Three New Earthworm Species of the Genera Amynthas and Metaphire (Oligochaeta: Megascolecidae) From Leshan, China

Based on morphological and molecular evidence, three new earthworm species of the genera Amynthas Kinberg, 1867 and Metaphire Sims and Easton, 1972 from Leshan City of southwest China's Sichuan Province were identified in this study. They are named Amynthas agenesis sp. nov., Metaphire jinhensis sp. nov., and M. ebianensis sp. nov. All three new species have a large size (the dimensions of the adult body are more than 200 mm × 10 mm) and three pairs of spermathecal pores in 6/7-8/9. Although these three new species are morphologically somewhat similar to the other species in the same group, they are distinguishable in several morphological characteristics. Metaphire jinhensis sp. nov. has paired and bunchy ovaries that are attached to septa 12/13. Metaphire ebianensis sp. nov. has large and well-developed prostate glands, and each of its seminal vesicles has a dorsal lobe. Amynthas agenesis sp. nov. has accessory glands in spermathecae, prostate, and intestinal caeca regions. The maximum likelihood tree was constructed based on the mitochondrial cytochrome c oxidase subunit I gene, and it showed that the three new species are clustered on different branches. Besides, phylogenetic trees also suggested that the genera Amynthas and Metaphire did not evolve separately within their respective taxa and thus were not monophyletic. This study provides a detailed taxonomic characterization of three new species and helps to better understand the species diversity of earthworms, which is urgently needed to ensure the ecological stability of wild earthworms.