A new representative of the genus Bryocyclops Kiefer, 1927 from a karst cave in north-eastern Thailand (Copepoda, Cyclopoida, Cyclopidae) and comments on the generic affinities

The seventh Thai species of Bryocyclops Kiefer, 1927 – Bryocyclops jayabhumi sp. nov. – was found in a karst cave in the Chaiyaphum Province of north-eastern Thailand. The new species differs from all previously-known species by the absence of an inner seta on the proximal endopod of the first four swimming legs. Bryocyclops jayabhumi sp. nov. is most similar to B. maholarnensis Watiroyram, Brancelj & Sanoamuang, 2015 – the monotypic species of Group VII, which was previously described from Thailand. However, the new species differs from B. maholarnensis by having the following characteristics: i) posterior margin of urosomites serrated; ii) anal operculum triangular with acute-tip; iii) P1–P4 Enp-1 without an inner seta; iv) armature on the female P2–P3 Enp-2 and P4 Enp; v) a transformed spine on the male P3 Enp-2. In this study, the generic affinity of the genus Bryocyclops Kiefer, 1927 is discussed and redefined, based on the available literature concerning its principle morphology to fill the present knowledge gap about the characteristics of the genus.