Systematics Section / ASPT
Der, Joshua , Nickrent, Daniel .
Molecular systematics of Santalaceae: phylogeny and classification of a paraphyletic family of hemiparasitic plants.
Santalaceae is a cosmopolitan family of root and stem hemiparasitic plants in the sandalwood order (Santalales). Santalaceae are paraphyletic with respect to Viscaceae and Eremolepidaceae and therefore these taxa were included in a broadly defined family by APG2. Previous classifications recognized Santalaceae sensu stricto (35 genera, ca. 440 species), which included four tribes (Amphorogyneae, Anthoboleae, Santaleae, and Thesieae), as well as Eremolepidaceae (three genera, 11 species) and Viscaceae (seven genera, 550 species). Phylogenetic analyses based on nuclear SSU rDNA and chloroplast rbcL and matK DNA sequences were performed on partitioned and combined datasets using maximum parsimony, maximum likelihood and Bayesian methods. Phylogenies inferred from separate gene partitions are congruent, but differ in their level of resolution. Seven well-supported clades are recovered in all analyses of the combined dataset. Deep-level relationships among many of these clades are ambiguous and have short branch lengths, possibly representing rapid radiation within the family. However, Bayesian analyses provide some support for a topology among these groups. Here we propose a new classification for santalaceous genera based on this phylogeny that recognizes seven families: Viscaceae, Amphorogynaceae, Santalaceae, Nanodeaceae, Pyrulariaceae, Thesiaceae, and Comandraceae. With respect to previous classifications, generic circumscription in Viscaceae and Amphorogynaceae remain intact and these are well-supported sister taxa. Eremolepidaceae is monophyletic and emerges as one clade from our revised Santalaceae. Santalaceae also includes a basal clade containing Exocarpos and Omphacomeria, formerly classified in tribe Anthoboleae. Anthobolus, however, is excluded from Santalaceae and allied with Opiliaceae. Three distinct clades (Nanodeaceae, Pyrulariaceae, and Comandraceae) are segregated from the polyphyletic tribe Santaleae and Buckleya and Kunkeliella are members of Thesiaceae. The placement of Arjona and Quinchamalium is uncertain, but these taxa may be allied with Thesiaceae where they have been traditionally classified.
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1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
nuclear ribosomal DNA
Presentation Type: Oral Paper
Date: Tuesday, August 16th, 2005
Time: 11:00 AM