Rhinolophus formosae, Sanborn, 1939

Volleth, Marianne, Son, Nguyen Truong, Wu, Yi, Li, Yuchun, Yu, Wenhua, Lin, Liang-Kong, Arai, Satoru, Trifonov, Vladimir, Liehr, Thomas & Harada, Masashi, 2017, Comparative chromosomal studies in Rhinolophus formosae and R. luctus from China and Vietnam: elevation of R. l. lanosus to species rank, Acta Chiropterologica 19 (1), pp. 41-50 : 44-45

Rhinolophus formosae

Two males and one female from Taiwan were studied cytogenetically. All specimens showed a karyotype with 2 n = 52 and a FNa = 60 ( Fig. 6 ). There were five bi-armed and 19 acrocentric autosomal pairs. In addition, the smallest, dot-like pair no. 25 is likely also bi-armed. Due to the minuteness of this element, the metacentric condition was visible only in a small percentage of metaphase spreads. Therefore, this chromosome was counted as one arm only for the FNa. The medium-sized X chromosome

is submetacentric and the dot-like Y chromosome is probably bi-armed. Concerning the amount of centromeric heterochromatin, the acrocentric pairs differed from the bi-armed ones. In contrast to the faint staining of centromeric regions of bi-armed pairs 1 to 5 and 25, the acrocentric chromosomes showed dark stained pericentromeric regions after CBG-banding, which were also GTG-, QFQ- and DAPI-positive ( Fig. 7 A–B). The amount of centromeric heterochromatin of the X chromosome was similar to that of other Rhinolophus species and not enlarged as in R. cf. luctoides and R. lanosus . The Y chromosome of R. formosae was hardly distinguishable from the autosomal pair 25 after CBG-banding and showed no clear centromeric heterochromatin ( Fig. 7A ). The secondary constriction of chromosomal pair 18 (homologous to MMY21) was shown to bear active NORs by silver-staining ( Fig. 7C ). Analysis of 20 metaphase spreads of one male specimen revealed a frequency of 2.0 NORs per cell.

The complete set of AST painting probes and some selected MMY probes (MMY8, 14, 23) were applied on R. formosae . The results are given on the G-banded karyogram ( Fig. 6 ) and examples of FISH experiments are shown in Fig. 3C and 3F . Of the chromosomal pairs 1 to 5, only two, i.e., 4 and 5, show the same combination of chromosomal arms as found in R. luctoides , R. lanosus and R. morio . Pairs 1 to 3 show a unique combination hitherto found in no other rhinolophid species.

Figures

FIG. 6. G-banded karyotype of a male R. formosae. Numbers to the right of each chromosome pair indicate homology to A. stoliczkanus (AST) chromosomal arms as revealed by FISH with AST probes and G-band comparison. On the left of each chromosomal pair, homology to chromosomal arms or segments of the vespertilionid M. myotis (MMY) is given. The inset shows

FIG. 7. Metaphase spreads of R. formosae after CBG-banding (A, B) and silver-staining (C). A — Centromeric heterochromatin is clearly visible at acrocentric chromosomes but only faintly stained at the metacentric ones. The arrows point to the smallest autosomal pair no. 25 which is presumably bi-armed. B — The C-banded X chromosomes of the female R. formosae showed the usual appearance for the family without a large hetero-chromatic block. The arrows indicate pair 25. C — Silver-stained metaphase plate with arrows indicating the NORs

FIG. 3. FISH examples showing the hybridization patterns of A. stoliczkanus (AST) chromosome-specific painting probes onto metaphase spreads of R. cf. luctoides (A, D), R. lanosus (B, E) and R. formosae (C, F). A–C — hybridization signals of AST1 (red) and AST8 (green) meet in chromosome 5 in R. cf. luctoides (A) and R. lanosus (B) but not in R. formosae (C). In B and C AST X (yellow) was applied in addition. D, E — hybridization signals of AST2 (green) and AST5 (red) meet in chromosome 3 of R. cf. luctoides (D), but not in R. lanosus (E), where AST2 (green) is found in combination with AST1 (red) on chromosome 4 instead.