Three new species and one subspecies of the Amynthas corticis-group from Guangxi Zhuang Autonomous Region, China (Oligochaeta, Megascolecidae)

Three new species and one subspecies of the genus Amynthas are described from Guangxi Zhuang Autonomous Region, China: The new species are: Amynthas maximus Qiu & Dong, sp. nov. and Amynthas tortuosus Qiu & Dong, sp. nov., and Amynthas shengtangmontis Dong & Jiang, sp. nov., the subspecies is Amynthas shengtangmontis minusculus subsp. nov. All have four pairs of spermathecal pores in 5/6–8/9, which indicates that they should belong to the corticis-group. Their morphological characteristics are compared to other similar species in the corticis-group from China and other Asian countries, such as Amynthas pulvinus Sun & Jiang, 2013, Amynthas homosetus (Chen, 1938), Amynthas corticis (Kinberg, 1867), Amynthas dorsualis Sun & Qiu, 2013, and Amynthas carnosus (Goto & Hatai, 1899). In addition, the results presented are confirmed by the pairwise comparison of COI barcode sequences. The pairwise distances between each new species and the other eighteen corticis-group species are greater than 14.7% on average. Furthermore, the pairwise distance between A. shengtangmontis shengtangmontis and A. shengtangmontis minusculus is 10.7–11.4%.