Descriptions and biological notes of Ctenoplectra bees from Southeast Asia and Taiwan (Hymenoptera: Apidae: Ctenoplectrini) with a new species from North Borneo

Abstract

Six Ctenoplectra species are recorded from Southeast Asia and Taiwan. They are C. chalybea Smith, C. cornuta Gribodo, C. davidi Vachal, C. elsei Engel, C. sandakana sp. nov. and C. vagans Cockerell. Females of C. sandakana sp. nov. from North Borneo are similar to the mainland species C. chalybea, but differ mainly in the clypeal keel and the length of the antennal segments. The small blackish species, C. cornuta, is distributed in Myanmar, China and Taiwan and C. davidi is distributed in China, Russia and Taiwan; both species are seen at the flowers of Thladiantha. Ctenoplectra chalybea was collected from the Malay Peninsula, Myanmar, Taiwan and Vietnam. Ctenoplectra apicalis Smith and C. kelloggi Cockerell are allied to C. chalybea; however, C. kelloggi is excluded from this study due to insufficient material. A key to the six known Ctenoplectra species is given. The large metallic species, C. chalybea and C. elsei, visit flowers of Momordica cochinchinensis (Lour.) Spreng. For the first time observations on the nest structures of C. chalybea and C. cornuta are presented. They choose remarkable places, such as artificial structures and buildings, for nest sites. The nest architecture prevents rain and direct sunlight from entering the nest. Bees used pre-existing holes or crevices in wood for nesting shelters and collected soil and appeared to mix it with some other substance to build nests. The cell lining materials and rubbing behaviors against the cell wall suggest that Ctenoplectra bees use floral oil mainly for cell lining materials.

Plant-pollinator interactions in East Asia: a review

“…Ctenoplectra (Apidae) and Macropis (Melittidae) are specialized to visit oil-producing flowers. For example, Ctenoplectra visits flowers of cucurbit species like those in the genera Momordica and Thladiantha (Li 1997;Sung et al 2009), and Macropis dimidiata visits those of Lysimachia vulgaris var. davurica (Myrsinaceae) (Yasumatsu & Hirashima 1956).…”

Immatures of the Old World Oil-Collecting BeeCtenoplectra cornuta(Apoidea: Apidae: Apinae: Ctenoplectrini)

“…These fragments show that fresh cell walls are smooth, and at least some are covered with a dark, shiny material, as reported by Sung et al (2009); cell walls that were less reflective may have belonged to earlier generations. When tested with water droplets placed on the inner surface of the fresh wall and on unworked broken surfaces, both surfaces were hydrofuge, probably indicating impregnation by floral oils either at the time of soil collection or during cell construction.…”

“…With the immatures of Ctenoplectra cornuta, I-Hsin Sung provided fragments of the cells and cocoons that offer insight into the nesting biology of the species not included it his treatment of its biology (Sung et al, 2009). These fragments show that fresh cell walls are smooth, and at least some are covered with a dark, shiny material, as reported by Sung et al (2009); cell walls that were less reflective may have belonged to earlier generations.…”

“…Their fragments were coated with a semitransparent, waxy substance (as also mentioned by Sung et al, 2009) that when scraped with forceps left a shiny streak as would wax. Beneath, the waxy material penetrated the soil in some places by 0.5 mm and elsewhere perhaps much more.…”

“…Added also is information on larval development and a few observations on nesting biology. All specimens studied became available through I-Hsin Sung's research on the nesting biology of the genus (Sung et al, 2009).…”