Journal of Phytogeography and 60：11-20, 2012 ©The Society for the Study of Phytogeography and Taxonomy 2012

Nobuko Yamamoto1, Hiroshi Ikeda2 and Takuji Hoshino3 : Cytotaxonomical studies of flowering in Yakushima Island, Kagoshima Prefecture, Japan Part II : noteworthy taxa

1Graduate School of Informatics, Okayama University of Science, Ridai-cho 1-1, Kita-ku, Okayama-shi, Okayama 700-0005, Japan ; 2The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan ; 3Department of Biosphere-Geosphere Science, Faculty of Biosphere-Geosphere Science, Okayama University of Science, Ridai-cho 1-1, Kita-ku, Okayama-shi, Okayama 700-0005, Japan

Abstract Chromosome numbers of 23 taxa of noteworthy plants collected from Yakushima Island are reported, in- cluding seven taxa in six families published for the first time: Acer morifolium（ 2n = 26）, Tripterospermum distylum（ 2n = 46）, Ophiorrhiza japonica（ 2n = 22）, apiculata vars. acerifolia（ 2n = 26） and ro- tundifolia（ 2n = 26）, Smilax china var. yakusimensis（ 2n = ca. 90）, and Juncus wallichianus（ 2n = 80）. The chromosome number for Smilax china var. yakusimensis was found to be different from that of the typical variety, var. china in Honshu（ 2n = 60, 64）, and we consider that Smilax china may exhibit a polyploid se- ries within the species. The chromosome number for Aruncus dioicus var. kamtschaticus（ 2n = 14） is different from that of materials in Hokkaido（ 2n = 18）. Although chromosome number of Euphorbia jolkinii（ 2n = 26） is different from a previous report based on Korean material（ 2n = 28）, the number of the previous report is considered doubtful. Chromosome counts for the remaining 14 taxa agree with those already published: Il- licium anisatum（ 2n = 28）, Trochodendron aralioides（ 2n = 40）, Heterotropa kumageana（ 2n = 24）, Sorbus commixta（ 2n = 34）, Viola iwagawae（ 2n = 22）, Viola sieboldii（ 2n = 24）, Rhododendron yakushimanum（ 2n = 26）, Utricularia yakusimensis（ 2n = 16）, Ainsliaea apiculata var. apiculata（ 2n = 26）, Ainsliaea faurieana （2n = 26）, Ixeris yakuinsularis（ 2n = 21）, Chionographis koidzumiana（ 2n = 24）, Metanarthecium luteo-viride f. luteo-viride（ 2n = 52）, and Arisaema sazensoo（ 2n = 28）. When comparing these chromosome numbers with those of closely related taxa, no differences were found except for Aruncus dioicus and Smilax china.

Key words : chromosome number, cytotaxonomy, endemism, noteworthy taxa, Yakushima Island.

The flora of Yakushima Island, Kagoshima Materials and methods Prefecture in southern Japan, is characterized Root tips for 23 taxa in 19 genera in 15 fami- by a high rate of endemism and occurrence of lies from Yakushima Island（ Table 1） were col- many dwarf taxa（ Sugimoto 1957; Yahara et al. lected and fixed in the field. Field preparation 1987）. In a previous paper we reported chromo- and cytological observation procedure followed some numbers for 33 dwarf taxa collected from Yamamoto et al.（ 2008）. Voucher specimens Yakushima Island（ Yamamoto et al. 2008）. are deposited in the Herbarium of Okayama This second report is concerned with the chro- University of Science（ OKAY）. mosome numbers for noteworthy taxa, such as those that are endemic to Yakushima Island, Results and discussion those which represent the southernmost or Chromosome numbers of 23 examined taxa northernmost limit of distributions, and those are presented in Table 1. The chromosomes for which chromosome numbers have not previ- observed in a somatic cells of nine taxa which ously been reported. show the first or new records of chromosome numbers are shown in Fig. 1. Taxonomic notes and cytological characteristics are described be-

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Table 1. Localities（ all in Yakushima Island）, voucher specimens（ all vouchers at OKAY）, and chromosome counts of examined taxa.

