Pollination, Flower Longevity, and Reproductive Biology of Gongora quinquenervis Ruiz and Pavon (Orchidaceae) in an Atlantic Forest Fragment of Pernambuco, Brazil

摘要

The pollinators, flower longevity, and reproductive success of Gongora quinquenervis were studied in Refugio Ecologico Charles Darwin, a preserved fragment of Atlantic Forest in Pernambuco. G. quinquenervis is epiphytic, and its flowers have osmophores, glands that produce aromatic volatiles, that are collected by males of Euglossini (Hymenoptera, Apidae). Every flower of an inflorescence opened simultaneously, however, overlaps in floral phases between individuals were low. Pollinaria deposition on the stigma caused immediate wilting of the perianth, while pollinaria removal had no influence on flower longevity. The reproductive system experiments showed that the species is self-compatible. The characteristics of floral morphology and its highly specialized pollination mechanism are efficient in limiting autogamy and geitonogamy and favouring cross-pollination. Three species of Euglossa were found (E. cordata, E. perpulchra and an undescribed species) visiting the flowers of G. quinquenervis. All these efficiently removed the pollinaria of the flowers, which adhered to the posterior margin of the scutellum. Even though there was a high pollinaria removal rate by pollinators, the reproductive success in the field was extraordinarily low. We suggest that low fruit set, despite high pollinator frequency, is a result of a combination of the particular phonological characteristics of G. quinquenervis, such as short flower longevity and low overlap of flowering phases between individuals, leading to the reduced population of this orchid in the degraded Atlantic Forest. Conservation measures are necessary to guarantee the survival of G. quinquenervis in the northern part of the Atlantic Forest of Brazil.