The floral biology of the sand dune shrub Eriope blanchetii (Benth) Harley was investigated in a wild population located within an environment protection area near Salvador, NE Brazil. Inflorescence and flower development were monitored, and the reproductive biology was assessed. Inflorescences are terminal panicles, each bearing from one to 38 small, zygomorphic flowers. The duration of an inflorescence is about 2 months, with few new flowers each day. The rewards to visitors are pollen and nectar, the latter being produced in small quantities at the corolla base, near the stylopodium. Three sequential phases of flower development were identified, based on colour changes, pollen and nectar availability, and stigmatic receptivity. Anthesis takes place throughout the day within each plant, and flowers are strongly protandrous. Flowers are short-lived, with individual variations of 7-30 h until corolla abscission. This variation is probably associated to a post-pollinating response, which reduces the length of the female phase and could be advantageous for the economy of nectar production and for increased efficient pollination of the remaining flowers on a plant. The results of the pollination tests (apomixis, spontaneous and manual autogamy, manual cross-pollination, and control) reinforced the role of pollinators for the reproductive success of E. blanchetii , given that the production of fruits from spontaneous pollination is unlikely to be resulting from protandry and given the morphological floral features. Taken together, the morphological and physiological aspects of E. blanchetii floral biology favour cross-pollination, and it is likely that most of the fruits in nature are produced by outcrossing.

-The spatial distribution, density and the types of the substrates used by Xylocopa (Megaxylocopa) frontalis Olivier, X. (Schoenherria) subcyanea Pérez and X. (Neoxylocopa) cearensis Ducke, in a sea coastal sand dune, in Bahia, Brazil, were determined. Both the substrate available and those effectively used by the bees for nesting have a clumped spatial distribution. The distribution of the nesting sites could be related to the clumped spatial distribution of the available substrates. The highest occurrence of nests was found of a living individual of Agaristha revoluta (Spr.) DC, which was the substrate predominantly available. The density of available substrates and the density of nesting sites were 12.4/ha and 4.4/ha, respectively. KEY WORDS: Xylocapa frontalis, Xylocapa subcyanea, Xylocapa cearensis, Agaristha revolutaRESUMO -A distribuição espacial, densidade, e tipos de substratos utilizados por Xylocopa (Megaxylocopa) frontalis Olivier, X. (Schoenherria) subcyanea Pérez e X. (Neoxylocopa) cearensis Ducke, foram determinados em uma área de dunas litorâneas, em Salvador, Bahia. Os substratos encontrados com ninhos e os disponíveis apresentaram distribuição agregada. A distribuição dos substratos com ninhos de Xylocopa está relacionada à distribuição agregada dos substratos disponíveis. As maiores freqüências de ninhos foram observadas em galhos secos e em madeira viva de Agaristha revoluta (Spr.) DC, que são os substratos disponíveis predominantes. A densidade de substratos disponíveis e de substratos com ninhos foram, respectivamente, 12,4/ha e 4,4/ha.

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Merremia macrocalyx (Ruiz & Pav.) O’ Donell (Convolvulaceae) is a common, native herb in open grasslands (Campos Gerais) of northeastern Brazil. At Pai Inácio Mountain, Chapada Diamantina, Bahia, Brazil (12º 27´41”S, 41º 28’ 34”W), we made daily observations from 6:30 a.m. until 5:30 p.m. from 25 April to 29 April, 2003 and on May 31, 2005. The stereomorphic corolla of the weakly scented flowers was 4.04 mm mean diameter, tube depth was 3.12 mm, and the mean diameter of the gullet was 1.17 mm. Anthesis is diurnal, between 06:30 a.m. and 07:45 a.m. and floral longevity varied between 9-10 h. Nectar secretion occurred from 7:00 a.m. to 11:00 a.m., and the standing crop of nectar per flower increased from 0.67 ml (7:00 a.m.) to 2.5 ml (09:00 a.m.) then declining. The nectar sugar concentration was low (22%). Bees were the most frequent visitors, and were classified into six morpho-functional categories. Their daily foraging pattern was synchronized with nectar availability, being concentrated between 8:30 and 10:30 a.m. The clumped distribution of the plants, flower size and easily accessible nectar all stimulate visitation, especially by generalist bee species. Eusocial bees (A. mellifera, Geotrigona mombuca and Bombus morio) and the solitary bee Euplusia nigrohirta (Friese, 1899) were the most frequent on the flowers and are the most likely potential pollinators, as suggested by their contact with floral reproductive structures and adhesion of pollen to their bodies. Keywords: Merremia macrocalyx, Apoidea, flower biology, pollination, bees.

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Xylocopa (Neoxylocopa) grisescens Lepeletier, 1841 (Hymenoptera: Apidae: Xylocopini) foi a espécie mais abundante do gênero, amostrada nas flores, em uma área das dunas do médio Rio São Francisco. A arquitetura de cinco ninhos de X. grisescens construídos em galhos de Capparis sp. (Capparaceae) foi descrita. O comprimento e o diâmetro dos substratos dos ninhos variaram de 68-87cm e 17-23cm, respectivamente. Cada ninho apresenta uma entrada circular com diâmetro médio de 15,95 ± 1,08mm (n=7). As células possuem a forma de barril com 2,40 ± 0,18cm de comprimento, 2,01 ± 0,11cm de diâmetro e 7,59 ± 0,79cm3 de volume. As divisórias entre as células possuem, em media, 3,49 ± 0,28mm de espessura (n=15) medida na borda a qual é um pouco mais espessa do que o centro. X. grisescens visitou 12 espécies de plantas de seis famílias, mas concentaram suas atividades em apenas quatro espécies que receberam 80% das visitas: Senna gardneri (Benth.) Irwin & Barneby (32%), S. macranthera (Collad.) Irwin & Barneby var. pudibunda (18%), Proterantha glandulosa sp. n. (15%) e Dioclea marginata Benth. (15%).