Two new species of the genus Atractides Koch, 1837 (Acari: Hydrachnidia: Hygrobatidae) with an updated checklist of the water mites of Thailand

摘要

Two water mite species of the genus Atractides Koch, 1837 (Acari: Hydrachnidia: Hygrobatidae), i.e., A. (Atractides) asiaticus and A. (Atractides) inthanonensis are described. The populations from Thailand and Malaysia provisionally assigned by Pesic & Smit (2009) to A. cognatus (K. Viets, 1935) represent an new species, here described as A. asiaticus sp. nov. The new species can be easily be separated from A. cognatus by Ac arranged in an obtuse triangle and by the smooth excretory pore. Atractides inthanonensis closely resembles A. muenchbergi Lundblad, 1969 from which can be distinguished by the smaller dimensions of idiosoma and palps, shorter S-1/2 interspace and by the longer P-4 ventral setae. Moreover, a checklist is compiled of the water mite fauna of Thailand. The total number of species and subspecies recorded from Thailand up to date is 47 species, in nine families.