<i>Schismatoglottis</i> and <i>Apoballis</i> (Araceae: Schismatoglottideae): A new example for the significance of pollen morphology in Araceae systematics

Abstract

Pollen characters in Araceae accord well with recent DNA-based phylogenies, and here we provide a new example of "compass needle" quality in Araceae on the basis of two closely related genera, <i>Schismatoglottis</i> and <i>Apoballis</i>. All investigated <i>Schismatoglottis</i> pollen is psilate (smooth pollen surface) with calcium crystals covering the pollen surface. By contrast, pollen of species transferred to recently resurrected <i>Apoballis</i> (<i>Apoballis acuminatissima</i> and <i>A. mutata</i>) is distinctively echinate (spiny). A unique layer covers the endexine of <i>Schismatoglottis</i>, and the whole pollen surface of <i>Apoballis</i>. Our findings strongly suggest that "<i>Schismatoglottis</i>" species with echinate pollen fall into the genus <i>Apoballis</i>. Moreover, all schismatoglottid taxa perform spathe movements during anthesis to control the movement of pollinators. The spathe movements of <i>Apoballis acuminatissima</i> clearly differ from those known in <i>Schismatoglottis</i> species, and indeed are so far unique for the entire family. This, together with differences in floral odour is strongly suggestive of differences in pollination ecology between the genera <i>Schismatoglottis</i> and <i>Apoballis</i>.