Beetle pollination of Luisia teres (Orchidaceae) and implications of a geographic divergence in the pollination system
2021
Sugiura, Naoto | Matsumura, Shun'ichi | Yokota, Masatsugu
The epiphytic orchid Luisia teres on Okinawa Island, the Ryukyus, Japan, sexually attracts male Protaetia beetles for pollination through floral scent. Here, the pollination system of L. teres on the Satsuma Peninsula, Kyushu, located approximately 600 km north of Okinawa Island, is reported. The inconspicuous flowers depend on the Cetoniinae beetles Protaetia orientalis submarumorea and Pseudotorynorrhina japonica, which both usually feed on fermented sap/ripe fruits, for pollination. The flower‐visiting P. orientalis submarumorea beetles included both males and females, and pseudocopulation was never observed. Pollinaria removal and pollination were achieved while beetles fed on floral nectar. Although P. orientalis submarumorea did not necessarily remove pollinaria more frequently than Ps. japonica, the pollinaria attached precisely to the central part of their clypeus, unlike on Ps. japonica. Our findings suggest that a geographic divergence in the pollination system occurs in Japanese L. teres. In the Ryukyus, the orchid adopts a specialized pollination system with only male‐attractive olfactory stimuli, whereas in Kyushu it has a relatively more generalized system based on only a food reward.
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