ON THE EVOLUTION OF DIPODIUM R. BR.
ABSTRACT: Dipodium R. Br. (Orchidaceae),
a genus of ca. 38 species, should be divided into an Australasian clade and a
Malesian clade, based on morphological and geographic evidences. Dipodium
section Dipodium and section Leopardanthus (Blume) O. Kuntze are re-defined to
accommodate this change. An evolutionary scenario that explains this division
is proposed. The lack of diversity of floral structure in the genus is probably
caused by pollinator-specificity, while the diversity of plant form may be due
to long-term environmental factors. An evolutionary explanation is suggested
for the complex between Dipodium fevrellii J. J. Sm. and the hybrid D. pandanum
Bailey in New Guinea. The complex in Java involving D. pictum (Lindl.) Rchb. f.
and D. scandens (Bl.) J. J. Sm. is discussed, and the presence of a hybrid
noted. In Borneo, the complex taxonomic situation caused by repeated
inter-breeding of populations is noted.
Key words: Dipodium,
evolution, inter-specific complex, hybrid, New Guinea, Orchidaceae, section
Dipodium, section Leopardanthus
Author: PETER O’BYRNE
Journal Code: jpbiologigg140021
