Vasco, Alejandra , Rouhan, Germinal , Moran, Robbin .
Monographic and Phylogenetic Study of the Elaphoglossum ciliatum Clade (Dryopteridaceae).
Being one of the most diverse genera of ferns (more than 600 species), Elaphoglossum is remarkable for lacking monographic studies for any of its subgroups. This is probably because this genus is taxonomically difficult at the species level, its species being remarkably uniform and their distinguishing morphological characters being typically few and subtle. For these reasons, monophyletic groups of suitable size for monographic study are difficult to identify.
The primary goal of this study was to define which species of Elaphoglossum sect. Lepidoglossa belonged to a distinctive group (the ‘ciliatum-group’) of three species recovered as monophyletic in previous molecular analyses. The other goals were to test the criteria of our species concepts using the molecular trees, determine the phylogenetic relationships among the species, and finally monograph the clade.
The molecular analyses using a combined data set of three chloroplast intergenic spacers (atpB-rbcL, rps4-trnS, and trnL-trnF) recovered a monophyletic ‘ciliatum-group’ of 10 species, three endemic to the oceanic island of St. Helena in the southern Atlantic Ocean; and seven with neotropical distributions, from Mexico and the West Indies to southern Brazil. Our analyses suggest that the three species of St. Helena are the result of a single dispersal event from the New World (either from South America or from the West Indies). Nine of the ten species of the ‘ciliatum-group’ are morphologically recognizable by having laminar scales reduced to minute dots, spiny perispores, and resinous rhizomes. These characters, however, are not exclusive to the ‘ciliatum-group’ and can be found in other species of Elaphoglossum sect. Lepidoglossa. Our trees indicate that these characters have evolved at least two times in the genus.
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1 - New York Botanical Garden, City University of New York Graduate Center, 200Th Street & Southern Boulevard, Bronx, New York, 10458-5126, USA
2 - New York Botanical Garden, Institute of Systematic Botany, 200Th Street & Southern Boulevard, Bronx, New York, 10458-5126, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 28th, 2008
Time: 3:30 PM