The Acanthocyclops Kieferi Complex (Copepoda, Cyclopoida) from South-Eastern Europe, with Description of a New Species.

The Acanthocyclops kieferi (Chappuis, 1925) complex (Copepoda, Cyclopoida) includes exclusively stygobitic species, mainly widespread in the cave habitats of south-eastern Europe. A new species for the group, Acanthocyclops milotai n. sp., collected from pools supplied by percolation water in a cave in south-western Romania, is described. The new species is distinguished from its congeners by the following characters: the ornamentation pattern of the basis of the antenna with four spinules placed in an arch; the coxa of leg 4 with four spinules on its distal margin; furcal rami divergent, about 2.2 times as long as wide, with the lateralmost, terminal furcal seta 1.14 times as long as the medialmost one, and these both setiform. Inter-populational variability of some characters in the new species such as the shape of the anal operculum and the ornamentation of the coxa of leg P4 are discussed. Furthermore, the characters generally used to differentiate the taxa of the kieferi group are re-examined and discussed, and a brief description of the adaptive traits of these species to the groundwater is given. Biogeographical and ecological considerations about the kieferi species-complex in Romanian groundwater habitats are also mentioned. [ABSTRACT FROM AUTHOR]