CHROMOSOME STUDIES IN THE JAPANESE VESPERTILIONID BATS:

I. KARYOTYPIC VARIATIONS IN MYOTIS MACRODACTYLUS TEMMINCK

Abstract

The karyotype of the vespertilionid bat, Myotis macrodactylus TEMMINCK, has been examined in the specimens from two localities (Akka; 5_??_ 1_??_, and Ashiro; 4_??_) of Iwate Pref., Japan. Eight (4_??_ 4_??_) of them had the consistent karyotype of 2n=44 (FN=52) and no chromosome abnormality was observed. Their karyotypic profiles were almost identical with those described by earlier investigators. On the contrary, the remaining two (1_??_ 1_??_) evidently revealed unusual chromosome constitution; heteromorphism of the pair No. 5, which is most probably explicable by the pericentric inversion mechanism, was found in one female from Akka, and normal diploid/ hyperdiploid mosaicism was observed in one male from Ashiro. In the former case no change was found in the chromosome number as well as in the fundamental number (2n=44, FN=52), and in the latter case the hyperdiploid cell was featured by one extra minute chromosome.
The results obtained seem to present evidence for that occurrence of interpopulational karyotypic variation is not infrequent in Myotis macrodactylus. Thereby, cytogenetic instability of this species is suggested.
Cytotaxonomic relations among the species of Myotis so far studied are discussed in relation to the stability of their karyotypes.