China. Hubei Province: Shennongjia Forestry District, Shennongjia National Park, in rock crevices of Abies forest, alt. 2700–2900 m, 11 June 2019 (fl.), Lin-Sen Yang 103 (holotype HIB!; isotype PE!).

This new species resembles Primula gemmifera and P. munroi subsp. yargongensis but differs significantly from the latter in several aspects: umbels are 1–2-flowered, scapes are 5–10 cm long, bracts measure 2–4 mm long, campanulate calyx is 3–4 mm long, flowers are homostylous, and the corolla throat lacks an annular appendage. Among the homostylous types in Primula sect. Aleuritia, P. clutterbuckii, P. meiotera, and P. weiliei share some similarities but are distinct from each other. P. clutterbuckii and P. meiotera feature multiple short stems with clustered leaves showing large and deep serrations along the leaf margin, along with a thick powder abaxially. In contrast, P. weiliei has a single rhizome, fewer leaves with fewer dentate or shallow teeth on the margin, and a slightly farinose abaxial surface.

Figure 1. 

Primula weiliei L.S.Yang, Z.K.Wu & G.W.Hu A habitat B inflorescence C leaves D habits E corollas, long homostyly F corollas adaxial surface G calyxes, the upper abaxial, the lower adaxial H fruits I seeds.

Perennial herbs, 3–5 cm tall, with a small rhizome and few fibrous roots. Leaves scale-like at the lower part, cauline on the upper part, 4–6; petiole 15–20 mm long, ca. 1/3–1× length of the blade, upper concave; blade spatulate, 13–23 × 8–18 mm, base attenuate, margin shallowly serrate to sharply incised-serrate, apex blunt, slightly farinose or none on both surfaces. Scape 5–10 cm long, obviously white farinose, 1–2(–3) flowered; bracts usually 2(when 1 flower)–3(when 2 flowers), linear-lanceolate, ca. 2–4 mm long, farinose on both surfaces, denser adaxially; pedicel 5–8 mm long, farinose. Flower homostylous; calyx campanulate, farinose on both surfaces, denser adaxially, tube c. 2 mm long, parted to middle, lobes 5, c. 2 mm long, lanceolate to triangular, apex mucronate or acuminate; corolla pink or purplish red, tube 7–9 mm long, tubular, narrowed in the middle, gradually widened apically, throat without annular appendage, mouth 2–3 mm wide, limb 10–14 mm wide, lobes obovate, 6–7 × 4 mm, slightly to deeply emarginate; stamen attached to near 3/4 of the tube, 1 × 0.2 mm, apex blunt, slightly lower of tube mouth; ovary nearly spherical, with a smooth surface, placentation free central, style 6 mm long, stigma spherical, c. 1 mm in diam., extending to tube apex. Capsule oblong, 4–7 × 3–4 mm, 1.5× to 2× as long as calyx; seeds 60–150, irregularly polygonal, light earthy yellow, black after exposure.

Figure 2. 

Primula weiliei A habit B leaf abaxial side C flower lateral view D corollas, long homostyly E ripe fruit F calyx, abaxial view (left), adaxial view (right). (Drawn by Ms Xiang-Li Wu).

Flowering occurs from June to July, and fruiting occurs from July to August.

The specific epithet ‘weiliei’ honours Prof. Chen Weilie, a plant ecologist and geobotanist in China, and the first director of the Shennongjia Biodiversity Positioning Research Station, Chinese Academy of Sciences.

Chinese Mandarin: wei lie bao chun (伟烈报春).

Distribution and habitat. Primula weiliei was found exclusively in Shennongjia National Park, located in Hubei, China (Fig. 3). It thrives in rock crevices near forests of Abies fargesii Franch., while coexisting with other herbs and bushes, such as Rhododendon concinnum Hemsl., Juniperus squamata Buch-Ham. ex D.Don, Allium cyaneum Regel, Lonicera tangutica Maxim and Androsace henryi Oliv.

Figure 3. 

The distribution of Primula weiliei (star).

Primula weiliei is an exceedingly rare species found in only two small, closely situated populations, with a total population size of approximately 50 individuals. According to the IUCN Red List Categories and Criteria (IUCN 2022), it meets the criteria for being classified as a Critically Endangered species (CR A2acde; B2ab; C2a(i)). Given the threats of climate change and animal damage contributing to population decline, it is imperative to monitor these populations closely to prevent further degradation or extinction.

Primula gemmifera: China, Sichuan, 11500 ft, July 1904, E. H. Wilson, 4031 (A barcode A00073544, image seen!); Yunnan, 14200 ft, Aug 1914, George Forrest 13231 (K barcode K000750072, image seen!). Primula meiotera: China, Xizang, Kongbo, 11500 ft, 12 Jul 1938, F. Ludlow, G. Sherriff, & G. Taylor 5218 (BM barcode BM000996905, E barcode E00024506, images seen!). Primula clutterbuckii: India, Bangladesh & Pakistan, [ca. 28°21'N, 96°37'E], 10000–11000 ft, 23 May 1928, F. Kingdon-Ward 8235 (E barcode E00024452, K barcode K000750416, images seen!).

We have thoroughly compared the new species and several closely related species, as detailed in Table 1. Notably, Primula weiliei and its closely related species exhibit similar characteristics, including irregularly denticulate leaf margins, winged leaf stalks, lanceolate bracts, campanulate calyx typically splitting to the middle or below, lanceolate sepals, and generally purple corollas. However, a few distinct characteristics can differentiate the new species from its closely related species. For instance, the calyx length of P. gemmifera and P. munroi subsp. yargongensis exceeds that of the new species by double its length. Furthermore, while the latter species typically bear more than two flowers on one scape, the new species only bear 1–2 flowers. Additionally, both the latter species are heterostylous with throat appendages in the corolla tubes, making them easily distinguishable (Hu 1990; Hu and Kelso 1996). The scarcity of homostylous types in Primula sect. Aleuritia underscores the importance of their characteristics. Despite many similarities among the three known species with homostylous flowers, such as the presence of 1–2 flowers in the inflorescence, sepals splitting in half, and the stigma and anther tips located near the corolla tube mouth, notable differences exist among these species. For instance, P. weiliei has sparse leaf teeth, scarcely farinose leaves, and a 7–9 mm corolla tube length. In contrast, P. clutterbuckii and P. meiotera have corolla tubes that are 15–16 mm and 4 mm long, respectively, and their leaves have coarse marginal teeth and are densely farinose on the abaxial surface.

Shennongjia, located in central China, is recognised as a biodiversity hotspot that has garnered the attention of numerous botanists, increasing botanical surveys conducted in the area in recent years. The discovery of Primula weiliei further expands the known distribution of Primula species within this region, emphasising the significance of continual botanical exploration within biodiversity hotspots. Notably, the four species mentioned above, P. munroi subsp. yargongensis, P. gemmifera, P. clutterbuckii, and P. meiotera, closely related to P. weiliei, are distributed in southeastern Tibet and the Hengduan Mountains. This suggests a potential correlation between the plant floras of western Hubei and eastern Himalaya, necessitating further analysis involving a broader range of plant taxa to establish a confirmation. Given the limited number of known specimens originating from its type locality, it is imperative to expedite an investigation into the conservation status of this newly discovered species. Accordingly, the development and implementation of effective conservation strategies are pivotal to ensure the long-term survival of this species.