Morphometric Variation in Three Species of Cyrtostylis (Orchidaceae)

Character choice in the delimitation of Cyrtostylis oblonga, C. reniformis, and C. robusta, orchid species in the Acianthinae, was evaluated using morphometric methods, specifically canonical variates analysis of several traditional measurements, thin plate spline analysis of leaf perimeter landmarks, and eigenshape analysis of leaf outlines. We measured five linear parameters and char- acterized leaf shape using thin plate spline and eigenshapes to determine morphological distance between the three species. Our work indicates that C. oblonga and C. reniformis are well delimited, but that C. robusta is morphologically indistinguishable from C. reniformis. Cyrtostylis R. Br. is a small genus of Acian- thinae Schlechter originally established by Robert Brown (1810) on the basis of its blunt sepals, unreduced petals, almost naked label- lum, and winged column. It is closely allied to Acianthus R. Br., as currently circumscribed, and is distinguished from Acianthus only by the ses- sile, rather than petiolate, leaf, and by the pres- ence of a different fungal endosymbiont (Jones and Clements 1987; Warcup 1981). Various au- thors treat the two taxa as congeneric (Cheese- man 1906; Moore and Edgar 1970; Schlechter 1906), but Cyrtostylis has been recently rein- stated by Weber and Bates (1986), Jones and Clements (1987), and Jones (1989). As currently delimited, the genus includes four or five species and is restricted to Australia and New Zealand. The currently recognized