Primula xilingensis K.Huang & Z.X.Fu, 2023

Luo, Junjia, Zhang, Mingke, Liu, Xiaofeng, Chen, Hui, Li, Tingyu, Ma, Xudong, Huang, Ke & Fu, Zhixi, 2023, Primula xilingensis (Primulaceae), a new species from Sichuan, China, PhytoKeys 234, pp. 135-143 : 135

Primula xilingensis K.Huang & Z.X.Fu sp. nov

Diagnosis.

The new species is easily recognised by the following combination of characters: the scape densely yellow farinose, leaf apex acute, rarely broadly obtuse, corolla pale purplish blue and the style 3.0-6.0 mm above base of corolla tube, and stamens reaching the corolla tube mouth in thrum flower (Figs 1 - 3 ).

Type.

China. Sichuan: Dayi City, Xiling Snow Mountain , growing on moist rock surfaces amidst moss under the forest. 30°41′59.82″N, 103°9′47.63″E, alt. c. 3200m, 7th June 2023 (fl.), K. Huang & Zhixi Fu 7531 (holotype, SCNU!) (Figs 1 - 3 ) .

Description.

A perennial herb, 1.0-4.0 cm tall. Stolons dark red, 2.0-6.0 cm long developing onwards leafless flagellate, each with a tiny rosette at the end, and clothed the base by the withered remains of the old leaves. Roots numerous, fibrous, without hairs, 3.0-12.0 cm long. Leaves in a loose to tight rosette, 1.0-2.0 cm in diameter, leaf rosette less than or equal to corolla; leaf blade ovate to ovate-elliptic, 5.0-8.0 × 3.0-6.0 mm, margin dentate generally in the upper half only, apex acute, rarely broadly obtuse, tapering to base forming a winged petiole, petioles usually shorter than leaf blade and sparingly farinose, densely yellow farinose abaxially, midvein prominent, sparingly yellow farinose adaxially, veins inconspicuous. Scape solitary, 0.2-1.5 cm tall, erect, densely yellow farinose, usually with a single flower. Bracts solitary, 1.0-2.0 mm long, lanceolate, not swollen at base. Pedicel slightly bent, densely yellow farinose. Flowers heterostylous. Calyx narrowly campanulate, prominent 5-veined, 3-9 mm long, densely yellow farinose, parted to 2/3 of its length or slightly below, lobes linear lanceolate to lanceolate, apex acute. Corolla pale purplish blue, lacking the appendage on the corolla tube, 5 lobes spreading, obovate, 4.0-8.0 mm long, densely yellow farinose abaxially, efarinose and glabrous adaxially, deeply emarginate. Pin flower: corolla tubes 5.0-10.0 mm long in length, 2-3 mm in diameter, longer than calyx, stamens 2.0-5.0 mm above base of corolla tube, style nearly as long as tube. Thrum flower: corolla tubes 7.0-13.0 mm long in length, c. 3 mm in diam, longer than calyx, style 3.0-6.0 mm above base of corolla tube, stamens reaching the corolla tube mouth (Figs 1 - 3 ). Capsule unknown.

Phenology.

Flowers collected in May and June.

Etymology.

The epithet " xilingensis " is derived from Xiling Snow Mountain, the snow mountain located in Dayi City, Sichuan Province, China.

Distribution and habitat.

P. xilingensis is currently known only from its type locality in Yingyangjie, Xiling Snow Mountain, Xiling Town, Dayi City, Sichuan Province, China (Map 1 ). It grows on moist rock surfaces amidst moss under the forest, at elevations of approximately 3200 m (Fig. 2 ).

Additional specimens examined

(paratypes). CHINA. Sichuan: Dayi City, Xiling Snow Mountain , 30°41′59.82″N, 103°9′47.63″E, 21 May 2022 (fl.), Zhixi Fu 6052 (SCNU!); ibid., 7 June 2023 (fl.), K. Huang & Zhixi Fu 7532 & 7533 (SCNU!) .

Conservation status.

Data Deficient (DD). Currently, only one population with more than 100 individuals has been found in the type locality. The population of P. xilingensis grows on moist rock surfaces amidst moss, and the Xiling Snow Mountain has corresponding protective measures for the environment and plants. Whilst currently only known from Xiling Snow Mountain, it is very possible that the taxon is found in other localities and, without a more comprehensive collecting programme, and known only from two collections, it would be best to assess the conservation status of the species as Data Deficient (DD) following the IUCN Red List criteria ( IUCN 2022).

Relationship with related species.

Critical examination of collected specimens, comparison with type material of allied taxa, and relevant taxonomic literature revealed that P. xilingensis is a new member of the P. sect. Minutissimae . Morphologically, P. xilingensis shares certain similarities with P. dujiangyanensis . However, P. xilingensis differs from P. dujiangyanensis in having the style nearly as long as tube in pin flowers (vs. the style slightly exceeding the corolla tube mouth in pin flowers), stamens reaching the corolla tube mouth in thrum flowers (vs. stamens inserted on the apex of the corolla tube, scarcely exceeding 1 mm in thrum flowers), lacking an appendage on the corolla tube (vs. a yellow appendage present on the corolla tube), having numerous roots without hairs (vs. few roots with dense white hairs), corolla pale purplish blue (vs. corolla pinkish purple), leaf apex acute (vs. leaf apex broadly obtuse to sub-rounded) and distributed at about 3200 m elevation (vs. 1550-1650 m). To some extent, it also resembles P. tenella as a perennial herb with stolons, farinose leaves, margin dentate generally on the upper half only, but differs from P. tenella in leaf blade (ovate to ovate-elliptic vs. rhomboid to ovate-spatulate), leaf size (5.0-8.0 × 3.0-6.0 mm vs. 6.0-15.0 × 5.0-8.0 mm), leaf farinose (yellow vs. white) and altitude (at an altitude of approximately 3200 m vs. 4700-5000 m). The species of P. xilingensis is similar to P. pengzhouensis , but can be easily distinguished from the former by its stolons (present with 2-6 cm long vs. absent), scape visibility (vs. almost obsolete) and altitude (c. 3200 m vs. c. 1170 m). Further morphological comparisons among the species of P. xilingensis , P. dujiangyanensis , P. pengzhouensis , and P. tenella are shown in Table 1 .

Figures

Figure 1. Primula xilingensis sp. nov. A plant and roots B stolon C leaves D calyx E stamens F scape and bract G thrum flower H pin flower. (Photos A, B by XM, and C-H by MZ).

Map 1. Location of the population of Primula xilingensis in Dayi County, Sichuan (red star).

Figure 2. Primula xilingensis sp. nov. A, B habitat C plants of thrum flower D habit E plants of pin flower F stolons. (Photos A, B by ZF, C, D by KH, and E, F by MZ).

Figure 3. Holotype image of Primula xilingensis K. Huang & Z. X. Fu, sp. nov.