A New Species of Parasite Discovered in Japan

A new species of parasitic plant has been discovered on the Japanese island of Yakushima. A small population was found by Suetsugu Kenji during a survey of the lowland laurel forests that cover much of the island. Despite being an authority on parasitic plants of this region, Professor Suetsugu did not recognize these plants. As such, a specimen was collected for a closer look.

An in depth examination revealed that this was indeed a new species. It has been named Sciaphila yakushimensi in honor of the island on which it was discovered. It belongs to a family of plants called Triuridaceae. They are closely related to the family Alismataceae and many members of this family have foregone photosynthesis for a parasitic lifestyle.

S. yakushimensi is what we call a mycoheterotroph. It parasitizes mycorrhizal fungi, taking the nutrients it needs and giving nothing in return. The fungi themselves are getting their nutrient needs from the trees that grow in the forest. As such, S. yakushimensi could not exist without an intact forest to support its fungal host.

This is the troubling part. Only two populations of S. yakushimensi have been discovered. Its parasitic lifestyle makes it difficult to get an accurate estimation of its numbers. These plants live most of their lives underground, only appearing when it is time to flower. Because of this, researchers are already suggesting that this species be considered endangered.

Sadly, its native forest is under constant threat of logging. Much of this region remains unprotected. Since mycoheterotrophs like S. yakushimensi rely on an intact forest capable of supporting its host fungi, any disturbance that threatens the forest can spell disaster for these parasites. Far from being a detriment to the forests in which they live, parasitic plants like S. yakushimensi can serve as a very important reminder of how crucial it is to preserve entire ecosystems rather than single species.

Photo Credit: Yamashita Hiroaki

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