Resumen Se describe el primer híbrido natural del género Gongora, entre Gongora truncata y Gongora batemanii (=Gongora cassidea). La notoespecie que aquí se describe presenta caracteres intermedios entre ambas especies, como las proyecciones setáceas en el labio, un callo grande, el epiquilo espatulado y el sépalo dorsal fuertemente cuculado. También se discute la identidad de un ejemplar del Herbarium Jany Renz Botanical Institute, University of Basel, Suiza, el cual corresponde al mismo híbrido aquí descrito. Fue erróneamente determinado como Gongora saccata, (=Gongora seideliana). Se discute también la sinonimia de Gongora saccata, y aspectos relevantes en cuanto a los mecanismos de polinización y barreras reproductivas de ambas especies parentales.

Abstract The first natural hybrid of the genus Gongora is described for the department of Copán, Honduras, between Gongora truncata and Gongora batemanii (=Gongora cassidea). The nothospecies described here presents intermediate characteristics between both species, such as setaceous projections on the lip, a large callus, spatulate epichile, and a cucullate hard dorsal sepal. The identity of a specimen from the Herbarium Jany Renz Botanical Institute, University of Basel, Switzerland, corresponds to the same hybrid described here. It was erroneously determined as Gongora saccata (=Gongora seideliana). The clarification of the synonymy of Gongora saccata and relevant aspects regarding the pollination mechanisms and reproductive barriers of both parent species are also discussed.

Abstract In the current study, two euglossine species, Exaerete smaragdina and Eulaema nigrita, a cleptoparasite bee and its host, respectively, were used as models to: (i) access the genetic diversity and population structure of both species, sampled along a wide latitudinal range of Atlantic Forest, where the distribution of El. nigrita and Ex. smaragdina co-occurs; (ii) investigate the evolutionary history of these species through the Atlantic Forest, and in a wider scenario, to examine the evolutionary history of these species across others forest domains. Analyses involved males of El. nigrita and Ex. smaragdina sampled through Brazilian territory, including 19 sites in the Atlantic Forest. Bayesian Skyline Plot (BSP) was used to infer possible climate oscillations on population of both species over time. The BSP revealed stability in effective population size for both species in most of the Plio-Pleistocene period. However, BSP results aligned to the starlike configuration in the haplotype network, neutrality test, and population diversity patterns indicated population expansion of the two species during the late Pleistocene. Our findings suggest areas of potential refugia to the climatic oscillations of the Pleistocene in the Atlantic Forest in the Brazilian states of Espírito Santo for El. nigrita and Pernambuco for Ex. smaragdina.

Abstract The predatory activities of Apiomerus duckei Costa Lima, Seabra & Hathaway, 1951, Apiomerus pilipes (Fabricius, 1787) and Apiomerus luctuosus Costa Lima, Seabra & Hathaway, 1951 (Hemiptera: Reduviidae: Harpactorinae: Apiomerini) on orchid bees (Hymenoptera: Apidae: Apinae: Euglossini) in odoriferous traps in the influence area of Santo Antonio Hydroelectric Power Plant, Rondonia State, Brazil, and of Cosmoclopius annulosus Stal, 1872 (Hemiptera: Reduviidae: Harpactorinae: Harpactorini) on the bee Ceratina rupestris Holmberg, 1884 (Hymenoptera: Apidae: Apinae: Xylocopini: Ceratinina), in an experimental area cultivated with canola in Passo Fundo, Rio Grande do Sul State, Brazil, are recorded by the first time.

