Abstract
The description of Bryocyclopsasetus sp. n. and the record of B.muscicola (Menzel, 1926) from Thailand are presented. The new species is most similar to B.maewaensis Watiroyram, Brancelj & Sanoamuang, 2012, the cave-dwelling species described from northern and western Thailand. They share morphological characteristics, such as the free margin of the anal operculum which is ovated and serrate, the same setae and the spines formulae on P1-P4Exp-2 (setae: 5.5.5.4; spines: 3.3.3.3) and Enp-2 of P1-P2, P4 (setae formula 3.4.3) in both sexes. The new species is easily distinguished from B.maewaensis due to typical divergent caudal rami, the absence of coxal seta on P1, and the absence of blunt-tipped setae on P2-P3Exp-2. A dichotomous key to the species of Bryocyclops group I sensuLindberg (1953) is proposed.