SáNCHEZ-DEL PINO, IVONNE1*, HILDA FLORES OLVERA2, and TIMOTHY MOTLEY1. 1The Lewis B. and Dorothy Cullman Program. The New York Botanical Garden 200th Street and Southern Boulevard Bronx, New York 10458-5126 U.S.A; 2Departamento de Botánica, Instituto de Biología, UNAM. Ap. Postal 70-233, C.P. 04510, México, D.F., México. - Phylogenetic analysis of Tidestromia Standl. (Amaranthaceae-Gomphrenoideae).
Phylogenetic relationships within Gomphrenoideae (Amaranthaceae)
remain unresolved. The subfamily contains approximately 14 genera and
374 species; all of the genera occur in America with some species
distributed in Africa, Australia, and Japan. Within Gomphrenoideae,
the classification of the North American genus Tidestromia has
been controversial. To test the monophyly of Tidestromia and to
determine the phylogenetic relationships among the species, six
recognized species were included in a cladistic analysis using
Alternanthera sessilis, A. pycnantha, Gossypianthus
lanuginosus, Guilleminea densa, and Froelichia
interrupta as outgroups. In total, 15 micro and
macro-morphological characters were scored. They were observed from
vegetative and reproductive structures studied in herbarium material
and through the use of scanning electron microscopy. Phylogenetic
analysis of the morphological data supported Tidestromia as
monophyletic. This clade is supported by tepals with ramified
trichomes and dichasium inflorescences. Although resolution among the
species of Tidestromia was poor, Tidestromia lanuginosa,
T. carnosa, and T. tenella form a monophyletic clade
supported by the annual habit. The analysis yielded 18
most-parsimonious trees of 26 steps, with a consistency index (CI) of
0.80 and retention index (RI) of 0.84. A combined data analysis using
sequences of the 5S non-transcribed spacer and the nuclear ribosomal
ITS region will also be included in this investigation.
Key words: Amaranthaceae, Froelichiinae, Gomphreneae, Gomphrenoideae, North America., Tidestromia