Rhododendron pudingense X.Y. Dai, C.H. Yang & Y.P. Ma., 2020

Dai, Xiao-Yong, Yang, Cheng-Hua, Yang, Bing, Chen, Pu & Ma, Yong-Peng, 2020, A new species of Rhododendron (Ericaceae) from Guizhou, China, PhytoKeys 146, pp. 53-59 : 53

Rhododendron pudingense X.Y. Dai, C.H. Yang & Y.P. Ma. sp. nov. Figs 1 , 2

Type.

China. Guizhou: Puding County, Machang town, Longjinshan, 26°17'34.08"N, 105°35'20.04"E, altitude 1400 m alt., 7 May 2018, XiaoyongDai 180507112 (fl., Holotype GF!, isotypes KUN!, PE!).

Description.

Shrubs evergreen. Branches subverticillate, young shoots with coarsely strigose, hairs flat. Leaves hard leathery, crowded at branch top, obovate to obovate-elliptic, 8-20 × 5-10 mm; apex obtuse, obtusely pointed or mucronate, base cuneate, margin slightly revolute; abaxial surface sparsely with coarsely brown strigose except for midvein; adaxial surface green, margin sparsely with coarsely strigose at first, and then fall off gradually except for midvein; adaxial abaxial surface greyish white, while yellow-white when dry; midrib and lateral veins concaved on abaxial surface and projecting on abaxial surface, lateral veins inconspicuous visible on both sides, anastomosing margin. Petioles 2-4 mm at length, densely with coarsely dark brown strigose. Floral bud ovoid, paleta ovoid, 7-10 × 4-6 mm, outer surface ridge coarsely strigose, margin villous. Inflorescence terminal, 4-6-flowered. Pedicel 4-10 mm at length, densely coarsely strigose. Calyx slightly 5-lobed, delta, sinuate, 1 × 1.5 mm, outer side coarsely strigose, margin densely. Corolla funnel, bilaterally symmetric, 15-20 mm at length; tube cylindric, inner surface slightly puberulent, 8-11 × 2-3 mm; lobes 5, apex obtusely pointed or mucronate, equal, 6-9 × 4 mm. Stamens 5, subequal, exerted, 15-28 mm at length; filaments pink, slightly puberulent; anthers purple; ovary ovoid, 3.5 mm at length, densely coarsely strigose. Style ca. 20-28 mm at length, longer than parts of stamens, purplish red at middle and lower part, glabrous; stigmas capitate, pink. Capsule oblong, 5 mm at length, coarsely strigose.

Etymology.

The specific epithet is named after the type locality Puding County, in which this plant was first discovered.

Vernacular name.

Chinese mandarin: pǔ dìng dù juān (普定杜鹃)

Phenology. This new species has been observed in flowering from mid-April to early May and fruiting from early May to October.

Distribution and habitat.

So far, this species is only known from the type locality (Pudding County) and from the Wangmo County, Guizhou Province, southwest China. At these locations Rhododendron pudingense grows in evergreen and deciduous broad leaved mixed open forests within the rock cracks of limestone hills, at an elevation of 1300 m to 1400 m.

Conservation status.

Rhododendron pudingense is currently known only from two locations, Puding County and Wangmo County (Guizhou Province, China) with a combined population estimated at 100 individuals, and an area of occupancy (AOO) of <500 kilometers. Within this species known range the populations are severely fragmented and occupy a vegetation association in decline; we therefore propose to treat it as [EN B2ab(iii); D] in accordance to the IUCN Red List Categories and Criteria version 13 (IUCN Standards and Petitions Subcommittee 2017).

Additional specimens examined.

China. Guizhou: Puding County, Machang Town, Longjinshan, altitude Longjinshan, 26°17'34.08"N, 105°35'20.04"E, 1400 m alt., 20 August 2018, Xiaoyong Dai 18082201 (fr., paratype GF!); China. Guizhou: Wangmo County, Mashan Town, Heidong, 25°14'21.05"N, 106°22'13.73"E, 1300 m alt., 10 April 2019, Xiaoyong Dai & Jianghua HUANG 19041002 (fl., paratype GF!).

Relationships.

The new species is morphologically similar to R. myrsinifolium and R. minutiflorum (Table 1 ), however, R. pudingense can be easily distinguished from these species by examination of the corolla tube, stamens and styles. Notably, R. pudingense has a longer corolla tube (8-11 mm long) than R. myrsinifolium and R. minutiflorum , whose corolla tube lengths are both < 4 mm (Table 1 ). In addition, R. pudingense has glabrous styles whereas the lower part of style in R. myrsinifolium and R. minutiflorum , is furnished with coarsely appressed setose hairs or sparsely shortly glandular-hairy (Table 1 ). Furthermore, the stamens of R. pudingense are 15-28 mm long and slightly puberulent below the middle of filament, where those of R. myrsinifolium , are 12-14 mm long and glabrous, and the stamens of R. minutiflorum are 7 mm long and puberulent in their lower portion (Table 1 ).

Figures

Figure 1. Rhododendron pudingense X. Y. Dai & C. H. Yang, sp. nov. A fruiting branch B flowering branch C leaf abaxial D flowers E side view of flower F stigma and ovary G stamen H capsule.

Figure 2. Rhododendron pudingense X. Y. Dai & C. H. Yang, sp. nov. A habitat B one flowering plant C inflorescence D flower viewed from different angles as well as stigma and filaments E fruit branch.