Lysimachia xiangxiensis D.G.Zhang & C.Mou, Y.Wu, 2020

Mou, Cun, Wu *, Yu, Xiang, Liang, Xiang, Xiao-Mei & Zhang, Dai-Gui, 2020, Lysimachia xiangxiensis (Primulaceae), a new species from limestone area in Hunan Province, central China, PhytoKeys 140, pp. 23-32 : 23

Lysimachia xiangxiensis D.G.Zhang & C.Mou, Y.Wu sp. nov. Figure 2 , 3 , 4

Type.

CHINA. Hunan Province, Huayuan County, Buchou Town, Da-long-dong, cliff of a valley, 28°19'06.42"N, 109°30'03.22"E, alt. 295 m, 26 August 2019, D. G. Zhang 0826075 (holotype: JIU!; isotype: JIU!).

Diagnosis.

The new species differs from L. melampyroides by the succulent leaves; the creeping or drooping stems (15-25 cm long); and the suborbicular to broadly elliptic corolla lobes.

Description.

Terrestrial, perennial herbs. Rhizome brown, reduced to a small tuber or rarely creeping, with sparse fibrous roots. Stems creeping or drooping on cliffs, 15-25 cm long, clustered, branched at base, unbranched or rarely branched from the middle, terete, purple-red, densely strigillose, the internodes usually 3-7 cm long. Leaves petiolate, opposite. Petioles 5-7 mm long, with a furrow on adaxial side, green or purple-red, strigillose. Leaf blade succulent; blade of lower leaves rhomboid-ovate to ovate, with 1 or 2 pairs of basal leaves scalelike (much smaller); blade of upper leaves ovate to elliptic-lanceolate, 2-5.5 cm × 1-2.3 cm, base cuneate, apex acuminate or acute to subobtuse, margin entire and revolute, adaxially dark green, shiny, subglabrous, abaxially purple-red (in arid places) or light green (in moist places), densely strigillose along the midrib, not glandular on both surfaces; secondary veins 3-4 pairs, blurry or invisible adaxially, slightly raising abaxially, veinlets invisible. Flowers bisexually, solitary in axils of upper leaves, occasionally in terminal racemes with bractlike leaves. Pedicels 1.5-3 cm long, gradually reduced toward stem apex, purple-red or light purple-red, densely strigillose, recurved in fruit. Calyx lobes 5, rarely 6, persistent, lanceolate with indistinct costa, 6-8 mm × 1.5-2 mm, apex acuminate-subulate, inside glabrous and with 3-4 veins, outside purple-red or green, densely strigillose. Corolla yellow, tube 1-2 mm long, actinomorphic, contorted; lobes 5, 7-9 mm × 7-9 mm, suborbicular to broadly elliptic, apex cuspidate or rounded, erose above the middle. Stamens 5, yellow, opposite to corolla lobes; filaments connate basally into a tube ca. 2.5 mm high, free parts 3.5-4.5 mm; anthers ca. 2 mm long, dorsifixed, opening by lateral slits. Style ca. 6 mm long, apex slightly expanded, strigillose on lower part. Ovary cylindrical, ca. 1.5 cm in diam., strigillose on apex, superior. Capsule brown, subglobose, 3-4 mm in diam., densely strigillose, dehiscing by valves. Seeds small, black, angular, papillate.

Phenology.

Flowering May-June, fruiting July-August.

Distribution and habitat.

This new species is currently known from Huayuan County and Jishou City in western Hunan Province, central China. It usually grows on limestone cliffs in valleys (Figure 2 ), and is associated with e.g. Eriophorum comosum (Wallich) Nees in Wight, Pteris vittata Linnaeus, Pteris deltodon Baker, and Dryopteris sp.

Etymology.

The specific epithet " xiangxiensis ", literally meaning western Hunan, refers to the Xiangxi Tujia and Miao Autonomous Prefecture in central China, to which Huayuan County and Jishou City belong. The Chinese name of the Lysimachia xiangxiensis is xiang xi guo lu huang in Pinyin.

Conservation status.

Lysimachia xiangxiensis usually grows on limestone cliffs in valleys so we suggest its placement in the Data Deficient category of IUCN (2017)

Additional collection.

CHINA. Hunan Province, Jishou City, Aizhai Town, National Forest Park, cliff of a valley, 31 May 2019, Y. Wu 0531001(paratype, JIU!).

Figures

Figure 2. Lysimachia xiangxiensis sp. nov. in the wild A habitat (dry limestone cliff) B stems drooping on the cliff.

Figure 3. Lysimachia xiangxiensis sp. nov. in the field A corolla opened, showing the suborbicular lobes B flower (lateral view), showing the lanceolate calyx lobes indistinctly costate C proximal stems and underground part, showing stems clustered, rhizome, sparse fibrous roots, and 1 or 2 pairs of scalelike basal leaves D longitudinal section of flower, showing filaments connate basally into a tube E pistil, showing strigillose hairs on apex of ovary and base of style F dehiscent capsule G plant in fruiting, showing the recurved pedicels H plant in flowering, showing the solitary flowers in axils of upper leaves I plant in flowering, showing the reduced basal leaves J papillate seeds

Figure 4. Lysimachia xiangxiensis sp. nov. A upper stem leaf (abaxial surface), showing revolute margins B lower stem leaf (adaxial surface) C portion of a leaf (abaxial surface), showing the revolute margins and strigillose midrib D plant in flowering E corolla lobes F pistil.