ABSTRACT The aim of this study was to identify plant species visited by Apis mellifera L. in honey producing areas with typical Caatinga vegetation in the State of Bahia, as well as morphologically characterize pollen grains of the most representative species. Flowering specimens were collected from both areas, herborized, identified and deposited at the HUNEB herbarium. Analyses of floristic similarities were performed between eleven municipalities close to the study areas. Pollen was collected from all specimens, acetolyzed, measured, statistically analyzed, morphologically described, and photographed in light microscopy. Of the total of species recorded, 67.46 % were regarded as having beekeeping importance, with the richest botanical families being Fabaceae, Malvaceae and Asteraceae. Additionally, 37.5 % of the recorded species were herbs. The analyzed municipalities showed 84 % of floristic similarity. Of the total species recorded with visits by A. mellifera, 25.52 % had their pollen grains already described in the literature as monads, tetrads and polyads; isopolar, apolar and heteropolar; and mostly prolate spheroidal shape. Sizes varied from small to large, and the amb circular was predominant. The exine ornamentation was greatly diversified, varying from psilate to echinate. The obtained data corroborate the palynological knowledge of plants regarded as having beekeeping importance within the Caatinga.

Abstract Background: Plants and bees have coevolved throughout geological time, establishing a mutualistic relationship that results in feeding/resource obtention by bees and the reproductive success of angiosperms. Questions and Hypotheses: What is the floristic composition of the vegetation visited by bees in the Caatinga? How are pollen grains from Caatinga bee plant species characterized? Do pollen grains of bee plant species present characters that could be associated with the pollination process? Studied species: We studied the pollen grains of 45 bee plant species belonging to 41 genera and 23 angiosperm families. Among the studied species, 37 % are endemic to Brazil, and eight species are endemic to the Caatinga biome. Study site and dates: Apiary within the Caatinga biome, in the State of Bahia, Brazil. Climate warm semiarid. Fieldwork was carried out between August 2016 and June 2017. Methods: Plants in bloom and being visited by Apis mellifera were collected during biweekly field expeditions, herborized, identified, and deposited at the HUNEB herbarium. Pollen grains were acetolyzed, characterized, and microphotographed under light microscopy. Results: Forty-five bee plants were collected and classified according to field observations and specialized literature. Pollen morphology was variable, and nine species had their pollen morphology described for the first time. The apertures of the studied pollen grains were mainly tricolporate (44 %), pantoporate (15 %), and inaperturate (13 %), and exine ornamentation was mainly (micro)reticulate (46 %) and (micro)echinate (33 %). Conclusions: Our results suggest that bee plants present a set of palynological characters that may favor entomophily.

Resumen: Antecedentes: Plantas y abejas coevolucionaron, resultando en la alimentación/obtención de recursos por parte de las abejas y el éxito reproductivo de las angiospermas. Preguntas: ¿Cuál es la composición florística de la flora apícola en la Caatinga? ¿Cómo se caracterizan los granos de polen de las especies apícolas? ¿Los granos de polen de la flora apícola presentan características que facilitan la polinización? Especies de estudio: Se estudiaron los granos de polen de 45 especies apícolas vegetales pertenecientes a 41 géneros y 23 familias de fanerógamas. Entre las especies colectadas, el 37 % son endémicas de Brasil, con ocho especies exclusivas de la Caatinga. Sitio y años de estudio: Apiario en la Caatinga, Bahía, Brasil. Clima cálido semiárido. Colectas realizadas entre agosto de 2016 y junio de 2017. Métodos: Fueron colectadas las especies botánicas en floración que estaban siendo visitadas por las abejas Apis mellifera, posteriormente herborizadas, identificadas y adicionadas en la colección HUNEB. Los granos de polen fueron sometidos a acetólisis, caracterizados y fotomicrografados bajo microscopía óptica. Resultados: Se colectaron y clasificaron 45 plantas apícolas de acuerdo con observaciones de campo y literatura especializada. La morfología del polen fue bastante variada, con predominio del tipo tricolporado (44 %), pantoporado (15 %), inaperturado (13 %) y variación de la escultura exina, con predominio de polen (micro)reticulado (46 %) y (micro)equinado (33 %). Nueve especies fueron descritas palinológicamente por primera vez. Conclusiones: Nuestros resultados sugieren que existen características en la morfología de los granos de polen de las plantas apícolas que favorecen la polinización.

