PERROTTETIA TARONENSIS

Found in the Babulongtan mountain range in northern Kachin state, Myanmar, and the Dulong Jiang valley in northwestern Yunnan province, China, this new species of fowering shrub is the frst species of Perrottetia to be reported in Myanmar. Named after the Taron River valley in Myanmar, P. taronensis has been found on slopes in subtropical broadleaved evergreen forests, in disturbed secondary forests, and among shrubs near river banks in the Ayeyarwady (Irrawaddy) river basin.

One specimen was collected in Myanmar in the Kachin Hills subtropical rainforest ecosystem, while six were collected in China near Dulong Jiang River, which drains into the Taron River in Myanmar and eventually into the Ayeyarwady River. The specimen from Myanmar is male while the six specimens collected in China are female, leading researchers to posit that this plant is dioecious, meaning male and female reproductive organs are in separate individuals. However, more feld studies are needed during the spring when plants are fowering to be certain.

This new species is physically most similar to a species that occurs over 2,500km away in Peninsular Malaysia and Indonesia on Sumatra and Java, as well as a few small islands nearby. Major physical diferences between the two species are in its leaf margins, inforescences and fruit. No other species of this genus occurs in locations in between these two species. The researchers who discovered it recommend it be classifed as Endangered in the IUCN Red List, given its small area of occurrence, the degradation of its habitat, and the low number of mature individuals found.

“I collected this plant as part of a large US National Science Foundation funded inventory of the region, where we aimed to document all vascular plant species,” said Dr Kate Armstrong of the New York Botanical Garden. “This one was, at frst, unremarkable, except that it was collected during a particularly harrowing trip, during a long trek over a mountain in the bucketing monsoon rain. So, I remember the conditions of the trip more than collecting the plant itself!

“Because I couldn’t easily identify the genus – it’s from a relatively obscure plant family with just 2 genera and 20 species – I asked the advice of colleagues who have also worked on the fora of that region, albeit on the Chinese side of the border. Bruce Bartholomew, from the California Academy of Sciences, recognized the genus immediately, and after going back through collections that he and other colleagues had made in Yunnan about 20 years ago, he realized that we had a new, undescribed species. That is the case with many new taxa – they are hiding in our herbarium collections waiting to be recognized and described.”

Bartholomew, B., Armstrong, K.E., Li, R. and Fritsch, P.W. (2021) Perrottetia taronensis B.M.Barthol. & K.Armstr., sp. nov. (Dipentodontaceae), a new species from northwestern Yunnan Province, China and northern Kachin State, Myanmar and a re-examination of the Asian and Australasian taxa of Perrottetia. PhytoKeys 183: 67-76. doi.org/10.3897/ phytokeys.183.71505