Acarinaria and mite associates of the large carpenter bee Xylocopa (Koptortosoma) ruficeps (Hymenoptera: Apidae) from Taiwan

Bees and wasps are associated with a wide variety of mites (OConnor and Klompen, 1999; Klimov et al., 2007). Some of them have evolved specialized acarinaria (mite chambers) on their body and harbor more or less specific groups of mites in them. Female carpenter bees of the genus Xylocopa are well known for having a metasomal acarinarium of various levels of specialization (Hurd and Moure, 1963; Eardley, 1983; Klimov and OConnor, 2008). In particular, female carpenter bees of the subgenera Koptortosoma and Mesotrichia have a distinct acarinarium on the first metasomal tergite (T1), which is the “largest known” (Klimov et al., 2007) acarinarium in insects. The metasomal acarinarium is a spacious chamber occupying a large portion in the first metasomal segment and is connected to the bee’s exterior through a small aperture on its anterior surface, and it harbors species-specific mites of the genus Dinogamasus (Klimov et al., 2007). Although the female metasomal acarinarium of Koptortosoma and Mesotrichia has long been known, its detailed structures have been described in only a few species including Xylocopa (Mesotrichia) caffra L. (Skaife, 1952) and Xylocopa (Mesotrichia) flavorufa (DeGeer) (Madel, 1975) from Africa. Detailed information regarding the morphology of the acarinaria in as many species as possible is indispensable to understand the evolution of the structure and the interrelationship between bees and mites. The carpenter bee Xylocopa (Koptortosoma) ruficeps Friese, distributed in the Oriental region (Hurd and Moure, 1963), has also been reported to possess a distinct metasomal acarinarium (Okabe and Makino, 2005). However, its structure has not been examined in detail. In addition to