Metagentiana jiangyouensis, a new species of Gentianaceae from Sichuan, China, is described and illustrated. This new species is similar to Metagentiana villifera, but differs by the fact that the plant is glabrous and has 1–4 flowering stems, well-developed basal vegetative rosettes, a pale purple corolla with dark purple spots on the tube and erose or denticulate, non-fringed plicae margins. It also somewhat resembles M. rhodantha, but can be easily distinguished by having shorter stems, entire leaf margins, smooth, shorter sepal lobes, spotted corolla tubes, non-fringed plicae and narrowly winged seeds.

Gentianaceae, Metagentiana, Morphology, taxonomy

The genus Metagentiana T.N.Ho & S.W.Liu in Gentianaceae was separated from Gentiana L. by Ho et al. (2002) based on comprehensive morphological and cytological evidence, and fourteen species were listed in this genus. A recent molecular phylogenetic study of subtribe Gentianinae confirmed that Metagentiana was monophyletic when excluding two yellow-flowered species, notably M. souliei (Franch.) T.N.Ho, S.W.Liu & Shi L.Chen and M. striata (Maxim.) T.N.Ho, S.W.Liu & Shi L.Chen, which were transferred to the new genus Sinogentiana Adr.Favre & Y.M.Yuan (Favre et al. 2014). Both morphological and molecular evidence indicates that Metagentiana has a close relationship with Sinogentiana, Tripterospermum Blume and Crawfurdia Wall. (Ho et al. 2002; Favre et al. 2014). Currently, excluding the new species, Metagentiana contains twelve species: Nine of these are restricted to southwestern China; one is relatively widespread in northwestern and central China; one is distributed in eastern Myanmar, and one is endemic to Thailand.

Metagentiana can easily be distinguished from Tripterospermum and Crawfurdia by having ascending to erect, not twining or trailing, stems. It can be distinguished from Gentiana by the following features: stem leaves sessile, widely separated, leaf blades broadly ovate to ovate-triangular; flowers bracteate; calyx keeled or winged, plicae asymmetrical, very oblique; stamens unequal in length, apically recurved; style filiform, as long as or longer than the ovary; capsules cylindrical, wingless; seeds triquetrous with three winged edges, rarely wingless or areolate; seed coat minutely to coarsely reticulate (Ho et al. 2002).

Metagentiana and Sinogentiana are closely related, and their morphological characteristics are similar but flowers of Metagentiana are pink, purple or blue and the stem leaves are 0.3–1.5 cm long or up to 3 cm long in M. rhodantha (Franch.) T.N.Ho & S.W.Liu, whereas the corolla of Sinogentiana is consistently whitish or yellow and the stem leaves are 1–3 cm long. Most species in Metagentiana are annual herbs, except for M. rhodantha and M. villifera (H.W.Li ex T.N.Ho) T.N.Ho & S.W.Liu, which are perennials with extremely short rhizomes and basal rosettes (Favre et al. 2014).

One of the authors (Y. Zou) photographed an unknown species of Gentianaceae on 22 December 2018. After collection and observation of living material, we confirmed that this species belongs to the genus Metagentiana because of the large bracts at the bases of the flowers, the keeled and winged calyx-tube, the unequal stamens that are unilaterally curved downwards, and the filiform and long style. Literature study (Ho and Pringle 1995; Ho and Liu 2001; Struwe et al. 2002; Cao et al. 2019; Li et al. 2019; Yang et al. 2020; Favre et al. 2022; Chen et al. 2024) showed that this perennial species is closely similar to M. villifera and M. rhodantha. But its fewer branches and well-developed rosette leaves, shorter stems, entire leaf margins and smooth, shorter sepal lobes, as well as its corolla tube with dark purple spots and non-fringed plicae margins distinguish it from M. villifera and M. rhodantha. We confirm that this species is new to science based on its morphological characters and provide a detailed description below.

The type specimens of the new species were collected from Qianyuan Mountain, Hanzeng Town, Jiangyou County, Mianyang City, Sichuan Province, and deposited in the herbaria of CSH, KUN, PE and SMCM (Shanghai Museum of TCM, Shanghai University of TCM). Measurements and description of morphological characters of the new species were based on dried specimens and living plants. Type specimens of Metagentiana villifera (holotype: CDBI 0172347!; isotype: SZ!, KUN!, PE!, SM!; topotype: SM!) and specimens of M. rhodantha, which is the most closely related to the new species, were consulted online (Chinese Virtual Herbarium, http://www.cvh.ac.cn/) firstly, and then examined from CDBI, KUN, SZ, PE and SM. The line drawings, the description and most of the photographs were based on the type specimens. The conservation status of the new species was evaluated according to the guidelines of the IUCN Red List Categories and Criteria (IUCN 2024).

Metagentiana jiangyouensis is morphologically similar to M. villifera and M. rhodantha by the perennial habit, the presence of basal rosettes and the similar leaves and flowers. In fact, these three are the only Chinese species of the genus with basal rosettes and can therefore easily be distinguished from all other Chinese species. M. jiangyouensis differs from the two closely related species of M. villifera and M. rhodantha by the fact that the whole plant is glabrous, the spatulate to lanceolate calyx lobes 1.3–2(–3) mm long, the corolla tube with dark purple spots and the non-fringed plicae margin. Basal rosettes and well-developed abbreviated vegetative shoots make M. jiangyouensis a distinctive species amongst other species of Metagentiana. Metagentiana villifera and M. rhodantha sometimes have basal rosette leaves or vegetative shoots, but they are usually not well-developed or the vegetative shoots would grow into longer stems at a later time in the development. The other species of Metagentiana are annuals or biennials without rosettes. M. jiangyouensis differs from M. rhodantha also by its seeds with a narrow wing along the edges, whereas seeds of M. rhodantha are broadly winged. Metagentiana jiangyouensis and M. villifera both grow on rock surfaces, but M. rhodantha grows in grasslands, alpine scrub, forests and on rock. Metagentiana jiangyouensis is distributed in Jiangyou County, northeastern Sichuan, at an elevation between 1160 and 1513 m, whereas M. villifera is distributed in Junlian county, southeastern Sichuan, more than 420 km away from Jiangyou County, at an elevation of about 800 m; and M. rhodantha is widely distributed in southwest, northwest, central and south China, at an elevation between 500 and 1800 m. Furthermore, the flowering and fruiting phenophase of M. jiangyouensis is from December to April, while that of M. villifera is from April to June and that of M. rhodantha is from October to February. A comparison of the morphological characters of M. jiangyouensis and its related species is summarized in Table 1.

We are grateful to Zi-Wei Li of Chongqing Academy of Chinese Materia Medica (SM) for sending us the specimens of M. villifera; to Ang Liu of Central South University of Forestry and Technology for providing a photograph of the paratype specimen of M. jiangyouensis; to the editor Petra De Block as well as the reviewer Lei Zhang and two anonymous reviewers for their constructive comments and valuable input on a previous version of this manuscript. And we appreciate the curators of the cited herbaria (KUN, SZ, CDBI, SM) and the website managers of the Chinese Virtual Herbarium for making the high resolution voucher images available to this study.