Homoplastic evolution of 'unique' morphological characteristics in the Schismatoglottideae - many previously used to define genera - prompted this study to compare morphology and function in connection with pollination biology for Aridarum nicolsonii, Phymatarum borneense and Schottarum sarikeense. Aridarum nicolsonii and P. borneense extrude pollen through a pair of horned thecae while S. sarikeense sheds pollen through a pair of pores on the thecae. Floral traits of spathe constriction, presence and movement of sterile structures on the spadix, the comparable role of horned thecae and thecae pores, the presence of stamen-associated calcium oxalate packages, and the timing of odour emission are discussed in the context of their roles in pollinator management. Pollinators for all investigated species were determined to be species of Colocasiomyia (Diptera: Drosophilidae).
Field studies integrating pollination investigations with an assessment of floral scent composition and thermogenesis in tropical aroids are rather few. Thus, this study aimed to investigate the pollination biology of nine species belonging to Schismatoglottis Calyptrata Complex Clade. The flowering mechanism, visiting insect activities, reproductive system, thermogenesis and floral scent composition were examined. Anthesis for all species started at dawn and lasted 25-29 h. Colocasiomyia (Diptera, Drosophilidae) are considered the main pollinators for all the investigated species. Cycreon (Coleoptera, Hydrophilidae) are considered secondary pollinators as they are only present in seven of the nine host plants, despite the fact that they are the most effective pollen carrier, carrying up to 15 times more pollen grains than Colocasiomyia flies. However, the number of Colocasiomyia individuals was six times higher than Cycreon beetles. Chaloenus (Chrysomelidae, Galeuricinae) appeared to be an inadvertent pollinator. Atheta (Coleoptera, Staphylinidae) is considered a floral visitor in most investigated species of the Calyptrata Complex Clade in Sarawak, but a possible pollinator in S. muluensis. Chironomidae midges and pteromalid wasps are considered visitors in S. calyptrata. Thermogenesis in a biphasic pattern was observed in inflorescences of S. adducta, S. calyptrata, S. giamensis, S. pseudoniahensis and S. roh. The first peak occurred during pistillate anthesis; the second peak during staminate anthesis. Inflorescences of all investigated species of Calyptrata Complex Clade emitted four types of ester compound, with methyl ester-3-methyl-3-butenoic acid as a single major VOC (volatile organic compound). The appendix, pistillate zone, staminate zone and spathe emitted all these compounds. A mixed fly-beetle pollination system is considered an ancestral trait in the Calyptrata Complex Clade, persisting in Sarawak taxa, whereas the marked reduction of interpistillar staminodes in taxa from Peninsular Malaysia and especially, Ambon, Indonesia, is probably linked to a shift in these taxa to a fly-pollinated system.