ABSTRACT
Due to plasticity of sexuality and fl exibility in the mating system, the identifi cation of sexuality among hermaphrodites is a highly complex issue: 1. Within a species, some females do not change sex at all (e.g. Scaridae: Sparisoma radians, Robertson and Warner, 1978; Sparidae: Pagrus pagrus, Kokokris et al., 1999; Serranidae: Mycteroperca bonaci, Crabtree and Bullock, 1998), 2. The presence of small males, which are not homologues of primary males in some species, suggests the development of secondary gonochorism. But their testes are derived from ovaries (e.g. Scaridae: Sparisoma rubripinne, Robertson and Warner, 1978; Serranidae: Hypoplectrodes maccullochi, Webb and Kingsford, 1992; Paralabrax maculatofasciatus, Hastings, 1989; Sparidae: Pagrus pagrus, Kokokris et al., 1999), 3. Within a species, some are harem owners, while others are group spawners (e.g. Sparisoma cretense, de Girolamo et al., 1999), 4. Within a species, there are single-male groups restricted to <3 m depth and others are multi-male groups residing at depths between 3 and 22 m (van Rooij et al., 1996), 5. Within a species, the mating system changes from place to place; Halichoeres maculipinna has a haremic mating system in Florida but not in Panama; H. garnoti is suggested to be haremic in Panama but is found not to be haremic in Florida (Robertson, 1981), 6. Apart from these, there are also reports on the gonochores such as, the Nassau grouper Epinephelus striatus (Serranidae, Sadavy and Colin, 1995) and the Mediterrnean wrasse Symphodous spp (Labridae), who are on the ‘wings’ to switch over to protogyny. For instance, Warner and Lejeune (1985) have recorded that 4% and 23 % males of S. tinca and S. melanocercus are secondary males, and 7. Variability in sexuality is further complicated by contradictory reports from several authors (see also Garratt, 1986; Moyer, 1990).
