Apios chindiana K. W. Jiang, J. F. Wang, Z. H. Chen & B. Pan bis, 2025

Apios chindiana K. W. Jiang, J. F. Wang, Z. H. Chen & B. Pan bis , sp. nov. Figs 2 View FIGURE 2 & 3 View FIGURE 3

Type: — CHINA. Zhejiang: Lishui, Qingtian, Jupu, on slopes, forest margins, alt. 1,172 m, 16 July 2023 (fl.), J. F. Wang & D. H. Wu QT23071601 [ holotype NPH (herb. no. NPH 2724!), isotypes NPH (herb. no. NPH 2724!), ZM!].

Description: —Slender, herbaceous, twining climbers, deciduous with their above-ground parts dying back in winter. Root with fusiform tubers, brownish, 10–20 mm long, 6–14 mm in diameter. Branches striate, green, sparsely to moderately pubescent with pale, appressed or ± ascending hairs ca. 0.5 mm long, slightly denser at nodes. Leaves imparipinnate with 3–5 leaflets. Stipules linear, sparsely pubescent with ± ascending hairs, sub-caducous. Petiole and rachis slender, striate, hairy as branches, dark-purple, petiole 16–61 mm, with a basal pulvinus 2–4 mm, somewhat swollen, sparsely to moderately pubescent with pale, ascending hairs, rachis between lateral leaflets 21–30 mm, rachis of terminal leaflet 7–21 mm. Petiolules 1.5–4.0 mm, slender, pubescent. Stipels not seen. Leaflets membranous-chartaceous, ovate to broadly lanceolate, margin often shallowly undulate or sometimes entire, broadly cuneate, rounded to almost truncate at base, acuminate with an acumen 3–10 mm at apex; lateral ones asymmetric, 23–76 × 13–50 mm; terminal one 36–95 × 29–74 mm; sparsely pubescent with appressed, pale hairs adaxially, denser along midvein, green; sparsely pubescent with appressed hairs abaxially, ± glaucous; pubescent with appressed hairs along margins; midvein and lateral veins often dark-purple abaxially, especially at basal part; lateral veins 3–5 pairs, anastomosing; tertiary veins reticulate. Inflorescence a nodose pseudoraceme, usually axillary, solitary, occasionally terminal on lateral branches, 72–220 mm; axis glabrous; nodes swollen, usually 3-flowered. Bracts narrowly triangular, sometimes the apical part ± reflexed, 6–8 × ca. 1.5 mm, scarious and brown, subglabrous, caducous. Pedicels 4.5–6.0 mm, moderately pubescent with ascending hairs. Bracteoles subtending the calyx, ovate, ca. 0.5 mm, with pale hairs along margins. Calyx campanulate, usually bilabiate, upper lip ca. 4.5 × 4 mm, lower lip ca. 4.5 × 3 mm, or sometimes shallowly 4-lobed (with the lower lip further divided into 3 lobes and the lowest one the longest); outer surface sparsely pubescent with pale, ascending hairs; inner surface pubescent with pale, appressed hairs, which are denser towards apex, sparser to almost glabrous towards base; pubescent with pale, ascending hairs along calyx mouth. Corolla reddish to dull red, bilaterally symmetric; standard incompletely opening with apex nearly adnate to keel apices, broadly obovate ca. 19.5 × 17 mm, somewhat hooded, emarginate at apex (when unfolded), with a green patch on the lower part, with short claw ca. 1 mm; wing petals much smaller, oblong, ca. 9.0 × 1.5 mm, including claw 1.5–2.0 mm, the apical part darker in colour, often irregularly folded; keel petals narrowly falcate, curved towards apex, connate to each other, ca. 1.9 × 0.2 cm, including claw ca. 3 mm. Stamens (9+1) diadelphous, ca. 15 mm; filaments glabrous; anthers dorsifixed, equal, ca. 0.7 mm. Pistil filiform, ca. 16 mm; ovary puberulent with pale, appressed hairs, ca. 12- ovuled; style puberulent as ovary, coiled towards apex; stigma capitate, funnel-shaped. Pods linear-falcate, 116–145 × 8–9 mm, valves coriaceous, elastically dehiscent along both sutures when mature, surface glabrous but punctate with raised, scattered dots, brownish when mature, somewhat thickened along both sutures; septa presented between seeds, yellowish-white, those are loose, falling easily. Seeds ellipsoid, smooth, grey with mottled patterns, compressed laterally, 5–5.5 × ca. 4 × ca. 1.5 mm; hilum oblong, ca. 1.5 mm, attached to the funicle at one end of the short axis, this often eccentric and positioned towards one face of the seed.

Phenology: —Flowering from July to August, fruiting in October.

Distribution and ecology: —Herbarium records currently document the distribution of Apios chindiana in Qingtian County, southern Zhejiang Province, and Taining County, Fujian Province ( Fig. 4 View FIGURE 4 ). Online photographs of plants that appear to be A. chindiana suggest a potentially wider distribution, including Linhai County in eastern Zhejiang Province (https://ppbc.iplant.cn/tu/3774182, by Yu-Xing Gu) and Changshan County in western Zhejiang Province (https://www.cfh.ac.cn/User/ShowPhoto.aspx?photoid=b066bae9-35f1-44eb-aff1-09688f798d8e&album id=bf0d5b2d-d930-487b-8124-4a82a467755c&page=2&order=TakeTime%20, by Xian-Xing Chen). These online records warrant further investigation to confirm the presence of the species in these locations and adjacent areas.

