 with punctures less distinct, separated by ca. 1.0 puncture diameter medially; T5 with apical impunctate margin medially ca. 3.0 puncture diameters in length. S1–S3 with punctures moderately impressed, ovate. S4 with integument punctate basally, grading to shagreened and papillate at bases of hairs apically. S5–S6 shagreened.

Structure: Mandible with outer and condylar ridges converging apically; with two teeth, upper and lower teeth nearly the same width and length; inner margins of upper and lower teeth forming nearly 90 degree angle; upper tooth with inner and dorsal margins forming ca. 45–60 degree angle; inner, ventral margin of mandible weakly diverging away from condylar ridge basally. Clypeus apical margin lacking distinct apical truncation, medially very weakly concave, laterally with weakly tuberculate swelling. Flagellar segments subequal in length, except F1 about three-fourths length of F2 and F11 slightly longer than other segments. Vertex behind lateral ocellus 1.5 OD in length or slightly longer. Genal width ca. three-fourths that of compound eye in lateral view or slightly wider. Preoccipital margin rounded, not carinate. Hypostomal carina relatively shallow, about the same height along length of head, gradually tapering to near obsolescence at angle, not forming distinct tooth. Malus forming small but distinct, pointed apical spine. Foretarsal segments excluding basitarsal and apical-most segments with anterior lobes very slightly more swollen than posterior. Mid- and hind tarsal segments not swollen. Hind tibial spurs relatively stout, very weakly curved along length, outer spur slightly shorter than inner. Hind basitarsus with lateral margins of outer surface subparallel, with very small tooth on inner margin about one-fourth from apical margin along length. T6 midapically with moderate emargination, forming one-half of circle in outline or nearly so (Fig. 22); T6 lateroapical margin smoothly, weakly convex, not forming distinct tooth or forming very weak lateral tooth. T7 midapically strongly emarginate, forming semicircle about as wide as deep (slightly smaller than 1.0 OD in width), with spines on either side of emargination slender, about one-fourth as wide as emargination width (Fig. 22). S2 evenly convex, covering most of S3 (in one specimen with weak emargination at midapex). S3 with midapical emargination strongly semicircular, about as wide and long (half entire width of sternum, 1.5 OD in length or slightly more, measuring only apical margin of sternum and not including basal fringe of hairs; Fig. 23). S4 midapically with wide, poorly defined truncation (about third width of entire sternum). S6 with midapical truncation ca. one-fifth width of sternum, truncation as wide as long, apical margin of truncation distinctly emarginate. Gonoforceps narrowed apical to subapical bend, weakly pointed at apical tip in dorsal view (Fig. 25), more or less straight along length in lateral view (Fig. 26).

Known only from Highlands County, Florida.

“USA: FL [Florida]: Highlands Co. Lake Placid, 18 March 2002, J. S. Ascher, ex: Calamintha ashei//HOLOTYPE ♀ Osmia calaminthae Rightmyer, Ascher, Griswold [red label]” (New York). The type locality is southwest of the town of Lake Placid in an area of the subdivision of Placid Lakes Development that still includes many vacant lots: N27.2502, W81.3898.

USA: FLORIDA, Highlands Co., Lake Placid, 18 March 2002, Calamintha ashei, J. S. Ascher (4♀, New York; 1♀, Logan), Archbold Biological Station, 28 March 1988, Satureja ashei, A. Warneke (1♀, Lake Placid), 29 March 2000, Calamintha ashei, M. Deyrup (1♀, Lake Placid), 10 April 2001, Calamintha ashei, M. Deyrup (1♀, Lake Placid), 18 April 1983, H. L. Dozier (1♀, Gainesville), 25 April 1983, Lupinus diffusus, A. Schreffler (1♀, Gainesville), Archbold Biological Station, Junction roads 40 & 36 Rosemary Bald, 27 March 2001, Calamintha ashei, M. Deyrup (2♀, Lake Placid); Lake Wales Ridge Wildlife and Environmental Area, Gould Road Preserve, N27.13657, W08132495, 15 March 2009, Ceratiola scrub, Townes and bowl traps, M. & N. Deyrup, A. May, H. Otte (4♀, Lake Placid; 1♀, Logan); Lake Wales Ridge Wildlife and Environmental Area, Holmes Avenue Preserve, N27.28097 W081.31862, 24 April 2009, Calamintha ashei, M. Deyrup (1♀, Lake Placid); Placid Lakes, 8 April 2001, Calamintha ashei, Florida scrub habitat, M. Deyrup (3♀, Lake Placid); Placid Lakes Development, 16 March 2002, Calamintha ashei, sand pine scrub habitat, M. Deyrup (3♀, Gainesville; 4♀, Lake Placid; 1♀, Logan), 29 March 2007, Calamintha ashei, M. Deyrup (2♀, Lake Placid), 30 March 2009, Calamintha ashei, J. S. Ascher, D. Webber (3♀, 2♂, New York), 31 March 2009, Calamintha ashei, J. S. Ascher, D. Webber (8♀, New York), 3 April 2006, Calamintha ashei, J. S. Ascher, C. Dong (4♀, New York), 4 April 2006 (8♀, New York; 1♀, Logan).

Four females were collected by H. G. Hall at the type locality on 31 March and others were observed and photographed there by T. Lethbridge on 31 March and 2 Apr 2010 (Figs 1–3; additional photos and informative captions here: http://bugguide.net/node/view/394002/bgimage).

The name “calaminthae” is Latin, referring to mint, and is derived from the name of its presumed pollen host plant.