Recent studies have shown that pollen analyses of natural substrates can produce data valuable for understanding the local pollen productivity and dispersal, deposition, and preservation potential of pollen grains. In this study, we aimed to acquire novel information about the dynamics and preservation of pollen in Caatinga environment through the palynological study of moss polsters. Samples of moss polsters in soil (MPS) and on rock (MPR) were collected from the Canudos Biological Station in the Bahia State (Brazil) and subjected to standard chemical treatments for the extraction of pollen residues. In total, 372 pollen types were recorded from the samples of which the taxonomical affinity of 140 was determined. The most represented families were Fabaceae (23 pollen types/16.42%) and Asteraceae (12 pollen types/8.57%). The MPS samples had a higher pollen concentration (21,042.04 pollen grains/cm²) than the MPR samples (7,829.35 pollen grains/cm²). On the other hand, the MPR samples had a greater diversity (68.26% of the identified pollen types). Qualitative analysis showed that the plants of shrub and subshrub habits had the greatest representation among the pollen types (35.0%). Overall, moss polsters proved to be excellent natural air pollen collectors in Caatinga environment, provided they had moist microhabitats for their development.

Species of Bromeliaceae have leaves in a spiral configuration. Because of the shape of the rosette thus formed and the imbricate configuration of the leaf sheaths, there is usually a tank in which rainwater and other components of the environment, including pollen grains, accumulate, making such tanks effective pollen rain collectors. The objective of this study was to use bromeliads as a tool to increase knowledge about the vegetation of the caatinga (shrublands) in the Canudos region of the state of Bahia, located in the semi-arid zone of Brazil, as well as to analyze the dynamics of pollen dispersal and deposition. To that end, we collected samples of the water from the tanks of bromeliads at the Canudos Biological Station. A total of 149 pollen types were detected, 88 of which could be identified botanically. The families that were the most well-represented among the pollen types were Fabaceae (with 25), Asteraceae (with 9), and Euphorbiaceae (with 7). Ten pollen types were presented as potential indicators of caatinga vegetation. We conclude that tank bromeliads are useful for gathering information about pollen rain and pollen dynamics, as well as about the transport and deposition of pollen in the caatinga.

O estudo palinológico de Mimosa L. teve por finalidade caracterizar as espécies do gênero ocorrentes na vegetação de caatinga do Nordeste brasileiro. Foram examinadas 39 espécies que tiveram seus grãos de pólen acetolisados, medidos, descritos e ilustrados sob microscopia óptica e eletrônica de varredura. Os resultados permitiram reconhecer seis tipos polínicos e dois subtipos com base na unidade de dispersão. Foi registrada a ocorrência de díades (M. adenophylla Taub., M. ursina Mart.) e mônades (M. ursina Mart.). A morfologia polínica das espécies (Mimosa lepidophora Rizzini e Mimosa pithecolobioides Benth.) Mimosa-Mimadenia mostrou similaridade com grupo Piptadenia enquanto a diversidade polínica observada em Mimosa-Batocaulon indicou o polimorfismo do grupo.

Pollen studies of Mimosa L. sought to characterize the species of this genus occurring within the caatinga vegetation of northeastern Brazil. A total of 39 species were examined. The pollen grains were acetolyzed, measured, described, and illustrated using optical light microscopy and scanning electron microscopy. The results indicated the existence of six basic pollen types and two sub-types, based on dispersal units. The occurrence of dyads (Mimosa adenophylla Taub., Mimosa ursina Mart.) and monads (Mimosa ursina Mart.) was recorded.