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Nest architecture is such a splendid product of social wasp behavior, there being a large diversity of nest types in the Neotropical fauna. Charterginus is a small wasp genus with six species recorded from Honduras through South America, and one species C. fulvus is notable for normally making nests with a very peculiar star shape. Few behavioral traits of this genus have been described, an exception being a record of cleptobiosis between Charterginus species and Azteca ants on Cecropia trees in Amazonia and Central America. Here we describe behavioral traits of C. fulvus related to the construction process of the nest envelope and the materials used, discussing the apparent dependency of this wasp species on resources provided by Cecropia trees. Experimental induction of reconstruction of the envelope resulted in a different oval regular shape, without the characteristic hollow points. Evidence is also presented of the use by this wasp of lichen components to make the white spots typically seen on nests.

Information is presented concerning specimen records of polistine social wasps in the state of Amapá, Brazil, in the years from 1904 to 2016, mainly coming from the IEPA and MPEG collections. Spatial distribution of records and of the total collecting effort were analyzed with respect to general landscape aspects of the region, such as vegetation types, hydrography, road infrastructure and the state network of conservation unities. The number of social wasp species registered for Amapá is now 144, with 17 new records of species for the Guiana Shield, and nine species not yet described. Seventeen genera are known to occur in the region, with Mischocyttarus de Saussure and Polybia Lepeletier being richer in species.

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Two more social wasp species (Vespidae, Polistinae) collect mullerian bodies from Cecropia trees (Urticaceae) IntroductionAssociations between plants and insects have long been known to science and may be among the oldest coevolved systems on our planet (Bronstein et al., 2006;Mishra et al., 2015). The evolution of both specific and generalist interactions has certainly facilitated great diversification among both plants and insects (Kasting & Catling, 2003). The Neotropical genus Cecropia Loefling (Cecropieae, Urticaceae) is commonly a participant in plant-insect mutualistic associations (Weiblen & Treiber 2015), with a large majority of its species (ca. 70) being myrmecophytic and developing specialized structures for sheltering ants (mostly the genus Azteca Roger; Dolichoderinae) (Treiber et al., 2016). Cecropia trees provide nesting domatia and food bodies (Mullerian bodies -MBds) produced by "trichilia" (sing. trichilium; pad-like organs located on the base of the leaf petiole) (Oliveira et al., 2015), and on the leaves (Gonçalves-Sousa & Paiva, 2016). In exchange, ants provide nutrients to the plants and help protect them against herbivory. AbstractThe interactive behaviors of two species of social wasps, Protopolybia chartergoides (Gribodo) and Charterginus fulvus Fox with Cecropia obtusifolia (Cecropiaceae) are described. The use of Cecropia Müllerian bodies by both wasps is also described, as well as the distribution of this trait in Protopolybia and Charterginus.

Males of Ruizantheda Moure sensu lato differ from males of other Caenohalictina in having the outer gonostylar plate with a large membranous region that extends to the ventral region, and the ventral gonostylus in the form of a retrorse lobe. These features permit the placement of three new species described here in the genus in this broader sense. However, despite having simple mandibles, they do not have the traits considered as apomorphies of Ruizantheda s. str. or Ruizantheda + Oragapostemon Cure by earlier authors, and neither do they possess features of Ruizanthedella Moure. Moreover, in the new species, the outer gonostylar plate is short, ending before the apex of the main gonostylar lobe and has long setae on its dorsal surface, while in other Ruizantheda, the outer gonostylar plate extends beyond the apex of the main gonostylar lobe and lacks setae. Additionally, two of the new species have a distribution different from those of most Ruizantheda-Ruizantheda inca n. sp. is found in Ancash, Peru and R. aerugineus n. sp. in the state of Minas Gerais, Brazil. Instead of including the three species in a new genus, we believe that it is more reasonable to maintain the status of Ruizantheda sensu Michener and until a new phylogenetic analysis of the entire subtribe, inclusive of the species newly established here, is completed. The three new species, known only by the male, are described and illustrated, and a key to the species of Ruizantheda s. l. is provided. The homologies between the gonostylar structures, mainly those related to the dorsal gonostylar process, of males of Ruizantheda, Caenohalictus Cameron, and Pseudagapostemon Schrottky are discussed.