[Botany • 2026] Monotropa callistoma (Ericaceae) • A New Species based on morphological and molecular evidence from Hunan, China

Monotropa callistoma  Ze Wei, Li J.Liu & Bing Liu,

in Wei, L.-J. Liu, Xuan, Mo, Yang, B. Liu, Li et Wang, 2026. 

美冠水晶兰  ||  DOI: doi.org/10.3897/phytokeys.271.177609

Abstract

The subfamily Monotropoideae (Ericaceae) comprises unique non-photosynthetic and mycoheterotrophic plants. Their extensive morphological reduction often poses significant challenges for species delimitation. In this study, we investigated an unknown Monotropa taxon collected from Hunan Province, China, through an integrative approach combining detailed morphological observation and phylogenetic analysis. We sequenced it, assembled the complete plastid genome and reconstructed phylogenetic trees using both chloroplast genomes and the nrITS region. Morphologically, this new entity is readily distinguished from its congener, Monotropa uniflora, by several key characteristics: 4–5 glabrous petals apically one-quarter orange and basally three-quarters white, 8–10 stamens with glabrous filaments, a nodding berry at maturity and a distinctly earlier flowering period (March–June vs. June–October). Phylogenetic reconstructions, based on both chloroplast genomes and nrITS data, consistently resolved this unknown taxon as a distinct lineage, clearly separating it from M. uniflora with strong support. Integrating evidence from morphology, phylogeny and phenology, we hereby describe it as a new species, Monotropa callistoma.

Key words: Ericaceae, Monotropa, morphology, new species, phylogeny, taxonomy

Morphology of Monotropa callistoma. A. Flower; B. Flowering plant showing scale-like leaves; C. Petals; D. Stamens; E. Transverse section of the ovary; F, G. Baccate fruit (berry) and its transverse section showing the parietal placentation; H. Mycorrhiza.

B–E. Photographed by Zi Wang and others photographed by Ze Wei.

Monotropa callistoma sp. nov.
A. Habitat and flowering plant; B. Flower, viewed from the top; C. Sepal; D. Petal; E. Stamen; F. Pistil; G. Berry; H. Transverse section of the berry fruit showing the parietal placentation; I. Mycorrhiza.

Drawn by Yi F. Li.

Monotropa callistoma Ze Wei, Li J.Liu & Bing Liu, sp. nov.

 

Diagnosis. Monotropa callistoma is characterised by its 4 or 5 glabrous petals (apically orange and basally white), 8–10 stamens with glabrous filaments, flowering period starting from March and nodding capsule at maturity. It is morphologically most similar to M. uniflora and Monotropastrum humile, but differs by the characters summarised in Table 2.

Etymology. The specific epithet callistoma is derived from the Greek calli- (beautiful) and -stoma (mouth), alluding to the aesthetically pleasing form and colouration of the corolla orifice.

Vernacular name. (Chinese name). 美冠水晶兰 (měi guān shuǐ jīng lán).

Habitat and flowering habit of Monotropa callistoma.

 Photographed by Ze Wei.

 Ze Wei, Li-Jia Liu, Jing Xuan, Zhi-Qiong Mo, Wen-Xiang Ou Yang, Bing Liu, Min Li and Qiang Wang. 2026. Monotropa callistoma (Ericaceae), A New Species based on morphological and molecular evidence from Hunan, China. PhytoKeys. 271: 145-160. DOI: doi.org/10.3897/phytokeys.271.177609 [27 Feb. 2026]