Subfamily Megachilini

Genus Coelioxys Latreille, 17 taxa

These are all parasitic bees, mostly parasitizing Megachile in Florida, but elsewhere, rarely parasitizing other genera. Females and males have distinctive metasoma and resemble more slender, pointed Megachile in color and form. They are often more densely punctate and females lack scopa. The 17 taxa are widely distributed, being found where their hosts are located. As is usual for most parasitic species, they are widely under collected and are likely found in many counties not listed here. A few taxa are described on the basis of one or two specimens of one sex. One endemic species, C. obtusiventris and one subspecies (a color form), C. slossoni slossoni, are known solely from Florida. Species are members of several subgenera, including Coelioxys (2), Boreocoelioxys (3), Xerocoelioxys (3), Synocoelioxys (2), Glyptocoelioxys (1), Acrocoelioxys (1), Neocoelioxys (2), Cyrtocoelioxys (3), and Haplocoelioxys (1).

Key references to Florida Coelioxys

Baker, J. R. 1975. Taxonomy of five Neartic subgenera of Coelioxys (Hymenoptera: Megachilidae). The University of Kansas Science Bulletin 50(12): 649-730.

A key to subgenera is provided in Michener (2000), page 528-529. This key is not used here but is a good key to learn the main subgenera if interested. Several subgenera have only one species and subgenera with more than one species have the keys to species within subgenera are taken from Baker and/or Mitchell.

Key to subgenera with more than one species and to species from only one subgenus (modified from Baker)

Key to subgenera of females of Coelioxys in Florida

  1. Ocellar area swollen, impunctate..2

    2. Ocellar area not swollen, or if raised then closely punctate..4

  2. Sixth metasomal sternum broadly rounded to acute apically, not notched subapically..(Synocoelioxys)

    3. Sixth metasomal sternum apically or subapically notched..3

  3. Vertex between lateral ocellus and compound eye completely or almost impunctate, shining; scutellum almost impunctate medially, with a large rounded projection posteriorly; sixth metasomal tergum blunt or truncate; wings blackish-brown; large bee (13-16mm)..C. dolichos (Acrocoelioxys)

    Vertex moderately to closely punctured; scutellum closely, evenly, and deeply punctured, but with no projection; sixth metasomal tergum usually rounded..C. slossoni (Neocoelioxys)

  4. (1) Sixth metasomal sternum notched subapically..5

    5. Sixth metasomal sternum with margin entire..7

  5. Scutellum with longitudinal, raised, impunctate line medially..C. mexicanus (Haplocoelioxys)

    6. Scutellum without raised, impunctate line medially..6

  6. Posterior margin of scutellum straight or very broadly angular but without a median tubercle..(Boreocoelioxys)

    7. Posterior margin of scutellum with a distinct median tubercle..C. germanus (Glyptocoelioxys)

  7. (4) Axillae with projecting portion as long as basal portion. .C. obtusiventris (Cyrtocoelioxys)

    8. Axillae with projecting portion about half as long as basal portion..8

  8. Sixth metasomal tergum in lateral view turned upwards..C. modestus (Cyrtocoelioxys)

    9. Sixth metasomal tergum in lateral view tapering horizontally

  9. Prothoracic tubercle with strong carina expanded into thin, plate-like structure.. (Xerocoelioxys)

    10. Prothoracic tubercle with strong carina but not expanded into thin, plate-like structure..(Coelioxys)

Key to subgenera of males of Coelioxys in Florida

  1. Ocellar area impunctate and swollen..2

    2. Ocellar area closely punctured and not swollen..4

  2. Sixth metasomal tergum with dorsal spines modified into a crenulate plate..(Synocoelioxys)

    3. Sixth metasomal tergum with two distinct dorsal spines..3

  3. Metasomal tergum 3-5 with longitudinal, median ridge; vertex with scattered punctures; scutum practically impunctate on disc; scutellum impunctate medially with a large, rounded projection posteriorly; wings blackish-brown; large bee (10-14mm).. C. dolichos (Acrocoelioxys)

    4. Metasomal terga 3-5 without longitudinal, median ridge; vertex variably punctured; scutellum evenly, closely, deeply punctured on dorsal surface; carina separating dorsal and posterior surfaces incomplete laterally, only a small median portion raised above level of dorsal surface; thoracic and metasomal fasciae narrow, inconspicuous.. C. slossoni (Neocoelioxys)

  4. Foveae on metasomal tergum 2 (in C. mexicana foveae may be very small on tergum 2 but they are in an otherwise impunctate area)..5

    Foveae not present or present on metasomal tergum 3 only..6

  5. (1) Foveae present on metasomal tergum 3..C. mexicanus (Haplocoelioxys)

    6. Foveae absent on metasomal tergum 3..(Boreocoelioxys)

  6. (4) Foveae absent, fovea area may be closely punctured on metasomal terga 2 and 3..7

    Foveae present only on tergum 3..8

  7. Thoracic and metasomal fasciae distinct; prothoracic tubercle produced into thin, plate-like structure; gradulus of tergum 2 curved toward apical margin medially..(Xerocoelioxys)

    8. Thoracic and sometimes metasomal fasciae inconspicuous; carina of prothoracic tubercle conspicuous but not expanded into thin, plate-like structure; gradulus of tergum 2 almost straight..(Coelioxys)

  8. (6) Posterior margin of scutellum in dorsal view with a median projection half as long as wide..C. germanus (Glyptocoelioxys)

    9. Posterior margin of scutellum without median projection..9

  9. Scutellum with narrow, impunctate, longitudinal median carina C. mexicanus (Haplocoelioxys)

    Scutellum without longitudinal median carina..(Cyrtocoelioxys)