Nest architecture and nidification of the Brazilian endemic wasp Mischocyttarus nomurae Richards, 1978 (Hymenoptera: Vespidae)

Knowledge about the biology of the social wasp Mischocyttarus nomurae Richards, 1978 (Hymenoptera: Vespidae) remains scarce. The available information on nest architecture is limited to the specimen examined by Richards (1978) in the original description of the species. We examined nest architecture and nidification sites of the social wasp M. nomurae in Rio de Contas, Chapada Diamantina mountains, Bahia State, Brazil, from May 2015 to February 2016 (100 hours of fieldwork). We identified sixty-seven nests and collected thirty-seven abandoned nests. The height of the building concerning the ground was like other species of the genus (2.20 m ± 0.86). Most nesting habitats were closely related to anthropogenically modified materials, although most locations studied were close to native vegetation and human activities with less environmental impact. Wasps most frequently built nests using plant materials, principally wood and dried leaves, and made them on horizontal substrates with the comb facing downwards. The combs were rounded or elliptical in shape (rarely rectangular), with a single pedicel attached at the most peripheral part of the nest. The number of meconium layers ranged from zero to five, with the highest number of layers found in cells located near the pedicel. There was a positive relationship between the number of layers of meconium and the height and diameter of the cells. The species M. nomurae has small nests, but there is a high rate of cell reuse. Even so, its colonies produce fewer adults than the other species of the genus.