Primula dongchuanensis Z.K.Wu & Yuan Huang, 2019

Wu, Zhi-Kun, Zhao, Fu-Wei, Chen, Jia-Hui & Huang, Yuan, 2019, Primula dongchuanensis (Primulaceae), a new species from northern Yunnan, China, PhytoKeys 130, pp. 171-181 : 173-177

Primula dongchuanensis Z.K.Wu & Yuan Huang sp. nov. Figs 1 , 2 , 3A

Diagnosis.

The new species most resembles P. aurantiaca , sharing a similar flower color, leaf shape, efarinose and glabrous, and long calyx parted below the middle. But it can be distinguished by having much smaller statue, inflorescence raceme, scapes nearly obsolete at early anthesis and deep yellow flowers. The main morphological differences between P. dongchuanensis and P. aurantiaca are summarized in Table 1 .

Type.

CHINA. Yunnan: Jiaozi Snow Mountain, Dongchuan district, ca. 3860 m, 102°55.75'E, 26°9.45'N, July 2016, Z. K. Wu & Yuan Huang, ZKWu2016060 (holotype: KUN!; isotype: KUN!).

Description.

Perennial efarinose herb, glabrous, with a short root stock and 5-10 robust fibrous roots. Leaves forming a dense rosette, leaf blade obovate-oblong to oblanceolate, 3-6 × 2.0-3.5 cm, base attenuate, decurrent to petiole, margin erose-denticulate, apex rounded, petiole slightly differentiated to 1/3 as long as leaf blade; Scapes nearly obsolete with “compressed” 6-20-flowered inflorescences arising from leaf rosette at early anthesis, elongating up to 10 cm with 2-8 flowers forming solitary racemes at late flowering; bracts 1-2, linear, 1.0-1.8 cm long, glabrous. Pedicel 1-3 cm, glabrous. Flowers heterostylous. Calyx tubular-campanulate, 6-9 mm long, lobed to 1/2 of its length; lobes lanceolate, each with one prominent midvein, acuminate at apex. Corolla deep yellow; limb 1.2-1.8 cm wide; lobes oblong-obovate, emarginate. Pin flowers: corolla tube 0.8-1.2 cm long; stamens ca. 5 mm above base of corolla tube; style ca. 9 mm. Thrum flowers: corolla tube 0.9-1.4 cm long; stamens ca. 1.2 cm above base of corolla tube; style ca. 5 mm. Capsule subglobose, ca. 4 mm in diameter, ca. as long as calyx.

Phenology.

Flowering occurs from late April to early June; fruiting from July to August.

Distribution and ecology.

P. dongchuanensis is only known from the type locality in northern Yunnan, China. The plant has been found on alpine meadow and forest margin at elevation of ca. 3800-4000 m ( Fig. 2 ), associated with Sibbaldia purpurea var. macropetala (Murav.) T.T.Yu & C.L.Li, Oxygraphis glacialis (Fisch. ex DC) Bunge, Androsace rigida Hand.-Mazz. and Primula faberi Oliv.

Etymology.

The epithet of the new species is derived from the name of Dongchuan in northern Yunnan, where the new species was discovered and collected.

Vernacular name.

Chinese mandarin: dong chuan bao chun (东川报春)

Molecular evidence.

The phylogenetic tree obtained from ML analysis is shown in Figure 4 . Phylogenetic analysis showed that the new species clustered with other sampled species of sect. Proliferae and together formed monophyletic clade with a strong support (UFBoot value = 100%, SHaLRT value = 100%), which indicates it is a member of sect. Proliferae , and the tree shows that P. dongchuanensis is well differentiated from its close relatives; this is consistent with its special morphological characters in sect. Proliferae .

Conservation status.

Currently, P. dongchuanensis is only known from the top of Jiaozi Snow Mountain in a single population with fewer than 1000 individuals on ca. 2000 m2 occupancy along the alpine meadow. Although there is no obvious population change observed, the original habitat suffered severely from over-grazing based on three field expeditions conducted in 2011, 2016 and 2019. Living collections introduced to Lijiang alpine botanical garden in 2011 were able to flower and set seeds in the following two years, but no individuals were flowering after the fourth year. Other ex-situ conservation actions, such as seed banking, may apply to secure conservation of this unique Primula species. According to the guideline of IUCN red list criteria ( IUCN 2017), this new species is assessed as ‘Vulnerable’ (VU D1).

Figures

Figure 1. Primula dongchuanensis sp. nov. A Habit B Calyx and corolla C Calyx D Thrum flower E Pin flower F Bract.

Figure 2. Primula dongchuanensis sp. nov. A, B Habit in early flowering C, D Habit in late flowering E specimen of late flowering F dissected corolla showing the anthers and stigma, pin flower (left) and thrum flower (right).

Figure 3. P. dongchuanensis and four of its close species A P. dongchuanensis B P. aurantiaca C P. cockburniana D P. chungensis E P. pulverulenta.

Figure 4. Maximum likelihood tree of new Primula species and other Primula species based on nuclear ITS, chloroplast matK and trnH-psbA combined sequenced data, constructed by IQ-TREE under the GTR + G model, clade supports were reported as Shimodaira-Hasegawa approximate Likelihood Ratio Test (SH-alRT) / Ultrafast Bootstrap Approximation (UFBoot), each estimated by 10000 replicates, and only support value more than 50 % were reported.