Monday, June 26, 2017

[Botany • 2017] Sedum danjoense • A New Species of Succulent Plants (Crassulaceae) from the Danjo Islands in Japan


Sedum danjoense 
Takuro Ito, H. Nakanishi & G. Kokub. 


Abstract

We compared Sedum formosanum with related species using morphological traits and molecular phylogenetic analysis of nrITS sequences. Morphological comparisons revealed that the plants historically treated as S. formosanum in the Danjo Islands of Japan had 4-merous flower; 8 stamens; narrow triangular sepals of equal size; horizontal carpels when matured; and an irregular branching form. These traits differed from those of S. formosanum in other regions, which has 5-merous flowers; 10 stamens, thick spatulate sepals of unequal size; erect carpels when matured; and a trichotomous branching form. Phylogenetic analysis indicated that plants known as S. formosanum in the Danjo Islands were sister group to S. tetractinum, which are endemic to China and belong to a different clade than S. formosanum, which are found in other regions. Based on the present morphological comparisons and phylogenetical analyses, we describe plants from the Danjo Islands as a new speciesSedum danjoense, which is distinct from S. formosanum.

Keywords: East Asia, ITS, Phylogeny, Sedum formosanum, Succulent, Eudicots


FIGURE 3. Sedum danjoense Takuro Ito, H. Nakanishi & G. Kokub.
 A. Habitat and habit. B. Inflorescence. C. Adaxial surface. D. Abaxial surface. E. Flower. F. Sepals. G. Carpels. H. Branching.

Scale bars are 25 mm for A, 5 mm for B–H [A. Wild individuals in Yorishima island photo by Yoshiro Chichibu in May 1989; B. Cultivated in Nagasaki Subtropical Botanical Garden photo by Kiyotaka Minota in Sep. 2011; C-H. Takuro Ito 3658 in Oct. 2016] 

Sedum danjoense Takuro Ito, H. Nakanishi & G. Kokub., sp. nov.  
 Type:— JAPAN. The Kyusyu, the Danjo Islands, Yorishima Island, 25 October 2016 (cultivated in Nagasaki Subtropical Botanical Garden after collecting its natural habit in 1989), Takuro Ito 3658. (holotype TNS!).

Etymology:— The epithet refers to the Japanese name of type locality of the Danjo Islands.
Japanese common name:—Danjo-mannen-gusa (nov.).

 Distribution and habitat:— Endemic to the Danjo Islands (Kyusyu), on sunny, coastal rocky slopes exposed to direct sunlight; in typical coastal vegetation within “a community of Miscanthus condensatus Hackel (1899: 639)– Crepidiastrum lanceolatum (Houtt.) Nakai (1920: 150)” similar to those in other regions of Japan, Taiwan and the Philippines. Itow & Nakanishi (1990) mentioned that this species was distributed throughout the Danjo Islands (as S. formosanum), and thus further field surveys are required on the islands.


Takuro Ito, Hiroki Nakanishi, Yoshiro Chichibu, Kiyotaka Minoda and Goro Kokubugata. 2017. Sedum danjoense (Crassulaceae), A New Species of Succulent Plants from the Danjo Islands in Japan. Phytotaxa. 309(1); 23–34. DOI:  10.11646/phytotaxa.309.1.2


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