RESEARCH ARTICLE Paternally inherited alleles in male body parts of an ant (Diacamma sp.) sex mosaic: implication for androgenetic male production in the Hymenoptera S. Dobata • H. Shimoji • H. Ohnishi • E. Hasegawa • K. Tsuji Received: 4 May 2011 / Revised: 7 July 2011 / Accepted: 11 July 2011 / Published online: 26 July 2011 Ó International Union for the Study of Social Insects (IUSSI) 2011 Abstract Sex mosaicism, also called gynandromorphism, refers to an accidental phenomenon in dioecious organisms (mainly animals) in which an individual phenotype includes both female and male characteristics. Despite the rarity of this phenomenon, elucidating the mechanisms of naturally occurring sex mosaicism should deepen our understanding of diverse sex determination and differentiation systems in nature. We report the results of a genetic study of a sex mosaic individual of the ant Diacamma sp. from Japan’s Okinawa Island. Parentage analysis using microsatellite markers revealed that the female and male parts of the sex mosaic showed different inheritance patterns: female parts had alleles consistent with their biparental inheritance, whereas most of the male parts had alleles consistent with their paternal inheritance (i.e., androgenesis). We discuss plausible cytogenetic mechanisms that gave rise to the male parts of this individual: polyspermy and the subsequent independent cleavage by a surplus sperm pronucleus, and maternal genome elimination after fertilization of an ovule. Moreover, we hypothesize that the androgenetically pro- duced males found in some Hymenoptera might share the same underlying cytogenetic mechanism with hymenop- teran sex mosaicism. Keywords Gynandromorph Á Androgenesis Á Haplodiploid Á Male clonality Á Polyspermy Introduction Sex mosaicism (also called gynandromorphism) has been reported frequently, mostly as single cases, in ants [Yang and Abouheif (2011); Yoshizawa et al. (2009); and refer- ences therein]. Due to their haplodiploid sex determination system, the genetic descent of female and male body parts in ant sex mosaics is of particular interest. In haplodiploidy, females arise from fertilized (diploid) eggs that have bipa- rentally inherited genomes, whereas males arise from unfertilized (haploid) eggs that exclusively contain the maternally inherited genome. Previous studies in honeybees and braconid wasps have described various aberrations from the normal haplodiploid inheritance pattern in sex mosaics (e.g., Clark et al., 1968; Rothenbuhler et al., 1952). These aberrations can be summarized from the perspective of heredity as follows: (1) unfertilized eggs develop female parts and (2) fertilized eggs develop male parts. The latter case includes three additional cases: the genome of the male parts is (2a) maternally inherited (gynogenesis), (2b) paternally inherited (androgenesis), or (2c) a combination of both. However, these inheritance patterns were typically S. Dobata and H. Shimoji contributed equally to this work. Electronic supplementary material The online version of this article (doi:10.1007/s00040-011-0187-5) contains supplementary material, which is available to authorized users. S. Dobata (&) Á H. Shimoji (&) Á H. Ohnishi Á K. Tsuji Department of Agro-Environmental Sciences, Faculty of Agriculture, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan e-mail: dobatan@gmail.com H. Shimoji Resource and Environmental Science of Agriculture, Forestry and Fisheries, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan e-mail: toireikitaimitai@gmail.com E. Hasegawa Laboratory of Animal Ecology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan Insect. Soc. (2012) 59:55–59 DOI 10.1007/s00040-011-0187-5 Insectes Sociaux 123