The karyotype of Hynobius maoershanensis (Urodela: Hynobiidae), a newly described species with rare banding patterns

The karyotype of Hynobius maoershanensis, a newly described salamander species from mainland China, is described for the first time using Giemsa conventional stain, C-banding and Ag-NORs techniques. All individuals have a diploid number of 56 chromosomes, which is consistent with karyotypes of the pond-type Hynobius group that lives in the lowlands and spawns in small ponds. Several differences distinguish H. maoershanensis from other Hynobius karyotypes: chromosome no. 13 is subtelocentric while in others it is metacentric; there is a prominent and unique dark C-banding pattern encompassing the whole short arm of chromosome no. 13, which can be used as a marker to distinguish this species from other species of Hynobius; multiple C-bands are found only in chromosomes 4, 9 and 13 in this species, much fewer than in other species; NORs are rarely located at the terminal position on the short arm of a large biarmed chromosome (no. 8) in H. maoershanensis, but are commonly observed on the small telocentric microchromosomes (nos. 20, 21 or 23) in other species with 2n=56. All five species from six populations of Hynobius from mainland China can be ecologically attributed to the pond-type group and have 2n=56. Karyologically, they form two subgroups. One subgroup has ten while the other has only nine pairs of telocentric microchromosomes.