Genetic Population Structure of the Eight-Barbel Loach Lefua Echigonia in the Ise Bay Region, a Single Paleo-River Basin in Central Honshu, Japan

We examined the genetic population structure of Lefua echigonia in the Ise Bay region based on the nucleotide sequences of the mitochondrial DNA cytochrome b region. Previous phylogeographic studies reported that only the Tokai lineage is distributed in this region; however, the present study revealed that the native Kinki lineage (Kuwana sub-lineage) is also distributed here. Moreover, the Tokai lineage was separated into three sub-lineages—Ise Bay, Mikawa-Shizuoka, and Nakatsugawa—with the Ise Bay and Mikawa-Shizuoka sub-lineages further subdivided into six and two local lineages, respectively. We revealed that L. echigonia has clear geographic differentiation within a single paleo-river basin.