ORIGINAL PAPER Discovery of mycangia and the associated xylose-fermenting yeasts in stag beetles (Coleoptera: Lucanidae) Masahiko Tanahashi & Kôhei Kubota & Norihisa Matsushita & Katsumi Togashi Received: 18 September 2009 / Revised: 17 December 2009 / Accepted: 18 December 2009 / Published online: 27 January 2010 # Springer-Verlag 2010 Abstract Most wood-feeding insects need an association with microbes to utilize wood as food, and some have special organs to store and convey the microbes. We report here the discovery of the microbe-storage organ (mycan- gium) in stag beetles (Coleoptera: Lucanidae), which develop in decayed wood. The mycangium, which was discovered in the abdomen, is present in all adult females of 22 lucanid species examined in this study, but absent in adult males. By contrast, adult insects of both sexes of selected Passalidae, Geotrupidae, and Scarabaeidae, which are related to Lucanidae, lacked mycangia similar to those of the lucanid species. Yeast-like microbes were isolated from the mycangium of five lucanid species. DNA sequence analyses indicate that the microbes are closely related to the xylose-fermenting yeasts Pichia stipitis, Pichia segobiensis, or Pichia sp. known from the gut of a passalid species. Keywords Lucanidae . Mycangium . Pichia . Symbiosis . Yeast . Xylose Introduction Wood-inhabiting insects have difficulty utilizing wood as a food resource because wood is composed mostly of cellulose, lignin, and hemicelluloses that together comprise about 90% of the total volume, and these polymers are difficult to digest (Parkin 1940; Haack and Slansky 1987; Geib et al. 2009). Some wood-inhabiting insects are associated with symbiotic microbes that help digestion of wood in the insect gut. For example, termites and wood- feeding cockroaches have protozoa or bacteria in their digestive organs which produce cellulolytic enzymes (Cleveland 1924; Slaytor 1992; Breznak and Brune 1994); passalid beetles (Coleoptera: Passalidae) and longicorn beetles (Coleoptera: Cerambycidae) are associated with xylose-fermenting yeasts that may help in the digestion of wood hemicelluloses (Suh et al. 2003, 2006). Ambrosia beetles culture symbiotic fungi in their galleries in wood and feed on the fungi (Batra 1963). They possess a special organ, which is called mycangium (pl. mycangia), to convey the fungi to new locations (Beaver 1989). Symbiotic associations with microbes are not clearly recognized in most other wood-feeding (saproxylic) insects, although they consume wood colonized with wood-rotting fungi. One group of typical saproxylic insects is stag beetles (Coleoptera: Lucanidae), the larvae of which feed on decayed wood (Araya 1993). They are considered to be fungivorous because newly hatched larvae of Dorcus rectus (Motschulsky) can develop on freeze-dried mycelia of wood-rotting fungi (Tanahashi et al. 2009). Females of most species of the genera Dorcus, Prosopocoilus, Lucanus, Aesalus, and Platycerus in Japanese Lucanidae make a small pit with their mandibles on the surface of decayed wood, insert their abdominal tip into the pit, pack granulated wood made by the female into the pits using their hind legs, and M. Tanahashi (*) : K. Kubota : K. Togashi Laboratory of Forest Zoology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan e-mail: kawotuptera@fr.a.u-tokyo.ac.jp N. Matsushita Laboratory of Forest Botany, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan Naturwissenschaften (2010) 97:311–317 DOI 10.1007/s00114-009-0643-5