Petrocodon hunanensis X. L. Yu & Ming Li, 2015

Petrocodon hunanensis X. L. Yu & Ming Li View in CoL , sp. nov. (See Figs. 2 View FIGURE 2 and 3 View FIGURE 3 ).

Diagnose: —The new species differs from Petrocodon coriaceifolius (Y.G. Wei) Y.G. Wei & Mich. Möller by having subterete terrestrial stem with distinct internodes, both surface of leaf densely with white pubescence, petiole densely with reddish-purple or white pubescence, corolla white to pale purple and 2–3 cm long, tube infundibuliform, pedicels 0.3–2 (2.8) cm long, densely pubescent, stamens 4 and staminodes 1, ovary and capsule stipitate.

Type: — CHINA. Hunan Province: Dong’an Xian, Zixishi Zhen, Huzhu Village [26°17 ′ N, 111°15 ′ E], elevation ca. 230 m, on the rock surface or at the entrance of karst caves. 28 August 2014, J.J. Zhou 14082801 (holotype CSFI! GoogleMaps , isotypes CSFI! GoogleMaps )

Perennial herbs, terrestrial stem subterete, with distinct internodes, 5–20 cm long, ca. 5 mm in diameter. Leaves crowded at the top of the stem; leaf blade thickly papery, ovate, 2–3.2 × 1–2.5 cm, apex slightly acuminate to obtuse, base cuneate to broadly cuneate, leaf blade adaxial surface green and abaxial surface reddish-purple (or rarely pale green), both surfaces densely white pubescent, margin crenate, petiole 0.5–2.5 cm long, densely with reddish-purple or white pubescence; lateral veins 4 pairs, adaxially impressed, abaxially prominent. Cymes 1–4, 1–4-flowered; peduncles 2–7 cm long, densely reddish-purple pubescent; bracts 2, opposite, ovate-lanceolate, 1–3 × 1 mm, apex obtuse, margin entire, outside densely villous, inside with sparse pubescence. Pedicels 0.3–2 (2.8) cm long, densely pubescent. Calyx 5-parted to the base, lobes triangular-lanceolate, 3–5 × 1 mm, densely with short puberulence except the base of inside glabrous, margin entire. Corolla white to pale purple, 2–3 cm long, outside densely puberulent, inside pubescent and with short glandular hairs, tube infundibuliform, 0.8–1.2 cm in diameter at the mouth, 1.5–2 cm long, inside with several pale purple stripes; limb 2-lipped, adaxial lip ca. 4 mm long, 2-lobed, lobes ovate, abaxial lip ca. 1.2 cm long, 3-lobed, central one longer, long ovate, 6–7 mm long, ca. 4 mm in diam., lateral ones diagonal ovate or triangular ovate, ca. 6mm long and 5 mm in diam.. Two pale yellow patches at the base of the central abaxial lip lobe, densely with short glandular hairs. Stamens 4 (coherent in pairs of two), two of them longer, adnate to ca. 1.1 cm above the base of the corolla tube, filaments 0.7–1 cm long, the other two adnate to ca. 0.9 cm above the base of the corolla tube, filaments 0.5–0.7 cm long, and all filaments densely with short glandular hairs and pubescence; anthers elliptic, ca. 1.5 mm long, with short glandular hairs and pubescence, pollen chambers 4; staminodes 1, adnate to ca. 0.6 cm above the base of corolla tube, ca. 1 mm long, glabrous. Pistil ca. 1.6 cm long, ovary distinctly stipitate and ca. 1 cm long, style 0.6–0.8 cm long, all densely with glandular hairs and pubescence; stigma 2, ovate, ca. 1 mm long, densely pubescent. Disc annular, yellow, ca. 1 mm in height, margin entire. Capsule linear and distinctly stipitate, 4-valved, 2.5–4 cm × 1–2 mm, with densely short puberulence. Seeds black, elongated or spindle.

Distribution and habitat: —The new species is only known from its type locality, namely Dong’an Xian, Zixishi Zhen, Huzhu Village, Hunan Province, China. It grows on moist shady rock surfaces or at the entrance of a limestone hill, at an elevation of ca. 230 m.

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

Etymology: —The specific epithet is derived from the type locality of the new species, i.e. Hunan Province, China.

Similar species: — Petrocodon hunanensis is morphologically similar to Petrocodon coriaceifolius in having similar leaf blade shape and corolla shape, but it differs from P. coriaceifolius by having subterete terrestrial stem with distinct internodes, both surfaces of leaf densely with white pubescence, petiole densely with reddish-purple or white pubescence, corolla white to pale purple, tube infundibuliform and 0.8–1.2 cm in diam. at the mouth, pedicels 0.3–2 (2.8) cm long, densely pubescent, stamens 4 and staminodes 1, ovary ca. 1 cm long, capsule densely with short puberulence and ovary and capsule distinctly stipitate. The detailed contrasting characters between two relative species are shown in Table 1 View TABLE 1 .