Present Previous Family Taxon Locality and voucher specimen counts counts References （2n） （n**, 2n） Illiciaceae Illicium anisatum Near Yodogawa-hut, 1,380 m alt. 28 14** Morinaga et al.（ 1929） シキミ （Ikeda et al. 04102399） Trochodendraceae Trochodendron aralioides Near Yodogawa-hut, 1,370 m alt. 40 20** Ratter and Milne（ 1976） ヤマグルマ （Ikeda & Yamamoto 05060813） 38 Whitaker（ 1933） 40 Okada（ 1975） Aristolochiaceae Heterotropa kumageana Along Hanaage River, 120 m alt. 24 24 Yuasa and Maekawa クワイバカンアオイ （Yamamoto 06012014） （1976） Rosaceae Aruncus dioicus Near the summit of Mt. Miya- 14 14, 18 Zhukova（ 1980） var. kamtschaticus noura, 1,935 m alt.（ Ikeda et al. ヤマブキショウマ 05092007） 18 Kawano（ 1963）, Kiehn et al.（ 1991） Sorbus commixta Yodogawa Tozan-guchi -- Yodoga- 34 34 Nishikawa（ 2004） ナナカマド wa-hut, 1,360 m alt.（ Ikeda et al. 04042302） Euphorbiaceae Euphorbia jolkinii Nagakubo, 3 m alt.（ Ikeda et al. 26 28 Chung et al.（ 2003） イワタイゲキ 04042109） Aceraceae Acer morifolium Kurio, Hanayama pass, 100--200 m 26* ヤクシマオナガカエデ alt.（ Ikeda & Yamamoto 05061104） Violaceae Viola iwagawae Hanano-ego Moor -- Yodogawa-hut, 22 22 Yoshioka and Tanaka ヤクシマスミレ 1,620 m alt.（ Ikeda & Yamamoto （1981） 05060816） Viola sieboldii Mt. Miyanoura -- Nageshi-daira, 24 24 Yoshioka and Tanaka フモトスミレ 1,710 m alt.（ Yamamoto 06012006） （1981） Ericaceae Rhododendron yakushima- Near Yodogawa-hut, 1,370 m alt. 26 26 Janaki Ammal et al. num （Ikeda & Yamamoto 05060814） （1950） ヤクシマシャクナゲ Gentianaceae Tripterospermum distylum Nageshi-daira -- summit of Mt. 46* ハナヤマツルリンドウ Miyanoura, 1,720 m alt.（ Ikeda et al. 04102307） Rubiaceae Ophiorrhiza japonica Mugio, Senpiro-no-taki Waterfall, 22* サツマイナモリ 460 m alt.（ Yamamoto 06011400） Lentibulariaceae Utricularia yakusimensis Near Shikano-sawa-hut, 1,560 m 16 16 Tanaka and Uchiyama ムラサキミミカキグサ alt.（ Ikeda et al. 05092103） （1988） Compositae Ainsliaea apiculata var. apiculata Mugio, Senpiro-no-taki Waterfall, 26 26 Watanabe et al.（ 1992） キッコウハグマ 540 m alt.（ Yamamoto 06012013） var. acerifolia Yodogawa-tozan-guchi -- Yodogawa- 26* モミジバキッコウハグマ hut, 1,360 m alt.（ Yamamoto 06012008） var. rotundifolia Mugio, Senpiro-no-taki Waterfall, 26* マルバキッコウハグマ 540 m alt.（ Ikeda et al. 04042413） Ainsliaea faurieana Mugio, Senpiro-no-taki Waterfall, 26 26 Watanabe et al.（ 1992） ホソバハグマ 540 m alt.（ Yamamoto 06012007） Ixeris yakuinsularis Hanano-ego Moor -- Nageshi- 21 21 Watanabe（ 1997） コスギニガナ daira, 1,670 m alt.（ Ikeda et al. 04042898） Liliaceae Chionographis koidzumi- Hanano-ego Moor -- Yodogawa-hut, 24 24 Hara and Kurosawa ana 1,590 m alt.（ Ikeda & Yamamoto （1962） チャボシライトソウ 05060820） Metanarthecium luteo- Near the summit of Mt. Nagata- 52 52 Satô（ 1942） viride dake, 1,900 m alt.（ Ikeda et al. f. luteo-viride 05092116） ノギラン Smilax china Near Hanano-ego Moor, 1,680 m ca. 90* var. yakusimensis alt.（ Ikeda et al. 05092216） ヤクシマカカラ Juncaceae Juncus wallichianus Yodogawa, near Kigen-sugi, 1,220 80* ハリコウガイゼキショウ m alt.（ Ikeda et al. 05091999） Araceae Arisaema sazensoo Kosugi-dani, 790 m alt.（ Ikeda et 28 28 Kurakubo（ 1940）, Hotta ヒメテンナンショウ al. 04042523） （1971）, Murata and Iijima（ 1983） * : First record of chromosome numbers. － 12 － December 2012 J. Phytogeogr. Taxon. Vol. 60. No. 1

Fig. 1. Mitotic chromosomes of noteworthy taxa in Yakushima Island. A : Trochodendron aralioides （2n = 40）. B: Euphorbia jolkinii（ 2n = 26）. C : Acer morifolium（ 2n = 26）. D : Tripterospermum distylum （2n = 46）. E : Ophiorrhiza japonica（ 2n = 22）. E’ : Drawing of chromosomes in E. F : Ainsliaea apicu- lata var. acerifolia（ 2n = 26）. G : Ainsliaea apiculata var. rotundifolia（ 2n = 26）. H: Smilax china var. yakusimensis（ 2n = ca. 90）. I : Juncus wallichianus（ 2n = 80）. I’ : Drawing of chromosomes in I. Arrows in B indicate larger chromosomes. Bar = 5 μm.

