タイワンチャルメルソウの類縁性について  [in Japanese] On the affinity of Mitella formosana (HAYATA) MASAMUNE  [in Japanese]

1) An endemic species of Mitella in Taiwan, M. formosana, was examined for clarifying its affinity. For this purpose the outer morphology of flowers and seeds, and the chromosomes of the species were observed in detail, through cultivation of the individuals collected at Mt. Alishan in Taiwan. The results are shown in Figs. 1-3. 2) The chromosome number of this species was counted to be 2n=28. Although the number 2n=14 was reported by HSU (1968) for M. japonica var. formosana, we should varify the material to be M. formosana or not. The karyotype shows that the plants are diploidized tetraploids (allotetraploids) characteristic of Japanese species in sect. Mitellaria, and resemble well those of M. furusei var. furusei, M. furusei var. subramosa, M. stylosa var. stylosa and M. doiana. 3) A cladistic analysis was made in order to presume the phylogenetic position of M. formosana in sect. Mitellaria, on the basis of 7 characters listed in Table 1. The result is shown in Fig. 4. 4) M. furusei var. furusei, M. furusei var. subramosa, M. formosana, M. stylosa var. makinoi, M. stylosa var. stylosa and M. doiana are presumed as the members which constitute a monophyletic group. Among them M. furusei var. furusei is inferred to be most primitive and M. stylosa var. stylosa and M. doiana most specialized. 5) The ancestor of this monophyletic group might have occurred in the central Honshu which lie east of Ibuki-Suzuka mountains, and have differentiated into several taxa in the area westward from this mountain range. M. formosana is considered to be one of these taxa, and to be most strongly related to M. furusei var. subramosa and M. stylosa var. makinoi.