Sedum ichangensis Y. B. Wang, 2019
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publication ID |
https://dx.doi.org/10.3897/phytokeys.132.35428 |
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persistent identifier |
https://treatment.plazi.org/id/8E152EB5-6268-5CE2-B924-39BBE84F5367 |
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treatment provided by |
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scientific name |
Sedum ichangensis Y. B. Wang |
| status |
sp. nov. |
Sedum ichangensis Y. B. Wang sp. nov. Figures 1 View Figure 1 , 2 View Figure 2
Diagnosis.
Sedum ichangensis has papillate carpels and appears to be morphologically similar to S. elatinoides and S. rosthornianum . It can be distinguished from S. elatinoides by its perennial habit (vs. annual) and solitary flower (vs. flowers in cymes) and from S. rosthornianum in its entire leaf margins (vs. leaf margins dentate), its branched stems (vs. stems simple) and its solitary flowers (vs. flowers in paniculiform cymes). (Table 1 View Table 1 , Fig. 1 View Figure 1 , 2 View Figure 2 ).
Type.
CHINA: Hubei Province, Yichang city, Changyang County, Longzhouping Town, on rocks, alt. 130 m. 30°28'N, 111°11'E, 19 Jul 2017, ycmy032 (holotype, CTGU!; isotypes HIB!, and PE!).
Description.
Perennial herbs. Roots fibrous. Stems procumbent, divaricately branched, 1-2 mm in diameter, up to 35 cm long, with scattered reddish dots. Leaves 4-6-verticillate, entire, sessile, narrowly ellipsoid, 5-12 × 1.5-2.5 mm, base attenuate, apex acute. Flowers 5-merous, solitary in the axils of upper leaves, 5-8 mm in diameter. Pedicel 1.5-2.5 cm long. Sepals 5, lanceolate, 1.5-2 mm long, apex acute. Petals 5, white, pinkish towards the apex, lanceolate, 4-5 × 1-2 mm, apex acute. Stamens 10, in 2 whorls, slightly shorter than the petals, antesepalous ones ca. 4 mm long, antepetalous ones ca. 3 mm long, inserted ca. 1 mm above the petal base, filaments white, 1.6-2.4 mm long, anthers ca. 0.4 mm long, reddish. Nectar scales spatulate, ca. 0.4 mm long. Carpels 5, white, suberect, adaxially minutely papillate, broadly ovoid, ca. 2 mm long, base united for ca. 0.2 mm, styles ca. 1.5 mm long. Follicles divergent, 0.8-1.1 mm long, with scattered reddish dots, seeds numerous, brown, ca. 0.5-1 mm long, papillate.
Phenology.
Flowering from early May to July, fruiting from August to October.
Distribution and habitat.
Sedum ichangensis is known from Longzhouping town of Changyang County, Gufu town of Xingshan County and Muyang River of Yiling County in Yichang City of western Hubei Province, central China ( Fig. 3 View Figure 3 ). It grows on rocks of roadsides, especially in fissures filled with soil, at an elevation of ca. 100-280 m.
Chinese name.
Yi-chang-jing-tian (宜昌景天).
Etymology.
The specific epithet of this new species is dedicated to the Yichang city.
Taxonomic notes.
Sedum ichangensis belongs to Sedum sect. Filipes on account of its carpels adaxially not gibbous, its spurless leaf base and its white flowers ( Fu and Ohba 2001). Sedum ichangensis is a species easily identifiable by its floral, stem and leaf features. The new species resembles S. elatinoides in the leaf characters, as well as the structure of the flowers. However, S. ichangensis differs from S. elatinoides in its perennial habit with branched stems and its solitary flowers. Sedum ichangensis differs from S. rosthornianum in its much branched, decumbent stems, entire leaf margins and its solitary flowers. Here, we provide photographs ( Fig. 1 View Figure 1 ), line drawings ( Fig. 2 View Figure 2 ) and a detailed morphological comparison (Table 1 View Table 1 ), as well as a key to the species of Sedum sect. Filipes in China to facilitate its identification.
Additional specimens examined (paratypes).
CHINA. Hubei Province: Xingshan County, Gufu town, 200 m alt., 31°20'N, 110°45'E, 15 May 2017, YB Wang ycmy022 (CTGU), same loc. XJ Xiong XXJ024 (CTGU); Yiling County, Muyang River, 280 m alt., 30°44'N, 111°02'E, 3 August 2017, YB Wang ycmy139 (CTGU).
Conservation status.
Based on field investigations, S. ichangensis occurs only in three scattered areas. The total area of occupancy is less than 500 km 2; each population possesses no more than 300 mature individuals. It prefers habitats on rocks along roads. Human activities are impairing its populations severely. The type population, which grew close to a road, was seriously impacted in its survival due to herbicide spraying in 2018. Based on currently available information, the conservation status of this species is categorised as Endangered [EN] following the IUCN Categories and Criteria ( IUCN 2017).
Key to the species of Sedum sect. Filipes in China (adapted from Fu and Ohba 2001):
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