Indigofera jintongpenensis Huan C.Wang, L.Yao & X.L.Zhao, 2024

Yao, Lan, Yang, Yan, Zhao, Xue-Li, Wang, Qiu-Ping & Wang, Huan-Chong, 2024, Indigofera jintongpenensis (Fabaceae, Papilionoideae, Indigofereae), a new species from Yunnan, southwest China, PhytoKeys 241, pp. 91-101 : 91

publication ID	https://dx.doi.org/10.3897/phytokeys.241.120230
persistent identifier	https://treatment.plazi.org/id/01352C0A-9473-5548-9813-5220A05F51CC
treatment provided by	PhytoKeys by Pensoft
scientific name	Indigofera jintongpenensis Huan C.Wang, L.Yao & X.L.Zhao
status	sp. nov.

Treatment

Indigofera jintongpenensis Huan C.Wang, L.Yao & X.L.Zhao sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type.

China. Yunnan Province: Fumin County, Jintongpen Mountain , alt. 2,730 m, in the scrub of the limestone mountains, 10 June 2022, H. C. Wang et al. FM16943 (Holotype: YUKU!; isotypes: YUKU!)

Diagnosis.

Indigofera jintongpenensis is most morphologically similar to I. balfouriana Craib, but it clearly differs from the latter by its habit being prostrate (vs. erect), much-branched stems and branches flexible, leaves usually 7-13-foliolate (vs. 5-9-foliolate), stipules usually 5-7 mm (vs. 3-6 mm) long, inflorescences racemose, 1-2 (-3.5) cm (vs. 2-6 cm) long, 6-8-flowered, legumes 1.5-2.5 cm (vs. 2.5-4.0 cm) long, endocarp not blotched (vs. blotched).

Description.

Shrubs, prostrate, 10-20 (-30) cm in height. Stems much-branched, terete, slightly 4-angled when young, flexible, usually 1.0-2.5 mm in diameter. Branchlets nearly terete, flexible, 10-20 cm long, with dense spreading white and brown sub-basifixed curly and asymmetrically 2-branched trichomes. Leaves imparipinnate, 2-7 cm × 1.0-2.5 cm, 7-13-foliolate. Stipules narrowly triangular to linear, 5-7 mm long, purple when young, turning brown when old, with spreading, brown, curled and asymmetrically 2-branched trichomes. Petioles 0.2-1.0 cm long, rachis adaxially grooved, with spreading, curled, sub-basifixed, brownish-black, 2-branched trichomes. Leaflets opposite, 0.5-1.5 cm × 0.4-0.8 cm, adaxial surface green, covered with short, spreading, white, 2-branched trichomes, abaxial surface pale green, covered with long, spreading, sub-medifixed, white, 2-branched trichomes and brown, 2-branched trichomes along primary venation; mid-vein abaxially prominent and adaxially impressed, secondary veins inconspicuous; terminal leaflets obovate, apex rounded or retuse, base broadly cuneate; lateral leaflets oblong or elliptic, apex rounded, with a mucro ca. 1 mm long, base rounded or shallowly cordate; petiolules ca. 1 mm long. Inflorescences racemose, 6-8-flowered, axillary, obviously shorter than their subtending leaf, 1-2 (-3.5) cm long. Peduncles 0.2-0.5 cm long; peduncle and rachis densely covered with spreading, white and brown, sub-basifixed, curly and asymmetrically 2-branched trichomes. Bracts narrowly lanceolate to linear, revolute, ca. 2 mm long, caducous. Pedicels ca. 2 mm long, slightly curved, with densely spreading, sub-basifixed, white and brown, 2-branched trichomes. Calyx discoid, spreading, outside with spreading brown and white, sub-basifixed, asymmetrically 2-branched trichomes, glabrous inside; tube ca. 1 mm long; lobes 5, unequal, triangular-lanceolate, ca. 1.5-2.0 mm long, apex long acuminate. Corolla pink; standard obovate-elliptic, 7-9 mm × 4-6 mm, apex rounded, base broadly cuneate, outside with white, soft, 2-branched trichomes, margin ciliate; wings narrowly oblong, ca. 8 mm long, ca. 2 mm wide, base bristly, margin ciliate; keel petals 7-9 mm × ca. 1.5 mm, outside covered with spreading white trichomes towards apex, with spur ca. 1 mm long. Stamens 10, diadelphous, 9 stamens fused and the vexillary one free, 5-6 mm long; anthers ovoid, apically convex. Ovary hairy; style glabrous. Legume cylindrical, sutures thickened, 1.5-2.5 cm × ca. 0.2 cm, apex beaked, with white and brown, medifixed, symmetrically 2-branched trichomes, endocarp not blotched. Seeds 5-7 per legume, oblong to rectangle, 1-2 mm × ca. 1 mm, transverse septa present between seeds.

