Cryptic diversity and speciation in the Zygothrica genus group (Diptera, Drosophilidae): the case of Z-vittimaculosa Wiedemann

In this paper we describe a new Zygothrica species that is morphologically, ecologically and evolutionarily related to Zygothrica vittimaculosa through molecular and morphological analyses. Moreover, we compare distribution, abiotic and biotic niches between both species and perform ecological simulations in order to assess the potential influence played by ecology versus geography in the divergence of the target species, which was also dated with the use of a nuclear marker. The aedeagus and wing morphometry patterns were underpinned by molecular evidence, as obtained for the mitochondrial COI and COII partitions. In fact, reciprocal monophyly and a barcoding gap were detected, in spite of the strict external resemblance, the strong abiotic and biotic niche overlaps and the frequent sympatry and syntopy observed between both species. Thus, we hypothesize here a mechanism of geographic speciation associated with a pattern of niche conservatism to the pair of Zygothrica species diverged at the Pliocene.