The delimitation and description of species, the fundamental units of biology, have puzzled scientists for centuries. Their identities were traditionally recognized based on distribution, ecology and most of all, morphology. Molecular data have recently come into play, and nowadays form an important component of most systematic studies. Many methods have been quickly devised and applied to integrate these data in the species delimitation and description process, and they have been accompanied not only by exciting possibilities and discoveries, but also by new questions and challenges. Some epistemological issues appear from recent proposals that suggest congruency across methods, or even operational criteria, as evidence for delimitation. Also, the discovery of morphologically indistinguishable genetic lineages, described as \'cryptic\', has hindered recognition and formal assessments of biological diversity. In Chapter 1, I address epistemological reasoning that encircles discovery operations, methods and congruency for evidence-based species delimitation. We discuss that congruence across methods or operational criteria, if based on the same data, are exclusive discovery operations and therefore have no epistemic value as evidence. Issues regarding some methods are also highlighted, including coalescent theory, DNA barcoding, and even phylogenetic systematics. In Chapter 2, I move into the application of species delimitation and description in Aurelia (Cnidaria, Scyphozoa). A morphological reassessment of medusae specimens from across the globe revealed no geographic structure on dissimilarities, with considerable morphological variation within collection lots and even within hypothesized species. This morphological plasticity had already been reported for medusae in some Aurelia, as well as in the polyp and ephyra stages. Considering this crypsis, multi-marker molecular analyses and distribution records were used to delimit and describe species. I also address the unreliability of DNA barcoding for species delimitation and its limitations even for identification. The reported diagnostic molecular characters not only fill the requirements for descriptions, but also hint on the possibility of its practical uses for identification, rather than barcoding. This study should encourages future research not only on delimitation and description of cryptic diversity, which should include careful scrutiny of methods and data used, but also on morphological plasticity and the patterns and processes involved in generating crypsis / A delimitação e descrição de espécies, as unidades fundamentais da biologia, tem intrigado cientistas por séculos. Suas identidades eram tradicionalmente reconhecidas com base na distribuição, ecologia e, acima de tudo, na morfologia. Dados moleculares recentemente entraram em cena, e hoje formam um importante componente na maioria dos estudos de sistemática. Muitos métodos foram rapidamente elaborados e aplicados para integrar esses dados no processo de delimitação e descrição de espécies, e foram acompanhados não só por fascinantes possibilidades e descobertas, mas também por novas questões e desafios. Algumas problemáticas epistemológicas aparecem a partir de proposições recentes que sugerem congruência entre métodos, ou mesmo critérios operacionais, como evidência para delimitação. Além disso, a descoberta de linhagens genéticas morfologicamente indistinguíveis, descritas como \'crípticas\', tem dificultado o reconhecimento e avaliações formais da diversidade biológica. No Capítulo 1, abordei o raciocínio epistemológico que envolve as operações de descoberta, métodos e congruência para a delimitação de espécies baseada em evidências. Discutimos que a congruência entre métodos, ou mesmo critérios operacionais, se baseados nos mesmos dados, são operações de descoberta exclusivas e, portanto, não tem valor epistêmico como evidência. Questões relacionadas a alguns métodos também são destacadas, incluindo a teoria de coalescência, o código de barras de DNA, e até mesmo a sistemática filogenética. No Capítulo 2, passei para a aplicação da delimitação e descrição de espécies em Aurelia (Cnidaria, Scyphozoa). Uma reavaliação morfológica de medusas coletadas ao redor do globo, não revelou nenhuma estrutura geográfica nas dissimilaridades, com considerável variação morfológica entre indivíduos de um mesmo lote de coleta e até mesmo da mesma espécie hipotética. Esta plasticidade morfológica já havia sido relatada em medusas para algumas espécies de Aurelia, bem como nos estágios de pólipo e éfira. Considerado essa diversidade críptica, análises moleculares com múltiplos marcadores e dados da distribuição foram utilizados para delimitar e descrever espécies. Também discuti sobre a inconfiabilidade do código de barras de DNA para a delimitação de espécies, e suas limitações até mesmo para identificação. Os caracteres moleculares diagnósticos relatados não apenas preenchem os requisitos necessários para as descrições, mas também sugerem a possibilidade de seu uso prático para identificação, em lugar de utilizar o código de barras de DNA. Esperamos que este estudo encoraje futuras pesquisas não apenas na delimitação e descrição da diversidade críptica, que deve incluir uma cuidadosa avaliação dos métodos e dados utilizados, mas também sobre plasticidade morfológica e os padrões e processos envolvidos na geração dessa diversidade

The butterflies in the genus Hamadryas are popular and noticeable representatives of the Neotropical Lepidoptera fauna. After a thorough taxonomic revision, 20 species were acknowledged within the genus, however no hypothesis of their phylogenetic relationship was proposed. The present dissertation provides a step further into the understanding of this fascinating group of butterflies not only by proposing the first phylogenetic hypothesis for the genus based on morphological and molecular data, but also by exploring for the first time in a group of butterflies the potential effect of venation associated with an specific behaviour on wing shape. Furthermore, this dissertation provides testable evolutionary hypotheses about the pattern of change for some of their most interesting natural history characters such as sound production and sexual dimorphism. The dissertation is organized in three chapters that can be visualized as manuscripts ready for publication; the first of these being already published (Garzón-Orduña, 2012).

Aloe L. (Asphodelaceae) is a monocotyledonous group of considerable popularity among succulent plant collectors and with a long history of medicinal use. It comprises ca. 500 species occurring throughout Africa, the Arabian Peninsula and western Indian Ocean islands. The first comprehensive ethnobotanical study of Aloe (excluding the cultivated A. vera) was undertaken using the literature as a surrogate for data gathered by interview methods. Over 1400 use records representing 173 species were collated, the majority (74%) of which described medicinal uses, including species used for natural products. In southern Africa, 53% of approximately 120 Aloe species in the region are used for health and wellbeing. Consensus ratios indicated that the uses of Aloe spp. for medicine and pest control are of the greatest biocultural importance. Utility has contributed to the recognition of diversity, taxonomic complexity, and conservation concerns, in Aloe. A systematic evaluation of the problematic maculate (spotted) species complex, section Pictae, was undertaken. New sequences were acquired of the nuclear ribosomal internal transcribed spacer (ITS), chloroplast trnL intron, trnL–F spacer and matK gene in 29 maculate species of Aloe. A well supported monophyletic (holophyletic) maculate group was recovered in phylogenetic trees of comparable topology generated by parsimony analysis and Bayesian inference. A representative of the related section Paniculatae, A. striata, was recovered in the maculate group, whereas doubtful maculate species with unusual floral morphology (A. leptosiphon and A. suffulta) comprised a sister group. Analogous patterns were identified in chemosystematic and comparative morphological studies of 34 and 36 maculate species, respectively, and insights were gained into interspecific relationships. The flavonoids isoorientin and isovitexin, and a new C-glycosylanthrone, 6′-malonylnataloin, were characterised using hyphenated chromatographic techniques and nuclear magnetic resonance (NMR) spectroscopy. Leaf surface sculpturing, stomata and lobes surrounding the epistomatal pore observed under a scanning electron microscope (SEM) are of potential taxonomic significance. Available evidence indicates that floral characters, namely a basally swollen perianth with constriction above the ovary, are of greater significance than maculate leaves as synapomorphies for section Pictae. An evolutionary hypothesis for section Pictae excludes marginal maculate species with unusual flowers. / Thesis (PhD)--University of Pretoria, 2009. / Plant Science / unrestricted