Reiter, NoushkaBohman, BjornFreestone, MarcBrown, Graham R.Phillips, Ryan2020-12-040067-1924http://hdl.handle.net/1885/216696Prior to undertaking conservation translocations of plants with specialised pollination systems, it is important to ensure the presence of pollinators at recipient sites. Here, for two threatened species, Caladenia concolor Fitzg. and Caladenia arenaria Fitzg. (Orchidaceae), we determine (i) the pollination strategy used, (ii) which floral visitors are involved in pollination, and (iii) whether the pollinator species are present at potential translocation sites. For both orchid species, pollination was primarily achieved by nectar-foraging thynnine wasps, with a single species responsible for pollination in C. concolor, whereas C. arenaria utilised at least two species to achieve pollination. Both orchid species secreted meagre quantities of sucrose onthe upper surface ofthelabellum. VisitstoC. concolor occurred primarilyinthelate afternoon, with some wasps perching on the flowers overnight. Surveys revealed that pollinators were present at all extant populations and most potential translocation sites for both orchids. The specialisation on one pollinator species in C. concolor means that the distribution of the pollinator needs to be considered for conservation translocations. With C. arenaria, the risk of hybridisation with other Caladenia that are known to share one of its pollinator species needs to be taken into account when selecting translocation sites.Funding for this study was received from the New South Wales Government Office of Environment and Heritage via the Saving our Species Fund distributed through the Murray Local Land Service. RDP and BB were supported by ARC Discovery Early Career Research Awards (DE150101720 and DE160101313 respectively).application/pdfen-AU© CSIRO 2019201910.1071/BT190332020-07-19