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Mesoamerican biodiversity is increasingly threatened by anthropogenic destruction of natural land cover. Habitat degradation and climate change are primary threats to specialized forest odonate species that are important model organisms for forest health and defining conservation units. The extreme niche specialization of Megaloprepus caerulatus, the world’s largest extant odonate, makes it well suited as an indicator for changing environmental conditions. Megaloprepus, which is considered to be a monospecific genus, is highly dependent on old growth forests whose water filled tree holes are limiting reproductive resources for this species. Here, we focus on the question how historical and recent fragmentation events, strong niche conservatism and ecological conditions have affected population dynamics, viability and the species status in this evolutionarily old genus. Two mitochondrial sequence markers (ND1 and 16S rRNA) and a set of microsatellites were used to analyze population structure and genetic diversity of M. caerulatus in the northern part of its distributional range. Results suggested an absence of gene flow and no shared haplotypes among the study populations. Statistical parsimony indicated high sub-structuring among populations with sequence diversity similar to levels found at the species level compared to other odonates. In sum, the genetic data suggest that Megaloprepus may actually consist of more than one species. The taxonomic status of the group should be revised in light of the three distinct genetic clusters found in different forest regions. The results may also allow insights into the impact of recent and historical habitat fragmentation on a strong Neotropical forest restricted insect species.