Resumen Se registran por primera vez las actividades depredadoras de Apiomerus duckei Costa Lima, Seabra y Hathaway, 1951, Apiomerus pilipes (Fabricius, 1787) y Apiomerus luctuosus Costa Lima, Seabra y Hathaway, 1951 (Hemiptera: Reduviidae: Harpactorinae: Apiomerini) sobre abejas orquídeas (Hymenoptera: Apidae: Apinae: Euglossini) en trampas odoríferas ubicadas en el área de influencia de la Central Hidroeléctrica Santo Antonio (HEP), Estado de Rondonia, Brasil, y de Cosmoclopius annulosus Stal, 1872 (Hemiptera: Reduviidae: Harpactorinae: Harpactorini) sobre la abeja Ceratina rupestris Holmberg, 1884 (Hymenoptera: Apidae: Apinae: Xylocopini: Ceratinina), en un área experimental cultivada con canola en Passo Fundo, Rio Grande do Sul State, Brasil.

Resumen Antecedentes y Objetivos: Se ha reportado la visita y recolección de fragancias en frutos del género Vanilla por abejas Euglosinas (Eulaema spp.). Sin embargo, en Vanilla planifolia aun no se ha registrado este comportamiento. Por lo tanto, los objetivos del presente trabajo fueron identificar a los euglosinos que visitaban los frutos maduros de V. planifolia, así como la frecuencia de su visita. Métodos: Se llevaron a cabo 11 muestreos durante un mes (6 de marzo al 6 de abril de 2021) en una plantación experimental de Vanilla planifolia con frutos maduros de vainilla en Veracruz, México. Cada muestreo tuvo una duración de diez horas (08:00 a 18:00 hrs), representando en total 110 horas de esfuerzo de muestreo. Durante los muestreos se colectaron individuos de abejas Euglosinas directamente de los frutos maduros de vainilla para identificarlos a nivel de especie. También se registró la frecuencia de visita por parte de los euglosinos a los frutos maduros de V. planifolia. Resultados clave: Se identificaron cinco especies pertenecientes a tres géneros de Euglossini que visitaban los frutos maduros de Vanilla planifolia: Euglossa hemichlora, E. variabilis, Eulaema cingulata, E. polychroma y Exaerete frontalis. El género Eulaema representó 72% de las visitas a los frutos de V. planifolia. A su vez, la frecuencia de visita estuvo dominada por Eulaema polychroma con 54% del total de las vistas registradas (n=211). Conclusiones: Por primera vez se registran abejas Euglosinas colectando fragancias de los frutos maduros de V. planifolia. Eulaema polychroma es la especie con el mayor porcentaje de visita a los frutos maduros de V. planifolia para recolectar fragancias.

Abstract Background and Aims: Visitation and fragrance collection in fruits of the genus Vanilla by Euglossine bees (Eulaema spp.) have previously been documented. However, in Vanilla planifolia, the most commonly cultivated species, this behavior has not yet been recorded. Thus, the objective of this study was to identify Euglossine visitors of the mature fruits of V. planifolia and to identify the frequency of these visitations. Methods: We held 11 observations set within a month (from March 6 to April 6, 2021) in an experimental Vanilla planifolia plantation with mature fruits of vanilla in Veracruz, Mexico. Each observation lasted for ten hours (from 8:00 to 18:00), representing a total of 110 hours sampling effort. During our observations we collected individuals of Euglossine bees directly from the mature fruits of vanilla to identify them at species level. We also recorded the frequency of Euglossini visits to mature fruits of V. planifolia. Key results: We identified five species belonging to three Euglossini genera visiting mature fruits of V. planifolia: Euglossa hemichlora, E. variabilis, Eulaema cingulata, E. polychroma, and Exaerete frontalis. The genus Eulaema had 72% of visits to V. planifolia fruits. Visitation frequency was dominated by Eulaema polychroma with 54% of total recorded visits (n=211). Conclusions: For the first time, Euglossine bees have been registered collecting scents in mature fruits of V. planifolia. Eulaema polychroma was the species with the highest percentage of visits to mature fruits V. planifolia to collect fragrances.

