Lespedeza danxiaensis Q. Fan, W.Y. Zhao & K.W. Jiang, 2021

Zhao, Wan-Yi, Jiang *, Kai-Wen, Chen, Zai-Xiong, Tian, Bin & Fan, Qiang, 2021, Lespedeza danxiaensis (Fabaceae), a new species from Guangdong, China, based on molecular and morphological data, PhytoKeys 185, pp. 43-53 : 43

Lespedeza danxiaensis Q. Fan, W.Y. Zhao & K.W. Jiang sp. nov.

Type.

China. Guangdong: Renhua County, Danxiashan National Nature Reserve , 24°56'N, 113°45'E, 290 m a.s.l., 30 Sept 2020, Q. Fan 18409 (holotype, SYS!; isotypes IBSC!, NPH!, SWFC!, SYS!). (Figs 3 , 4 )

Diagnosis.

L. danxiaensis is most similar to L. pilosa morphologically both being densely villous throughout, and having procumbent stems with ovate to obovate leaflets, but differs from the latter by its leathery leaflets with obviously concave veins (vs. leaflets papery, veins slightly concave), pink to pale purple corolla (vs. corolla yellowish-white to white, with purple spots at base of the standard) and longer peduncles of chasmogamous flowers (1.1-2.8 cm vs. peduncles of chasmogamous flowers rather short, 0.5-1.0 mm in L. pilosa ).

Description.

Perennial herbs, evergreen, with densely erect or ascending villous hairs throughout, turn sparse when old. Stems procumbent or ascending, woody at base, 50 cm tall. Leaves alternate, 3-foliolate; stipules persistent, ovate-triangular to triangular-lanceolate, apex acute, 3.5-4.5 mm, with 3-5 veins, sparsely pubescent; petioles 1.4-3.8 cm, densely pubescent; rachis 0.5-1.3 cm, densely pubescent, leaflets leathery, adaxially green, pubescent with ± adpressed hairs, more dense along the margin, abaxially greyish-green, more densely pubescent with ± adpressing hairs and more dense along the veins, lateral veins 8-12 pairs, obviously concave adaxially and prominent abaxially; terminal leaflets slightly larger than lateral ones, ovate to obovate, 2.2-3.8 × 1.5-2.5 cm, obtuse at apex, apiculate, rounded at base; lateral leaflets ovate to sub-rounded, 1.7-3.0 × 1.4-2.3 cm; petiolule ca. 1 mm; the leaves on flowering branches obviously smaller (with rachis 2-5 mm long; terminal leaflets obovate, 1.2-1.8 × 0.8-1.7 cm, apex obtuse or emarginate, broadly cuneate at base, lateral ones rounded to obovate, 0.9-1.5 × 0.7-1.2 cm). Inflorescence a pseudoraceme, 1-2 axillary, with 2-4 flowers per inflorescence, 2-flowered per node; peduncles of chasmogamous flowers slender and pubescent, (0.2-)1.1-2.8 cm, those of cleistogamous flowers reduced to 1-4 mm, on upper part of stems sometimes reduced; bracts 2 per node, narrowly ovate-triangular to broadly triangular, acute at apex, 1.5-3.3 mm, sparsely pubescent adaxially, glabrous abaxially, 3-5-veined. Pedicel 0.5-2.0 mm, pubescent; bracteoles 2, adnate to the base of the calyx, shorter than the calyx tube, oblong-ovate to ovate-lanceolate, 3.5-5.5 mm, sparsely pubescent, 5(-7)-veined. Calyx deeply 5-lobed almost to the base, densely pubescent adaxially, glabrous abaxially; tube ca. 1 mm; lobes lanceolate, sub-equal, 7-8 × ca. 1 mm, acute at apex. Corolla exserted (absent in cleistogamous flowers), pink to pale purple; standard pale purple, with dark purple spots at base, longer than wings and keels, inflexed-auriculate at base, lamina 7.5-8.0 × 6.5-7.0 mm, broadly elliptic to sub-orbicular, apex obtuse or emarginate, attenuate to a claw ca. 1 mm long at base; wings pale purplish-white, slightly shorter than keels, 7.5-8.3 mm with lamina 5.5-6.0 × 2.3-2.6 mm, narrowly ovate, obtuse at apex, slightly auriculate at base, with a basal claw ca. 2.5 mm; keel petals white to pale purplish-white, 7.5-8.5 mm with lamina 5.5-6.0 × 2.8-3.0 mm, obovate to elliptic, obtuse at apex, attenuate to a claw ca. 2.5 mm at base. Stamens glabrous, (9+1) diadelphous, ca. 9 mm, curved upwards in distal part; staminal tubes ca. 5 mm; anthers uniform, ovate, ca. 0.5 mm. Pistils ca. 10 mm, longer than stamens (shorter than stamens in cleistogamous flowers); ovary narrowly elliptic, shortly stipitate, style filamentous, curved upwards in distal part, ascending-pubescent; stigma terminal, capitate. Pods brownish, 1-seeded, elliptic, style persistent at apex, rostrate, 7-9 × ca. 3 mm, densely ascending-pubescent; those of cleistogamous flowers not seen. Seeds ovate, ca. 3.0 × ca. 1.4 mm.

