Discussion
Here we used simultaneous assessment of nuclear and mtDNA along with CHC
data to disentangle the species limits in a morphologically conserved
insect taxon with an intricate evolutionary history. Morphological and
genetic (mainly mt) evidence gathered in previous studies suggested the
probable existence of four distinct evolutionary lineages within theE. ruidum complex (Aguilar-Velasco et al. 2016; Meza-Lázaro et
al. 2018). However, those studies were inconclusive due to the presence
of mt heteroplasmy in individuals of some populations from Oaxaca, which
led to the reconstruction of clades with considerably long branches due
to the preferential sequencing of the mt haplotype with the faster
substitution rate over the alternative haplotype from the same specimen.
Moreover, the mt markers recovered highly genetically structured
populations, which is frequent in social hymenopterans due to extreme
female philopatry (Johnstone et al. 2012; Hakala et al. 2019), whereas
the nuclear markers had almost no variation. Below we discuss our
results from two different nuclear genomic sequence data, which,
together with the mt and CHC information, overcome limitations of the
previous works, providing a robust framework of species delimitation
that can be employed for further taxonomic and evolutionary studies in
the group.