Petrocodon parviflorus F. Wen & K. Tan, 2025

Petrocodon parviflorus F. Wen & K. Tan

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Diagnosis.

The new species resembles P. lui in leaf blade shape, but can be easily distinguished from the latter by corolla limb lobes oval (vs. oblong, obovate to suborbicular), longer style length 10–11.5 mm long (vs. 4–6 mm long), longer central staminode 1–1.3 mm long (vs. 0.5–0.8 mm long), calyx lobes sparsely puberulent abaxially (vs. glabrous abaxially).

Type.

China • Guangxi Zhuang Autonomous Region, cultivated in Guilin Botanical Garden, introduced from Hechi City, Fengshan County, Jiangzhou Town , 24 ° 19 ' N, 106 ° 59 ' E, 650 m a. s. l., growing on moist shady rock surfaces in a karst cave. 8 August 2024, Fang Wen et al. FZYYZBZ 10339. (Holotype: IBK! IBK 00470679 About IBK ; Isotypes: IBK!) GoogleMaps .

Description.

Perennial herbs. Rhizome brown, subterete, 5–7 cm long, ca. 1 cm in diameter, with distinct internodes, abundant fibrous roots. Leaves 13–19, congested at the apex of rhizome, petiolate; petiole brown, up to ca. 7 cm long, 1.5–4 mm in diameter, transversely elliptic in cross section, slightly grooved adaxially, densely white pubescent; leaf blade slightly chartaceous, green adaxially and pale green abaxially, broadly ovate to suborbicular, 4–6.5 × 4–5.5 cm, apex subacute or obtuse, base cordate to shallowly cordate, oblique, densely white pubescent adaxially and abaxially, margin crenate, lateral veins 4–5 on each side of median vein, impressed adaxially, slightly prominent abaxially. Cymes 10–13, axillary, 3–4 - branched, 8–18 - flowered; peduncle brownish, 5–9 cm long, 1.5–2 mm in diameter, densely white puberulous pubescent; bracts 2, opposite, green, linear, 5–7 × 1–1.5 mm, outside densely pubescent and inside sparsely pubescent, bracteoles 2, shape similar to bracts but smaller, 3–4 × 0.5–1 mm; pedicels green or brown, 0.5–1 cm long, ca. 1 mm in diameter, puberulous. Calyx 5 - partited to the base, lobes equal, narrowly lanceolate, 7–8 × 0.5–1 mm, green to brown, puberulous adaxially, sparsely puberulent abaxially, margin entire, apex acute. Corolla whitish purple to pinkish purple, 1.5–2.5 cm long, 3–5 mm in diameter at the mouth; outside glandular-puberulent, inside puberulent; tube slender, infundibuliform-tubular, 1–1.5 cm long, 1.5–2 mm in diameter at the middle, tube slightly upward curved, 2–2.5 mm in diameter at the base; limb distinctly 2 - lipped; adaxial lip 2 - lobed to the base, lobes oval, apex acute, 3.5–4 × 2.5–3 mm; abaxial lip 3 - lobed to the base, lobes equal, oval, apex acute, 4–4.5 × 3–3.5 mm, with 2 pale yellow nectar guides at the base of the abaxial lip lobe. Stamens 2, adnate to 5–6 mm above the base of the corolla tube, filaments white, 2–2.5 mm long, linear, straight, glabrous; anthers pale yellowish to nearly white, fusiform to ellipsoid, 0.7–1 × 0.6–0.8 mm, glabrous. Staminodes 3, translucent to white, glabrous, lateral ones adnate to 5.5–6 mm above the tube base, 1.5–1.8 mm long, clavate, straight, apex capitate; the central one adnate to 5–5.5 mm above corolla tube base, 1–1.3 mm long. Disc annular, pale yellow, ca. 0.5 mm in height, margin repand. Pistil 1.2–1.4 cm long, ovary pale green, cylindric, 2–2.5 mm long, 0.8–1 mm in diameter, glandular-pubescent; style 10–11.5 mm long, 0.4–0.6 mm in diameter, light green, densely puberulous mixed translucent glandular-puberulous; stigma 2, each ovate, ca. 0.5 mm long, 0.8–1 mm wide, sparsely translucent glandular-hispid. Capsule not seen.

Distribution and habitat.

The new species can only be found at its type locality, Jiangzhou Township, Fengshan County, northwestern Guangxi, China. It grows on moist shady rock surfaces in a karst cave at an altitude of 600–700 m. The average temperature in Fengshan County is 19.7 ° C, and the average annual precipitation is 1628.9 mm. The main associated plants of Petrocodon parviflorus include Primulina tribracteata (W. T. Wang) Mich. Möller & A. Weber , Mitreola pingtaoi D. Fang & D. H. Qin , Elatostema obscurinerve W. T. Wang , Begonia luzhaiensis T. C. Ku and others.

Phenology.

Flowering from August to November and fruiting from September to December.

Etymology.

The epithet ‘ parviflorus ’ reflects the relatively small flowers. The corolla is distinctly smaller compared to other species previously classified under the former Lagarosolen W. T. Wang , particularly L. lui Yan Liu & W. B. Xu (syn. Petrocodon lui ).

Vernacular name.

小冠石山苣苔 (Chinese pronunciation, Xiáo Guàn Shí Shān Jù Tái).

Provisional conservation status.

To date, two populations of Petrocodon parviflorus have been documented. Both populations grow within karst caves in Jiangzhou Township, Guangxi Zhuang Autonomous Region. The caves essential for the survival of both populations are bisected by a highway. One population is confined to the lower section of a penetration cave, representing a relict subpopulation. Our six years of continuous monitoring (2019–2025) indicate that as of March 2025, this population comprises fewer than 50 mature plants, exhibits limited seedling regeneration, and suffers ongoing habitat degradation driving a persistent population decline. The other population inhabits the entrance complex of a large karst cave, primarily distributed on moist vertical cliff faces within the cave’s entrance zone, with additional occurrences in rock crevices that maintain favorable moisture levels and receive bright scattered light. This population maintains a relatively large size, with more than 6,000 estimated mature individuals and healthy seedling regeneration supporting population sustainability. The cave currently experiences minimal anthropogenic disturbance, primarily limited to cave research activities (e. g., geological and geographical studies), with no observed evidence of significant human impacts elsewhere in the system. The Extent of Occurrence (EOO) for the species is less than 8 km 2 and the known Area of Occupancy (AOO) is less than 5 m 2. Consequently, we suggest that the new species P. parviflorus should be considered “ Vulnerable ” [VU, D 2] according to current IUCN Red List Categories and Criteria ( IUCN 2024).