Phenology.

Flowering from June to September, fruiting from August to December.

Etymology.

The specific epithet " Indigofera jintongpenensis " is derived from the type locality of the new species, the Jintongpen Mountain and the Latin suffix - ensis, indicating the place of origin or growth.

Distribution and ecology.

According to the present investigations, Indigofera jintongpenensis is only found in its type locality, the Jintongpen Mountain of Fuming County, located in central Yunnan Province, southwest China (Fig. 5 View Figure 5 ). With a maximum altitude of 2,817 m, the Jintongpen Mountain is the highest peak in Fuming County. I. jintongpenensis has been observed at elevations ranging from 2600-2817 m in the summit region of the mountain. It usually grows in the limestone scrub and its association includes Allium wallichii Kunth ( Amaryllidaceae ), Asparagus filicinus Buch.-Ham. ex D.Don ( Asparagaceae ), Berberis wilsoniae Hemsley ( Berberidaceae ), Buddleja myriantha Diels ( Scrophulariaceae ), Impatiens yaoshanensis K.M.Liu & Y.Y.Cong ( Balsaminaceae ), Lolium perenne Linn. ( Poaceae ), Quercus pannosa Hand.-Mazz. ( Fagaceae ), Quercus rehderiana Handel-Mazzetti ( Fagaceae ), Silene gracilicaulis C.L.Tang ( Caryophyllaceae ) and so on. It can also be found occasionally under the thickets predominated by Quercus pannosa Hand.-Mazz. ( Fagaceae ).

Conservation status.

Indigofera jintongpenensis is a rare species with a restricted distribution and small population size. It is only known from a single locality on the Jintongpen Mountain in the Fumin County, southwest China, which is not within any protected area. The estimated area of occupancy (AOO) is less than 20 km2. The total population size is estimated to be fewer than 250 mature individuals. Following the IUCN criteria ( IUCN 2022), this new species should be classified as Endangered [EN (B2abiii, D)].

Taxonomic notes.

Indigofera jintongpenensis is mainly characterised by having a prostrate habit, 2-branched trichomes that are spreading and asymmetrical, and racemose inflorescences that are 6-8-flowered and relatively short (mostly 1-2 cm in length). It is most morphologically similar to I. balfouriana Craib in terms of indumentum on various parts of the plant, as well as flower shape and size, but is clearly distinguished by the features pointed out in the diagnosis as well as others (Table 1 View Table 1 ).

Indigofera jintongpenensis is also similar to Indigofera szechuensis Craib in overlapping leaf length, the number of leaflets and overlapping standard size (Table 1 View Table 1 ). However, I. szechuensis differs from I. jintongpenensis in having an erect habit, 2-branched trichomes appressed, symmetrical and medifixed, stipules 2.5 mm long, inflorescences 10-19 cm long, peduncles 8-27 mm long (Table 1 View Table 1 ).

Additional specimens examined

(Paratypes). China. Yunnan: Fumin County, Jintongpen Mountain, alt. 2770 m, 6 September 2023, H. C. Wang et al. FM22978, FM22988, FM23008 (YUKU); Fumin County , Jintongpen Mountain , alt. 2710 m, 2 November 2023, H. C. Wang et al. FM23540 (YUKU) .