Contributions to Western Australian orchidology: 2. New taxa and circumscriptions in Caladenia

Abstract

Hopper, S.D. & Brown, A.P. Contributions to Western Australian Orchidology: 2. New taxa and circumscriptions in Caladenia. Nuytsia 14(1): 27-xx (2001). Some 260 species oi Caladenia R. Br. will be recognized Australia-wide following this taxonomic treatment of Western Australia's largest genus of orchids. A new key to the 112 Western Australian species is provided, as well as updated descriptions of all taxa needing attention as a consequence of our revisionary studies. Most taxa recognized herein are newly named, including 69 species and 26 subspecies. In addition, 15 new hybrids are recognized. There are also two new combinations, Caladenia nana Endl. subsp. unita (Fitz.) Hopper & A.P. Br. and C. longicauda Lindl. subsp. eminens (Domin) Hopper & A.P. Br. Currently 15 taxa are declared as Rare Flora and 21 have a conservation priority.Two of the proposed new genera, Cyanicula Hopper & A.P. Br. and Praecoxanthus Hopper & A.P. Br., were formally described (Hopper &. Brown 2000), after support for them was obtained from recent DNA sequence studies of the Orchidaccae and the Diurideae in particular (Figure 1). The molecular data also supported the reinstatement of Leptoceras. However, the third proposed new genus, Drakonorchis, appeared from this molecular research to be deeply embedded as a distinct group (now regarded as a subgenus) within Caladenia sens. lat.By excluding Le/Jtoceras, Cyanicula and Praecoxanthus, we consider Caladenia to be much more clearly circumscribed than has been the case in the past. At the same time as we reduced the circumscription of Caladenia we formalized a new subgeneric classification for the genus, elevating three of Bentham's (1873) sections to subgenera {Caladenia, Phlebochilus [as Phlebochila] and Calonema), and describing two new subgenera, Drakonorchis and Elevatae [as Elevata] (Hopper & Brown 2000). The remaining two sections of Caladenia recognized by Bentham (1873) are now removed from the genus, with section Leptoceras Benth. now recognized as two separate genera {Leporella A.S. George and Leptoceras), and section Pentisia Benth. constituting the new genus Cyanicula (with the addition of C. caerulea (R. Br.) Hopper & A.P. Br. and C. deformis(R. Br.) Hopper & A.P. Br.), which Bentham placed in the typical section). As well as including part of Cyanicula, Bentham included the Caladenia flava group (now Caladenia subg. Elevatae) and Praecoxanthus in his concept of sect. Caladenia [as Eucaladenia].These are now regarded as quite distinct evolutionary groups. Some change is also needed for Bentham s circumscription of his sections Calonema (typified by Caladenia longicauda and including all the spider orchids, i.e. taxa with elongate petals and sepals) md Phlebochilus (typified by Caladenia cairnsiana and including the group of wasp-pollinated species with short petals and sepals). Of major interest, based on DNA sequence data (Figure 1), is that the wispy spider orchids of the Caladenia fdamentosa complex are actual ly more closely related to species in Caladenia subg. Phleboch...