New plant genus established for one of our rare orchid species!!

Limestone canyon of the Rio Anzu.

Our Rio Anzu Reserve in the Amazonian foothills near Mera, Ecuador, protects a special forest growing on limestone outcrops. These outcrops are usual in this part of Amazonia, and the unusual geology (combined with an unusually wet climate) had led to the evolution of special plants that are restricted to this habitat. About fifty plant species known only from the area around Mera and nowhere else in the world!

One of the most unusual plants of the Rio Anzu is a small orchid I had found several years ago in the area. Usually the first step to identifying an orchid species is to figure out its genus. But I could not get past this first step; it had traits that didn’t match any known genus of orchids. Eventually I showed it to a visiting orchid scientist from Mexico, Gerardo Salazar, who specializes in the taxonomy and evolution of the large group of orchid genera most closely related to this one (genera in the subtribe Spiranthinae). He was also puzzled by it. He did some research and discovered that the species had in fact been named previously, as “Spiranthes glabrescens“, based on a plant found in Peru. It was interesting to find that this plant had been seen a thousand kilometers away in Peru, but it was only known in Peru from that original discovery (made in the 1970’s) and one recent collection, and it had never been seen in Ecuador prior to my discovery of it in the Rio Anzu area. It was clearly a very rare plant. However, we felt sure that “Spiranthes glabrescens” could not really belong to the genus Spiranthes. For one thing, the flowers were “upside down” (non-resupinate) compared to all other Spiranthes species, and the leaves, roots, and pollen were also different.

New orchid genus, Quechua.

Quechua, a new genus of orchids established for one of the special plant species protected by our Rio Anzu Reserve.

A few decades ago taxonomists would have argued endlessly about the proper genus for a given plant species. The decision to place an unusual plant in one genus instead of another often seemed like a judgement call, with no way to judge who had the correct answer (the correct answer being the one which matched the evolutionary history of the species and its relatives). DNA analysis changed all that. Now we can learn something about the evolutionary history of a species by seeing how much its non-coding DNA (which tends to accumulate mutations at a constant rate, unaffected by natural selection) differs from its relatives.

Gerardo did that, and confirmed that this plant was not very closely related to the other species in the genus Spiranthes, and in fact did not group itself with any other of the known genera either. This confirmed what we could also observe with our naked eyes–this plant belonged in its own genus. Gerardo suggested the name “Quechua“, after the language of the major Peruvian and Ecuadorian indigenous groups. By the rules of plant taxonomy, the old species name had to stick with the plant, so our unusual orchid became “Quechua glabrescens“. Our scientific description of the genus was recently published as “Quechua, a New Monotypic Genus of Andean Spiranthinae (Orchidaceae)”, Gerardo Salazar and Lou Jost, p. 78-86 in Volume 37, Jan.-March 2012, of the journal Systematic Botany. Interested readers can get a copy from me.

Lou Jost

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