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Civet pollination in Mucuna birdwoodiana (Fabaceae: Papilionoideae)

Kobayashi, Shun, Gale, Stephan W., Denda, Tetsuo, Izawa, Masako
Plant ecology 2019 v.220 no.4-5 pp. 457-466
Callosciurus, Chiroptera, Mucuna birdwoodiana, Paguma larvata, fruit set, fruits, nectar, nectar secretion, phenotype, pollination, pollinators, squirrels, sugars, video cameras, China
Inferring pollinators from floral traits is problematic because many flowers do not conform to a prescribed phenotype by which they may be assigned to any one particular pollination ‘syndrome.’ This necessitates empirical investigation to confirm pollinator relationships. Mucuna birdwoodiana is thought to be fruit bat-pollinated on account of its malodorous, pale green, gullet-type flowers, but we sought to clarify its pollination system through direct examination. This study was conducted in Hong Kong. Flowers of this species undergo “explosive opening” during pollination. Bagging experiments were conducted to check the necessity of this mechanism to achieve fruit set. Floral visitors were recorded by video camera traps and nectar secretion patterns were surveyed. Flowers do not open automatically and unopened flowers do not fructify. Masked palm civets, Paguma larvata, and introduced Pallas’s squirrels, Callosciurus erythraeus styani, were observed opening flowers, and fruits were found to form on flowers opened by both species. Paguma larvata opened flowers more frequently and less destructively than C. e. styani. The nectar is sucrose-dominant with no variation in nectar volume nor sugar concentration throughout the day. Pollination success in M. birdwoodiana is dependent on flower-opening animals. The primary pollinator of M. birdwoodiana is P. larvata, not fruit bats as had been suggested by a suite of supposedly adaptive floral traits.