﻿Primulajiaozishanensis (Primulaceae), a new species in Primula sect. Petiolares subsect. Davidii from Yunnan, China

﻿Abstract Primulajiaozishanensis Z.K.Wu, W.H.Yang & Yuan Wu, a new species of Primulaceae is described and illustrated from Jiaozi Snow Mountain of Dongchuan District, Yunnan, China. Morphological evidence supports P.jiaozishanensis as a member of P.sect.Petiolaressubsect.Davidii, which is characterized by firmly papery or leathery leaves, with veins impressed adaxially, often prominently raised and alveolate abaxially. The new species is characterized by having long and stout rhizomes, smaller leaves with short petioles, short or almost obsolete scape, and larger flowers. The distribution, phenology and conservation status of the new species are also provided.

described species, P. bergenioides C.M.Hu & Y.Y.Geng, P. tenuituba C.M. Hu & Y.Y.Geng (Hu and Geng 2003), P. dejuniana G.Hao, C.M. Hu & Yuan Xu (Xu et al. 2014), P. wawushanica G.Hao, C.M. Hu & Yuan Xu (Xu el al. 2016), P. luteoflora X.F.Gao & W.B.Ju (Ju et al. 2018), and P. pingbaensis Na Zhang, X.Q.Jiang & Z.K.Wu . Primula sect. Petiolares subsect. Davidii comprises 22 species in total, which is characterized by the leaves that are more or less coriaceous, often bullate above and strongly honeycombed-reticulate below, long septate hair more or less clothes the veins, and basal buds covered with paleaceous scales (Smith and Fletcher 1944), mainly distributed in Sichuan, Yunnan and Guizhou in China. Yunnan is a particularly significant biodiversity hotspot in China, with a wide variety of ecological environments ranging from tropical to alpine subnival belt, possessing ca. 130 species of Primula distributed across its range (Fang 2003). With the increased exploration of the region, many new Primula species have been discovered and described over the past two decades (Gong and Fang 2003;Xue and Zhang 2004;Shui and Chen 2006;Li and Hu 2009;Hu and Hao 2011;Yang et al. 2017;Wu et al. 2019;Ma et al. 2021;Wang et al. 2022;Wu et al. 2023).
During a botanical expedition to the Jiaozi Snow Mountain in Dongchuan District, Yunnan, southwestern China in May 2017, we found a peculiar population of Primula with large flowers, coriaceous leaves persisting into the following spring, basal buds covering paleaceous scales, on a small patch of alpine meadow near the mountain top. For further clarification of the identity of the newly collected Primula, the Jiaozi Snow Mountain in Dongchuan District and adjacent areas were revisited in 2020 to observe and collect the plants in flowers. The collected Primula is a dwarf perennial herb with a long and stout rhizome, basal buds covered with paleaceous scales, leaves with short petioles and adaxially bullate, short or almost obsolete scape, and large flowers. These features indicate that it should be a member of P. sect. Petiolares subsect. Davidii. After a full observation of the morphological characteristics and comparing the relevant literature and specimens for related species, we confirmed that this plant represents an undescribed taxon of Primula. Therefore, we describe and illustrate the taxon as new to science here.

