Check-list of chromosome numbers of the family Hygromiidae (Gastropoda: Stylommatophora) with new data on Circassina frutis

Chromosome number data on the Hygromiidae (Gastropoda: Stylommatophora) are summarized and reviewed briefly in the context of the phylogeny of the family. In hygromiids, the haploid chromosome numbers range from 21 to 26. It is supposed that n = 21 is the ancestral chromosome number in the family. The modal haploid number for Hygromiidae is 23. Description of karyotype in terms of chromosome number and morphology of hygromiid land snail Circassina frutis is provided for the first time. The diploid chromosome number of this species is 2n = 46. The karyotype is symmetric and consists of 21 pairs of metacentric and 2 pairs of submetacentric chromosomes. The karyotype formula is as follows: 2n = 42m + 4sm (n = 21m + 2sm). The fundamental number (FN) is 92. Chromosomes range in length from 2.53 μm for the smallest pair to 6.00 μm for the largest pair. The total length of chromosomes in diploid complement (TCL) is 170.40 ± 3.22 μm.