A collaborative research team has identified a new species of Cucurbitaceae plant in Motuo County, Xizang, China. This new species has been named Herpetospermum motuoensis Y. S. Chen & B. Y. Zhang.

Herpetospermum motuoensis belongs to the genus Herpetospermum within the Cucurbitaceae family and is classified as a dioecious vine. This species is closely related to Herpetospermum operculatum, sharing a similar characteristic of lid-like dehiscence in mature fruits.

However, Herpetospermum motuoensis can be distinguished by several features, including its inconspicuous male flower bracts, which are round to broadly oval and measure 1-1.5 millimeters in length. The petals are nearly round to elliptical, and the plant contains six pendant ovules per locule, with stigmas that are nearly round to broadly elliptical. The fruits are yellow-green and spindle-shaped to ellipsoid-spindle-shaped, glabrous, while the seeds are oblong and hexagonal with projections at each corner.

In the winter of 2021, the research team received two specimens and several seeds from Motuo County. After thorough study and comparison with existing literature, they initially determined that these plants belonged to the genus Herpetospermum. However, the seeds sown in 2022 did not germinate. It was only in October 2023 that the team returned to Motuo County for a field investigation, successfully observing this plant in its natural habitat and collecting additional specimens. Following detailed observation and comparison of its morphological characteristics, the team confirmed that this was indeed an undescribed new species.

Herpetospermum motuoensis is currently known to exist exclusively in Motuo County, thriving in shrublands and along forest edges at altitudes ranging from 1300 to 2500 meters. The study reveals that five populations of this new species have been identified in Motuo County. One of these populations consists of just four individuals, located near a road, making it susceptible to the impacts of road construction and land reclamation, thus facing the risk of extinction.

The discovery of Herpetospermum motuoensis not only enriches the diversity of Cucurbitaceae plants in China but also provides new insights and materials for the taxonomic study of the genus Herpetospermum.

This study was published in Phytotaxa. The research team comprises members from the South China Botanical Garden of the Chinese Academy of Sciences, Xizang University, the Environmental Horticulture Research Institute, and the Guangdong Academy of Agricultural Sciences. Their work was supported by the Guangdong Basic and Applied Basic Research Flagship Program.

Herpelospermum motuoensis. A. Habitat; B. Habit; C. Tendril; D. Leaves; E. Male inflorescence; F. Top view of male flower; G. Back view of male flower; H. Longitudinal section of male flower; I. Top view of female flower; J. Back view of female flower; K. Longitudinal section of female flower; L. Fruits; M. Longitudinal section of fruit; N. Cross section of fruit; O. Seeds. A-O: all photos by BuYun Zhang based on the type, B. Y. Zhang, Y D. Xu, G. F. Liu et X.R. Zheng JZ20231191 (IBSC).（Imaged by CHEN et al）