Ligularia lushuiensis Long Wang, 2024

Chi, Xiao-rui, Wu, Hai-song & Wang, Long, 2024, Ligularia lushuiensis (Asteraceae, Senecioneae), a new species from northwestern Yunnan, China, PhytoKeys 238, pp. 75-83 : 75

Ligularia lushuiensis Long Wang sp. nov.

Figs 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.

Type.

China. Yunnan: Lushui, Daxingdi, Lamaku Shan , 26°06'10.18"N, 98°59'34.68"E, alpine meadows, 3322 m a.s.l., 6 August 2017 (fl.), Long Wang & Yun-yun Shao 1610 (holotype: IBSC; isotypes: IBSC). Fig. 2 .

Description.

Perennial herb. Stems solitary or 2, erect, 30-70 cm tall, 4-5 mm in diam. at base, proximal to middle part yellowish puberulent, distal part shortly yellowish and brownish puberulent. Basal leaves petiolate; petiole 5-12 cm long, not winged throughout; leaf blade ovate-cordate, 5-8(-10) cm long, 4.5-8(-11) cm wide, herbaceous, adaxially dark green, glabrous, abaxially greenish, slightly brownish puberulent only on veins, palmately-pinnately veined, base cordate, margin regularly dentate, apex obtuse; sinus narrow, basal lobes suborbicular, divergent. Stem leaves 3-6. Proximal stem leaves 1-2, similar to but smaller than basal leaves. Median stem leaves 1-2, shortly petiolate or sessile, base tubular-amplexicaul. Distal stem leaves 1-2, bracteal, scarious. Capitula (2-)5-9, in a lax raceme, oriented to one side of the synflorescence axis; peduncles short, ca. 1 cm long; bract 1, ovate-lanceolate, ca. 1 cm long, 6-7 mm wide, scarious, brown; bracteoles 2 or 3, oblong-lanceolate, ca. 1.1 cm long, 3 mm wide, scarious, brown. Involucres broadly cylindrical, 1-1.1 cm high, 1.1-2 cm in diam., outside more or less whitish arachnoid; receptacle whitish arachnoid outside; phyllaries 12-15, in 2 rows; outer phyllaries narrowly oblong, 2-2.5 mm wide, apex acute; inner phyllaries oblong, ca. 3 mm wide, margin membranous, apex acute to obtuse. Ray florets 10-13, yellow; lamina ovate-oblong, 1.5-1.6 cm long, 5-6 mm wide, apex obtuse, 2- or 3-denticulate; tube ca. 4 mm long. Tubular florets numerous, yellow, ca. 1 cm long; tube 2-3 mm long; limb campanulate, 4-5 mm long; style 6-7 mm long, branches dark yellow. Achenes (immature) narrowly oblong, 3.5-4 mm long, glabrous. Pappi white, ca. 7 mm long, as long as or slightly shorter than tubular corolla.

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.

Figures

Figure 1. Ligularia lushuiensis sp. nov. A habitat B habit C basal leaf (adaxial surface) D basal leaf (abaxial surface) E synflorescence F capitulum (top view) G capitulum (side view) H capitulum (back view) I outer phyllaries (abaxial surface) J inner phyllaries (abaxial surface) K ray florets L tubular florets. Photographs by Long Wang.

Figure 2. Holotype sheet of Ligularia lushuiensis sp. nov.

Figure 3. Distribution of Ligularia lushuiensis sp. nov. (black dot).