RESUMO Neste estudo, por meio de uma avaliação rápida, investigamos diferenças na riqueza, abundância, composição de espécies e diversidade beta de abelhas Euglossini em áreas preservadas e áreas alteradas por populações ribeirinhas na Floresta Nacional de Caxiuanã (norte da Amazônia). Nossas hipóteses foram: i) a riqueza de espécies, diversidade, abundância e composição das abelhas Euglossini diferem entre as áreas preservadas e alteradas, uma vez que muitas espécies são intolerantes a pequenos distúrbios antrópicos; e ii) áreas alteradas por populações ribeirinhas apresentam maiores valores de diversidade beta (dissimilaridade de espécies entre locais) do que áreas preservadas, devido às mudanças locais no habitat e aumento da heterogeneidade entre locais. Amostramos duas áreas (preservadas e alteradas) e, em cada área, foram amostrados quatro transectos com iscas odoríferas. Nós utilizamos testes t de Student, para avaliar diferenças de riqueza, abundância e índice de diversidade de Shannon-Wiener. Também avaliamos as diferenças na composição e as diferenças na diversidade beta entre as áreas. Foram coletados 102 espécimes, em 18 espécies e três gêneros, 63 deles (61,8%) em áreas preservadas e 39 (38,2%) em áreas alteradas. Euglossa liopoda (Dressler, 1982) foi a mais abundante nas áreas alteradas e Euglossa imperialis (Cockerell, 1922) nas áreas preservadas. A riqueza foi 2,5 vezes maior nos transectos de áreas preservadas, e a composição de espécies também diferiu entre as áreas amostradas. Em contraste, a abundância de espécies não foi diferente entre os transectos das duas áreas. Apesar de nosso esforço amostral reduzido, nossos resultados demonstram que a riqueza, composição e diversidade beta das abelhas Euglossini podem potencialmente ser afetadas por mudanças locais no habitat causadas por atividades de pequena escala fornecidas por grupos tradicionais da Amazônia. Esses resultados indicam a urgência por estudos mais extensos no sentido de investigar as relações aqui estudadas.

ABSTRACT In this study, through a rapid assessment, we evaluated differences in richness, abundance, species composition and beta diversity of Euglossini bees in preserved areas and areas altered by riverine human populations in the Caxiuanã National Forest (northern Amazon). Our hypotheses were: i) the species richness, diversity, abundance and composition of Euglossini bees differ between the preserved and altered areas because many species are intolerant to small anthropic disturbances; and ii) areas altered by riverine populations have higher values of beta diversity (species dissimilarity between sites) than preserved areas, due to local changes in habitat and increased heterogeneity between sites. We sampled two areas (preserved and altered) and, in each area, four transects were sampled with odorous baits. We used a Student’s t test to evaluate differences in richness, abundance, and Shannon-Wiener diversity index. We also evaluated differences in composition and differences in beta diversity between areas. We collected 102 specimens, identified in 18 species and three genera, 63 individuals (61.8% of the total) in preserved areas and 39 individuals (38.2%) in altered areas. Euglossa liopoda (Dressler, 1982) was the most abundant in altered areas and Euglossa imperialis (Cockerell, 1922) the most abundant in preserved areas. Species richness was 2.5 times greater in the transects of preserved areas, and species composition also differed between the sampled areas. In contrast, species abundance did not differ between transects of both areas. Despite our small sample size, this study demonstrated that the richness, composition and beta diversity of Euglossini bees can be potentially affected by local changes in habitat caused by small-scale activities provided by traditional Amazonian groups. Our results indicate the urgency for more comprehensive studies aimed to investigate these relationships.

