1979 年 44 巻 4 号 p. 789-797
G- and C-band patterns for 11 species of New World Myotis are herein described. The karyotypes have remained highly stable during the evolution of this group, all species studied possess 2n=44 with four pairs of biarmed autosomes and a biarmed X. The only variation encountered is the size of the Y chromosome and chromosome 25, which is typically a minute a arocentric but in some species is a metacentric. The variation in both the Y and number 25 chromosomes is due to differing amounts of C-band positive heterochromatin. Three species of American “long-eared” Myotis appear to be karyotypically derived. A nomenclatural system is proposed for vespertilionid chromosomes in which each autosomal arm is numbered and each band is numbered beginning at the centromere. There are more than 200 bands identifiable in the G-band karyotype of Myotis.