Dienia seidenfadeniana, a new orchid species from Australasia Dariusz L. SZLACHETKO, Hanna B. MARGONSKA & P. RUTKOWSKI Laboratory of Plant Taxonomy and Phytogeography, Gdansk University, Al. Legionow 9, PL-80-441 Gdansk, Poland. biodarek@univ.gda.pl KEYWORDS Dienia, Orchidaceae, Australasia. ABSTRACT Dienia seidenfadeniana Szlach., Marg. & Rutk., is described and illustrated. The new species appears to be related to Dienia latifolia (J.J. Sm.) M.A. Clem. & D.L. Jones, from which it is easily distinguishable by the lip form. MOTS CLES Dienia, Orchidaceae, Australie. RESUME Dienia seidenfadeniana, une nouvelle espèce d'Orchidaceae d'Australie. Dienia seidenfadeniana Szlach., Marg. & Rutk. est décrit et illustré. Cette nouvelle espèce est affine de Dienia latifolia (J.J. Sm.) M.A. Clem. & D.L. Jones, dont elle se distingue facilement par la forme du labelle. The genus Dienia Lindl. has been recently reinstated by CLEMENTS & JONES (1996). According to these authors it includes 6 species: Dienia benguetense (Ames) M.A. Clem. & D.L. Jones, D. curranii (Ames) M.A. Clem. & D.L. Jones, D. latifolia (J.J. Sm.) M.A. Clem. & D.L. Jones, D. montana (J.J. Sm.) M.A. Clem. & D.L. Jones, D. truncicola (Schltr.) M.A. Clem. & D.L. Jones and D. volkensii (Schltr.) M.A. Clem. & D.L. Jones. It is worthy to note that CLEMENTS & JONES (1996) transferred Epidendrum ophrydis J. Koenig to the genus Crepidium Blume, despite its similarity to both Malaxis latifolia Sm. and Dienia congesta Lindl. (GARAY, pers. comm.; SEIDENFADEN, pers. comm.). Both of the latter taxa are treated by SEIDENFADEN (1995) as synonyms of Malaxis ophrydis (J. Koenig) Ormerod. Although the gynostemium structure of Dienia Lindl. is similar to Crepidium Blume and Fingardia Szlach., this genus is characterised by the lip form. Additionally, unlike Crepidium and Fingardia, the lip of Dienia possesses a trans- verse, rather thick, ridge at the lip base. While revising the herbarium materials of Malaxidinae from Australasia we found two spe- cimens that in our opinion represent the same unknown taxon that deserves to be separated as a new species. We describe it below. Dienia seidenfadeniana Szlach., Marg. & Rutk., sp. nov. Species haec D. latifoliae próxima, sed recedit labello distincte latiori, lobis lateralibus oblique ovato-triangu- ADANSONIA, sér. 3 • 1999 • 21 (2) : 221-223 221