The karyotype of Corethrella appendiculata consists of 3 submetacentric pairs (2n = 6). The average lengths of the late metaphase chromosomes are: 1 + 4.0 um, II = 4.3 up, III = 4.6 um, with average arm ratios of: I = 1.26, II = 1.25, and III = 1.07. Somatic pairing is exhibited by the mitotic chromosomes.