Primula dujiangyanensis W.B.Ju, Bo Xu & X.F.Gao, 2021

Ju, Wen-Bin, Deng, Heng-Ning, Zhu, Da-Hai, Gao, Yun-Dong, Gao, Xin-Fen & Xu, Bo, 2021, Primula dujiangyanensis (Primulaceae) discovered from Sichuan, Southwest China, Phytotaxa 510 (3), pp. 275-280 : 276-278

Primula dujiangyanensis W.B.Ju, Bo Xu & X.F.Gao , sp. nov. ( Figs. 1 & 2 )

Diagnosis:— Primula dujiangyanensis is similar to P. kialensis Franchet (1895: 450) and P. pengzhouensis C.M.Hu, G.Hao & Y.Xu in Xu et al. (2017: 229), but it can be easily distinguished from them by the smaller plant size, stolons 3–6 cm long, roots densely white hairy, scape unitary, inflorescence with single lanceolate bract ca. 0.5–1 mm long, pedicel 3–6 mm long, and stamens of pin flower in middle of corolla tube and stamens of thrum flower at the mouth of corolla tube, the shorter style reaching middle of tube, the longer style slightly exceeding the corolla tube mouth.

Type:— CHINA. Sichuan: Dujiangyan City, Hongkou Town, Longxi-Hongkou National Nature Reserve , growing on moist cliffs amidst moss. 31°15’35.10” N, 103°38’58.32” E, elevation ca. 1568 m, 23 May 2012, B. Xu & Y.D. Gao DJY00272 (holotype CDBI!; isotypes KUN!, PE!)

Perennial herb, dwarf tufted plant up to 1.5 cm tall, flowering plant 3–5 cm tall, developing onwards leafless flagellate stolons 3–6 cm long, each with a tiny rosette at the end, with a very short rhizome and clothed the base by the withered remains of the old leaves, base without scales. Roots few, fibrous, dense white hairs. Leaves in a loose rosette, abaxially copiously yellow farinose, adaxially sparingly yellow farinose, membranous when dry; leaf blade ovate to ovate-elliptic, 4–8 × 3–5 mm, broadly obtuse to sub-rounded at apex, with a cuneate base, gradually tapering into the narrowly winged petiole, margin dentate or crenulate generally in the upper half only; petioles usually shorter than leaf blade, 2–5 mm long; lateral veins 4–5 pairs on either side of midvein. Scape 1, scarcely farinose, 1.0– 2.5 cm tall, usually with a single flower, very rarely two; bracts solitary, lanceolate, 0.5–1 mm long; pedicel 3–6 mm long, slightly bent, not extended in fruit. Flowers heterostylous. Calyx narrowly campanulate, 3–4 mm long, 5-veined, sparingly yellow farinose outside, densely so inside, parted to 2/3 of its length or slightly below; lobes linear lanceolate to lanceolate, apex acumen. Corolla pinkish purple with a yellow eye, annulate, limb 9–14 mm across, funnelform; lobes spreading, obovate, 4–6 × 3–4 mm, deeply emarginate. Thrum flower: corolla tubes 5–7 mm, no hairy inside; stamens inserted on the apex of the corolla tube, scarcely exceeding 1 mm; style in the middle of the corolla tube. Pin flower: corolla tubes 5–6 mm, no hairy inside; stamens in the middle of corolla tube, style slightly exceeding the corolla tube mouth. Capsule ellipsoid, shorter than persistent calyx.

Phenology:—Flowering in May and fruiting from June to July.

Etymology:—The specific epithet refer to the administrative name of the type locality.

Distribution and habitat:—The new species is presently known from the Heshangqiao, Longxi-Hongkou National Nature Reserve, Hongkou Town, Dujiangyan City, Sichuan Province, China. It grows on moist rock surfaces amidst moss in the forest, at elevations of 1550–1650 m.

Additional specimens examined (paratypes):— CHINA. Sichuan: Dujiangyan City, Hongkou Town, Longxi- Hongkou National Nature Reserve . 31°15’53.94” N, 103°38’18.96” E, elevation ca. 1623 m, 18 June 2014, B. Xu & Z.M. Zhu et al. DJY06717 (CDBI!) .

Conservation status:—This new species is a rare species with a restricted distribution. Until now, only known from the type collection with two population, and a total of approximately 500 individuals has been found in an area of 4 km 2. According to the IUCN red list categories and criteria (IUCN 2019), the conservation status is assessed as Critically Endangered (CR).

Figures

FIGURE 1. Primula dujiangyanensis.A. plant; B. roots and white hairs; C. leaves; D. scape; E. bracts; F. pedicels; G. pin flower; H. thrum flower; I. ovary and style; J. stamens; K. calyx; L. capsule.

FIGURE 2. Primula dujiangyanensis. A. Habitat; B. plant of pin flower; C. plant of thrum flower; D. pin flower; E. thrum flower.