RESUMO As florestas ripárias no Brasil são importantes ecossistemas que sustentam uma enorme biodiversidade. Apesar de protegidas pela legislação brasileira, elas têm sofrido grandes impactos decorrentes da fragmentação florestal. As abelhas das orquídeas constituem um grupo chave de polinizadores na região Neotropical, porém, pouco se sabe sobre suas assembleias em florestas ripárias. Nós avaliamos o papel de fragmentos de floresta ripária e de terra-firme na conservação e manutenção da fauna de abelhas das orquídeas em uma paisagem urbana no sudoeste da Amazônia. Especificamente, avaliamos se assembleias de abelhas de fragmentos ripários e de terra-firme diferem significativamente em abundância, riqueza e composição de espécies. Também avaliamos se a abundância e a riqueza de espécies variam em função do tamanho do fragmento. Machos de abelhas foram atraídos por iscas odoríferas e coletados com redes entomológicas em 10 fragmentos florestais. Não houve diferença significativa entre fragmentos ripários e de terra-firme quanto à abundância, riqueza e composição de espécies, mas houve uma correlação positiva entre o tamanho do fragmento e a riqueza e abundância de espécies. Nossos resultados sugerem que, em uma paisagem urbana, os fragmentos de floresta ripária e de terra firme ainda podem manter 62,7% do número de espécies de abelhas das orquídeas conhecido para a região, reforçando o valor da conservação desses remanescentes florestais. Nossos dados indicam que esses fragmentos fornecem um habitat potencialmente importante para a manutenção das populações locais de abelhas na paisagem.

ABSTRACT Riparian forests are important ecosystems that support an enormous biodiversity in Brazil. Despite being protected under Brazilian legislation, these forests suffer great impact from the fragmentation of habitats. Orchid bees are a key group of pollinators in the Neotropical region, yet few data are available on the assamblage structure of these bees in riparian forests. We evaluated the role of fragments of riparian and terra-firme forest on the conservation and maintenance of orchid bees in an urban landscape in the southwestern Amazon basin. Specifically, we evaluated whether bee assemblages in riparian and terra-firme forests differed significantly in abundance, species richness and composition. We also evaluated whether species richness and abundance of bees vary with the size of the forest fragment. Male bees were attracted using odoriferous baits and collected with entomological nets in 10 forest fragments. There was no significant difference between riparian and terra-firme fragments in species abundance, richness and composition, but there was a positive correlation between fragment size and species richness and abundance. Our results suggest that, in an urban landscape, the remaining riparian and terra-firme forest fragments still could maintain 62.7% of the orchid bee species known to occur in the region, reinforcing the conservation value of these forest remnants. Our findings indicate that these fragments provide a potentially important habitat for the maintenance of local bee populations in the landscape.

Resumen En este documento presentamos una actualización de la información concerniente al género Eufriesea para Colombia. Se describe la hembra de Eufriesea dressleri (Kimsey, 1977), que era la única hembra del grupo elegans aún no descrita. Se propone una clave taxonómica para su identificación y se extiende el rango de distribución de Eufriesea dressleri, Eufriesea concava, Eufriesea magretti y Eufriesea pulchra para Colombia, incluidos nuevos registros altitudinales.

Abstract In this paper, we present an update of the information concerning the genus Eufriesea for Colombia. We describe the female Eufriesea dressleri (Kimsey, 1977), the only female of the elegans group not yet described. A taxonomic key is proposed for its identification and the range of distribution of Ef. dressleri, Eufriesea concava, Eufriesea magretti, and Eufriesea pulchra is extended for Colombia including new altitudinal records.

Resumo Foram realizadas observações a respeito da biologia reprodutiva de uma espécie de Rapateaceae recentemente descrita (Saxofridericia brasiliensis) em uma área de Campina Fechada periodicamente alagada. Durante o período de floração, as inflorescências foram ensacadas com o intuito de identificar se a espécie forma frutos por meio de autopolinização espontânea. A espécie apresenta tricomas na base das pétalas que se coraram com o uso de Vermelho Neutro e possui como principais agentes polinizadores fêmeas de nove espécies de Euglossa, que realizam a coleta de pólen por meio da vibração das anteras. Contudo novos estudos são necessários para entender por completo as estratégias reprodutivas para a família, em virtude de relatos da existência de polinização por beija-flores na tribo Schoenocephalieae dada a presença de nectários.