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low under each family（ ordered following Mel- some number for this taxon, 2n = 24, was the chior 1964）. same as that reported by Yuasa and Maekawa （1976）. Illiciaceae 1. Illicium anisatum L. Rosaceae Illicium anisatum is distributed from cen- 4. Aruncus dioicus（ Walter） Fernald var. ka- tral to western Honshu, Shikoku, Kyushu and mtschaticus（ Maxim.） H. Hara Ryukyu in Japan, and southernmost Korea Aruncus dioicus var. kamtschaticus is distrib- （Ueda 2006）. On Yakushima Island, it grows uted in S. Kuriles, Hokkaido, Honshu, Shikoku under forests in the montane zone. The chro- and Kyushu in Japan, and widely distributed in mosome number for this taxon was counted as temperate regions of the Northern Hemisphere 2n = 28. Morinaga et al.（ 1929） reported game- （Ikeda 2001）. Yakushima Island is the south- tophytic number for this taxon as n = 14 from ernmost limit of distribution for the species, a cultivated , coincided to the sporophytic where it grows near the mountain summits. number in wild plants recorded in the present The chromosome number for this taxon was study. counted as 2n = 14. Chromosome numbers for A. dioicus have been reported as 2n = 18（ Kawano Trochodendraceae 1963; Kiehn et al. 1991）, and 2n = 14 and 2. Trochodendron aralioides Siebold et Zucc. 18（ Zhukova 1980）. For the Japanese plants, （Fig. 1A）. Kawano（ 1963） reported 2n = 18 for materials Trochodendron aralioides is distributed in from Hokkaido. It is possible that infraspecific Honshu（ southward from Yamagata Prefec- variation in chromosome number exists in A. ture）, Shikoku and Kyushu in Japan, and also dioicus, and this merits further study. in Taiwan, S. Korea, and S. China（ Akiyama 2006）. On Yakushima Island, it grows from 5. Sorbus commixta Hedl. montane zone to near the mountain summits, Sorbus commixta is distributed in S. Kuriles, and occasionally is epiphytic on trunks of Cryp- Hokkaido, Honshu, Shikoku and Kyushu in tomeria japonica（ L. f.） D. Don. We counted Japan, and also in Sakhalin, the Kuriles, and the chromosome number of this species as 2n Korea（ Iketani and Ohashi 2001）. Yakushima = 40. Although a chromosome number for this Island is the southernmost limit of distribution species was firstly reported as 2n = （ 38 Whita- for the species. On Yakushima Island, this spe- ker 1933）, later Ratter and Milne（ 1973） cies is often epiphytic on trunks of Cryptomeria reported a gametophytic number for this spe- japonica. Chromosome number for this species cies as n = 20, and Okada（ 1975） as 2n = 40. was observed as 2n = 34, agreeing with past In addition to the present study, chromosome reports from Hokkaido（ Nishikawa 2004）. number for this species was also studied in material collected from Hiroshima Prefecture, Euphorbiaceae again revealing counts of 2n = 40（ Yamamoto 6. Euphorbia jolkinii Boiss.（ Fig. 1B）. et al., unpubl.）. We therefore, conclude that Euphorbia jolkinii grows along the sea coasts Whitaker’s count is in error, and that the chro- of Honshu（ westward from Chiba Prefecture）, mosome number of T. aralioides should be 2n = Izu Islands, Shikoku, Kyushu and Ryukyu in 40. Japan, and also in S. Korea and Taiwan（ Ku- rosawa 1999）. The chromosome number of E. Aristolochiaceae jolkinii had been reported as 2n = 28 from Ko- 3. Heterotropa kumageana（ Masam.） F. Maeka- rea（ Chung et al. 2003）, whereas we recorded wa ex Yahara a chromosome number for this species as 2n = Heterotropa kumageana is endemic to 26. In addition we also counted chromosomes Yakushima Island, and grows on floor of ever- from materials collected in Okayama Prefecture, green forests below 1000 m alt. The chromo- which also proved to be 2n = 26（ Yamamoto

