﻿Ligularialushuiensis (Asteraceae, Senecioneae), a new species from northwestern Yunnan, China

﻿Abstract Ligularialushuiensis, a new species from northwestern Yunnan, China, is described and illustrated. It was tentatively placed in L.sect.Ligulariaser.Ligularia on the basis of the pinnate-palmate leaf venation, racemose synflorescence and pappus which is as long as tubular corolla. Within the series, it appeared somewhat close to both L.lamarum and L.pseudolamarum. However, L.lushuiensis can be easily distinguished from the latter two species by, among other characters, the leaf margin, bract size, involucre shape and size, and number and width of ray florets. Morphologically, L.lushuiensis is also superficially similar to L.secunda but differs readily by having distally shortly yellowish and brownish puberulent stems, palmately-pinnately veined leaves regularly dentate at margin, scarious, brown and larger bracts, and larger ray laminae. In addition, a distribution map and a diagnostic key to Chinese species of L.ser.Ligularia are also provided.


Introduction
Ligularia Cass.(Asteraceae, Senecioneae), with approximately 130 species recognized, is mainly distributed in eastern Asia (Liu 1989;Liu et al. 1994;Liu and Illarionova 2011;Ren et al. 2020).The center of species diversity of the genus lies in the eastern Himalayas and the Hengduan Mountains region in southwestern China (Liu et al. 1994(Liu et al. , 2006;;Liu and Illarionova 2011).In the last decade, many taxonomic revisions at specific level have been continuously carried out in the genus (see Fei et al. 2019;Lazkov and Sennikov 2019;Guo and Wang 2022;and literature cited therein).
During a botanical expedition to northwestern Yunnan, China in 2017, we discovered an unusual population of Ligularia in a less-botanized area in Lushui city (Fig. 1).It appeared to be similar to both L. pseudolamarum Long Wang & X.Q.Guo and L. secunda Y.S.Chen in the general habit, especially in the capitula that are oriented to one side of the synflorescence axis.However, they showed great differences in an array of characters.can also be easily distinguished from that species.We therefore determine that the plants in question represent a hitherto undescribed species, which we describe below.

Material and methods
For morphological comparison, we critically examined physical or digitalized herbarium specimens deposited at several major herbaria in China, including CDBI, HNWP, IBSC, KUN, NAS, PE, SZ, and WUK (acronyms follow Thiers (2023)).Specimens of L. lushuiensis were collected and photographed during our field investigation to Yunnan province in 2017.Morphological observations and measurements were based on fresh material as well as herbarium specimens deposited at IBSC.

Taxonomic treatment
Ligularia lushuiensis Long Wang, sp.nov.urn:lsid:ipni.org:names:77335783-1Figs 1, 2 Diagnosis.Ligularia lushuiensis should be placed within L. ser.Ligularia owing to character combination of palmate-pinnate leaf venation, scarious and brown bracts, single-oriented capitula, and broadly cylindrical involucres 1-1.1 cm high and 1.1-2 cm in diam.Morphologically, it is somewhat similar to L. lamarum, L. pseudolamarum, and L. secunda.From L. lamarum, it differs in the leaf margin, bract texture, color, and size, involucre shape and size, and ray floret number and width; from L. pseudolamarum, it differs in the leaf shape and margin, bract size, involucre shape and size, and ray floret number and size; and from L. secunda, it differs in the stem indumentum, leaf venation and margin, bract texture, color and size, and ray floret size.
Distribution and habitat.Ligularia lushuiensis is currently known only from its type locality, i.e.Lushui, northwestern Yunnan, China (Fig. 3).It grows in alpine meadows at an elevation of ~3322 m above sea level.
Etymology.The specific epithet 'lushuiensis' refers to the type locality of this new species, i.e.Lushui City.
Phenology.Flowering from July to August; fruiting from late August to September.
Vernacular name.泸水橐吾 (Chinese pinyin: lú shuǐ tuó wú).Conservation status.Ligularia lushuiensis is currently known only from a small population at its type locality, i.e.Lamaku Shan.The single population we discovered consists of no more than 200 mature individuals.Overgrazing might be the major threat to the habitat of this species.According to the IUCN Red List Categories and Criteria (IUCN 2019), this species should be categorized as Critically Endangered (CR): B1ab(iii)+2ab(iii).
Notes.Morphologically, Ligularia lushuiensis resembles both L. pseudolamarum and L. secunda, especially in the single-oriented capitula and racemose synflorescences.It is also superficially similar to L. lamarum, especially in the general habit and in the leaf shape and synflorescence type.Table 1 provides detailed morphological comparisons among these four species.In the genus Ligularia, L. confertiflora C.C.Chang is also recorded to have capitula that are oriented to one side of the synflorescence axis except for L. lushuiensis, L. pseudolamarum, and L. secunda.However, this species is characterized by having palmate leaf venation and short pappus which is as long as the tube of tubular corolla and is readily placed in L. ser.Speciosae Pojark.It is easily distinguishable from L. lushuiensis in having discoid capitula and leaflike bracts.
According to the infrageneric classification proposed by Liu (1985), Ligularia lushuiensis is tentatively assigned to L. sect.Ligularia ser.Ligularia because of the character combination of pinnate-palmate leaf venation, racemose synflorescence and pappus which is as long as tubular corolla.It is noteworthy that the pinnate-palmate leaf venation appears frequently in several species within this series.With the addition of this new species, 14 species are currently recognized in the series in China (Liu 1988;Grierson and Springate 2000;Guo and Wang 2022).We herein provide a diagnostic key to the Chinese species of L. ser.Ligularia to facilitate identification of this group of plants.