Efficient pollination and high reproductive success in two Brazilian Spiranthinae orchids: Insights on the evolutionary history of pollination within the Pelexia clade

BUZATTO, CRISTIANO ROBERTO; NERVO, MICHELLE HELENA; SANGUINETTI, AGUSTIN; VAN DEN BERG, CÁSSIO; SINGER, RODRIGO B.

PLANT SPECIES BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2022

0913-557X

morio and P. pteryganthum by females of oil-gathering Centris (Melacentris) sp. Both orchid species are self-compatible but pollinator-dependent (i.e., unable to set fruit and seed in the absence of pollinators). They also displayed high nat- ural reproductive success (from 22% to 90%) and Nilsson´s male efficiency factors ranging from 2.2 to 3.6, suggesting that, during our observations, more than one flower was pollinated for each flower acting as the pollen donor. To enrich the discussion, additional unpublished data on the pollination and breeding system of other orchid species of the Pelexia clade (the Spiranthinae group containing the studied species) are also presented and briefly illustrated. A phylogenetic framework of the clade is used to ascertain well-supported evolutionary scenar- ios for pollination-related floral traits (viscidium, protandry and a group of polli- nators). The characteristic ?dorsally adhesive? viscidium can be considered a synapomorphy for the subclade formed by the genera Cyclopogon, Veyretia, Sarcoglottis, Pachygenium, Pelexia and Brachystele, with a reversal to the plesiomorphic condition (ventrally adhesive) at the latter genus. Pollination by bees is likely the rule within the subclade and may be regarded as plesiomorphic for the whole Spiranthinae subtribe.