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Primula dongchuanensis (Primulaceae), a new species from northern Yunnan, China
expand article infoZhi-Kun Wu, Fu-Wei Zhao§, Jia-Hui Chen|, Yuan Huang
‡ Guizhou University of Traditional Chinese Medicine, Guiyang, China
§ Nanjing Institute of Environmental Sciences, Nanjing, China
| Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
¶ Yunnan Normal University, Kunming, China
Open Access

Abstract

Primula dongchuanensis Z.K.Wu & Yuan Huang, a new species of Primulaceae from Dongchuan of northern Yunnan, China, is described and illustrated. Both morphological and molecular evidence support P. dongchuanensis as a member of the sect. Proliferae. It is similar to P. aurantiaca W.W.Smith & Forrest, but is distinguished by having unique raceme inflorescences. Its distribution, phenology and conservation status are also provided.

Keywords

Primulaceae, Primula dongchuanensis, new species, Yunnan, China

Introduction

Primula Linn. is one of the largest genera of Primulaceae, including about 500 species worldwide. Most Primula species are indigenous to the north temperate zone, with only a few outliers on some mountains of Africa (Ethiopia), tropical Asia (Java and Sumatra) and South America (Hu 1994, Hu and Kelso 1996, Mast et al. 2001). The modern center of diversity of Primula is in southwestern China, with ca 300 species of 24 sections, most of which occur in western Sichuan, eastern Xizang, and northwestern Yunnan (Hu 1994, Hu and Kelso 1996). Increased exploration across this region results to the discovery and description of new Primula species in the past 15 years (Hu and Geng 2003, Wu et al. 2013, Xu et al. 2017a, 2017b, Yang et al. 2017, Ju et al. 2018)

Section Proliferae Pax (10:217, 1889) of the genus Primula comprises more than 20 species, mainly distributed in Eastern Himalaya and Hengduan Mountain in China. Most species in this section are horticulturally important plants. Morphologically, sect. Proliferae shows the distinct character of several whorls of flowers in superimposed umbels and is recognized as a ‘natural’ group in this genus. Previous studies presumed that the sect. Proliferae may represent the most primitive group of Primula alive today, and take a central position with respect to subsequent evolution and geographical migration in the genus (Richards 1993, 2002). However, molecular phylogenetic evidence posited the opposite conclusion and indicated that the sect. Proliferae represents relatively advanced members of Primula that exist today (Mast et al. 2001, 2004, Yan et al. 2015).

During the field investigation in the Jiaozi Snow Mountain in Dongchuan of Yunnan, southwestern China in 2011, we found a peculiar population of Primula in its vegetative stage on a small patch of alpine meadow near the mountain top. We transplanted some living individuals to Lijiang Alpine Botanical Garden (at elevation of ca. 3200m), northwest of Yunnan and they regained their bloom in subsequent years. The plant has a short rootstock and robust fibrous roots, obovate-oblong to oblanceolate leaves forming a dense rosette and flowers showed great similarity to the species of sect. Proliferae, except the inflorescences with obsolete scapes at early anthesis, then elongating to forming raceme at late flowering. We presumed the unusual inflorescence springs from abnormal variations of plant response to a different climate zone and soil type after translocation. After the field investigations in the same locality in 2016 and in 2019, we confirmed that the inflorescences we observed from the translocated individuals are morphologically consistent with those of the wild population. Further molecular phylogenic analysis revealed it is an undescribed taxon of sect. Proliferae. We concluded that the species is new to science and describe it here.

Materials and methods

Morphological descriptions and comparisons were based on living plants from the Lijiang alpine botanical garden and in the field, specimens from the herbarium of Kunming Institute of Botany, Chinese Academy of Sciences (KUN), and literatures (Chen and Hu 1990, Hu and Kelso 1996). All morphological characters of P. dongchuanensis and its morphological similar species P. aurantiaca were measured using a vernier caliper. The conservation status of P. dongchuanensis was assessed according to the IUCN Red list Categories and Criteria (IUCN 2017).