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et al., unpubl.）. There are two possibilities for land is the southernmost limit of distribution this incongruity; one is an error in counting, for the species. We observed that the chromo- and another is infraspecific variation within the some number for this species was 2n = 24, species. The chromosome complement of E. jol- same as that reported by Yoshioka and Tanaka kinii showed a bimodal karyotype, composed of （1981）. two larger chromosomes and 24 smaller ones. The larger chromosomes were metacentric and Ericaceae nearly two times as long as the smallest ones 10. Rhododendron yakushimanum Nakai （Fig. 1B : arrows）. Chung et al.（ 2003） showed Rhododendron yakushimanum is endemic to a figure of chromosomes of E. jolkinii, but we Yakushima Island, and grows from mountain could not see such larger chromosomes, and we sides to near the summits. The chromosome suggest that Chung et al.（ 2003） miscounted number for this species was counted as 2n = these two larger chromosomes as four smaller 26, the same as that reported by Janaki Am- chromosomes. This bimodal karyotype in chro- mal et al.（ 1950）. The chromosome number of mosome length for Euphorbia species were also the most closely related species, R. japonohep- reported for two Himalayan species, E. sikki- tamerum Kitam., was also reported as 2n = 26 mensis Boiss. and E. griffithii Hook. f.（ Ikeda （Nakamura 1931, as R. metternichii Siebold et et al. 2008）, and such bimodality might be a Zucc.）. cytological characteristic for some species of Eu- phorbia. Gentianaceae 11. Tripterospermum distylum J. Murata et Ya- Aceraceae hara（ Fig. 1D）. 7. Acer morifolium Koidz.（ Fig. 1C）. Tripterospermum distylum is endemic to Acer morifolium is endemic to Yakushima Yakushima Island, and grows on rocky slope or Island, and grows warm temperate forests at edge of bamboo thicket at higher elevation. （Ogata 1999）. The chromosome number for this Chromosome number for this species, 2n = 46, species, 2n = 26, is here reported for the first was counted for the first time. To our knowl- time. The chromosome number of the closely edge, the chromosome number of this has related species, A. capillipes Maxim., was also been reported on only one species, T. japonicum reported as 2n = 26（ Santamour 1971）. （Siebold et Zucc.） Maxim. among 25 species （Mabberley 2008）. The chromosome number Violaceae of T. japonicum has been reported as 2n = 46 8. Viola iwagawae Makino （Wada 1966; Nishikawa 1981; Shigenobu 1984; Viola iwagawae is distributed on Yakushima Yamamoto et al. 2008, for var. tenue（ Masam.） Island and the Ryukyu（ Amami-oshima, Toku- Honda）. noshima and Okinawa-jima）（ Akiyama et al. 1999）. Yakushima Island is the northern- Rubiaceae most limit of distribution for this species. On 12. Ophiorrhiza japonica Blume（ Figs. 1E and Yakushima Island, it grows in shady places or E’）. along the sides of streams. The chromosome Ophiorrhiza japonica is distributed in Hon- number for this species was seen to be 2n = 22, shu（ southward from Chiba Prefecture）, Shi- same as that reported by Yoshioka and Tanaka koku and Kyushu, and also in Taiwan, central （1981）. to southern China and north Vietnam（ Yamazaki 1993）. On Yakushima Island, it grows on moist 9. Viola sieboldii Maxim. ground under evergreen forest at lower eleva- Viola sieboldii is distributed in Honshu tions. The chromosome number for this species, （westward from Kanto District）, Shikoku and 2n = 22, was counted for the first time. Kyushu in Japan, and also in S. Korea（ Cheju Island）（ Akiyama et al. 1999）. Yakushima Is-

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Lentibulariaceae gata（ Blume） Sch. Bip. ex Maxim.（ Yahara et 13. Utricularia yakusimensis Masam. al. 1987; Yahara 1995）. Cytologically, the spe- Utricularia yakusimensis is distributed in cies of Ixeris are divided into two groups on the Hokkaido, Honshu, Shikoku and Kyushu in basis of chromosome numbers: one is with basic Japan（ Ohwi 1984）. Yakushima Island is the chromosome number x = 8, and another is with type locality and the southernmost limit of dis- x = 7（ Pak and Kawano 1990）. The chromo- tribution for this species. It grows in wet places some numbers of I. dentata are 2n = 14, 21, 28, or on wet mossy rocks in the temperate zone. and that of I. laevigata is 2n = 14, both with We counted chromosome number for this spe- basic chromosome number x = 7. Therefore, I. cies as 2n = 16, the same as that reported by yakuinsularis is thought to be a triploid taxon Tanaka and Uchiyama（ 1988）. with basic chromosome number x = 7.

