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Systematics Section / ASPT

Vidal-Russell, Romina [1], Nickrent, Daniel [1].

A molecular phylogeny of the mistletoe family Loranthaceae.

Loranthaceae is the largest mistletoe family with 73 genera and ca. 900 species with a pantropical distribution. Previous classifications based on floral morphology, inflorescences, and karyotype have been proposed, but no modern classification exists that includes all genera. The family comprises three tribes Elytrantheae (haploid base chromosome number of X=12), Lorantheae (X=9) and Psittacantheae (mostly X=8). The latter two base numbers are considered derived via aneuploid reduction. To elucidate the phylogeny of the family, we used sequences for 60 genera from chloroplast matK and nuclear small-subunit and large-subunit ribosomal DNA. Maximum parsimony analyses were performed on the matK partition and rDNA partitions separately and on both partitions combined. Four genera from Olacaceae were used as outgroups. Although the tree derived from the rDNA partition was less resolved than the matK tree, no major incongruences were detected. The tree obtained from the combined data placed the root parasite Nuytsia as sister to all other Loranthaceae. The other two root parasitic genera ( Atkinsonia and Gaiadendron) were part of a polytomy that included several well-supported clades as well as monotypic southern hemisphere genera. A group of eight New World X=8 genera is strongly supported as monophyletic. With present sampling (8 of 14 genera), tribe Elytrantheae appears to be monophyletic. The remaining strongly supported clade contains over 30 genera, mainly in tribe Lorantheae. Either Loranthus or an Ileostylus/Muellerina clade (New Zealand) is sister to the remaining genera. A clade of 18 African genera appears from a polytomy of Asian/Australian genera, but with low bootstrap support. The derived position of all African Loranthaceae conflicts with an interpretation of phylogeny based strictly on vicariance. Our data support the concept of relictual and ancestral genera being present in South America and Australia/New Zealand (Tupeia) with subsequent migration from the latter source to Asia, India, and Africa.


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1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA

Keywords:
Biogeography
matK
ribosomal DNA.

Presentation Type: Oral Paper
Session: 25-10
Location: 410/Hilton
Date: Tuesday, August 16th, 2005
Time: 10:45 AM
Abstract ID:101


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