Genomic DNA was isolated from silica gel-dried leaves using a modified Cetyl Trimethyl Ammonium Bromide (CTAB) protocol (Doyle and Doyle 1987). The nrDNA and two chloroplast matK and trnH-psbA regions of P. dongchuanensis were amplified and sequenced using previously published universal primers (White 1990, Taberlet et al. 1991, Kress and Erickson 2007, Yang et al. 2012). Sequences of the relatives of P. dongchuanensis were downloaded from NCBI (https://www.ncbi.nlm.nih.gov/) (Appendix 1). Sequences for each region were aligned with CLUSTALX (Thompson et al. 1997) and then manually adjusted in BIOEDT 7.0 (Hall 1999). Maximum likelihood (ML) methods for phylogenetic estimation were conducted using IQ-TREE v. 1.6.10 under the GTR+G model (Nguyen et al. 2015). Clade supports were evaluated by 10000 bootstrap replicates of nonparametric approximate likelihood-ratio test (SH-alRT) and ultrafast bootstrap approximation approach (UFBoot) (Guindon et al. 2010; Hoang et al. 2018). Pairwise genetic distances among P. dongchuanensis and its closest relatives revealed by phylogenetic analyses were calculated using the Kimura 2-parameter method (Kimura 1980).

Taxonomic treatment

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.

Morphological and phenological comparisons between Primula dongchuanensis and P. aurantiaca.

Characters P. dongchuanensis P. aurantiaca
Leaf blade 3–6 × 2.0–3.5 cm 4–15 × 1.8–5.0 cm
Scape scape nearly obsolete at early anthesis, elongating to 10 cm at late flowering scape 4.5–15 cm at anthesis, elongating to 30 cm in fruit
Inflorescence inflorescences 6–20-flowered arising from leaf rosette at early anthesis, elongating to 10 cm with 2–8 flowers forming solitary racemes at late flowering umbels 2–4(–6), superimposed, 6–15-flowered
Pedicels pedicel green, 1–3 cm long, glabrous pedicel reddish, 0.3–1.0 cm long, glabrous
Bracts 1–2, linear 1, linear
Flower color deep yellow deep reddish orange
Flowering time late April to early June late May to early July

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.

Figure 1. 

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

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.

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).

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).

Discussion

Sect. Proliferae Pax is a taxonomically well-known group in Primula, characterized by numerous whorls of flowers resembling candelabra (Fig. 3) (Chen and Hu 1990). Phylogenetic analyses by using DNA barcoding confirmed the monophyly of sect. Proliferae which could be used in narrowing the scope of identification in Primula (Yan et al. 2015). Preliminary molecular phylogenetic analyses in this study supports the view that P. dongchuanensis is a member of sect. Proliferae, but its molecular closed relatives are not clear yet. Further research is required to clarify the phylogenetic relationship by using enhanced molecular markers with a wider sampling in this section.

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.

Morphologically P. dongchuanensis has unique inflorescences architecture compared to other members of sect. Proliferae. The racemose inflorescence appears in some Primula species, but no report in the sect. Proliferae till the addition of P. dongchuanensis, which extended the delimitation of sect. Proliferae and increased our knowledge of the Primula diversity in China. Compared to other species of the sect. Proliferae with bigger and upright inflorescences when anthesis begins, P. dongchuanensis keeps the racemes in a condensed and short form. This could flow from adaptation to the harsh habit of the mountain top where it is usually very windy and insufficient water in late April and May when it starts anthesis, and the other species of sect. Proliferae are usually found in the open and wet alpine meadow and have a late bloom time.

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.

Acknowledgements

We thank Miss Min Yang for the illustration, Dr. Jie Cai for revision and constructive suggestions to the manuscript. This work was supported by grants from the National Natural Science Foundation of China (31560062), the Yunnan Education Department grant (2015Z057), the Science and Technology planning project of Yunnan Province 2016BC013, and the Major Project on Biodiversity Conservation of Ministry of Ecology and Environment.

