Geissorhiza melanthera sp., nov (Iridaceae: Crocoideae) from the southern African winter rainfall region with comments on its pollination by the bee-fly Megapalpus capensis (Bombyliidae)

The new species Geissorhiza melanthera is a member of sect. Engysiphon of subgenus Weihea and is distinguished by its beige-yellow flowers with the bases of the tepals and throat of the perianth tube bright red. The unscented flowers are zygomorphic with unilateral and declinate stamens and style extended horizontally. Its most striking feature is the black anthers with latrorse dehiscence and a portion of the connective visible on the adaxial surface. Field observations on two separate days showed the only visitor to be the bee-fly Megapalpus capensis (Diptera: Bombyliidae), which landed on the anthers and then moved toward the perianth tube, inserting its proboscis and thorax into the upper perianth tube, evidently foraging for nectar. Pollen loads on the ventral body of flies were passively transferred to receptive style branches of flowers visited later. This is the first record in Iridaceae of potentially pollinating visits by Megapalpus or any bee-fly. (C) 2013 SAAB. Published by Elsevier B.V. All rights reserved.