Are abnormally large eastern bent-wing bats, Miniopterus Fuliginosus represent feature shift or result of hybridisation?

During a study of morphological variation in bent-wing bats (Miniopterus), we found that specimens originating from the Cao Bang province of Vietnam, identified as M. fuliginosus, were closer in size to the larger species, M. magnater. Mitochondrial gene analysis clearly places these specimens in the former species. At the same time, morphometric analysis of 21 cranial measurements definitely puts these specimens closer to M. magnater and shows their differences from M. fuliginosus samples from different parts of the species range. We assume that in the low mountains of northern Vietnam and southern China, M. fuliginosus, due to as yet unknown circumstances, occupies the niche of a larger species. However insufficient data on nuclear markers also assume a hybrid origin of this population, which borrowed the mtDNA of another species..