Gentianales - trnL intron

Data: 151 aligned trnL intron sequences from Gentianales; Apocynaceae (incl. Periplocaceae and Asclepiadaceae), Gelsemiaceae, Gentianaceae, Loganiaceae (incl. Geniostomaceae), Rubiaceae, Saccifoliaceae, and Strychnaceae (incl. Antoniaceae), and some outgroups outside Gentianales. GENBANK accession numbers are indicated after each taxon name in the matrix. Gaps are indicated with "-"; "?" indicates missing data.

Matrix type: Parsimony jackknife format, text-only.

Reference: Struwe, L., M. Thiv, J. W. Kadereit, A. S.-R. Pepper, T. J. Motley, P. J. White, J. H. E. Rova, K. Potgieter, & V. A. Albert. 1998. Saccifolium (Saccifoliaceae), an endemic of Sierra de la Neblina on the Brazilian-Venezuelan frontier, is related to a temperate-alpine lineage of Gentianaceae. Harvard Papers in Botany 3: 199-214.

Summary of results: Saccifolium bandeirae is a monotypic taxon from high peaks of the tepui complex Sierra de la Neblina, which straddles the Brazil-Venezuela border. Saccifolium was given its own family because of its morphological uniqueness. Saccifolium is a shrub with saccate leaves and Gentianales-like flowers. The genus has been proposed to be close to Gentianaceae but no phylogenetic analyses had previously been performed. We have assembled new and databased sequences of the trnL intron from Saccifolium as well as 105 Gentianaceae, and to these sequences were added 45 data from outgroup taxa representing other Gentianales and asterid angiosperms. Parsimony and parsimony jackknife analyses were performed with the result that Gentianaceae are divided into five well-supported clades: (A) Exacum plus Ornichia, Tachiadenus, and Sebaea, (B) Blackstonia plus Canscora, Centaurium, Chironia, Cicendia, Coutoubea, Deianira, Eustoma, Geniostemon, Hoppea, Ixanthus, Orphium, Sabatia, Schinziella, Schultesia, Symphyllophyton, and Xestaea, (C) Calolisyanthus plus Chelonanthus, Irlbachia, Macrocarpaea, Neblinantha, Symbolanthus, Tachia, Tetrapollinia, and Wurdackanthus, (D) Anthocleista plus Djaloniella, Enicostema, Fagraea, Faroa, Lisianthius, Neurotheca, Potalia, Pychnosphaera, and Urogentias, and (E) Bartonia plus Chionogentias, Comastoma, Frasera, Gentiana, Gentianella, Gentianopsis, Halenia, Jaeschkea, Lomatogonium, Megacodon, Obolaria, Saccifolium, Swertia, and Veratrilla. Clade A is strongly supported as most basal within Gentianaceae, followed by clade B and clades C, D, and E, which each have strong individual support but are poorly resolved with respect to each other. Saccifolium appears to be the sister group of Gentiana (a mainly boreal genus with representatives in the Andes) and is basally positioned in clade E, which consists of cosmopolitan, temperate-alpine gentians belonging to Gilg’s Gentianinae. Saccifolium is the only member of this clade present on the Guayana or Brazilian Shields and is not closely related to any other genera of Gentianaceae from these areas. Saccifolium flowers resemble those of some North American Gentiana species and Obolaria, which suggests that Saccifolium may be a derived, austral member of a boreal clade and perhaps relictual from a more continuous, ca. 40 million-year old boreotropical distribution of Gentianinae. Further research will be necessary to clarify the specialized morphological and ecological features of Saccifolium, such as whether its saccate leaves can assist in nutrient or water uptake.

Contact person: Lena Struwe, The Lewis B. and Dorothy Cullman Program for Molecular Systematics Studies, The New York Botanical Garden, Bronx, NY, 10458, U.S.A., phone: (718) 817-8179, fax: (718) 817-8166, e-mail: lstruwe@nybg.org

Date posted on WWW: 12/18/98

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