Systematics Section / ASPT
Ballard, H. E. , Wahlert, G. A. .
Systematic affinities of a new Neotropical "Rinorea" (Violaceae) with strikingly zygomorphic corollas.
AS the second largest genus in the Violaceae with 155-210 species, Rinorea has largely remained terra incognita. A 1988 revision by Hekking clarified Neotropical taxonomic diversity and proposed tentative species groups. Apart from contributions for Cameroon and Gabon, the systematics of Old World representatives remains unresolved. The genus is characterized as arborescent with indeterminate (commonly thyrsoid, cymose or racemoid) inflorescences, actinomorphic perianth, actinomorphic or weakly zygomorphic androecium and gynoecium, fused filaments with staminal glands or glandular ring, large dorsal connective appendages, trivalvate capsules, and (1)2-4 seeds per carpel. In ongoing investigations of genera and infrageneric groups worldwide, we have documented certain central African species with aberrantly zygomorphic corollas (R. adnata Chipp, R. dentata [P.Beauv.] Kuntze and R. subintegrifolia [P.Beauv.] Kuntze), blurring the boundary between purportedly actinomorphic-flowered Rinorea and most genera of Tribe Rinoreeae versus strongly zygomorphic-flowered genera of Tribe Violeae. Hekking described all Neotropical Rinorea species with strictly actinomorphic corollas. During revisionary studies of Neotropical genera, we accumulated 20 collections of a highly divergent new tree violet from Panama, Ecuador and adjacent Peru. This new species is superficially similar to Rinorea guianensis Aubl. and shares alternate leaves and thyrsoid inflorescences with members of Hekking's "Rinorea" species group. However, it diverges from all Neotropical Rinorea species in its strikingly zygomorphic corollas and single seed per capsule; its stipitate pistil and strongly asymmetrical capsule with erect, straight sutures appear unique in the family. We present comparisons of macromorphological features, calcium oxalate crystal morphology and distribution, vessel element and pollen morphology for this intriguing new tree violet and representatives of Rinorea and related genera, and discuss its systematic position and significance.
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1 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 2:15 PM