DAVIS, CHARLES C. Department of Organismic and Evolutionary Biology, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA 02138. - Madagasikaria (Malpighiaceae): an exciting new discovery form Madagascar, with important implications for floral evolution within Malpighiaceae.
The Malpighiaceae comprise approximately 1250 species in 65 genera,
with approximately 100 species belonging to the 15 Old World genera.
Of the 100 species distributed across the Old World, 71 of them are
endemic to Madagascar and belong to nine genera. These Malagasy taxa
represent most of the major phylogenetic lineages within the family
and are represented in as few as six and as many as nine independent
clades. On a recent expedition to Madagascar I discovered a new genus
and species of Malpighiaceae. Madagasikaria has a schizocarpic
fruit with distinctive winged mericarps that possess a lateral wing,
which completely encircles the nut, and a peculiar dorsal wing, which
is folded over on itself. On the basis of ndhF and
trnL-F chloroplast data, Madagasikaria is closely related to
the Malagasy endemic genera Rhynchophora and
Microsteira. These plants all appear to be functionally
dioecious, and some of these appear morphologically to be
androdioecious (which is a very rare breeding system in flowering
plants). This has important implications for floral evolution within
the family. Neotropical Malpighiaceae are pollinated by specialized
oil-collecting bees and consequently exhibit highly conserved floral
morphology despite tremendous diversity in fruit morphology and habit.
These oil-collecting bees are absent from the paleotropics, where
lineages lack the oil glands and typical flower orientation crucial to
pollination by neotropical oil collecting bees. Based on my molecular
systematic studies of Malpighiaceae the shift from the neotropical
pollination syndrome has apparently taken place a number of times
independently.
Key words: biogeography, floral evolution, Malpighiaceae, pollination biology