Xishuangbanna Tropical Botanical Garden (XTBG) has collected and maintained a collection of about 100 plants of Annonaceae, a large pantropical flowering plant family. Recently, observations of flower morphology in the Annonaceae collection at XTBG have led to the identification of two unknown species belonging to the genus Polyalthiopsis. 

Two of the unknown species were introduced from southeastern Yunnan in 2000 and from Napo, Guangxi, in 2002, respectively, but without any information on their locations or habitats. Fortunately, XTBG researchers identified the locations and in April 2021 found these species in the wild. 

After morphological comparisons and phylogenetic analyses based on five chloroplast regions, the researchers confirmed two new species and named them as Polyalthiopsis nigra and Polyalthiopsis xui respectively. 

The two new species were published in Plant Diversity. 

Polyalthiopsis nigra is morphologically similar to P. chinensis with lemon to yellowish green petals and < 7 mm long pedicel, but clearly differs by having obovoid monocarps and the pericarp of the monocarps not secreting white liquid when injured, 15–25 pairs of secondary veins, the widest part of leaf blades usually above the middle, leaf blades 2.0–3.0 times as long as wide, and flowering from February to April. 

Polyalthiopsis nigra is known only from Napo County in Guangxi and Malipo County in Yunnan, SW China. Since very few details exist about its natural distribution, the researchers assigned its conservation status as data deficient (DD). 

Polyalthiopsis xui is morphologically similar to P. floribunda with inflorescences axillary, 1–3(–4) flowers, elliptic leaves, petals elliptic-ovate, but it clearly differs by having carpels 7–12 per flower, ovules 2 per carpel. It is known only from the type locality in Maguan County, Yunnan. It usually grows in the tropical rainforest of limestone areas, at elevations of 300–400 m. 

Polyalthiopsis xui is named after Prof. XU Zaifu, a former director of XTBG, for his contributions to plant introduction and ex situ conservation. It is known only from the type locality in southeastern Yunnan. 

“Although its habitat is under protection near Yunnan Daweishan National Nature Reserve, the forests are under severe pressure from agricultural expansion, and the population and mature individuals are near the roadside. We suggest the species be assessed as Vulnerable (VU),” said TAN Yunhong of XTBG. 

Contact   

TAN Yunhong  Principal Investigator        

Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China             

E-mail: tyh@xtbg.org.cn    

Polyalthiopsis nigra (Image by YANG Bin) 

Polyalthiopsis xui  (Image by YANG Bin)