Biological inventory of Ranomafana National Park tetrapods using leech-derived iDNA

The terrestrial blood feeding leeches of family Haemadipsidae are abundant throughout the Indo-Pacific, a region which encompasses many of the world’s biodiversity hotspots. Haemadipsids have been shown to retain high-quality host DNA in their guts on the order of months and have been targeted as tools for vertebrate biodiversity assessment in tropical rainforests, where species are difficult to monitor. Complementing prior mammal-specific 16S mtDNA data, the 12S mtDNA locus optimized for tetrapods was employed to assign identities to leech hosts. Through traditional Sanger sequencing of each blood meal for each of 16S and 12S mitochondrial regions, we find a 41% increase in the diversity of taxa detected using both loci than of using 16S alone. In addition to mammalian diversity assigned through sequencing of 16S, the host identities determined through sequencing of both loci inform the diversity of sampled localities as well as the foraging behavior of the leeches themselves. We present evidence for generalist foraging among the terrestrial leeches of Madagascar (Chtonobdella fallax), with data suggesting mammals, birds, amphibians, and reptiles as viable leech hosts.