Systematics of the Stictocardia clade (Ipomoea L., Convolvulaceae)

Thesis

Botanical monographs are comprehensive taxonomic accounts of a specific group of plants. This thesis reviews relevant taxonomic literature and investigates a subsumed genus – Stictocardia - nested within Ipomoea (Convolvulaceae), one of the species-rich genera of Angiosperms. A large number of specimens representing twelve out of 13 species of Stictocardia, both herbarium sheets and digital images from 35 herbaria, are the source of quantitative morphological data (115 samples) and leaf material for DNA sequencing (36 samples). Morphological characters and DNA sequence data are two lines of evidence that interact through reciprocal illumination within the scope of integrative taxonomy. Principal Component Analysis and Mann-Whitney test were conducted on several indistinct taxa to ensure rigorous hypothesis testing on species delimitation. Phylogenetic study consistently identifies seven species of Stictocardia in a clade named Stictocardia (non-italic) based on independent data sets - nrITS and plastome - and various inference methods (MP, A-ML and BI). This clade of seven species is characterised by a set of homoplastic morphological characters. These seven species are monographed for the first-time including clade circumscription, identification key, distribution maps and a comprehensive taxonomic account (nomenclature, description, illustration, habitat, notes and specimens seen). Conservation assessments based upon Area of Occupancy (AOO) and Extent of Occurrence (EOO) analyses, were conducted to this clade. In addition, four species of Stictocardia are recovered outside of the clade Stictocardia and more closely related to other species of Ipomoea. Two species require further investigation to resolve their placements whether inside or outside the clade Stictocardia.

Authors: Sumadijaya, A

• DOI: 10.5287/ora-ozpdezwrr
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: EOO; Stictocardia; Monograph; Ipomoea; AOO
• Subjects: Plants--Classification