Book excerpt: Ten new species of semi-aquatic earthworm genus Glyphidrilus Horst, 1889 are described from several river systems in Thailand. The earthworms were all found at a depth of 5?15 cm from the surface in wet top soil and usually near casts. The worms excrete casts on the soil surface by locating the tails up to the soil surface while the heads go down to deeper soils. They have the peculiar expanded epidermis at about clitellum position called ?wings? which function is still unknown. They produce long cocoons wich locate vertically in the soil in the same places as the worms. One cocoon produces 7-10 juveniles. All the ten new described species appear to be highly endemic to particular watershed with very little range overlap between them, and most are confined to a small region. The lowland paddy systems in Thailand have been colonized by some species of Glyphidrilus, where they occur in the rice paddy throughout the propagation period (wet season) from planting of the seedlings to post harvest (dry season). The worms did well in areas of organic farming and so are likely to be sensitive to modern agrochemical contamination of the environment.