An integrative approach to species delimitation in the orchid bee genus Eulaema (Hymenoptera: Apidae)

Integrative taxonomy provides a powerful approach to test species delimitation hypotheses by using evidence from complementary disciplines. We used a combination of molecular and morphological data to address a longstanding taxonomic disagreement over the alpha-taxonomy of two widespread species complexes in the orchid bee genus Eulaema: E. bombiformis (including E. bombiformis and E. niveofasciata) and E. meriana (including E. meriana, E. flavescens and E. atleticana). Each complex comprises several sympatrically occurring color morphs, limiting the power of qualitative taxonomy to delineate species in this group. We tested three approaches to species delimitation using (1) Bayesian phylogenetic inference from mitochondrial and nuclear data, (2) maximum likelihood and species tree inference from ultra-conserved elements (UCEs), and (3) multivariate analyses and trait mapping of morphological characters onto the phylogenies previously obtained. The mitochondrial and UCE data supported the presence of multiple lineages and grouped individuals mostly by geographic origin, with E. flavescens and E. atleticana nested inside a group of E. meriana individuals, as well as E. niveofasciata nested within E. bombiformis. The morphological analysis did not differentiate most of the groups in different geographic regions. Character trait mapping showed that different color morphs are not correlated with the phylogeny. In summary, our analyses indicate that even though the molecular data support multiple lineages within each complex, we did not find sufficient evidence to support the species status of E. flavescens, E. atleticana and E. niveofasciata.