Morphological and phylogenetic study describes Elatostema weizhianum from Zhejiang, China

A new species of Elatostema, named Elatostema weizhianum, has been formally described from two locations in southwestern Zhejiang Province, eastern China. The taxonomic study combined field collection, comparison of preserved specimens, and phylogenetic analysis of three DNA regions, finding that the plant forms a distinct, strongly supported lineage within the core Elatostema clade.

The discovery was made during a field survey in Zhejiang and is described in a taxonomic treatment of the nettle family, Urticaceae. The family comprises more than 2,500 species in 59 accepted genera, including 26 genera and about 400 species in China. The genus Elatostema contains 659 species across tropical and subtropical Asia, Africa, and Oceania, with major concentrations in the karst areas of southern China and several Southeast Asian archipelagos.

China has 280 endemic species of Elatostema, many of which have narrow distributions. Yunnan and Guangxi have the greatest recorded species richness, with 151 species, including 106 endemics, in Yunnan, and 99 species, including 65 endemics, in Guangxi. The genus is considered taxonomically difficult because it includes many species but has historically had limited collections, while differing interpretations of species boundaries have produced taxonomic instability.

Specimens of the new species were collected at Mt. Jiulong in Suichang County and Mt. Fengyang in Longquan County. The researchers compared features including hairs on stems, leaves and receptacles; leaf venation and serration; bracts and bracteoles in pistillate inflorescences; and achene surfaces. Type specimens of three related species—E. grandidentatum, E. longibracteatum and E. albovillosum—were examined in the PE and IBK herbaria for relevant comparisons.

For the phylogenetic analysis, the researchers included 103 species, 92 of them representatives of Elatostema. Only the new species was newly sequenced. DNA was extracted from silica-gel-dried leaves using the CTAB method, and paired-end libraries were sequenced on the DNBSEQ-T7 platform, producing 150-base-pair reads. The nuclear ITS region and the chloroplast psbA-trnH and psbM-trnD regions were analyzed; their aligned lengths were 1,152, 632 and 763 base pairs, respectively.

Maximum likelihood and Bayesian analyses produced largely congruent trees. Within Elatostema sensu lato, the analysis recovered the Procris, Elatostematoides, Weddellia, Pellionia, African Elatostema and core Elatostema clades. The two accessions of E. weizhianum formed a clade with 84% bootstrap support and a posterior probability of 1 within the core group. The new species was most closely related to E. hypoglaucum, while molecular data placed it more distantly from E. grandidentatum, the species considered its closest morphological match.

Elatostema weizhianum is described as a dioecious perennial terrestrial herb with a short tuberous root. Its stems are 10–40 cm tall, and its alternate, subsessile leaves have membranous or thin-chartaceous blades measuring 2.5–17 cm long and 2–7 cm wide. The leaves have a triplinerved base, three to five pairs of lateral veins and triangular-dentate margins. The species differs from E. hypoglaucum in features including its 4–6 mm, purple-brown-spotted stipules, short and densely hairy staminate inflorescence peduncles, and achenes about 1 mm long with five longitudinal ribs and a tuberculate surface.

Comparisons with E. grandidentatum further distinguished the new species by its spotted stipules, paired axillary pistillate inflorescences, glabrous receptacle, approximately 20 triangular bracts, differentiated outer and inner bracteoles, inconspicuous degenerative sepals, and five-ribbed tuberculate achenes. The authors assigned E. weizhianum to section Elatostema because of its capitate staminate inflorescences and conspicuous sub-orbicular receptacle, and to series Papillosa because of its longitudinally five-ribbed, tuberculate achenes.

The species was assessed as Endangered under the IUCN categories and criteria, using criterion B2(a). It is currently known from the two Zhejiang localities, where approximately 300 individuals in two populations occupy moist valley environments; the reported area of occupancy is less than 200 km². The authors state that the species requires conservation attention and protection. Its limited known range and the study’s reliance on specimens and observations from these two populations define the present scope of the assessment. Flowering and fruiting occur from mid-June to early August, and the specific epithet weizhianum honors Prof. Zhi Wei, a Chinese taxonomist at the Zhejiang Museum of Natural History who studies vascular plants, particularly Fabaceae.

Subject of Research: Taxonomic description and phylogenetic placement of the new Urticaceae species Elatostema weizhianum

Article Title: Elatostema weizhianum , a new species of Urticaceae from Zhejiang, East China

Article References: Xu, Y.-L., Zheng, Z.-H., Lu, Y.-F., Tang, Z.-S., & Jin, X.-F. (2026). Elatostema weizhianum, a new species of Urticaceae from Zhejiang, East China. PhytoKeys, 277, 65-75. https://doi.org/10.3897/phytokeys.277.200946

Image Credits: AI Generated

DOI: 10.3897/phytokeys.277.200946

Keywords: Elatostema weizhianum, new species, Urticaceae, plant taxonomy, phylogenetics, Zhejiang, China, species conservation, morphology, DNA sequencing, Elatostema, weizhianum