Chelostoma Latreille 1809
Creators: name: Engel, Michael S.
name: Griswold, Terry
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Megachilidae
Chelostoma

description: Key to Subgenera of Chelostoma
(modified from Griswold & Michener, 1998; Michener, 2007)
1. Third labial palpomere flatened, its axis a continuation of that of second palpomere; seventh metasomal tergum of male with dorsal pit .................... 2
—. Third labial palpomere not flatened, its axis directed laterally as in most megachilid bees; seventh metasomal tergum of male without dorsal pit (male unknown in Ceraheriades Tkalců) ................................................................ 5
2(1). Preoccipital carina present (sharply angled medially in C. ventrale Schletterer but not carinate); propodeum with sloping basal zone litle more than one-half as long as metanotum; first metasomal tergum shallowly concave anteriorly [Palearctic] ......................................................... Gyrodromella Michener
—. Preoccipital carina absent; propodeum with horizontal basal zone at least two-thirds as long as metanotum; first metasomal tergum with anterior surface convex except for longitudinal groove ........................................................ 3
3(2). Parapsidal line half as long as tegula or more; second metasomal sternum of male without sloping platform, or, if present, then not carinate; labrum of female less than twice as long as broad (longer in C. isabellinum Warncke) ..... 4
—. Parapsidal line less than half as long as tegula; second metasomal sternum of male with median prominence, its posterior surface a flat sloping platform margined by carina; labrum of female elongate, nearly 3× as long as broad or more (shorter in C. nasutum Pérez) [Palearctic, introduced into Nearctic] ................................................................... Chelostoma Latreille, s.str.
4(3). Male seventh metasomal tergum without lateral processes (Fig. 6); setae of outer surface of probasitarsus pectinately branched to plumose (Fig. 4) [Palearctic] .......................................................................... Foveosmia Warncke
—. Male seventh metasomal tergum with lateral processes (Fig. 5); setae of outer surface of probasitarsus simple (Fig. 3) [Nearctic] .... Neochelostoma, n. subgen.
5(1). Metacoxa not carinate [Nearctic] .............................. Prochelostoma Robertson
—. Metacoxa with longitudinal carina along inner ventral margin .................. 5
6(5). First metasomal tergum not concave on anterior surface; female mandible elongate, bidentate; labrum apically thickened [Central Asia] ................................... ....................................................................................................... Ceraheriades Tkalců
—. First metasomal tergum shallowly concave on anterior surface; female mandible not elongate, tridentate; labrum not apically thickened [Himalayas to Thailand] ............................................................................. Eochelostoma Griswold
description: Published as part of Engel, Michael S. & Griswold, Terry, 2019, On the classification of North American Chelostoma (Hymenoptera: Megachilidae), pp. 1-6 in Journal of Melittology 2019 (90) on pages 3-5, DOI: 10.17161/jom.v0i90.11760, http://zenodo.org/record/8057463