Materials and methods
The morphological observation, measurements and description of the new species were based on living plants from Jiaozi Snow Mountain. Morphological comparison with closely related species was performed based on living plants collected from their type locality, specimens from the key herbaria of China (KUN, PE, WUK), type specimen images online from P, E, K, and relevant literature were also consulted (Smith and Fletcher 1944;Hu 1990;Hu and Kelso 1996). All morphological characters of P. jiaozishanensis and its morphologically similar species in the P. sect. Petiolares subsect. Davidii, including Primula esquirolii Petitm. and Primula sinoexscapa C.M.Hu, were measured using a Vernier caliper. The conservation assessment of the new species was evaluated using the IUCN categories of threat (see IUCN 2012 and IUCN Standards and Petitions Committee 2022). Diagnosis. The new species most resembles P. esquirolii and P. sinoexscapa, sharing similar leaves with a more or less rugose surface and short or almost obsolete scape at flowering time. However, the new species differs from the latter two mainly in its long and stout rhizome with 1-3 rosettes, smaller leaf blades with shorter petioles, shorter and stouter pedicels, and larger flowers (Figs 1-3). The main morphological distinctions between P. jiaozishanensis, P. esquirolii and P. sinoexscapa are summarized in Table 1 Description. A perennial hairy robust, dwarf herbaceous, efarinose, with a long stout rhizome and numerous fibrous roots, rhizome 3-4 cm long, ca. 0.5 cm in diameter; at flowering time girt at the base by ovate to oblong paleaceous bud scales, scales 1.5-1.8 cm long, 0.4-0.6 cm broad, acute at the apex, outer surface with a sparse covering of long multicellular hairs. Leaves forming 1-3 rosettes, leaves of current year not well-developed at anthesis, leaves of previous year at flowering time 2-4 cm long including the petiole, 1.5-2.5 cm broad, spatulate or elliptic-obovate, obtuse or rounded at the apex, gradually tapering into  the winged petiole; petiole 0.5 to 1 cm, 1/4 as long as leaf blade, stout with a thick covering of long multicellular hairs; lamina coriaceous, adaxially bullate, covered with sparse white long hairs, abaxially with multicellular hairs along veins, margin with regular sparsely acute serrate. Scape at flowering time almost obsolete or to 1 cm, usually solitary, covered by bud scales, with a thick covering of long multicellular hairs, usually 1 flowered or occasionally 2 flowered. Bracts linear-lanceolate, 3-6 mm long, glabrous; pedicel 1-3 mm, shorter than bract, with a thick covering of long multicellular hairs. Flower heterostylous; calyx campanulate, 6-8 mm long, puberulous, parted to 1/2 of its length, lobes ovate to ovate-lanceolate, apex obtuse or occasionally serrate; corolla funnel-shaped, purplish blue or violet, tube 15-20 mm long, usually twice the length of the calyx, limb 30-45 mm wide, lobes obcordate, 13-18 mm long, apex deeply emarginate. Pin flowers: corolla tube 14-16 mm long, stamens ca. 7 mm above the base of the corolla tube, style 14-16 mm long. Thrum flowers: corolla tube 16-20 mm; stamens 16-18 mm above base of corolla tube, style ca. 8 mm long. Capsule unknown. Distribution and ecology. Primula jiaozishanensis is only known from the type locality on Jiaozi Snow Mountain in Dongchuan District, Yunnan, China. The plant grows in the open alpine meadow (Fig. 1, Map 1).

Taxonomic treatment
Phenology. Flowering occurs from April to May. Etymology. The specific epithet of the new species is taken from the Chinese Pinyin, "Jiaozishan", the name of the mountain in Northern Yunnan, China, where the type specimen was collected (Map 1). Vernacular name. Chinese mandarin: jiao zi shan bao chun (轿子山报春). Provisional Conservation status. Critically Endangered (CR B2ab(iii)). The authors have conducted field surveys several times in the type locality and adjacent districts (e.g., Luquan, Qiaojia and Huize) for this new species, and discovered only one population of Primula jiaozishanensis, with approximately 100 adult individuals, distributed over about 100 m 2 in the type locality. This site is in a dry alpine meadow; the new species grows very close to the path for visitors and faces a strong threat from grazing and human activities. Its status should therefore be of concern and addressed by further investigations. We estimated the extent of occurrence of the species to be less than 10 km 2 . Over the last five years, we have observed a steady decline in the territory area of the habitat due to road construction and grazing. Considering the present field information and IUCN categories of threat (IUCN Standards and Petitions Committee 2022), this species should be included in the category Critically Endangered (CR B2ab(iii)).

Discussion
The species in Primula sect. Petiolares subsect. Davidii usually tend to have larger leaves because the plants grow in small groups on shady and moist cliffs beside streams and waterfalls. The leaves of P. davidii we found in the field of Sichuan can even reach 30 cm in length, and they also have a short and stout rhizome. The new species P. jiaozishanensis grows in open alpine meadow, and its habitat differs from that of other members in the P. sect. Petiolares subsect.
Davidii. Compared to other species in the same subsection, it is distinctive in its long and stout rhizome with 1-3 rosettes, smaller leaf blades, and very short and stout scape with one or occasionally two larger flowers. These features may be an adaptation to the harsh habit of the open alpine meadow, which is usually very windy and has insufficient water in late April and May when it starts anthesis.