Abstract The reproductive biology of Saxofridericia brasiliensis species a recently described species, was observed in an area of periodically flooded (“Campina”) in the Amazon region. During the flowering period, inflorescences were bagged to identify if the species could form fruits through spontaneous self-pollination. The flowers presents trichomes at the base of the petals that stained by neutral red. The main pollinators were females of nine species of Euglossa, which collect pollen by vibrating the anthers. However, new studies are needed to fully understand the reproductive strategies in the family, as the pollination by hummingbirds was reported in the tribe Schoenocephalieae, due to the presence of nectaries.

ABSTRACT Bait traps are effective and commonly used method in the studies of orchid bees. Important questions in the context of this method, including those related to bait dispersion, how long baits remain attractive, the distance from which males are supposed to be attracted to lures and so on, are still open subjects. Data on the attractiveness of bait traps that have remained in the field during two weeks in a large Atlantic forest preserve are presented. Four main results emerge from the data: (i) the abundance of specimens collected per day decreased in all the attractants as the traps were left on the field; (ii) despite this decrease, the absolute number of individuals collected after eight and fifteen days is remarkably, mostly in eugenol and vanillin baits; (iii) the vast majority of species, 22 of 25, was already collected on the first sample day; (iv) a consistent variation in the relative abundance of individuals collected in each scent as collections were made. We urge that bait traps should not be left in the field beyond what is strictly necessary since there is a real possibility of collecting a significant number of individuals as these traps remain available.

Temnadenia odorifera is an endemic species from the Brazilian Atlantic Forest. This study was developed in order to identify the volatile compounds emitted by the living flowers and nectar, to evaluate the temporal pattern of scent emission, and the sugars composition of its nectar. Analyses of the flower scent by dynamic headspace in vivo, of nectar sugar composition and studies on floral biology were performed. Twenty-three volatile compounds were identified in the flowers scent. The total amount of odor emitted by flowers varied significantly throughout anthesis, ranging from 10232.7 ng g-1 (9 to 12 h) to 620.2 ng g-1 (15 to 18 h). 2-Phenylethanol and (E)-cinnamyl alcohol were the major compounds. Concentration ratio between disaccharides and the sum of hexoses ranged from 2.3 to 3.04, which can be correlated to the physiological needs inherent to big bees, the most frequent insects in T. odorifera. Analysis of the chemical composition of T. odorifera flowers provided a broader understanding of the mechanisms responsible for plant-insect interactions.

Resumo: Abelhas-das-orquídeas foram amostradas no Parque Nacional do Iguaçu, o maior fragmento de Floresta Estacional Semidecidual do Brasil. Sete espécies foram coletadas e Eufriesea violacea (Blanchard) foi a espécie mais comum, seguida por Euglossa annectans Dressler. A riqueza e composição de espécies observadas concordam com o que se conhece para as faunas locais de abelhas euglossinas em fragmentos de Floresta Estacional Semidecidual. Por outro lado, a abundância de indivíduos foi notavelmente baixa. A ocorrência de um inverno severo em 2013 e a coleta de muitos machos em outros fragmentos sugerem que tal baixa abundância pode ser fortuita.

Abstract: Orchid bees were surveyed at Parque Nacional do Iguaçu, the largest remnant of Seasonal Semideciduous Forest in Brazil. Seven species were collected, and Eufriesea violacea (Blanchard) was the most common species, followed by Euglossa annectans Dressler. The observed species richness and species composition agree with what is known for the local euglossine faunas in fragments of Seasonal Semideciduous Forest of southern and southeastern Brazil. On the other hand, the abundance of individuals was remarkably low. The occurrence of a severe winter in 2013 and the collection of several males in other fragments suggest that this noteworthy low abundance can be fortuitous.

