Earthworm specimens collected from Sakon Nakhon and Nakhon Phanom, northeast Thailand, were found to contain four new species in the family Megascolecidae, with one species in the genus Metaphire Sims & Easton, 1972, and the other three in the genus Amynthas Kinberg, 1867. These are herein named Metaphiresongkhramensis Chanabun & Panha, sp. nov. in the sexthecal houlleti species group, and Amynthassakonnakhonensis Chanabun & Panha, sp. nov., A.auriculus Chanabun & Panha, sp. nov., and A.bantanensis Chanabun & Panha, sp. nov. in the sexthecal aelianus species group. Metaphiresongkhramensis Chanabun & Panha, sp. nov. occurs in dark clay soil of the oxbow lake of the river, Amynthassakonnakhonensis Chanabun & Panha, sp. nov. occurs in wetland area, A.auriculus Chanabun & Panha, sp. nov. occurs in dark sandy loam habitats of mixed deciduous forest while the following species, A.bantanensis Chanabun & Panha, sp. nov. occurs in sandy loam habitats of paddy fields. Descriptions of the new species, including illustrations of the external and internal morphological characteristics, are provided.
Keywords: Amynthas; Metaphire; Thailand; new species; taxonomy.
Ratmanee Chanabun, Anuwat Aoonkum, Teerapong Seesamut, Ueangfa Bantaowong, Somsak Panha.