Robert Brown's Caladenia revisited, including a revision of its sister genera Cyanicula, Ericksonella and Pheladenia (Caladeniinae: Orchidaceae)

Abstract

Nomenclatural confusion has been generated regarding the large Australasian terrestrial orchid genus Caladenia following publication from 2001 onwards of three major treatments of Caladeniinae. Here, we review concepts for Caladenia and allied genera in the subtribe, we revise three sister genera of Caladenia (Cyanicula, Ericksonella and Pheladenia), and we present an annotated nomenclatural checklist with many new synonymies and some new combinations. A revised circumscription of ten genera in the Caladeniinae is presented, including both Adenochilus and Eriochilus, which have recently been segregated as monogeneric subtribes by others. We argue for retaining Caladenia in the broad sense, largely reflecting Robert Brown's original concept, differing only in the recognition as genera of Cyanicula, Pheladenia, and Leptoceras, as well as two monotypic genera not known to Brown but later described as species of Caladenia (Praecoxanthus and Ericksonella). Thus Caladenia remains a large Australasian genus of terrestrial orchids with 243 species and six subgenera. This approach maximises nomenclatural stability while ensuring that hypothesised monophyly is upheld in the light of molecular phylogenetics analyses. The valid type for Caladenia is C. carnea, while that for Caladenia sect. Calonema is C. longicauda. The genus Jonesiopsis and generic combination Phlebochilus (Benth.) Szlach. were validly published. These conclusions call into question many recently erected taxa and combinations of other authors. Synonyms of Caladenia include Arachnorchis, Calonemorchis, Drakonorchis, Jonesiopsis, Petalochilus, Phlebochilus and Stegostyla. Pentisia is a synonym of Cyanicula. Calonema (Lindl.) Szlach. and Calonema (Lindl.) D.L. Jones and M.A. Clem. are invalid generic combinations as the name Calonema had already been used for a fungal genus.

New taxa described herein include Ericksonella, Cyanicula subgenus Trilobatae, C. aperta, C. ixioides subsp. candida, × Cyanthera and × C. glossodioides. New combinations include Caladenia subgenus Stegostyla (D.L. Jones and M.A. Clem.) Hopper and A.P. Br., C. graniticola (Hopper and A.P. Br.) Hopper and A.P. Br., C. saccata (R.S. Rogers) Hopper & A.P. Br., C. orientalis (G.W. Carr) Hopper & A.P. Br., and C. villosissima (G.W. Carr) Hopper & A.P. Br., and Ericksonella saccharata (Reichb.f.) Hopper and A.P.Br.