We report that the triploid apogamous species Dryopteris hondoensis Koidz. shares its sequences with the D. erythrosora complex (D. erythrosora, D. caudipinna and D. koidzumiana) and D. chinensis at two nuclear markers (PgiC and GapCp). This is the first report of reticulate evolution between subg. Erythrovariae sect. Erythrovariae, to which D. erythrosora, D. caudipinna and D. koidzumiana and D. hondoensis belong, and sect. Aemulae of subg. Dryopteris, to which D. chinensis belongs. Apogamous species of Dryopteris may hybridize with distantly related species congeners.
The extent of reproductive isolation in various organisms increases with genetic distance. It was suggested that Asplenium setoi in the Ogasawara and Ryukyu islands were genetically differentiated and it was suspected that reproductive isolation may exist between them. In this study, rbcL sequences of the plants from these two localities were determined. They were found to have a 5-bp difference out of 1,203 bp. Artificial crossing experiments were also performed between A. setoi from the two localities to elucidate the extent of reproductive isolation between them. Although hybrids were obtained, the rate of hybrid formation differed between the reciprocal crosses. Twenty-three hybrids from 80 crosses were obtained when the maternal plants were from Ogasawara and the paternal plants were from Ryukyu. In the opposite combination of 80 crosses, only two hybrids were obtained. Thus, hybrids were easily formed only when plants from Ogasawara were the maternal parent. Asplenium setoi from the Ogasawara and Ryukyu islands may be bound for speciation.
The species of Trachelospermum (Apocynaceae) are evergreen, woody lianas widely distributed in Japan. Morphologically intermediate plants between T. asiaticum and T. jasminoides have been observed. We conducted morphological and genetic investigations to clarify the possibility of hybridization events between T. asiaticum and T. jasminoides. Analysis of floral and vegetative characters of living and herbarium specimens indicated that morphologically intermediate plants frequently and widely grow in overlapping distribution areas. The results of sequencing and PCR-RFLP analyses partly confirmed natural hybridization between the two species and detected suspected hybrids among samples morphologically identical to T. jasminoides.
Two new species of Praravinia (Rubiaceae) from Borneo, P. longicalyx Koizumi & Nagam. and P. nitida Koizumi & Nagam., are described and illustrated. Characters of the fruit of P. subtomentosa Bremek. are described for the first time. A new combination, Urophyllum oresitrophum (Bremek.) Koizumi & Nagam. based on P. oresitropha Bremek., is proposed and the original description is amended. A revised key to the Bornean species of Praravinia is provided.
Alocasia azlanii is described as a new species and the fifth Bornean member of the Cuprea Group of Alocasia. It is distinguished from its closely related congeners by its leaf venation and the staminate zone of the spadix not entirely accommodated within the lower spathe chamber.
Begonia togashii Nob. Tanaka & C.-I Peng (Begoniaceae), a new species from central Myanmar is described and illustrated. The presence of a rhizome, basal protandrous staminate flowers and distal pistillate flowers, 2-locular ovaries and placentas with two branches place it in sect. Platycentrum A. DC. It is somewhat similar to Begonia thomsonii A. DC., which was described from India, but is also in northern Myanmar. Begonia togashii, however, is distinct in having sub-symmetric basal leaves with a glabrous upper surface, 3-tepalled carpellate flowers and glabrous capsules. Thus far B. togashii is known only from Myanmar.
We report four examples of morphological variation in the species of Cephalanthera (Orchidaceae) in Japan. We recognized a new peloric form, C. subaphylla Miyabe & Kudo f. conformis Hiros. Hayak. The new form has a tepal-like lip morphology. We also report variegation mutants of C. erecta (Thunb.) Blume var. erecta, which are albino-like in appearance. The above-ground parts of the mutants were withered at the immature seed stage during the end of June. We also observed variegated individuals of C. falcata (Thunb.) Blume f. falcata and C. falcata f. albescens S. Kobay. Finally, we discovered individuals of C. falcata f. falcata with a malformed flower at the top of an inflorescence with normal flowers in other parts of the same inflorescence from two localities.
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