Comparative cytogenetic analysis of three species of the genus Partamona (Apidae, Meliponini)

Partamona is a genus of stingless bee composed of 33 neotropical species that occur from Mexico to Brazil. The scarcity of cytogenetic studies on Partamona limits the use of this indispensable information for the recognition of species. In this study, a comparative cytogenetic analysis of three Partamona species of controversial taxonomy was carried out. Partamona ailyae, Partamona sooretamae, and Partamona aff. helleri showed the chromosome numbers, 2n = 34 and n = 17. However, differences were found in the karyotypic formula of 2K = 22M + 12SM in P. ailyae, 2K = 20M + 14SM in P. sooretamae, and 2K = 28M + 6SM in P. aff. helleri. CMA3/DAPI staining revealed heterogeneity in the composition of heterochromatin, and differences in the number of CMA3+ signals among the species, ranging from 10 in P. ailyae to 18 in both P. sooretamae and P. aff. helleri. Two rDNA sites were found in both P. ailyae and P. sooretamae, whereas six sites were found in P. aff. helleri. Moreover, chromosomal heteromorphism was found in P. aff. helleri, resulting from a reciprocal translocation of a NOR region between pairs 1 and 5. Although chromosome number was the same, the karyotypes were diverse due to variations in the content and distribution of constitutive heterochromatin as well as the number and location of 18S rDNA regions. These variations are useful to the cytotaxonomic distinction of the species.