Osmia (Diceratosmia) conjunctoides Robertson

Rightmyer, Molly G., Deyrup, Mark, Ascher, John S. & Griswold, Terry, 2011, Osmia species (Hymenoptera, Megachilidae) from the southeastern United States with modified facial hairs: taxonomy, host plants, and conservation status, ZooKeys 148, pp. 257-278 : 266-269

Osmia (Diceratosmia) conjunctoides Robertson stat. n. Figs 82732

Osmia conjunctoides Robertson 1893: 276; Sandhouse 1939: 140 [synonymy with Osmia subfasciata ]; Mitchell, 1962:83 [synonymy with Osmia subfasciata subfasciata ]; LaBerge (in Webb 1980: 118) [lectotype designation].

Diceratosmia subfasciata conjunctoides (Robertson); Michener 1949: 264 [diagnosis].

Osmia (Diceratosmia) subfasciata miamiensis Mitchell 1962: 84. syn. n.

Diagnosis.

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).

Material examined.

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).

Comments.

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.