NEINHUIS 1, CHRISTOPH*, KHIDIR, W. HILU 2, AND THOMAS BORSCH 1. 1 Botanisches Institut und Botanischer Garten, Universität Bonn, Germany, 2 Institute of Biology, Virginia Tech. University, Blacksburg, USA. - Systematics of Aristolochiaceae: Molecular Evidence.
Aristolochiaceae comprises some 600 species occurring worldwide with
concentration in tropical and subtropical regions. The family belongs
to a basal angiosperms clade concisting of Piperaceae, Saururaceae,
and Lactoridaceae; the latter is either nested in or sister to
Aristolochiaceae. Although Aristolochiaceae is generally split into
subfamilies Asaroideae and Aristolochioideae, strong disagreement
exists in systematic relationships at the generic level. This is
particularly true for Pararistolochia and Isotrema, although they can
be recognized by several morphological synapomorphies. We present a
phylogeny based on trnT-trnF for Aristolochiaceae. The two
subfamilies are well supported with Saruma and Asarum being
sistergroups. Pararistolochia and Isotrema form well supported
monophyletic clades, with Endodeca sensu Huber beeing closlely related
to Isotrema. The morphologically unique, monotypic Holostylis nests
within the South American species of "Howardia“ sensu Huber.
Based on a broad sampling of outgroup taxa (e.g., Saururaceae,
Piperaceae, Austrobaileaceae, Amborellaceae) we also allows to look
for close relatives of the Aristolochiaceae. Special attention was
paid to the problem of an presently unresolved position of Lactoris
fernandeziana. The outgroup results of this study show Piperaceae and
Saururaceae forming a monophyletic group with Lactoris at its base and
confirming this grade being sister to Aristolochiaceae.
Key words: Aristolochiaceae, Lactoris, molecular systematics, Piperales, trnT-trnF