Goro Kokubugata

Phylogenetic systematics of the monotypic genus Hayataella (Rubiaceae) endemic to Taiwan

Hayataella (Rubiaceae) is a monotypic genus endemic to Taiwan that comprises H. michelloides. In recent years, Hayataella was considered to be synonymous with Ophiorrhiza; however, no specific data have been reported, and the systematic treatment of Hayataella has been unclear. To elucidate the systematic treatment of Hayataella, molecular phylogenetic analyses based on ITS of nrDNA, atpB–rbcL, and trnK/matK of cpDNA were conducted with four Ophiorrhiza species. In the Bayesian and the most parsimonious trees, H. michelloides was included in the Ophiorrhiza clade. The monotypic status of Hayataella is, therefore, not considered appropriate, and the combination Ophiorrhiza michelloides (Masam.) H. S. Lo is supported.

Ribosomal DNA distribution in somatic chromosomes of Stangeria eriopus (Stangeriaceae, Cycadales) and molecular-cytotaxonomic relationships to some other cycad genera

Somatic chromosomes ofStangeria eriopus (Stangeriaceae, Cycadales) were investigated by fluorescentin situ hybridization (FISH) using an 18S ribosomal DNA (rDNA) probe.Stangeria eriopus showed a chromosome number of 2n=16 with a karyotype of 12 median-, 2 subterminal-, and 2 terminal-centromeric chromosomes. FISH study ofS. eriopus revealed 16 signals made up of rDNA sites located on the terminal regions of the long arms of the 7 median- and 2 subterminal-centromeric chromosomes, on terminal region of the short arm of the 1 median-centromeric chromosome, on the terminal regions of the long and the short arms of 1 median- and 2 terminal-centromeric chromosomes. This result suggests that, not only karyomorphologically but also molecular-cytologically, the genusStangeria may be more closely related to the genusCeratozamia than the genusBowenia or the genusMicrocycas previously hypothesized.

A comparison of chromosome number and karyotype in somatic chromosomes of Stangeriaceae (Cycadales)

Somatic chromosomes at mitotic metaphase of two species and two undescribed populations of Bowenia, and Stangeria eriopus, which were classified in Stangeriaceae, Cycadales, were compared using the standard aceto-orcein staining method. All Bowenia taxa showed a chromosome number of 2n = 18, while S. eriopus showed a chromosome number of 2n = 16. The chromosome number of 2n = 18 in B. Kuranda is reported for the first time. The present karyotype analysis indicates that B. Kuranda and another undescribed taxon, B. Tinaroo, are cytotaxonomically closer to B. spectabilis than B. serrulata, and that the karyotype of Stangeria is unlikely to have been derived from that of Bowenia by a simple chromosomal change such as centromeric fission and deletion.

EAPDC Symposium : Note on the taxonomy, biogeography and conservation of endangered plant species in the Ryukyus

The Ryukyus Archipelago consists of about 200 nearly subtropical islands located between Japan proper and Taiwan. Previous studies have found the Ryukyus to be a region of high biodiversity with many endangered vascular plant taxa, but they are not comprehensive. Here, we discuss the phytogeographic features and circumstances of the endangered plant taxa, make suggestions for effective in situ conservation, and highlight endangered plants in the Ryukyus that require further study.

FLORAL MORPHOLOGY AND RECOGNITION OF VARIETIES IN CONANDRON RAMONDIOIDES (GESNERIACEAE) FROM JAPAN AND TAIWAN

Comparisons of corolla morphology were made between plants of Conandron ramondioides ( Gesneriaceae ) from 23 localities in Japan and Taiwan. Lobe-length to tube-length ratios were found to correlate with geographical distribution and support the recognition of two previously described varieties: var. ramondioides in mainland Japan (lobe length less than twice tube length) and var. taiwanensis from Iriomote Island (Japan) and Taiwan (lobe length more than three times tube length). Mitotic chromosomes were also observed but no differences were seen between accessions, all of which had 2 n =32.

Structural Differences of Chromosomes in Plants Detected by Fluorescence in situ Hybridization Using Probes of rDNA, Arabidopsis-type Telomere Sequence Repeats and pCrT7-4

The chromosomal sites of 5S rDNA, 45S rDNA and Arabidopsis-iypt telomere sequence repeats characterize individual species and population constitutions in chrysanthemums and cycads and those of Sau3A in spruces. The sites of the telomere sequence repeats in the cycad chromosomes occur not only in the usual terminal regions of chromosome-arms as small dots, but also in several centromeric to proximal regions as relatively large signals. Large signals of the 278 bp DNA segment with respect to Cycas revoluta involved with pCrT7-4. The Y-chromosome of Cycas revoluta was distinct by lack of the large signal of pCrT7-4 and the Arabidopsis-type telomere sequence repeats. A highly conserved chromosomal location of these genes lead to speculation on the karyotype evolution and species property of the chrysanthemum and cycad groups.