Abstract Detail



Systematics

Maya Lastra, Carlos Alonso [1], Steinmann, Victor [2].

The untouchables: taxonomy and phylogenetics of Cnidoscolus (Euphorbiaceae).

The genus Cnidoscolus is a New World assemblage containing 99 species, seven of which include nine subspecies and one variety. It is noteworthy due to the presence of stinging hairs, a feature otherwise very rare in Euphorbiaceae. Major centers of diversity occur in Brazil and Mexico, and most species inhabit seasonally dry tropical forests. In order to understand the evolutionary history of the genus and to assess its classification in a phylogenetic context, we constructed a phylogenetic hypothesis for relationships using both nuclear (ITS) and chloroplast (psbA-trnH, trnL-trnF) markers. Forty-four species and 12 subspecies (of five species) were included. These represented a broad geographic and taxonomic sample of the genus. The nuclear and chloroplast datasets were analyzed separately. Some incongruences were detected between the nuclear and plastid phylogenies. In both analyses, Cnidoscolus is confirmed to be monophyletic and composed of two major lineages: a northern clade that comprises species distributed primarily in North and Central America and a southern clade composed of mostly South American species. We conducted ancestral reconstructions of three characters important in the classification of the genus: 1) primary leaf venation, 2) number of staminal whorls in the androecium, and 3) petiolar glands. Based on morphology and the molecular phylogeny, we propose an updated infrageneric classification that recognizes eight sections and two subsections, and we place the accepted species into this new classification.


1 - Columbia University, Ecology, Evolution and Enviromental Biology, 1200 Amsterdam Ave., Schermerhorn Ext. 1014A, New York, New York, 10027, USA
2 - Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales, Av. de las Ciencias s/n, Del. Sta. Rosa Jáuregui, Querétaro, Querétaro, 76230, Mexico

Keywords:
Crotonoideae
sectional taxonomy
ITS
psbA-trnH
trnL-trnF.

Presentation Type: Oral Paper
Number:
Abstract ID:249
Candidate for Awards:None


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