Osmia (Diceratosmia) conjunctoides Robertson

Rightmyer, Molly G., 2017, A revision of the subgenus Osmia (Diceratosmia), with descriptions of four new species (Hymenoptera, Megachilidae), Zootaxa 4337 (1), pp. 1-37 : 7-8

Osmia (Diceratosmia) conjunctoides Robertson

( Fig. 1C )

Osmia conjunctoides Robertson 1893: 276 [Lectotype male: Champaign]; Sandhouse 1939: 140 [synonymy with O. subfasciata ]; LaBerge (in Webb 1980): 118 [lectotype designation]; Rightmyer et al. 2011: 270 [rejection of synonymy with O. subfasciata ].

Diceratosmia subfasciata conjunctoides (Robertson) ; Michener 1949: 264. Osmia (Diceratosmia) subfasciata miamiensis Mitchell 1962: 84 [Holotype female: Washington, D.C.]; Rightmyer et al. 2011: 270 [synonymy].

Diagnosis. Females of this species are distinguished from all other Diceratosmia by the nearly uniformly short, straight to distally curved hairs on the clypeus. These hairs are slightly longer and less uniform on the frons. These clypeal hairs are very similar to those of Osmia (Melanosmia) calaminthae Rightmyer, Ascher & Griswold ; however, in O. calaminthae the punctures of the metasomal terga are smaller, there is no carinate ridge on the hind coxa, and the parapsidal line is punctiform. Osmia conjunctoides has historically been confused with O. subfasciata ; in addition to the diagnostic facial hair of O. conjunctoides noted above, females of these two species may be distinguished by differences in the scopal hairs. In O. conjunctoides , the scopal hairs are tapered at their apical tips, while in O. subfasciata the scopal hairs are blunt, widened and slightly rounded at their apical tips ( Fig 12A ).

Males of O. conjunctoides are extremely similar to O. subfasciata , as these are the only known species of Diceratosmia in which the hairs on the apical margin of S4 are short, stout, and form an apical comb. In addition to generally being slightly larger (body length ca. 8–9 mm vs. 6–7 mm) and bluer bee than the greenish-blue O. subfasciata , O. conjunctoides is distinguished from that species by several subtle but consistent features: the mesoscutum is more finely and densely punctate relative to the scutellum ( O. conjunctoides with ca. 16 punctures between parapsidal line and midline, these punctures distinctly smaller than those on the scutellum; O. 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 O. conjunctoides is less concave along its anterior margin, while in O. subfasciata the anterior margin is strongly curved, forming anterolaterally rounded corners. In O. conjunctoides , the lower propodeal triangle tends to be weakly shagreened throughout, while in O. subfasciata the lower propodeal triangle tends to be shiny.

Distribution. Southern Florida north to Georgia (St. Catherines Island) and Mississippi (Forrest County) ( Fig. 18 ).

Floral Associations. Fabaceae : Crotalaria .

Comments. Males of this species are extremely similar to those of O. subfasciata ; although previous workers were able to detect differences in the males that merited subspecific recognition ( Michener 1949, Hurd & Michener 1955), recent examination of the associated females has allowed us to recognize more distinctive characters and to justify recognizing O. conjunctoides as species separate from O. subfasciata ( Rightmyer et al. 2011) .

Figures

FIGURE 1. Female mandibles: A) O. marilaunidii (DRO 0115730), B) O. azteca (34211), C) O. conjunctoides (BBSL 204519), D) O. exquisita (BBSL 989169). Scale bar = 0.25 mm.

FIGURE 12. Female habitus lateral view: A) O. subfasciata (BBSL 210392) with inset showing apically blunt scopal hairs, B) O. marilaunidii (DRO 4915) with inset showing apically pointed scopal hairs. Scale bar = 0.5 mm.

FIGURE 18. Known distributions of O. conjunctoides (green triangles), O. exquisita (white circles), O. gonzalezi (red circles), O. lacunosa (yellow circles), O. spinulifera (blue circles), and O. stangei (purple triangles). Scale bar = 200 km.