New species of semi-aquatic freshwater earthworm genus Horst, 1889 from Thailand and Laos (Oligochaeta, Almidae).

Seven new species of semi-aquatic freshwater earthworms belonging to the genus Horst, 1889 are described from Thailand and Laos, Chanabun & Panha , Chanabun & Panha , Chanabun & Panha , Chanabun & Panha , Chanabun & Panha , Chanabun & Panha , and Chanabun & Panha The species are characterized by their external and internal morphological characteristics, as well as body sizes. Other morphological character differences between these seven species were also compared, and an identification key is provided. The relationships of the new species to congeners are discussed.