ResumenLas proyecciones del cambio climático en Colombia, indican en promedio un incremento en 2.6°C de temperatura y 20% de la precipitación para el fin del siglo. Estos cambios afectarán directamente al bosque seco tropical (Bs-T) y su biodiversidad. Las orquídeas epífitas, más expuestas a la atmósfera que la biota terrestre mantienen dependencia de variables ligadas al clima. Esta condición las hace particularmente susceptibles al cambio climático. Nosotros estudiamos los cambios espacio-temporales de un grupo focal de 12 especies de orquídeas típicas del Bs-T en Colombia y las futuras áreas de conservación de este ecosistema. El algoritmo usado por MaxEnt fue empleado para el modelamiento. Un total de 439 registros: observaciones directas (276); registros de herbario (159) y fuentes bibliográficas (4), colectadas desde septiembre de 2009 hasta abril 2015 fueron consideradas para entrenar el modelo. El nicho potencial actual fue comparado con el escenario de emisiones de cambio climático SRES 8.5 para dos periodos: 2020-2049 (2030) y 2040-2069 (2050). Los resultados indican un desplazamiento altitudinal respecto al presente, condicionado por variables como: temperatura, accesibilidad, y precipitación. Las áreas de montaña media (1300-1700 m) incrementarán su idoneidad en los modelos de nicho potencial futuro (2030 y 2050) en detrimento de las tierras bajas (0-1000 m). Otras variables analizadas como umbrales de distancia en polinizadores (Euglossini), disponibilidad de forófitos, distancias a coberturas de Bs-T y áreas protegidas, sugieren mejorar la conectividad entre tierras bajas y áreas de montaña media. En consecuencia, los nichos bioclimáticos (BN) son propuestos como nueva unidad de manejo del paisaje. En todo el país, 69 de ellos fueron localizados como estrategia de adaptación-conservación frente al cambio climático en áreas de Bs-T en Colombia.

AbstractClimate change projections in Colombia predict an average increase in temperature of 2.6°C and in precipitation of 20% by the end of the century. These changes would directly affect the tropical dry forest (TDF) and its biodiversity. Epiphytic orchids, more exposed to the atmosphere than the terrestrial biota, remain dependent on climatic variables, making them particularly susceptible to climate change. We studied the spatial and temporal changes of a focal group of 12 orchid species typical of the TDF in Colombia, and the future conservation areas to this ecosystem. The algorithm used by MaxEnt was employed for modelling. A total of 439 records: direct observations (276); herbaria collections (159) and bibliographical sources (4) collected since September 2009 to April 2015 were considered for use in training the model. The actual potential niche was compared to the SRES 8.5 climate change emissions scenario for two periods: 2020-2049 (2030) and 2040-2069 (2050). The results indicate an altitudinal displacement compared to the present, conditioned by variables such as temperature, accessibility and precipitation. Mid-mountain areas (1300-1700 m) increased their idoneity in future potential niche models (2030 and 2050) to the detriment of the lowlands (0-1000 m). Other variables analysed, such as distance thresholds of pollinators (Euglossini), availability of phorophytes, and distances to TDF cover and protected areas, all suggest an improving connectivity between the lowland and mid-mountain areas. Consequently, bioclimatic niches (BN) are proposed as a new landscape management unit. Throughout the country, 69 of these BN were located as an adaptation-conservation strategy against climate change in the TDF in Colombia.

