Limpet Dispersal or Parallelism? The lottiid limpet Notoacmea is restricted to Australia and New Zealand (Lindberg 1986). The most recent revision of the Australian fauna by Ponder & Creese (1980) recognized 6 species, as well as 2 further species in the closely related genus, Collisella. In addition the genus Naccula comprises two species found only on seagrass that have a radula very similar to Notoacmea (Wilson 1993). The New Zealand Notoacmea fauna was held by Powell (1979) to consist of 7 species, although he also recognized 2 further subspecies and 2 clear forms. Recent molecular work (Nakano & Spencer 2007; Nakano et al. 2009), however, revealed both polyphenism and crypsis at the species level; these authors recognized 14 species. Interestingly, the species that inhabits seagrass in New Zealand, N. scapha, also lives on nearby stones and shells, but these two habitats induce very different shell morphologies, those from seagrass not unlike those of the Australian Naccula. All New Zealand species are endemic, indeed often with ranges covering just part of the country; all Australian species are also endemic, occurring on coasts in the southern half on the country. This extreme endemism is perhaps unsurprising: the veliger spends only a week or two in the water column before metamorphosis (Lindberg 1998). Nevertheless, many pairs of Australian and New Zealand species bear a remarkable resemblance. In addition to the seagrass-limpet example above, N. petterdi, from eastern Australia, and N. pileopsis, from northern New Zealand, are large for the genus, have a black interior edge of their shells, which have a similar outline and an anterior apex, and occur on vertical rock faces on exposed coasts. This project aims to elucidate whether these examples arise from evolutionary convergence induced by similar habitats or whether the species involved are close relatives, the result of a number of trans-Tasman dispersal and colonization events. The project involves careful field work, collecting living individuals from around the coast of southern Australia (Queensland to Freemantle, including Tasmania) as a prelude to molecular-genetic work to obtain mitochondrial and nuclear DNA sequences that will be used to estimate the phylogeny of the genus. It is quite possible that cryptic species will be discovered and almost certain that the will require revision. If the answer is convergence (rather than dispersal), both radular and conchological measurements could be made that may reveal the selection pressures leading to convergence, using the approach of Holland et al. (2010).

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