Willdenowia 36
Willdenowia – Annals of the Botanic Garden and Botanical Museum Berlin-Dahlem
ISSN 0511-9618
© 2006 BGBM Berlin-Dahlem.
Dathe, S. & Dietrich, H.: Comparative molecular and morphological studies in selected Maxillariinae
orchids.
Willdenowia 36 (Special Issue): 89-102.
doi:10.3372/wi.36.36106
Abstract
The phylogenetic relationships within Orchidaceae
subtribe Maxillariinae s.str.were investigated by Maximum
Parsimony and Bayesian analyses of nuclear ribosomal ITS1 and ITS2
DNA sequences in 27 species. While the monophyly of Maxillariinae
is supported, Maxillaria in its current, narrower
circumscription is clearly paraphyletic, since all presently
accepted genera examined (Chrysocycnis, Cryptocentrum,
Mormolyca, Trigonidium) and the former segregates Camaridium,
Heterotaxis, Marsupiaria, Neourbania, Ornithidium and Pseudomaxillaria
are nested within it. Camaridium, Heterotaxis and Ornithidium
are, moreover, polyphyletic. The resulting molecular trees show six
more or less well supported clades but are not very well resolved in
their basal parts. To study character evolution, the molecular data
were compared with pollinarium morphology, using scanning electron
microscopy in 22 taxa, and further morphological data. The
comparison indicates that most features have evolved several times
independently. In growth habit a trend from caespitose to
rhizomatous is found. Palynologically three morphological lines are
indicated: (1) from four greater pollinia in two pairs to four
smaller, equal, separate pollinia; (2) from spherical to clavate
pollinia; (3) from pollinia with rugulate (sometimes gemmate,
granulate, fossulate, microfoveolate) to psilate surface. A more
extensive taxon sampling is needed to decide if and how Maxillaria
s.l. has to be divided in smaller monophyletic genera.
Key words:
phylogeny, systematics, ITS, pollinarium, Maxillaria, Orchidaceae.
