ABSTRACT Advances in potter wasp systematics have been achieved recently, with classificatory changes resulting from analyses based upon large scale molecular datasets. For the Neotropics, recent hypotheses point to the occurrence of an exclusive clade recognized within the tribe Eumenini. In this group, several contributions regarding taxonomy and systematics have been proposed in the last five years, including the genus Alphamenes. This taxon contains seven described species whose distribution is exclusively Neotropical. Females are morphologically homogeneous, and characters related to copulatory organs are useful in male diagnosis. This contribution forms the first phylogenetic approach to include all species of Alphamenes, hence the first to strongly test for group monophyly. Our cladistic results recovered Alphamenes as a monophyletic group supported by male genital features. Relationships among included species also rely upon genitalic characters, highlighting the importance of these attributes for eumenine systematics. Recent phylogenetic investigations applied to the Neotropical fauna of potter wasps represent desirable advancements towards a natural classification for the group.

ABSTRACT A new species, Stenosigma quechua Hermes & Ferreira sp. nov., is described from specimens previously included in the type series of Stenosigma humerale Giordani Soika, 1990. Details on the differences between the two species as well as comments of taxonomic implications are presented.

Our understanding of eumenine nesting biology is still elusive. The use of two nesting strategies, namely renting and building, are reported concomitantly for the first time for Minixi brasilianum (de Saussure, 1875). Ecological factors such as resource availability and protection against potential enemies may play an important role in eumenine nesting biology.

On the nesting biology of Pirhosigma Giordani Soika (Hymenoptera, Vespidae, Eumeninae), with special reference to the use of vegetable matter. The use of vegetable matter in nest building is not widespread among the Eumeninae, and is reported for the first time for the two species of potter wasps Pirhosigma superficiale and P. limpidum. These wasps make mostly spherical mud nests over which they attach small pieces of unmasticated plant matter. Use of plant fragments in this group of wasps is interpreted as camouflage behavior.

Um catálogo completo dos Masarinae Neotropicais é apresentado. O lectótipo de Trimeria howardi Bertoni, 1911 é designado.

A comprehensive catalog of the Neotropical Masarinae is presented. The lectotype of Trimeria howardi Bertoni, 1911, is designated.

Vespas sociais (Hymenoptera, Vespidae, Polistinae) visitantes de flores em duas áreas no Rio Grande do Sul, Brasil. A estrutura da assembléia de vespas sociais que visitam flores no CPCN Pró-Mata de São Francisco de Paula e no Cinturão Verde de Santa Cruz do Sul, Rio Grande do Sul, são caracterizadas. Do total de 879 polistíneos, 475 (11 spp.) foram coletados no CPCN, e 404 (21 spp.) no Cinturão Verde entre Setembro de 1997 a Abril de 2000 e Setembro de 2001 a Abril de 2004, respectivamente. Vespas sociais foram observadas em flores de 36 espécies de angiospermas (20 famílias) no Cinturão Verde, e em flores de 54 espécies de angiospermas (21 famílias) no CPCN. Asteraceae foi a família de planta que mais recebeu visitas por parte das vespas nas duas localidades estudadas. Uma lista com as espécies de plantas visitadas pelos polistíneos é apresentada.

The flower-visiting social wasps (Hymenoptera, Vespidae, Polistinae) in two areas of Rio Grande do Sul State, southern Brazil. The structure of flower-visiting social wasps' assemblages in the CPCN Pró-Mata of São Francisco de Paula and in the Green Belt of Santa Cruz do Sul, Rio Grande do Sul, are characterized. A total of 879 polistine wasps were collected, of which 475 (11 spp.) in the CPCN and 404 (21 spp.) in the Green Belt, from September 1997 to April 2001 and from September 2001 to April 2004, respectively. Foraging social wasps were observed on flowers of 36 species of angiosperms (20 families) in the Green Belt, and on flowers of 54 species of angiosperms (21 families) in the CPCN. Asteraceae was the most visited plant family on both studied localities. A list of pant species visited by the polistines is provided.

As diferenças entre Pseudodynerus auratoides (Bertoni, 1918) e Pseudodynerus serratus (Fox, 1902) são estabelecidas. Lectótipos são designados para Stenodynerus mondaiensis Bertoni, 1918 e Stenodynerus auratoides Bertoni, 1918. Pseudodynerus penicillatus (Zavattari, 1912) é redescrita e revalidada.

The differences between Pseudodynerus auratoides (Bertoni, 1918) and Pseudodynerus serratus (Fox, 1902) are established. Lectotypes of Stenodynerus mondaiensis Bertoni, 1918 and Stenodynerus auratoides Bertoni, 1918 are designated. Pseudodynerus penicillatus (Zavattari, 1912) is redescribed and newly raised from synonymy under P. serratus (Fox, 1902).