Compositae Liliaceae 14. Ainsliaea apiculata Sch. Bip. 17. Chionographis koidzumiana Ohwi 14a. var. apiculata Chionographis koidzumiana is distributed in 14b. var. acerifolia Masam.（ Fig. 1F）. Honshu（ Mikawa and Kii Prov.）, Shikoku and 14c. var. rotundifolia Masam.（ Fig. 1G）. Kyushu（ Yakushima）（ Ohwi 1984）. Yakushima Ainsliaea apiculata is distributed in Hok- Island is the southernmost limit of distribution kaido（ Okushiri-jima）, Honshu, Shikoku and for this taxon. Chromosome number for this Kyushu in Japan, and also in S. Korea（ Koyama species was 2n = 24, the same as that reported 1995）. On Yakushima Island, it grows un- by Hara and Kurosawa（ 1962）. der forests, and shows great variation in leaf shape. Within this species three varieties are 18. Metanarthecium luteo-viride Maxim. f. luteo- distinguished by leaf shape: var. apiculata with viride normal 5-angled leaves; var. acerifolia with pal- Metanarthecium luteo-viride is distributed in mately-lobed leaves; and var. rotundifolia with Hokkaido, Honshu, Shikoku and Kyushu（ Ohwi rounded leaves（ Masamune 1934）. Chromosome 1984）. On Yakushima Island, a dwarf form（ f. numbers for these infraspecific taxa were all yakusimense Masam.） occurs as well as normal counted as 2n = 26. Chromosome number for form（ f. luteo-viride）. Chromosome number for var. apiculata was same as that reported by the dwarf form, f. yakusimense, in the preced- Watanabe et al.（ 1992）, while those for vars. ing paper（ Yamamoto et al. 2008）, as 2n = 52 acerifolia and rotundifolia are reported for the + 1B. Chromosome number for f. luteo-viride first time. was 2n = 52, the same as that reported by Satô（ 1942）. The cytological difference between f. 15. Ainsliaea faurieana Beauverd luteo-viride and f. yakusimense is the presence/ Ainsliaea faurieana is endemic to Yakushima absence of a B-chromosome. Island, and grows on wet rocks along stream sides. The chromosome number for this spe- 19. Smilax china L. var. yakusimensis Masam. cies was 2n = 26, the same as that reported by （Fig. 1H）. Watanabe et al.（ 1992）. Smilax china var. yakusimensis is endemic to Yakushima Island. The chromosome number 16. Ixeris yakuinsularis Yahara for this taxon, 2n = ca. 90, was counted for Ixeris yakuinsularis is endemic to Yakushima the first time. The chromosome number for the Island, and grows in open grassland at higher typical variety, var. china, has been reported as elevations. Chromosome number for this spe- 2n = 60 based on material from Japan（ Nakajima cies was 2n = 21, the same as that tentatively 1937; Satô 1942）. Kong et al.（ 2007） reported reported by Watanabe（ 1997）. Ixeris yakuin- a polyploid series in S. china, diploid（ 2n = sularis is considered to be of hybrid origin be- 32）, tetraploid（ 2n = 64）, and hexaploid（ 2n = tween I. dentata（ Thunb.） Nakai and I. laevi- 96） with the basic chromosome number x = 16.

