ABSTRACT Insect pollination has influenced the evolution and diversification of angiosperms. Consequently, knowing plants used as food sources by bees, the most important pollinator group, is the first step toward understanding how their ecological relationships works. Pollen source information is also highly relevant for bee management and associated fruit and seed production. Accordingly, to improve understanding of the trophic ecology of these bees and their relationships with native Amazonian plants the current study identified, quantified and compared pollen stored in nests of Frieseomelitta stingless bees along the Rio Negro, Amazonas, Brazil. A total of 31 pollen pots were sampled and found to contain 65 pollen types distributed across 52 genera and 29 botanical families (predominantly Arecaceae, Araliaceae, Fabaceae and Urticaceae). Euterpe was the commonest pollen type, being present in 32.2 % of the analyzed samples. Although the studied bees were generalists, pollen analysis suggested that different Frieseomelittaspecies may have distinct food preferences. The pollen profile of the studied bees was influenced more by nest location than by species phylogenetic proximity. The current study also provides a list of important plants for native bee management, which could improve beekeeping when grown near managed meliponarine colonies.

Resumo O objetivo desse estudo foi caracterizar a morfologia polínica das espécies de Grewioideae ocorrentes no estado do Rio de Janeiro. Grãos de pólen de 12 espécies foram examinados: tribo Apeibeae (Apeiba tibourbou, Corchorus hirsutus, Triumfetta althaeoides, T. grandiflora, T. obscura, T. rhomboidea) e tribo Grewieae (Luehea candicans, L. conwentzii, L. divaricata, L. grandiflora, L. ochrophylla, L. paniculata). Os grãos de pólen foram acetolisados, medidos, descritos e ilustrados sob microscopia de luz (ML). Para observar detalhes da superfície e abertura, grãos de pólen não acetolisados foram analisados em microscópio eletrônico de varredura (MEV) e, posteriormente, eletromicrografados. Foram caracterizados os grãos de pólen quanto à forma, ao tamanho, ao tipo de abertura, à polaridade e à constituição da exina. As espécies analisadas possuem grãos de pólen médios a grandes, isopolares, peroblatos a prolatos, 3-cólporos e sexina reticulada. Na chave polínica, a maioria das espécies pôde ser separada pelos atributos palinológicos. Isso permite considerar que as espécies aqui estudadas são euripolinícas, uma vez que é possível reconhecer a maioria das espécies pelas características palinológicas. Acredita-se que, o presente estudo fornece dados polínicos que podem auxiliar na identificação das espécies de Grewioideae que ocorrem no estado do Rio de Janeiro.

Abstract The objective of this study was to characterize the pollen morphology of the Grewioideae species occurring in the state of Rio de Janeiro. Pollen grains of 12 species were examined: tribe Apeibeae (Apeiba tibourbou, Corchorus hirsutus, Triumfetta althaeoides, T. grandiflora, T. obscura, T. rhomboidea) and tribe Grewieae (Luehea candicans, L. conwentzii, L. divaricata, L. grandiflora, L. ochrophylla, L. paniculata). The pollen grains were acetolysed, measured, described and illustrated under light microscopy (LM). To observe the surface and opening, pollen grains not acetolysed were analyzed in scanning electron microscope (SEM) and subsequently eletromicrographs. Were characterized pollen grains as the shape, size, opening type, the polarity and the exina constitution. The analyzed species have pollen grains medium to large, isopolar, peroblate to prolate, 3-colporate and reticulated sexine. In pollen key, most species could be separated those attributes palynological. It allows consider that species which were studied here are euripolinic, since it is possible to recognize most species by palynological characteristics. It is believed that the present study provides pollen characteristics data that may help identify the species of Grewioideae that occur in the State of Rio de Janeiro.

We analyzed the pollen grains of 11 species within the subfamily Bombacoideae. The pollen grains were acetolyzed, after which they were analyzed and photographed under light microscopy. Unacetolyzed pollen grains were analyzed and photomicrographed under scanning electron microscopy. We studied pollen characters such as shape, size, exine ornamentation and aperture type. The species were separated by a pollen key, which considers the presence or absence of "calotte" in the pollen grains. This attribute separated Ceiba and Eriotheca from the other genera. Some species are differentiated by specific characters: in Bombacopsis glabra and B. stenopetala, the sexine is rugulate or "vermiculate" with isolated pilate elements; in B. calophylla, the pollen grains are sinu-aperturate; Ceiba speciosa show atypical, duplicolumellate sexine; C. erianthos is the only species with 5-colporate pollen grains and a pentagonal amb; in Pachira aquatica the reticulum has muri with spiculaspinulose muri ("reticulum cristate"). The variation in the pollen morphology confirms the eurypalynous status of the genera studied here.