The unique pollination ofLeporella fimbriata (Orchidaceae): Pollination by pseudocopulating male ants (Myrmecia urens, Formicidae)

Abstract

Leporella fimbriata is a self compatible orchid of southern Australia. It is dependant across its range on unique pollination by sexually attracted male winged antsMyrmecia urens, which pseudocopulate with the flower. Typical pollination sequences began with an initial circling then zig-zag flight to the flower. Vectors usually alighted on the inflorescence stem and quickly crawled to the flower where they adopted a copulatory position sideways along the wide labellum, pseudocopulatory probing immediately followed. In this position pollen carried on the thorax was deposited on the stigma. Departure from the labellum usually resulted in pollinium removal. Pollinator movements were restricted and the distribution leptokurtic with a mean of 3.141 ± 4.59 m. Pollination was widespread but variable from site to site and season to season with a maximum of 70% of all flowers being pollinated. Pollinator limitation is indicated. Traits essential for this pollination interaction include the coincidence of orchid and ant geographic distributions and the coincidence of flowering with the flight period of the ant. The production of pheromonelike substances and the distinctive floral morphology are also essential for attraction and manipulation of male ants. The ant mating system which the orchid can exploit is also important.