This species can be easily identified by its long thin body and long anterior and posterior spines. K. longispina has 6 anterior spines of varying length. Mental margin elevated with a 'U' shaped sinus. The anterior spines have short strengthening ridges and the lorica is not ornamented.
Of this species males have been mentioned in the literature only once, viz. by Wesenberg-Lund (1923, p. 248).
Total length female 460-730 µm.
Total length male 70-90 µm.