Apios chindiana typically inhabits forest margins and semi-shaded, moderately humid secondary forests at elevations of 900–1,200 meters above sea level. In these habitats, it is a climber on trees and shrubs.

Conservation status: —The area of occupancy (AOO) and extent of occurrence (EOO) for Apios chindiana were calculated using GeoCAT ( Bachman et al. 2011) based on herbarium specimen records. This analysis resulted in an AOO of 16.000 km ² and an EOO of 626.523 km ², both initially suggesting an Endangered (EN) status under IUCN Criterion (IUCN Standards and Petitions Committee 2024). When photographic records of living plants from Changshan and Linhai Counties were included, the AOO increased to 24.000 km ² (still within the EN threshold), while the EOO expanded significantly to 32,025.764 km ², shifting the classification to Near Threatened (NT). Given the species’ high-altitude range ( 900–1,200 m), its actual geographic distribution may be more restricted than the EOO suggests. While we lack direct evidence of an observed or inferred decline, the limited number of known locations (fewer than 10) and specimens supports a precautionary assessment. Thus, following the IUCN Standards and Petitions Committee (2024), we classify A. chindiana as Near Threatened (NT), indicating that it does not currently qualify as threatened but could do so if conservation measures are not maintained. Surveys suggested that its habitats, though generally remote, may still experience some human disturbance.

Etymology: —The specific epithet chindiana is derived from 'Chindia', the romanization of ' ûm ' (Standard Chinese Pinyin: Qīngtián), the toponym in the local dialect (IPA: [tɕʰiŋ 44 dia 51]). The dialect belongs to Shangli ( 上 丽/上ª) subgroup of Wu Chinese. This romanization approach follows the conventions of the Wugniu School ( DZDz ※堂, https://www.wugniu.com/).

The Chinese name of Apios chindiana is therefore given as ûm土圞儿/ûm土圞兒 (Standard Chinese Pinyin: Qīng tián tǔ luán ér), 土圞儿/土圞兒 is the common name for the genus Apios .

Taxonomic remarks: —Compared to its closest relative, Apios fortunei , the unknown species is primarily characterized by its thinner, membranous-chartaceous ( vs. generally thicker, chartaceous) leaflets with often shallowly undulate ( vs. usually entire) margins, and a reddish to dull red corolla ( vs. yellowish-green to light green, with wing petals sometimes pink) that is bilaterally symmetrical ( vs. asymmetrical with keel petals twisted to one side).

In addition to Apios fortunei , A. chindiana may sometimes be confused with another Asian species, A. carnea , which has red, reddish-purple, or orange flowers ( Egan & Pan 2015b). A. chindiana can be readily distinguished by its developed tubers ( vs. tubers usually undeveloped), its bilabiate or sometimes shallowly 4-lobed calyx with inconspicuous lobes ( vs. conspicuous lobes) and its mature standard that remains incompletely open, somewhat hooded and nearly adnate to keel apices ( vs. mature standard completely opening, flat and widely separating from keel apices).

Apios chindiana may, to some extent, be confused with the two American species, A. americana and A. priceana , both of which have maroon or pink corollas. However, these two species can be readily distinguished from A. chindiana by their inflorescences with more congested flowers and wing petals that are more than half the length of the keel petals ( vs. flowers more loosely arranged; wing petals less than half the length of the keel petals in A. chindiana ).

Additional specimens examined ( paratypes):— CHINA. Fujian: Taining, Mt. Emei-feng, alt. 1,200 m, 30 July 1979 (fl.) C. J. Chen, Z. Y. Zhang & Z. Y. Li 11 ( PE). Zhejiang: Lishui [Li-syu]: Qingtian [Chin-dia], Jupu Township, in the gully, along stream-sides, margin of bamboo forests, alt. 920 m, 21 July 2023 (sterile), J. F. Wang, J. P. Zhong & Z. H. Chen QT23072101 ( NPH, ZM). ibid., on slopes, forest margins, in thickets, ead. die (fl.), coll. iid. QT23072103 ( CSH, NPH, ZM). ibid., on slopes, along path-sides, 5 October 2023 (fr.), J. F. Wang & J. P. Zhong QT23100501 ( NPH, ZM). ibid., along path-sides, on slopes, climbing on pines, alt. 1,190.75 m, 27 July 2024 (fl.), K. Chiang, Z. H. Chen, J. F. Wang, D. H. Wu & L. H. Wu KC1963 ( NPH). Qingtian [Chin-dia], Zhenbu Township, on slopes, under bamboo forests, climbing on bamboos, less common, alt. 919.5 m, ead. die (fl.), coll. iid. KC1963bis ( NPH). Qingtian [Chin-dia], Shimendong [Zyq-man-don] Forest Farm, along forest margins of Cunninghamia lanceolata , climbing on thickets, alt. 1,096 m, 30 August 2024 (fl.), Y. R. Zhu, J. S. Wang & G. Y. Li QT2024083001 ( NPH, ZM). ibid., along forest margins of a mixed coniferous and broad-leaved forest, climbing on thickets, alt. 1,096 m, ead. die (fl.), F. Chen, G. K. Chen & Z. H. Chen QT2024083002 ( NPH, ZM).