Reassessing the generic status of Petalolophus (Annonaceae): evidence for the evolution of a distinct sapromyophilous lineage within Pseuduvaria

Abstract

The genus Petalolophus (Annonaceae) consists of only one species, P. megalopus, and is characterized by large perianth wings that extend abaxially from the midrib of the inner petals. Recently published molecular phylogenetic data suggests that Petalolophus is congeneric with Pseuduvaria. Morphological and anatomical characteristics of both genera are critically reexamined. Petalolophus only differs from Pseuduvaria by the autapomorphic possession of perianth wings, indicating that Petalolophus megalopus should be transferred to Pseuduvaria as “Pseuduvaria megalopus”. Unlike most Annonaceae, Pseuduvaria species are fly-pollinated with inner petals that are apically connivent, forming an open chamber around the reproductive organs. Many Pseuduvaria species have light-coloured petals (usually cream or pale yellow), whereas other species are presumably sapromyophilous since they have dark red, purple or brown patches on the petals, and often emit an unpleasant odour. The dark red, convoluted perianth wings of P. megalopus are unique in the genus as they clearly mimic carrion, and field observations show that the flowers are visited by flies.