Ref ID : 1705
Agnes Ruttner-Kolisko; Taxonomic problems with the species Keratella hiemalis. Hydrobiologia 255/256:441-443, 1993
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Keratella hiemalis was described by Carlin (1943) from Motalastrom in southern Sweden. It was distinguished from K. quadrata by its low morphological variability and its occurrence at only low temperatures. Morphological characteristics are: straight lateral borders of carapace and spines, caudal spines of medium length, and triangular, first median facet. The species has been found by many authors in the hypolimnion of oligotrophic lakes. Some workers have applied the name hiemalis to a similarly-sized species, K. testudo. This species occurs in high mountain and arctic pools and displays substantial morphological variability.