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Smilax china var. yakusimensis is thought to Acknowledgments be a hexaploid taxon of the species, but further We express our thanks to Mr. Takaki Fu- work is needed to clarify an accurate chromo- kada, Yakushima Ranger Office, Ministry of the some number for this taxon. Environment and Mr. Ken’ichi Kai, Yakushima Forest Environment Conservation Center, Min- Juncaceae istry of Agriculture, Forestry and Fisheries, for 20. Juncus wallichianus Laharpe（ Figs. 1I and their kind advices to get permission for col- I’）. lecting materials. We appreciate Dr. Mark F. Juncus wallichianus is distributed from Watson, Royal Botanic Garden Edinburgh, for Hokkaido to Ryukyu in Japan, and also in his critical reading and for the English of the Sachalin, Ussuri, Taiwan, China, and India manuscript. This study was partly supported by （Ohwi 1984）. It grows on wet ground from low a Grant-in-Aid from the Ministry of Education, elevation to near the summits of mountains in Science and Culture, Japan, No. 14405017（ to Yakushima Island. The chromosome number for Prof. Hirokazu Tsukaya, the University of To- this taxon, 2n = 80, was counted for the first kyo）, and Grant-in-Aid for Scientific Research time. （C）, No. 21570103（ to T. H.） and No. 22570085 （to H. I.） from the Japan Society for the Pro- Araceae motion of Science. 21. Arisaema sazensoo（ Blume） Makino Arisaema sazensoo is distributed in central References and southern Kyushu（ Ohashi and Murata Akiyama, S. 2006. Trochodendraceae. In: Iwat- 1980）. Yakushima Island is the southernmost suki, K., Boufford, D. E. and Ohba, H.（ eds.）. limit of distribution for this species. The chro- Flora of Japan IIa, Angiospermae, Dicotyle- mosome number for this species was 2n = 28, doneae, Archichlamydeae（a）, p. 255. Kodan- the same as reported by Kurakubo（ 1940）, sha, Tokyo. Hotta（ 1971）, and Murata and Iijima（ 1983）. Akiyama, S., Ohba, H. and Tabuchi, S. 1999. Violaceae. In: Iwatsuki, K., Boufford, D. E. Among the 23 taxa examined, chromosome and Ohba, H.（ eds.）. Flora of Japan IIc, An- numbers of seven taxa （Acer morifolium, giospermae, Dicotyledoneae, Archichlamydeae Tripterospermum distylum, Ophiorrhiza japon- （c）, pp. 161-190. Kodansha, Tokyo. ica, Ainsliaea apiculata vars. acerifolia and ro- Chung, G.-Y., Oh, B.-U., Park, K.-R., Kim, J.-H., tundifolia, Smilax china var. yakusimensis, and Kim, M.-S., Nam, G.-H. and Jang, C.-G. 2003. Juncus wallichianus） are reported for the first Cytotaxonomic study of Korean Euphorbia L. time. The chromosome number of Smilax china （Euphorbiaceae）. Kor. J. Plant Tax. 33: 279- var. yakusimensis is different from that of the 293. typical variety, var. china, in Honshu. Further- Hara, H. and Kurosawa, S. 1962. Morphological more, the chromosome number of Aruncus di- and chromosomal variations in Chionographis oicus from Yakushima Island is different from japonica Maxim. Acta Phytotax. Geobot. 20: that from Hokkaido with aneuploidal deviation. 34-38. No difference was found when comparing the Hotta, M. 1971. Study of the family Araceae. chromosome numbers of the plants examined General remarks. Jpn. J. Bot. 20: 269-310. with those of closely related taxa except Arun- Ikeda, H. 2001. Aruncus Koster. In: Iwatsuki, K., cus dioicus and Smilax china. This strengthens Boufford, D. E. and Ohba, H.（ eds.）. Flora of support for our hypothesis（ Yamamoto et al. Japan IIb, Angiospermae, Dicotyledoneae, Ar- 2008）, that there has not been sufficient time chichlamydeae（b）, pp. 101-102. Kodansha, since the last glaciation（ about 14,000 years） Tokyo. to influence chromosomal differentiation after Ikeda, H., Kurosawa, T. and Ohba, H. 2008. isolation from the mainland of Kyushu Island Chromosome numbers and karyomorphology （see Kimura 1996; Kuroda and Ozawa 1996）. of three species of the genus Euphorbia L.

