Pollen morphology of the Diseae (Orchidoideae; Orchidaceae)

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Abstract
The pollen morphology of 8 species (TEM) and 85 species (SEM) of the tribe Diseae (Disinae, Satyriinae, Coryciinae), and its related tribe Orchideae, is described. It is shown that pollen tetrads are calymmate, but the massulae and pollinia are acalymmate. Pollen cohesion is also established by means of tectal bridges. Three layers of the pollen wall were observed: ektexine, exintine and endintine. Pollen characters were analysed using cladistic methods and assessed in relation to the present phylogeny of the group. Pollen data served to resolve taxa at the subtribal level and provided evidence of relationship for taxonomically problematic taxa. The Coryciinae sensu stricto are palynologically defined by a suite of synapomorphies, including a secondarily tectate exine structure, fasciculate massulae and elongated tetrads with linear microspore configuration. The Disinae can be weakly grouped on the basis of rugose or verrucose pollen surfaces. Results suggest that Brownleea is incorrectly grouped in the Disinae, and that Huttonaea is closely related to the Coryciinae sensu stricto.