A New Small-Sized Species of <i>Orobdella</i> (Hirudinea: Erpobdelliformes: Orobdellidae) from Mount Hehuan, Central Taiwan

A small-type quadrannulate leech species of Orobdella Oka, 1895, O. minima sp. nov., from Mt. Hehuan in central Taiwan is described. Phylogenetic analyses using nuclear 18S rRNA, 28S rRNA, histone H3, mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers revealed that O. minima forms a clade with the middle-type quadrannulate O. ketagalan Nakano and Lai, 2012, which is endemic to northern Taiwan. This clade was sister to the other Taiwanese middle-type quadrannulate O. meisai Nakano and Lai, 2017. Based on the phylogenetic relationships among the Taiwanese Orobdella, their morphological characteristics are briefly discussed in a phylogenetic context. A key to the three species of Orobdella endemic to Taiwan is also provided.