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（Euphorbiaceae） in the Sikkim Himalaya. J. sity Press, New York. Jpn. Bot. 83: 295-300. Masamune, G. 1934. Floristic and geobotanical Iketani, H. and Ohashi, H. 2001. Sorbus L. In: studies on the Island of Yakushima, Province Iwatsuki, K., Boufford, D. E. and Ohba, H. Osumi. Mem. Fac. Sci. Agric. Taihoku Imp. （eds.）. Flora of Japan IIb, Angiospermae, Di- Univ. 11, Bot.（ 4）: 1-637. cotyledoneae, Archichlamydeae（b）, pp. 113- Melcior, H. 1964. A. Engler’s Syllabus der 114. Kodansha, Tokyo. Pflanzenfamilien Bd. 2. 12, Aufl. 666 pp., 1 Janaki Ammal, E. K., Enoch, I. C. and Bridg- map. Gebrüder Borntraeger, Berlin. water, M. 1950. Chromosome numbers in spe- Morinaga, T., Fukushima, E., Kanô, T., cies of Rhododendron. Rhododendron Yearb. 5: Maruyama, Y. and Yamasaki, Y. 1929. Chro- 78-91. mosome numbers of cultivated plants II. Bot. Kawano, S. 1963. Brief notes on the chromosomes Mag. Tokyo 43: 589-594. of some Japanese plants（ 2）. J. Jpn. Bot. 38: Murata, J. and Iijima, M. 1983. New or note- 47-50. worthy chromosome records in Arisaema. J. Kiehn, M., Vitek, E., Hellmayr, E., Walter, J., Jpn. Bot. 58: 270-280. Tschenett, J., Justin, C. and Mann, M. 1991. Nakajima, G. 1937. Cytological studies in some Beiträge zur Flora von Österreich: Chromo- dioecious plants. Cytologia, Fujii Jub. Vol.: somenzählungen. Verh. Zool.-Bot. Ges. Öster- 282-292. reich 128: 19-39. Nakamura, M. 1931. Caryological studies on Kimura, M. 1996. Quaternary paleogeography the genus Rhododendron. Soc. Trop. Agric. of the Ryukyu Arc. J. Geogr. 105: 259-285.（ in Taihoku Imp. Univ. 3: 103-108. Japanese with English abstract） Nishikawa, T. 1981. Chromosome counts of Kong, H.-H., Wang, A.-L., Lee, J. and Fu, C.- flowering plants of Hokkaido（ 5）. Rep. Tai- X. 2007. Studies of systematic evolution and setsuzan Inst. Sci.（ 16）: 45-53.（ in Japanese karyotypic variation in Smilax and Heteros- with English abstract） milax（ Smilacaceae）. Acta Phytotax. Sin. 45: Nishikawa, T. 2004. Chromosome counts of 257-273.（ in Chinese with English abstract） flowering plants of Hokkaido（ 24）. J. Hok- Koyama, H. 1995. Ainsliaea DC. In: Iwatsuki, kaido Univ. Edu.（ Sect. II B） 55: 43-51.（ in K., Yamazaki, T., Boufford, D. E. and Ohba, Japanese with English abstract） H.（ eds.）. Flora of Japan IIIb, Angiospermae, Ogata, K. 1999. Aceraceae. In: Iwatsuki, K., Dicotyledoneae, Sympetalae（b）, pp. 168-170. Boufford, D. E. and Ohba, H.（ eds.）. Flora Kodansha, Tokyo. of Japan IIc, Angiospermae, Dicotyledoneae, Kurakubo, Y. 1940. Über die Chromosomen- Archichlamydeae（c）, pp. 60-73. Kodansha, zahlen von Araceae-Arten. Bot. and Zool. 8: Tokyo. 1492.（ in Japanese） Ohashi, H. and Murata, J. 1980. Taxonomy of Kuroda, T. and Ozawa, T. 1996. Paleoclimatic the Japanese Arisaema（ Araceae）. J. Fac. and vegetational changes during the Pleis- Sci. Univ. Tokyo, III 12: 281-336. tocene and Holocene in the Ryukyu Islands Ohwi, J. 1984. Flora of Japan（ in English）. inferred from pollen assemblages. J. Geogr. 1066 pp. Smithsonian Institution, Washington 105: 328-342.（ in Japanese with English ab- D.C. stract） Okada, H. 1975. Karyomorphological studies of Kurosawa, T. 1999. Euphorbia L. In: Iwatsuki, woody Polycarpicae. J. Sci. Hiroshima Univ., K., Boufford, D. E. and Ohba, H.（ eds.）. Flora ser. B, div. 2, 15: 115-200. of Japan IIc, Angiospermae, Dicotyledoneae, Pak, J.-H. and Kawano, S. 1990. Biosystematic Archichlamydeae（c）, pp. 22-30. Kodansha, studies on the genus Ixeris（ Compositae- Tokyo. Lactuceae） II. Karyological analyses. Cytolo- Mabberley, D. J. 2008. Mabberley’s Plant Book gia 55: 553-570. -A portable dictionary of plants, their classi- Ratter, J. A. and Milne, C. 1973. Chromosome fication and uses. 3rd ed. Cambridge Univer- counts in primitive angiosperms: II. Notes

