Petrocodon rubiginosus Y.G.Wei & R.L.Zhang, 2020
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publication ID |
https://dx.doi.org/10.3897/phytokeys.157.32270 |
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persistent identifier |
https://treatment.plazi.org/id/825D9EA8-A805-5E14-999F-9D008EB77F1D |
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treatment provided by |
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scientific name |
Petrocodon rubiginosus Y.G.Wei & R.L.Zhang |
| status |
sp. nov. |
Petrocodon rubiginosus Y.G.Wei & R.L.Zhang sp. nov. Figure 1 View Figure 1
Diagnosis.
It is morphologically close to Pet. hechiensis , but can be distinguished by its petioles, peduncles and pedicels densely curly rubiginous to ferruginous villous, bracts lanceolate to subulate and both surfaces densely rubiginous to dark brown pubescent, corolla lobes oblong to nearly rounded and margin entire, calyx lobes densely rubiginous to ferruginous pubescent.
Type.
CHINA. Guangxi Zhuangzu Autonomous Region: Jingxi city, Yuexu Town, Siming village, 22°56'N, 106°37'E, alt. 470 m, 12 November 2015, flowering, Wen Fang et al. WF151112-01 (holotype: IBK; isotype: IBK).
Description.
Perennial herb, stemless. Rhizome subterete, 3-8 cm long, 5-7 mm in diam. Leaves 8-16, all basal; leaf blades herbaceous, green to yellowish-green, zygomorphic to slightly unequal in each pair, broadly ovate to nearly rounded, 3.5-20 × 3.8-15 cm, apex obtuse to rounded, base cordate or obliquely cordate and bases on both sides usually overlapping, margin obviously crenate to undulate, pubescent on both surfaces, 5-6 nerves on each side, adaxially impressed, abaxially prominent, densely ferruginous and erect villous along abaxial main vein and lateral veins; petioles 15-25 cm or longer, densely ferruginous and erect villous. Cymes 4-8, 20-30 cm long, usually curved or squiggly,1-2-branched, 8-12-flowered; peduncle 15-20 cm long, ca. 2 mm in diam., densely curly rubiginous to ferruginous villous; bracts 2, opposite, lanceolate to subulate, 5-6 × 1-2 mm, entire, both sides densely rubiginous to dark brown pubescent; bracteoles 2, opposite, linear-lanceolate, ca. 5 × 0.8 mm, both sides densely rubiginous to dark brown pubescent; pedicel 4-7 mm long, 0.8-1 mm in diam., densely rubiginous to dark brown pubescent. Calyx 5-parted to the base, sepals lanceolate-linear to subulate, ca. 10 mm long, 0.6-0.7 mm at base, both sides densely rubiginous to dark brown pubescent. Corolla bilabiate, pale yellow, throat with two brightly yellow longitudinal stripes and dark yellow glands on stripe surface, ca. 3 cm long, outside white pubescent; tube slender, 2-2.2 cm long, 6.5-7 mm in diam. at middle, slightly constricted at ca. 6 mm above base of corolla base; adaxial lip 7-8 mm long, 2-partite nearly to base, lobes oblong to nearly rounded, apex acuminate, abaxial lip 2-2.5 cm long, 3-partite nearly to base, lobes nearly rounded, apex obtuse. Stamens 2, sparsely glandular-puberulent, adnate to 1.1-1.2 cm above the base of corolla tube; filaments pale yellow to white, 5-5.5 mm long; anthers 1.2-1.5 mm long, elliptical, 1.8-2 mm long, 1-1.5 mm in diam. Staminodes 3, glabrous, lateral ones 6-7 mm long, adnate to ca. 10 mm above the base of corolla tube, median ca. 1.5 mm long, adnate to ca. 7 mm above the base of corolla tube. Disc glabrous, ca. 1.2 mm high, margin entire. Pistil ca. 2 cm long; ovary ovoid, ca. 5 mm long, covered pale rubiginous or white pubescent, style ca. 1.5 cm long, densely pubescent; stigmas inapparent triangular, 2, each one semicircular, ca. 0.8 mm long. Capsule ovoid, valvular dehiscence, pubescent.
Phenology.
Flowering occurs in November and fruiting from December to January of next year.
Etymology.
The specific epithet is derived from the conspicuous indumentum of petioles, peduncles and pedicels, which are covered with densely long ferruginous or rubiginous hairs.
Vernacular name.
Xìu Géěng Shí Shān Jù Tái (Chinese pronunciation); 锈梗石山苣苔 (Chinese name).
Distribution and habitat.
Petrocodon rubiginosus is hitherto only known from two close localities at elevational ranges from 450-500 m in Jingxi city, Guangxi, China, growing on shaded and moist rock surface with no more than 50 individuals at each of the localities. Two localities are about three kilometres apart. The species grows in subtropical broad-leaved evergreen monsoon forest with sufficient seasonal run-off water.
Preliminary conservation assessment.
Population information of Petrocodon rubiginosus is still unclear, which makes it difficult to determine an assessment of the extinction risk faced by this new taxon. At present, two distribution points of the species are known and its estimated area of occupancy is less than 10 km2. The main threat now comes from environmental damage caused by grazing and there is a risk of poaching in the future because its distribution is not far away from the villages. Furthermore, prolonged droughts and illegal logging in the area, including nearby potential habitat, should be considered as potential risks to the persistence of Pet. rubiginosus . Thus, following the IUCN Red List Categories and Criteria ( IUCN 2017), it is assessed temporarily as endangered [EN B2ab (ii, iii)].
Notes.
It is morphologically close to Petrocodon hechiensis because two congeners share some similarities, for example, they have look-alike leaf shape and size and a pale-yellow corolla ( Wei et al. 2008, 2010). As a result, it is sometimes mistaken for Pet. hechiensis . However, one of the largest differences between Pet. rubiginosus and Pet. hechiensis is the indumentum of petioles, peduncles and pedicels. There are absolutely no glandular-hairs on petioles, peduncles and pedicels of Pet. rubiginosus , but in Pet. hechiensis , all are covered by densely short and sticky glandular-hairs and pubescent-hairs (Figure 3 View Figure 3 ). The other major differences between the species are outlined in Table 1 View Table 1 .
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