Iris, in his 1993 revision of the genus Pteroceras, Henrik Pedersen listed both Sarcochilus uniflorus Gagnep (1934) and Pteroceras uniflorus (Gagnep.) Tixier (1967) as synonyms of Pteroceras semiteretifoliumH. Ae Peders (1992).
On page 23 he states that the Gagnepain name is illegitimate because it is a later homonym of S. uniflorus Schltr. Tixier's binary combination is invalid because he proposed it as a new combination, not a new name. If you accept Pedersen's reasoning, then the correct name for your Indochinese plant is Pteroceras semiteretifolium. Cheers, Peter O'Byrne in Singapore _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
