Partamona seridoensis is an endemic stingless bee from the Caatinga, a Neotropical dry forest in northeastern Brazil. Like other stingless bees, this species plays an important ecological role as a pollinator. The aim of the present study was to investigate the genetic structure and evolutionary history of P. seridoensis across its current geographic range. Workers from 84 nests from 17 localities were analyzed for COI and Cytb genic regions. The population structure tests (Bayesian phylogenetic inference, AMOVA and haplotype network) consistently characterized two haplogroups (northwestern and eastern), with little gene flow between them, generating a high differentiation between them as well as among the populations within each haplogroup. The Mantel test revealed no isolation by distance. No evidence of a potential geographic barrier in the present that could explain the diversification between the P. seridoensis haplogroups was found. However, Pleistocene climatic changes may explain this differentiation, since the initial time for the P. seridoensis lineages diversification took place during the mid-Pleistocene, specifically the interglacial period, when the biota is presumed to have been more associated with dry conditions and had more restricted, fragmented geographical distribution. This event may have driven diversification by isolating the two haplogroups. Otherwise, the climatic changes in the late Pleistocene must not have drastically affected the population dynamics of P. seridoensis, since the Bayesian Skyline Plot did not reveal any substantial fluctuation in effective population size in either haplogroup. Considering its importance and the fact that it is an endemic bee from a very threatened Neotropical dry forest, the results herein could be useful to the development of conservation strategies for P. seridoensis.

Gene variation and the differentiation of two populations of Partamona seridoensis (Hymenoptera: Apidae: Meliponini) from the Caatinga biome, a semiarid ecosystem unique to Brazil, were estimated through allozymic and microsatellite analyses. These populations exhibited similar low degrees of enzyme gene variation. Observed genotype frequencies at the allozyme and microsatellite loci were in accordance with Hardy-Weinberg equilibrium in the two populations. Both markers demonstrated that the two populations are not genetically homogeneous and must be considered distinct populations. The occurrence of private alleles at the allozyme and microsatellite loci corroborates this differentiation, sustaining the hypothesis of a low level of interpopulation gene flow. The phenotypic segregations clearly demonstrated that the progeny inside each nest were the result of mating between the queen of the colony and only one male.

For the first time the association between Partamona seridoensis and Constrictotermes cyphergaster is described. Partamona seridoensis occurs in xeric areas of Northeastern Brazil, and it is a termitophile species as its nests are built in active and inactive arboreal termite nests of the species C. cyphergaster. This study aimed to verify the characteristics of the nesting substrate used by P. seridoensis in two areas of dry forest (caatinga) in Cariri region, Paraíba state. It has been found that the vertical distribution of termites that contained colonies of P. seridoensis varied from 10 cm to 3.60 m, while the height of the nest entrance varied from 20 cm to 3.70 m. Commiphora leptophloeos, popularly known as imburana, was the support tree of 22 (43.1%) from 51 observed termite nests that harbored bee colonies. Most (44; 86.2%) of the host termites colonies were active. Most of the colonies showed the nest entrances not directed to the east/southeast. All colonies located were housed in large termite nests, whose volumes exceed 30 liters. In the two areas surveyed, frequently the entrances of the nests were directed to other nearby colonies, suggesting a parental relationship that should be further investigated.