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Roy. Bot. Gard. Edinburgh 32: 423-428. Yamazaki, T. 1993. Rubiaceae. In: Iwatsuki, K., Santamour, F. S. 1971. In IOPB chromosome Yamazaki, T., Boufford, D. E. and Ohba, H. reports. XXXII. Taxon 20: 355. （eds.）. Flora of Japan IIIa, Angiospermae, Satô, D. 1942. Karyotype alteration and phylog- Dicotyledoneae, Sympetalae（a）, pp. 206-240. eny in Liliaceae and allied families. Jpn. J. Kodansha, Tokyo. Bot. 12: 57-161. Yoshioka, H. and Tanaka, R. 1981. Chromo- Shigenobu, Y. 1984. Karyomorphological studies somes of Viola. Shin Kaki（ New Fl.） 112: 64- in some genera of Gentianaceae II. Gentiana 72.（ in Japanese） and its allied four genera. Bull. Coll. Child. Yuasa, H. and Maekawa, F. 1976. Chromosomes Develop., Kochi Women’s Univ. 8: 55-104. of Asarum and Heterotropa（ Aristolochiaceae） Sugimoto, J. 1957. On the pygmy plants of in the Ryukyu Islands. La Kromosomo II-1: Yakusima Island. Shokubutsu-Shumi 18: 8-18.（ in Japanese with English summary） 2-10.（ in Japanese） Zhukova, P. G. 1980. Chromosome numbers Tanaka, R. and Uchiyama, H. 1988. Chromo- of some South Chukotka plant species. Bot. somes of four species of Utricularia in Japan. Zhurn. 65: 51-59. J. Jpn. Bot. 63: 219-223. Ueda, K. 2006. Illiciaceae. In: Iwatsuki, K., 山本伸子 1・池田 博 2・星野卓二 3：鹿児島県屋久島 Boufford, D. E. and Ohba, H.（ eds.）. Flora of 産高等植物の細胞分類学的研究 Ⅱ. 特筆すべき分 Japan IIa, Angiospermae, Dicotyledoneae, Ar- 類群 chichlamydeae（a）, p. 238. Kodansha, Tokyo. 鹿児島県屋久島に生育する高等植物に関する細胞 Wada, Z. 1966. Chromosome numbers in Genti- 分類学的研究の第二報である。この報告では，屋久 anaceae. Chromosome Inf. Serv. 7: 28-30. 島に固有な分類群，屋久島を分布の南限・北限とす Watanabe, K. 1997. Index to chromosome num- る分類群，あるいはこれまで染色体数の報告のない bers of Japanese （ 1911-1996）. 分類群など，特筆すべき分類群に関する染色体数の Proc. Jpn. Soc. Pl. Taxon. 12（2）: 1-64. 報告をおこなう。 Watanabe, K., Yahara, T. and Kadota, H. 1992. 15科19属23分類群について染色体数を算定し Natural hybrid population between chas- たところ，7分類群（ヤクシマオナガカエデ（2n = mogamous and cleistogamous species, Ainsli- 26），ハナヤマツルリンドウ（2n = 46），サツマイ aea faurieana and A. apiculata（ Asteraceae; ナモリ（2n = 22），モミジバキッコウハグマ（2n Mutisiae）: morphology, cytology, reproductive = 26），マルバキッコウハグマ（2n = 26），ヤクシ mode and allozyme variation. Plant Sp. Biol. 7: マカカラ（2n = ca. 90），ハリコウガイゼキショウ 49-59. （2n = 80））については，今回はじめて染色体数を Whitaker, T. W. 1933. Chromosome number 算定した。ヤマブキショウマについては，2n = 14 and relationship in the Magnoliales. J. Ar- が算定されたが，北海道産のもの（ 2n = 18） と異 nold Arb. 14: 376-385. 数性の違いがみられた。また，イワタイゲキについ Yahara, T. 1995. Ixeris. In: Iwatsuki, K., ては，これまで，2n = 28の報告があったが，今回 Yamazaki, T., Boufford, D. E. and Ohba, H. 2n=26を算定した。14分類群（シキミ（2n = 28）， （eds.）. Flora of Japan IIIb, Angiospermae, ヤマグルマ（2n = 40），クワイバカンアオイ（2n Dicotyledoneae, Sympetalae（b）, pp. 15-19. = 24），ナナカマド（2n = 34），ヤクシマスミレ（2n Kodansha, Tokyo. = 22），フモトスミレ（2n = 24），ヤクシマシャ Yahara, T., Ohba, H., Murata, J. and Iwatsuki, クナゲ（2n = 26），ムラサキミミカキグサ（2n = K. 1987. Taxonomic review of vascular plants 16），キッコウハグマ（2n = 26），ホソバハグマ（2n endemic to Yakushima Island, Japan. J. Fac. = 26），コスギニガナ（2n = 21），チャボシライト Sci. Univ. Tokyo, III 14: 69-119. ソウ（2n = 24），ノギラン（2n = 52），およびヒ Yamamoto, N., Ikeda, H. and Hoshino, T. 2008. メテンナンショウ（2n = 28））については，これ Cytotaxonomical studies of flowering plants までの報告と同じ染色体数が算定された。 in Yakushima Island, Kagoshima Prefecture, 第一報と同様，同種内あるいは近縁種との間に細 Japan Part I: dwarf taxa. J. Phytogeogr. Tax- 胞学的変異は少なく，屋久島産高等植物においては on. 56: 79-93. 形態的多様性と細胞学的多様性の関連性は低いと考

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えられる。 （1 〒700-0005 岡山県岡山市北区理大町1-1 岡山 理科大学大学院総合情報研究科；2 〒113-0033 東 京都文京区本郷7-3-1 東京大学総合研究博物館； 3 〒700-0005 岡山県岡山市北区理大町1-1 岡山理 科大学生物地球学部生物地球学科）

（Received January 21, 2011; accepted April 22, 2012）

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