Sectional rearrangement of arborescent clades of Croton (Euphorbiaceae) in South America: Evolution of arillate seeds and a new species, Croton domatifer
Abstract:Most of the arborescent Croton species in the New World were treated by Webster as belonging either to C. sect. Cyclostigma Griseb. or C. sect. Luntia (Neck. ex Raf.) G.L. Webster. The circumscription of C. sect. Cyclostigma has been treated recently. In this paper we focus on C. sect. Luntia, which was subdivided by Webster into two subsections, C. subsect. Matourenses and subsect. Cuneati. Using chloroplast trnL-F and nuclear ITS DNA sequence data, morphology and a broader sampling of additional Croton lineages, we found that the two subsections are not closely related and form distinct monophyletic groups. Substantial morphological differences support the molecular data. A taxonomic recircumscription of the two subsections, elevated to sectional level, is proposed. A key and taxonomic revision, with new synonyms, is provided for C. sect. Cuneati; together with the description of a new species from the coastal mountains of Venezuela, Croton domatifer. The new species is the only one in the genus known to possess leaf domatia. We infer that species in the Cuneati clade have lost the typical Croton caruncle, and some of them have evolved a different, specialized type of aril. We hypothesize that the arillate seeds are an adaptation to dispersal by fish in the Orinoco and Amazon river basins.
Document Type: Research Article
Affiliations: 1: University of Michigan Herbarium and Department of Ecology and Evolutionary Biology, 3600 Varsity Drive, Ann Arbor, Michigan 48108-2228, U.S.A., Real Jardín Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain;, Email: firstname.lastname@example.org 2: University of Michigan Herbarium and Department of Ecology and Evolutionary Biology, 3600 Varsity Drive, Ann Arbor, Michigan 48108-2228, U.S.A., Harvard University Herbaria, 22 Divinity Ave, Cambridge, Massachusetts 02138, U.S.A. 3: Forest Products Laboratory, One Gifford Pinchot Drive, Madison, Wisconsin 53726-2398, U.S.A. 4: Universidad Central de Venezuela, Facultad de Agronomía, Instituto de Botánica Argrícola, Apartado 4579, Maracay, Edo. Aragua, Venezuela 5: University of Michigan Herbarium and Department of Ecology and Evolutionary Biology, 3600 Varsity Drive, Ann Arbor, Michigan 48108-2228, U.S.A.
Publication date: 2010-08-01
Impact Factor (2015): 2.9
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