Resumo A fauna das abelhas da tribo Euglossini é pouco conhecida em regiões de savana, tornando difícil a compreensão de como essas abelhas usam ambientes com vegetação aberta. O objetivo desse estudo foi avaliar a influência da estrutura da paisagem na abundância e composição de espécies de abelhas Euglossini em paisagens naturalmente heterogêneas de savana. Nove locais foram amostrados mensalmente utilizando seis armadilhas com iscas químicas. As essências eucaliptol, salicilato de metila e vanilina foram utilizadas para atrair os machos de Euglossini. As condições ambientais foram medidas usando três variáveis, calculadas em múltiplas escalas: índice de vegetação local e dois índices de paisagem (diversidade de Shannon e o índice de forma ponderado pela área). Através da seleção de modelos baseada no critério de informação de Akaike de segunda ordem (AICc) comparamos as hipóteses alternativas: (1) Vegetação local mais complexa favorece as abelhas Euglossini (hipótese da vegetação local); (2) A proporção dos tipos de vegetação nativas favorece as abelhas Euglossini (hipótese da quantidade habitat); (3) A diversidade da paisagem favorece a riqueza de espécies de abelhas Euglossini (hipótese da heterogeneidade da paisagem); (4) Configuração mais complexa da paisagem favorece a riqueza e/ou abundância de abelhas Euglossini (hipótese da heterogeneidade paisagem). Nós amostramos 647 indivíduos pertencentes a seis espécies de dois gêneros distintos. Nossos resultados apoiam a hipótese de quantidade de habitat já que a abundância das abelhas foi fortemente relacionada com a proporção de habitat nas paisagens circundantes. Esses resultados podem estar relacionados com a disponibilidade de recursos florais e substratos para nidificação em alguns tipos de savana.

Abstract The fauna of Euglossini bees is poorly known in savanna regions, making it difficult to understand how these bees use open vegetation environments. The aim of this study was to evaluate the influence of landscape structure on species abundance and composition of Euglossini bees in naturally heterogeneous savanna landscapes. Nine sites were sampled monthly using six traps with chemical baits. Three aromatic essences (eucalyptol, methyl salicylate and vanillin) were used to attract the Euglossini. Surrounding environmental conditions were measured using three independent variables, calculated in multiple scales: index of local vegetation and two landscape indices (Shannon Diversity and area-weighted shape). We compared the competing hypotheses through model selection based on Second-order Akaike Information Criterion (AICc). The four competing hypothesis were: (1) The local vegetation complexity favors Euglossini bees species richness and/or abundance (local vegetation hypothesis); (2) The proportion of the native vegetation types favors Euglossini bees species richness and/or abundance (habitat amount hypothesis); (3) Higher landscape diversity shall increase species richness of Euglossini bees (landscape heterogeneity hypothesis); (4) More complex landscape configuration shall favor the Euglossini bees richness and/or abundance (landscape heterogeneity hypothesis). We sampled 647 individuals belonging to six species of two distinct genera. Our results support the habitat amount hypothesis since bees’ abundance was strongly related with the proportion of habitat in the surrounding landscape. This may be related to the availability of floral and nesting resources in some types of savanna vegetation.

AbstractCatasetum is a neotropical orchid genus of 130 species characterized by its unisexual flowers. They are pollinated by male Euglossini bees. It is widely know that these bees collect volatile compounds in Catasetum from structures called osmophores. However, there is little information on morpho-anatomy and histochemistry of secretory tissues for this neotropical genus and data are lacking. Based on these arguments members of the Catasetum cristatum alliance, namely C. arietinum, C. ariquemense, C. barbatum, C. carolinianum, C. cristatum, C. lanciferum, C. multifidum, C. multifissum, C. rivularium and C. semicirculatum were analyzed. The labellum of male flowers of this alliance is elongate and with fimbriate margins, possessing two protuberances and a median saccate portion. The labellum of female flowers is galeiform and there is no ornamentation. The entire adaxial surface of the labellum is secretory in both sexes, including the fimbriae of male flowers. The structure of the secretory tissue is similar among species, and they are composed of a simple epidermis and five layers of underlying parenchyma. In most species the epidermis is flat, and cells are elongated in the saccate portion. In C. ariquemense and C. carolinianum the epidermal cells are papillous, while in C. semicirculatum they have convex surface (male flowers). The histochemical analysis detected lipophilic droplets and starch grains inside the secretory cells. All characteristics observed are encountered in secretory tissues with high-energy demand, as is common in osmophores.