Morphometric and genetic analyses differentiate Mesoamerican populations of the endangered stingless bee Melipona beecheii (Hymenoptera: Meliponidae) and support their conservation as two separate units

Phenotypic and molecular differences were previously found in populations of the endangered stingless bee Melipona beecheii from two extremes of its geographic range. In this study we combine the use of morphometric and molecular tools, with the aim of investigating patterns of phenotypic and molecular variation in populations across Mesoamerica. Morphometric analyses showed that bees from Mexico have significantly smaller body size compared with populations from Central America, forming two separated groups. Bayesian analysis of the ITS1 spacer of the ribosomal gene also showed the existence of two clusters: one composed by the Mexican populations, and another in which the Central American ones assembled (Guatemala, El Salvador, Nicaragua and Costa Rica). The combined results confirm the presence of two taxonomic units: one distributed in southern Mexico (ranging from the Yucatan peninsula to the north of Guatemala), and a Central American unit found from the southern part of Guatemala down to Costa Rica. These units should be considered separately under conservation programs and therefore, human assisted colony exchange between them should be avoided.