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Appendix 1

Information of samples used for phylogenetic inference in this study.

Species Section GenBank accession No. Voucher details
matK trnH-psbA ITS
Primula sinensis Sabine ex Lindl. Section Auganthus JF955776 JN046584 JF978054 Y2010045
Primula chapaensis Gapnep. Section Carolinella JF955683 JN046494 JF977966 GBOWS681
Primula partschiana Pax Section Carolinella JF955748 JN046558 JF978028 Zeng Q.W. s.n.
Primula rugosa Balakr. Section Carolinella JF955764 JN046574 JF978044 Hao 662
Primula wangii Chen et C. M. Hu Section Carolinella JF955791 JN046599 JF978067 Hao 666
Primula heucherifolia Franch. Section Cortusoides JF955715 JN046526 JF977995 Y2010035
Primula polyneura Franch. Section Cortusoides JF955749 JN046559 JF978029 GLM103026
Primula septemloba Franch. Section Cortusoides JF955767 JN046575 JF978045 Hao & Yan 989
Primula blattariformis Franch. Section Malvacea JF955666 JN046477 JF977949 Zhao Y.J. 029
Primula malvacea Franch. Section Malvacea JF955720 JN046530 JF978000 Zhao Y.J. 069
Primula oreodoxa Franch. Section Obconicolisteri JF955740 JN046550 JF978020 Hao 710
Primula dongchuanensis Section Proliferae MN181436 MN181434 MN181435 ZKWu2016060
Primula anidosora Balf. f. et Forr. Section Proliferae KP638609 KP638689 KP638569 Y2013062
Primula aurantiaca W. W. Smith et Fletcher Section Proliferae HM018224 HM018469 HM018175 Hao 536
Primula bulleyana Forr. Section Proliferae HM018235 HM018480 HM018186 Wu Z.K. 2004018
Primula burmanica Balf. f. et Word Section Proliferae KP638614 KP638694 KP638574 Y2013010
Primula chrysochlora Balf. f. et Word Section Proliferae KP638616 KP638696 KP638576 Y2011005
Primula chungensis Balf. f. et Word Section Proliferae HM018226 HM018471 HM018177 Hao 465
Primula cockburniana Hemsl. Section Proliferae KP638621 KP638701 KP638581 Hao 1037
Primula helodoxa Balf. f. Section Proliferae HM018228 HM018473 HM018179 Wu Z.K. 2005034
Primula mallophylla Balf. f. Section Proliferae KP638624 KP638704 KP638584 Y2011084
Primula melanodonta W. W. Smith Section Proliferae KP638626 KP638706 KP638586 Y2011070
Primula miyabeana Ito et Kawakami Section Proliferae HM018222 HM018467 HM018173 H280
Primula poissonii Franch. Section Proliferae HM018241 HM018486 HM018192 Wu Z.K. 2004011
Primula prenantha Balf. f. et W. W. Smith Section Proliferae KP638632 KP638712 KP638592 GLM092452
Primula pulverulenta Duthie Section Proliferae HM018219 HM018464 HM018170 Hao 230
Primula secundiflora Franch. Section Proliferae HM018254 HM018499 HM018205 Ge & Yuan 2003T-5
Primula serratifolia Franch. Section Proliferae HM018221 HM018466 HM018172 Hao 484
Primula smithiana Craib Section Proliferae HM018220 HM018465 HM018171 Hao 640
Primula wilsonii Dunn Section Proliferae KP638643 KP638723 KP638603 Y2013004
Primula pycnoloba Bur. et Franch. Section Pycnoloba JF955759 JN046569 JF978039 Hao 766
Omphalogramma delavayi (Franch.) Franch. KP638606 KP638686 KP638566 Y2013044