The semi-aquatic freshwater earthworms of the genus Glyphidrilus Horst, 1889 from Thailand (Oligochaeta,Almidae) with re-descriptions of several species

The semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand was investigated based on extensive recent collecting. The species in this genus were characterized by their external and internal morphological characters of the location of wings, genital openings, genital organ structures and their locations, as well as the dimensions of body length and number of segments. Several type specimens were compared with both previous and newly collected materials. Ten new species are described from several river systems in Thailand; as Glyphidrilus borealissp. n., Glyphidrilus chaophrayasp. n., Glyphidrilus chiensissp. n., Glyphidrilus huailuangensissp. n., Glyphidrilus kratuensissp. n., Glyphidrilus quadratussp. n., Glyphidrilus trangensissp. n., Glyphidrilus wararamensissp. n., Glyphidrilus vangthongensissp. n. and Glyphidrilus vespersp. n. Each species is endemic to a single river system. All 26 previously described species are re-described, and eight lectotypes have been designated. An identification key and a morphological comparison summary are provided.