Phenology.

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

Etymology.

The specific epithet refers to Mount Danxia , the locality of the type collection. The Chinese name of the new species is here given as 丹霞铁马鞭 ( Dān xiá

tiě mǎ biān), in which “丹霞” is the Chinese name for Mount Danxia , as well as “铁马鞭” being the common name for Lespedeza pilosa and its allies.

Distribution, ecology and habitat.

Lespedeza danxiaensis is currently known only from a few populations on Mount Danxia in Renhua County, Guangdong Province of China. It was observed to occur in bushwood on the mountaintop of Danxia landform at elevations between 270 and 310 m; plants in association included Osteomeles subrotunda K. Koch, Abelia chinensis R. Br., Lagerstroemia indica L., Selaginella tamariscina (P. Beauv.) Spring etc.

Conservation status.

The known localities of Lespedeza danxiaensis are in Danxiashan National Nature Reserve where they are well protected. However, its population size is quite small. There are fewer than 100 individuals surviving in an area of about 200 m2 in the currently known localities. We carried out several field surveys in 2020 from May to October, but no other populations were found. Due to its limited distributional range and small population size, Lespedeza danxiaensis is here recommended as Critically Endangered (CR, B2a) according to IUCN Categories ( IUCN Standards and Petitions Subcommittee 2019).

Additional specimens examined (paratypes).

China. Guangdong: Renhua County, Danxiashan National Nature Reserve , 24°56'N, 113°45'E, 290 m a.s.l., 3 July 2020, Q. Fan 18027 (IBSC, NPH, SWFC, SYS); ibid., 14 August 2020, Q. Fan & Y. S. Huang 18130 (IBSC, NPH, SYS) .

Figures

Figure 3. Lespedeza danxiaensis Q. Fan, W. Y. Zhao & K. W. Jiang and L. pilosa (Thunb.) Siebold & Zucc. L. danxiaensis (A-J) A habit, bushwood on the mountaintop of Danxia landform B plant, stems procumbent C adaxial view of leaf, surface green, leather D abaxial view of one leaflet, surface greyish-green with densely pubescent E flowering branchlet with flower bud, stipule triangular-lanceolate, apex acute F front view of flower G lateral view of flower, bracteoles long ovate, sepals narrowly lanceolate H fruiting branchlet, show the long peduncles I fruit, densely pubescent, stamens persistent J flowering branchlet, peduncles usually longer than 1 cm, flower pink to pale purple, young branch reddish brown L. pilosa (K-L) K branchlet with unripe fruit, leaf papery L flowering branchlet, peduncles short, flower white, young branch green. (Photographs: A-J by Qiang Fan K-L by Kai-Wen Jiang).

Figure 4. Lespedeza danxiaensis Q. Fan, W. Y. Zhao & K. W. Jiang A upper portion of plant B lower portion of plant C chasmogamous flower D cleistogamous flower E staminal tube F pistil G standard H wing-petal I keel-petal J chasmogamous fruit K abaxial view of calyx, flattened L bracts M bracteoles. (Drawn by Rong-En Wu).