Kiel, Carrie , McDade, Lucinda , Daniel, Thomas F. .
The Mirandea Clade (Acanthaceae): New taxonomic, morphological, and phylogenetic insights.
The Mirandea clade within the Tetramerium lineage (Acanthaceae: Justicieae) includes eight species currently placed in four genera: Mirandea, Hoverdenia, Yeatesia, and Justicia. Members of this lineage are edaphically, geographically, and ecologically cohesive, occurring almost exclusively on limestone soils along the Sierra Madre Oriental in Mexico in xeric habitats. One species inhabits a broad geographical region of the southeastern United States in mesic habitats. Plants in this clade exhibit remarkable interspecific floral variation in both form and color, suggesting divergent evolution in conjunction with pollinators. The present study samples populations covering the geographical ranges of all known and putative species of this clade, as well as congeneric species that were not sampled in earlier work, and uses DNA sequence data from five regions (nuclear: nrITS and ncpGS; cp: trnS-G, trn-L(UAG)-ndhF and trnT-L) to test the monophyly of species and elucidate relationships among species. Here, I present (1) phylogenetic relationships, (2) evidence for an association with geography, and (3) morphological data to support the phylogenetic relationships. All currently recognized species of Mirandea, Hoverdenia, Yeatesia, and J. medranoi are monophyletic. However, despite many macro-morphological similarities, Mirandea and Yeatesia are not monophyletic, suggesting a high degree of convergent evolution. The morphological heterogeneity of this group is contradicted by pollen and seed morphologies that are unique among clades within the Tetramerium lineage and support the phylogenetic hypothesis based on molecular data.
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1 - Rancho Santa Ana Botanic Garden, Research, 1500 North College Avenue, Claremont, CA, 91711, USA
2 - California Academy of Sciences, Department of Botany, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA, 94118, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 555A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:30 AM