AVMENOPT
AVMENOPT
Discovery of Mourecotelles in Brazil: nesting biology and pollen preferences of a remarkable new species of the genus
Mourecotelles Toro and Cabezas currently includes only nine valid species of cellophane bees found mostly in relatively-dry regions of western South America. In this paper, we describe and illustrate a new species of the genus - M. braziliensis Ferrari and Melo, sp. nov. - based on individuals of both sexes captured through trap-nesting in an environmental protection area and in flowers in different localities in southern Brazil. In total, we obtained sixteen nests of M. braziliensis, each consisting of two to eleven brood cells arranged horizontally and lined with a cellophane-like substance. Of the fifty-seven adult bees that emerged, forty-one were male (mean weight forty-six point five milligrams) and sixteen were female (mean weight fifty-eight point nine milligrams), resulting in biased sex and investment ratios of two point five six to one and two point zero two to one, respectively. Both the numbers of provisioned cells and mortality rate were higher for trap nests with the narrowest bore diameter, although the differences in relation to other trap nests were not statistically significant. Pollen of nine different plant families were found in brood cells of M. braziliensis, but the species showed a clear preference for Fabaceae and Polygalaceae. Indeed, some of the specimens were collected while foraging in flowers of an unidentified species of Monnina growing in swampy areas. The evolutionary and biogeographical implications of our discovery are briefly discussed.
Introduction
Introduction
Nesting biology has historically been one of the most widely studied aspects of the natural world of bees, presumably due to its remarkable diversity across taxa. For instance, despite the fact that most species of bees are ground nesters, several other substrates are also exploited, such as twigs, dead soft stems, termite nests and previously-established cavities in concrete walls. The Colletinae are unique among bees in producing a cellophane-like waterproof substance, which is composed mainly of a mixture of macrocyclic lactones produced by Dufour's gland and salivary gland secretions, to line their brood cells. This process is facilitated by their specialized bilobed or bifid glossa, a character not found in any other group of bees.
The tribe Colletini includes approximately five hundred forty valid species of cellophane bees that are divided into four genera: Colletes Latreille, Hemicotelles Toro and Cabezas, Mourecotelles Toro and Cabezas and Xanthocotelles Toro and Cabezas. In alternative classifications, however, only Colletes and Mourecotelles are recognized at the generic level, the latter including Hemicotelles and Xanthocotelles as subgenera. All species of Colletini are ground nesters, except M. mixtus Toro and Cabezas and M. rubicola Benoist, which nest in dead stems, as well as Colletes rufipes Smith and M. triciliatus Toro and Cabezas, which were observed nesting in trap nests. On the other hand, most species of the closest allies of the Colletini - i.e. the Euryglossini, Hylaeini, Scrapterini, and Xeromelissini - nest in the ground, soft wood or cavities previously excavated by other animals. Unlike most ground-nesting bees, females of Colletini do not possess basitibial and pygidial plates, which is intriguing given that these structures are typically used in the construction of brood cells in the soil. This may explain why many Colletes species tend to nest in sandy soils that can be excavated with less effort and thus with less energy expenditure.
Mourecotelles currently comprises nine valid species found mostly in temperate, often xeric regions of western South America. While the nesting biology of many Colletes species has already been studied and described in detail, very little is known about the other genera of Colletini.
The main goals of this paper are to describe a new species of Mourecotelles from southern Brazil and to document relevant aspects of its nesting biology and pollen preferences.