PHILBRICK, C. THOMAS1*, ALEJANDRO NOVELO R.2, ROLF RUTISHAUSER3, and DONALD H. LES4. 1Department of Biological & Environmental Sciences, Western Connecticut State University, Danbury, CT 06810, USA; 2Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, México, D.F., 04510, México; 3Botanischer Garten und Institut für Systematische Botanik, Universität Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland; 4Ecology & Evolutionary Biology, U-42, 75 North Eagleville Road, University of Connecticut, Storrs, CT 06269-3042, USA. - Phylogeny of New World Riverweeds (Podostemaceae): morphology.
Podostemaceae are restricted to tropical river-rapids and waterfalls.
About half of the 49 genera and 60% of the species occur in the New
World. This contribution focuses on phylogenetic relationships among
New World Podostemoideae (the largest subfamily) based on parsimony
analyses of morphological (vegetative and reproductive)characters.
Apinagia (ca. 50 spp.), Marathrum (ca. 25 spp.), and
Rhyncholacis (ca. 25 spp.) are the largest genera in the New
World. Our analyses indicate that neither Apinagia nor
Marathrum is monophyletic. Species of Apinagia occur in
several clades. Some species of Marathrum occur closely related
to those of Rhyncholacis, while others occur in different
clades. One well-supported group is composed of one species each of
Marathrum, Vanroyenella and Macarenia.
Mourera is monophyletic. The genus Oserya is
monophyletic, and occurs basal to a clade in which Ceratolacis,
Devillea, Castelnavia, Podostemum and
Crenias occur. Species of Podostemum and Crenias
form a monophyletic group. Podostemum, however, is
paraphyletic. Preliminary analyses indicate that Indian Podostemoideae
arose from ancestors that are shared with the New World genera
Podostemum and Crenias. Character state change will be
discussed relative to the phylogenetic hypotheses. For example, the
phylogenetic topology indicates that the andropodium (fused stamen
filaments) and dyad pollen each evolved once.
Key words: phylogeny, Podostemaceae, Podostemoideae, riverweeds