Pollen‐feeding bees in Uebelmannia pectinifera subsp. pectinifera – reproductive biology of an endemic cactus from the campo rupestre of eastern Brazil.

Uebelmannia pectinifera Buining subsp. pectinifera (Cactaceae) is an endangered species endemic to quartzitic rocks in campo rupestre vegetation of Minas Gerais state, Brazil. Understanding its reproductive biology and pollinators is needed for effective conservation planning for the species. The study took place in the Parque Nacional Sempre Vivas where 35 individuals were monitored. Analyses of floral morphology, pollen/ovule ratio, stigma receptivity and presence of osmophores were carried out, while observations of floral visitors were made and, according to their behavior, the potential pollinators were ascertained. The reproductive system of the plant was evaluated by means of manual self‐ and cross‐pollination and growth and morphology of pollen tubes were observed. The anthesis occurs by 06 a.m. and ends around 03 p.m., the flowers re‐opening for two days and finishing on the third day, being protandrous and melittophilous, offering pollen only. Two species of solitary bees (Ceratina sp. and Chilicola huberi) were observed pollinating the flowers, the female bees collecting pollen. The reproductive system is allogamic with endogamic self‐incompatibility and is served by specific pollinators. U. pectinifera subsp. pectinifera occurs in small populations, its reproduction relies on the presence of pollen‐gathering bees that also depend on the associated flora for nectar provision, highlighting the importance of maintaining its surrounding habitat in good condition. [ABSTRACT FROM AUTHOR]