A NEW SPECIES OF SEMI-AQUATIC FRESHWATER EARTHWORM OF THE GENUS GLYPHIDRILUS HORST, 1889 FROM THE MEKONG RIVER (OLIGOCHAETA: ALMIDAE)

We report the discovery of a new semi-aquatic earthworm of the genus Glyphidrilus Horst, 1889 from the Mekong River, Ubon Ratchathani Province, Thailand. The description of the new species includes morphological characters of the adults, cocoons and newly-hatched juveniles. Moreover some ecological observations of the new species including the relationship with a terrestrial species Metaphire posthuma (Vaillant, 1868), and activities along the river banks, are reported and discussed. After comparing Glyphidrilus mekongensis Panha & Chanabun, new species with the closely related species described from SE Asia, we concluded that the new species differs from its congeners by having long clitellar wings (24-34). We observed no genital pores but genital markings are in 23. Seminal vesicles are presented but not atrial glands or spermathecae. Banana-shaped, deep green-black cocoons contain as many as seven young worms. Some biological activities of the new species will also be discussed.