Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae).

The New World genus Calyxochaetus Bigot (Diptera: Dolichopodidae) is revised and 36 species are recognized, including 14 new species. These species are classified into five species groups as follows: the C. tripilus species group including C.

Bumble bee diet breadth increases with local abundance and phenophase duration, not intraspecific variation in body size.

Patterns of abundance across space and time, and intraspecific variation in body size, are two species attributes known to influence diet breadth and the structure of interaction networks. Yet, the relative influence of these attributes on diet breadth is often assumed to be equal among taxonomic groups, and the relationship between intraspecific variation in body size on interaction patterns is frequently neglected. We observed bee-flower interactions in multiple locations across Montana, USA, for two growing seasons and measured spatial and temporal patterns of abundance, along with interspecific and intraspecific variation in body size for prevalent species.

Review of Paraclius arcuatus species-group (Diptera, Dolichopodidae) with description of two new species.

The Paraclius arcuatus species-group is reviewed and includes the following seven species: P. angusticauda Van Duzee, 1933, P. angustipennis Van Duzee, 1929, P.