New plant species discovered on Yakushima -Time for a closer look at the island's lowland primeval forests

Feb 20, 2016

SuetsuguKenji, a Project Associate Professor at the Kobe University Graduate School of Science, has discovered a new species of plant on the subtropical Japanese island of Yakushima (located off the southern coast of Kyushu in Kagoshima prefecture) and named it Sciaphila yakushimensis.This research has published on 20th February in the Journal of Japanese Botany.

Sciaphila yakushimensis, the new plant species first discovered on Yakushima

Certain plant species known as mycoheterotrophic plants have abandoned photosynthesis and instead live as parasites, exploiting their fungal hosts for nutrients. However, these parasitic plants are small and only appear above ground when they are in flower or fruit, so accurate information on their distribution is limited.

Professor Suetsugu is involved in documenting the distribution andclassification of the mycoheterotrophic plants in Japan. In October 2015, while carrying out a survey of the lowland laurel forests in Yakushima with photographer Yamashita Hiroaki, he discovered an unfamiliar mycoheterotrophicspecies. He collected a specimen, and carried out a detailed examination of the plant’s morphological characteristics in collaboration with Professor Tsukaya Hirokazu (Tokyo University School of Science) and Professor Emeritus Ohashi Hiroyoshi (Tohoku University Botanical Gardens, Tsuda Memorial Herbarium).

The results of their examination showed that this 5cm long plant species is closely related to the Sciaphila japonica of the Triuridaceae family. They determined that it was a different species fromthe following observations: the parts above ground are a dark purple, the filament of the male (staminate) flower is no higher than the anther, and the style of the female (pistillate) flower is club-shaped with multiple papillae.They named the new species Sciaphila yakushimensis (Suetsugu, Tsukaya & H. Ohashi) after its place of discovery.

The presence of the Sciaphilayakusimensis, a parasitic species that relies on fungal hosts, is also evidence that a hidden network of symbiotic relationships between fungi and roots (mycorrhizae) exists in the lowland primeval forests of Yakushima. Professor Suetsugu comments, “Yakushima receives a lot of attention for its Jomon cedars, but this plant was discovered in an area where deforestation is permitted. The discovery of the Sciaphila yakushimensis, nurturedby the fungi and the nutrient-rich forests in which it grows, should make us reaffirm the value of Yakushima’s lowland primeval forests”.

Pistillate flowers of the Sciaphila yakushimensis (left) and Sciaphila nana (right). The pistillate flower of the Sciaphila yakushimensis has a club-shaped style with multiple papillae.
Staminate flowers of the Sciaphila yakushimensis (left) and Sciaphila nana (right)
Reference links

(Graduate School of Science, Communications Division)