Meishan City primrose (Primula meishanensis) from Sichuan similar to Primula dejuniana in sect. Petiolares

NEWS - Meishan City primrose (Primula meishanensis K.Huang & Z.X.Fu, sp. nov.) from Meishan City, Sichuan Province, China, was described based on morphology, phylogenetics and complete chloroplast genome as a separate species closely related to Primula dejuniana.

Primula L. is one of the most diverse members of the Primulaceae, comprising 38 sections and more than 500 species worldwide in temperate and cool Asia, tropical North Asia and Europe. Several new species have been discovered in China, such as P. lihengiana, P. wawushanica, P. undulifolia, P. pengzhouensis, P. surculosa, P. dongchuanensis, P. dujiangyanensis, P. longipilosa, P. wolongensis, P. sugongii and P. xilingensis.

Primula sect. Petiolares Pax includes more than 60 species currently known and well represented in the Himalaya-Hengduan Mountains region and only a few members extend to Kashmir, central China and some other regions. One of the most important characters is the spherical capsule that does not open with valves, but with disintegration at the apex of the membrane.

The new species specimens were collected during the botanical expedition of Zhongyan temple in Meishan City, Sichuan Province in 2022-2024, which is a taxon that has never been described. This study also analyzed the molecular data of the complete chloroplast genome to identify its relationship with P. dejuniana.

P. meishanensis and P. dejuniana form a highly supported clade. However, the branch lengths of the two species are different and the number of chloroplast genes is not the same. The complete chloroplast genome of P. meishanensis is 152,175 bp and that of P. dejuniana is 151,988 bp. The new species differs from the latter by its solitary scape, long leaf stalks, pointed leaf blade tips and pin flowers.

The new species is perennial herbs, 12.0-20.0 cm tall. Roots numerous, fibrous, without hairs. Leaves pilose, forming a spreading rosette, each rosette with only 2-4 leaves of previous year at flowering time; resting bud of rosette clothed by a few small paleaceous scales, basal bud scales ovate to ovate-oblong, ciliolate, rose red, apex acute.

Petiole 2.5-5 cm long, narrowly winged and densely covered with multicellular hairs; leaf blade oblanceolate, smooth, 19.5-25 × 2.5-5 cm, cuneate at base, abaxial surface densely along mid-vein, sparser on lateral veins covered with multicellular hairs; margin ciliate, sharply and remotely dentate; apex acute; mid-vein dull yellow in fresh state, turning brownish when dry; veins impressed adaxially, prominently raised and subalveolate abaxially.

Scape solitary, 7.2-11.8 cm long, pilose, carrying a terminal umbel of (1) 2-3 (4) flowers, dull yellow in fresh state, turning brownish when dry at base. Bracts lanceolate, 4-5.5 mm long, minutely ciliate. Pedicel 0.4-1.4 cm long, shorter than leaf blade, pilose. Flowers distylous.

Calyx campanulate, 8-9 mm long, parted to 1/2 of its length or slightly below; lobes linear lanceolate to lanceolate, apex acute. Corolla pastel violet, annulate, 5–6 lobes spreading, lobes broadly elliptic, 8.0–10.0 mm long, emarginate, densely yellow farinose abaxially, smooth adaxially.

Pin flower: corolla tubes 9.0-10.0 mm long, stamens inserted at middle of corolla tube, 9.5-10.5 mm long, style slightly exceeding the corolla tube mouth. Thrum flower: corolla tubes 11.0-12.0 mm long, ca. 2 mm in diam., 2 times as long as the calyx, style 4.0-7.0 mm above base of corolla tube, stamens reaching the corolla tube mouth, 7.0-12.0 mm above base of corolla tube.

Flowering period is December-February and fruiting period is March-May. The epithet “meishanensis” is derived from Meishan City in Sichuan Province, China. P. meishanensis is known from the type locality and may occur in other locations. It grows on damp rock surfaces among mosses under forest at elevations of 400-1000 m.

P. meishanensis is a new member of Primula sect. Petiolares that morphologically shares some similarities with P. dejuniana. However, P. meishanensis has pointed leaf tips (vs. pointed leaf tips, but with a small point at the tip in P. dejuniana), pastel purple corollas (vs. pale pink corollas).

Leaf stalks solitary, 7.2-11.8 cm long, bearing terminal umbels containing (1) 2-3 (4) flowers (vs. petioles usually one per rosette, 8-12 (18) cm long, bearing terminal umbels containing 2-6 flowers), petioles 2.5-5 cm long (vs. 1-3 cm), basal bud scales pink (vs. flesh pink) and flowering period from December-February (vs. February-March).

P. meishanensis is also similar to P. davidii. However, leaf blade margins (sharp vs. serrated) and tips (acute vs. rounded). P. meishanensis is similar to P. epilosa, but with acute leaf tips (vs. rounded), pastel purple corolla (vs. rose purple with yellow eye) and elevation 400-420 m (vs. 2000-2900 m).

Original research

Li T, Chen X, Li B, Hua D, Luo C, Luo H, Liang Y, Yue J, Xi X, Huang K, Fu Z (2024). Primula meishanensis (Primulaceae), a new species from Sichuan, China. PhytoKeys 248: 73-90, DOI:10.3897/phytokeys.248.127117

Dlium theDlium