Females of this species are distinguished from all other Diceratosmia, including typical Osmia (Diceratosmia) subfasciata, by the nearly uniformly short, straight to slightly hooked hairs on the clypeus and slightly longer hairs on the frons (Fig. 8). Osmia conjunctoides is also distinguished from Osmia subfasciata by the scopal hairs: in Osmia conjunctoides, the apical tips of the hairs on S2 and S3 are weakly tapered, while in Osmia subfasciata the hairs are blunt, widened and slightly rounded at their apical tips. The form of clypeal hairs in the female is very similar to that of Osmia (Melanosmia) calaminthae; however, in that species the punctures of the metasomal terga are not so large (compare Figs 16 and 32), there is no carinate ridge on the hind coxa, the parapsidal line is punctiform, and the metasomal terga (especially T1 and T2) lack the distinct, short, dense, pale, apicolateral hair bands characteristic of subgenus Diceratosmia (in Osmia calaminthae T1 has dense, pale hairs, but these hairs are long and contrast with the short, sparse hairs on T2).

Males of Osmia conjunctoides are extremely similar to Osmia (Diceratosmia) subfasciata. Finding reliable characters to distinguish the two species is made problematic by the availability of only seven male specimens of Osmia conjunctoides. This material suffices to permit the two species to be differentiated by the following characters: In Osmia conjunctoides, the mesoscutum is more finely and densely punctate than in Osmia subfasciata (Osmia conjunctoides with ca. 16 punctures between parapsidal line and midline, these punctures distinctly smaller than those on the scutellum; Osmia subfasciata with ca. 11 punctures between parapsidal line and midline, these punctures about the same size as those on the scutellum). In dorsal view, T1 of Osmia conjunctoides is less concave along its anterior margin, while in Osmia subfasciata the anterior margin is strongly curved, forming anterolaterally rounded corners. In addition, Osmia conjunctoides is usually a slightly larger bee than Osmia subfasciata (6–7 mm vs. 8–9 mm); all examined Osmia conjunctoides from Florida and Georgia are dark blue, while all examined Osmia subfasciata from throughout its range are a paler greenish blue; however, the male specimen of Osmia conjunctoides from Mississippi is greenish blue, similar to Osmia subfasciata. In Osmia conjunctoides, the lower propodeal triangle tends to be weakly shagreened throughout, while in Osmia subfasciata the lower propodeal triangle tends to be shining. In addition, T6 of Osmia conjunctoides has an apical, upturned flange that is longer than in examined specimens of Osmia subfasciata (ca. 2.0 adjacent puncture diameters in the former versus 1.0 adjacent puncture diameters in the latter).

USA: FLORIDA, Citrus Co., Inverness, Robertson [1♂, New York], 17 February 1891 [1♂, Champaign (holotype of Osmia conjunctoides)]; Highlands Co., Highlands Hammock State Park, 14 April 1968, malaise trap, H. V. Weems Jr. [1♀, Gainesville]; Hillsborough Co., Lutz, 17 March 1926, Krautwurm [1♀, Logan]; Liberty Co., Torreya Ravine, 15 April 1938, F. E. Lutz (1♀, New York); Miami-Dade Co., Cape Florida, 15 February 1925, Crotolaria, S. Graenicher [1♀, Washington DC (holotype of Osmia subfasciata miamiensis)]; Miami Beach, 8 February 1917, Graenicher [1♂, Raleigh (allotype of Osmia subfasciata miamiensis)]; Seminole Co., Lower Wekiva River Preserve State Park, Burn Zone LW-10, S39 T19S R29E, LLP-Turkey Oak, P. Russell, S. Fullerton, 6 February 2001, blue pan trap (1♂, Orlando), 19 February 2001, yellow pan trap (1♂, Orlando), blue pan trap (1♂, Logan); GEORGIA, St. Catherines Island, 16–22 April 1983, Rozen, Favreau, Stupakoff (1♀, New York); MISSISSIPPI, Forrest Co., Hattiesburg, 12 March 1944, C. D. Michener (1♂, New York), 6 April 1944 (1♀, New York).

Graenicher (1930) provides brief collecting notes on this species, under the name Osmia subfasciata:“This species occurs in the sand dunes at Miami Beach and on Biscayne Key (across the Bay southeast of Miami), and visits the flowers of Crotalaria pumila. Dates of capture: February 8, 15, and March 17.”

Michener (1949: 264) considered a male specimen of Osmia conjunctoides from northern peninsular Florida to intergrade with the typical Osmia subfasciata in features of T6 and T7 (although not in color). However, he was apparently unaware of the distinct facial and scopal hair features distinguishing females of Osmia conjunctoides from Osmia subfasciata. Specimens of Osmia conjunctoides that we have examined from northern peninsular Florida as well as Mississippi and Georgia are consistent with those from southern Florida in these diagnostic features of the females as well as in the finer punctures of the male mesoscutum. Although Osmia conjunctoides and Osmia subfasciata sensu stricto are extremely similar in the male S4, we do not agree with the historic placements of this bee as a subspecies or synonym of Osmia subfasciata due to the consistent differences in male punctation and female clypeal and scopal hairs.

According to Mitchell (1962: 84), two additional female paratype specimens of Osmia subfasciata miamiensis exist in Raleigh with the same label data as the male allotype. Pascarella (2008) also recorded the species from “Charlotte Harbor, ” possibly based on distributional records found in Michener (1949), but we have not been able to confirm this record. Until we have access to further material, Osmia conjunctoides is provisionally considered to range from southern Florida north to Georgia and Mississippi, while we can confirm the presence of typical Osmia subfasciata from northeastern Mexico and southeastern California southeast to Alabama and South Carolina, and northeast to Illinois and New Jersey.