Specific pollinators reveal a cryptic taxon in the bird orchid, Chiloglottis valida sensu lato (Orchidaceae) in south-eastern Australia
Colin C. BowerFloraSearch, PO Box 300, Orange, NSW 2800, Australia. Email: colbower@bigpond.net.au
Australian Journal of Botany 54(1) 53-64 https://doi.org/10.1071/BT05043
Submitted: 25 February 2005 Accepted: 1 August 2005 Published: 22 February 2006
Abstract
Orchid species belonging to the sexual-deception pollination syndrome exhibit highly specific, usually one-to-one, relationships with their pollinators. This specificity is mediated by the orchid’s mimicry of the sex-attractant pheromones emitted by females of the pollinator species. Chiloglottis valida D.Jones sensu lato is a widespread, sexually deceptive, terrestrial orchid found in south-eastern New South Wales, and eastern and southern Victoria from sea level to at least 1600 m in the Australian Alps. Flowers from 38 C. valida s.l. populations from throughout this area were compared in field choice experiments for the specificity of attracted pollinator species. Four potential pollinator wasps in the thynnine genus Neozeleboria Rohwer were attracted. The data demonstrate the existence of two attractant odour types among C. valida s.l. and its pollinators, and support the recognition of two partially sympatric cryptic species in the orchid, each with two potential pollinators. The copheromone pollinator pairs replace each other on the altitudinal gradient, albeit with some overlap. In alpine areas the pollinators of the two cryptic orchid species are themselves sibling species within Neozeleboria monticola Turner s.l. The results indicate that C. aff. valida, the sister species of C. valida s.s., has two geographically replacing pollinators.
Acknowledgments
This paper is dedicated to the memory of the late Tony Bishop, a distinguished orchidologist, who took a keen interest in this work before his untimely death. Graham Brown and David Jones identified the thynnine wasp and orchid samples, respectively. Ron Tunstall, Alan Logan, John Riley and Rod Peakall are thanked for providing location details of orchid populations. Discussions with Rod Peakall, Graham Brown, Florian Schiestl, Jim Mant and David Jones provided valuable insights and feedback. The manuscript was greatly improved following reviews by Rod Peakall, David Jones, Jim Mant and two anonymous referees. This work was supported by a bequest from Tony Bishop and grants from the Australian Orchid Foundation.
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