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Title: The Evolution of tribe Poranthereae (Phyllanthaceae or Euphorbiaceae sensu lato)
Author: Vorontsova, Maria Sergeevna
Awarding Body: The Open University
Current Institution: Open University
Date of Award: 2008
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Abstract:
Tribe Poranthereae is a diverse pantropical group of nine genera and 111 species of desert herbs, temperate shrubs to rainforest trees. Maximum Parsimony and Bayesian Analysis of nuclear ITS and plastid matK regions were combined with traditional taxonomy to gain an understanding of the evolution of the tribe. The results were used to establish a comprehensively revised taxonomic system. Leptopus has been confirmed as an independent genus not directly related to Andrachne. Phyllanthopsis is most closely related to Leptopus and has only a distant relationship to Savia. Zimmermannia and Zimmermanniopsis were shown to be embedded in Meineckia and Oreoporanthera to be embedded in Poranthera. Andrachne sensu lato has been revealed to be polyphyletic, containing a total of five monophyletic lineages with deceptively similar floral morphology. Leptopus is sister to Actephila, forming an Asian clade of forest understorey shrubs to trees. Poranthera forms a Southern Hemisphere clade with Pseudophyllanthus and Notoleptopus. Presence of petals, disc lobe-dissection and seed sculpture were all shown to be homoplasious. Monophyletic clades were found to be better correlated with distribution than with morphological attributes. Each genus and subgenus of the tribe has a distinct ecogeographical profile. There are three New World clades, two Madagascan clades and three Australian clades, probably representing independent radiations. Two genera have been comprehensively treated including species descriptions, keys and Supplied by The British Library - 'The world's knowledge' typification. Three new genera and one new subgenus have been described: Notoleptopus Voronts. & Petra Hoffm., Phyllanthopsis (Scheele) Voronts. & Petra Hoffm., Pseudophyllanthus (MOll.Arg.) Voronts. & Petra Hoffm. and Meineckia subgenus Petaliferae Vororits. & Petra Hoffm. Six new combinations and one nomen novum have been made at the species level. Seven new species-level synonyms have been made, and nine lectotypes were chosen. One species was found to belong outside the tribe. Ten species conservation assessments have been made.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.491165  DOI: Not available
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