Primula surculosa Y.Xu & G.Hao, 2022

Xu, Yuan, He, De-Ming, Yang, Lin-Zhong & Hao, Gang, 2022, Primula surculosa (Primulaceae), a new species from Yunnan, China, PhytoKeys 212, pp. 29-35 : 29

Primula surculosa Y.Xu & G.Hao sp. nov.

Figs 1 , 2

Type.

China, Yunnan: Wenshan City, Bozhu Town, Bozhu Mt. 23°22'N, 104°12'E, alt. 2910 m, 27 Feb. 2022 (fl.), Deming He Xu211011 (holotype: IBSC!) .

Diagnosis.

Primula surculosa is morphologically most similar to P. taliensis , but is distinctive in its indumentum in the throat of the corolla tube, and the markedly stoloniferous habit.

Description.

A perennial herb, efarinose, stoloniferous, lacking basal bud scales at anthesis. Leaves dimorphic, forming a rosette of 9.0-2.0 cm in diameter, with short appressed pubescent on both surfaces. Outer leaves spatulate to obovate-spatulate, 2.5-5.0 × 2.5-3.5 cm, tapering to base forming a broadly winged petiole, margin crenate to dentate, apex rounded. Inner leaves long petiolate; blade broadly ovate to suborbicular in outline, 4.0-7.0 cm in diameter, base rounded or cordate, margin coarsely dentate; petiole 3.0-6.0 cm long, up to 12 cm at fruiting time. Stolons arising from the basal of the leaf rosette after anthesis, terminated in a leaf rosette, with alternate and reduced ovate leaves (5-18 × 8-20 mm) on lower part, growing upwards to 5-8 cm, afterwards elongating up to 20-25 cm long, procumbent along the surface of the ground and rooting at the nodes. Scapes 1.5-3.0 cm, reaching 6.0 cm at fruiting, copiously pilose; umbel solitary, 2-8 flowered; bracts lanceolate, 3-6 mm. Pedicel 2-3 cm. Flowers heterostylous. Calyx campanulate, 6-8 mm, parted to 1/3; lobes ovate to broadly lanceolate, margin 3-toothed at apex and occasionally entire in fruiting. Corolla purplish rose to purple-blue; tube 8-12 mm, with a tuft of white hairs projecting the yellowish green annulus in throat; limb 1.2-1.6 cm wide; lobes broadly obovate, 3-toothed. Pin flowers: stamens 5-6 mm above base of corolla tube; style nearly as long as tube. Thrum flowers with positions reciprocal. Capsule subglobose, included in calyx, disintegrating at maturity.

Distribution and habitat.

The new species is presently known only from the type locality in Yunnan, Wenshan City, and is clustered in small groups in deep moss under secondary evergreen broad-leaved forests.

Phenology.

Flowering from February to April, fruiting from April to June.

Etymology.

The specific epithet “surculosa” refers to the remarkable root-suckers (stolons), with long slender internodes and reduced leaves arising after anthesis.

Conservation status.

Based on our field investigations in Wenshan City and adjacent regions (e.g., Pingbian, Maguan, Malipo and Mengzi) during the last three years, only one population with ca. 800 individuals of the new species has been found in an area of 10 km2. Moreover, according to the result of our investigation in the villages near the type locality, the local folks often collect this new species as a medicinal plant. Therefore, the conservation status of the new species is assessed as vulnerable (VU D1+2) according to the guidelines for using the IUCN Red List categories and criteria ( IUCN Standards and Petitions Subcommittee 2022).

Additional specimens examined (paratypes).

The same locality as holotype, 9 May 2021, Deming He Xu210577 (IBSC!); 26 April 2022, Deming He Xu211017 (IBSC!); 2 July 2022, Deming He Xu221030 (IBSC!).

Relationship with related species.

Group Taliensis is a small group of two species ( P. taliensis and P. comata ) in sect. Primula Petiolares , characterized by plants without basal bud scales at anthesis, scape equaling or exceeding the leaves at flowering time, plant glandular hairy, and efarinose ( Smith and Fletcher 1944). This group is mainly distributed in western Yunnan and adjacent northern Myanmar ( Smith and Fletcher 1944). The present new species is assigned to this group, being distinctive in the markedly stoloniferous habit, and some other morphological features, which are summarized in Table 1 .

The stolon, an unusual mechanism of vegetative propagation, is an outstanding feature of the new species. However, this feature appears to have multiple origins in this genus, since it also occasionally occurs in some species of other sections which are presumably not intimately connected, e.g., P. heucherifolia (sect. Primula heucherifolia Cortusoides Balf. f.), P. ranunculoides (sect. Primula ranunculoides Ranunculoides Chen et C.M.Hu), P. caldaria (sect. Primula caldaria Aleuritia Duby), and P. pseudodenticulata (sect. Primula pseudodenticulata Denticulata Watt) ( Hu 1990; Hu and Kelso 1996; Shao et al. 2012). So the stolon may have no phylogenetic significance in the genus Primula .

Figures

Figure 1. Primula surculosa sp. nov. A stolon B habit C leaf on abaxial surface (fruiting time) D outer leaf on abaxial surface (anthesis) E inner leaf on adaxial surface (anthesis) F capsule with persistent calyx G long and short-styled flowers H bract I calyx (dissected) J multicellular hairs. Drawn by Yun-Xiao Liu.

Figure 2. Living plant of Primula surculosa sp. nov. A, B habitat C habit (blooming) D long and short-styled flowers, also showing pilose corolla tube (the circular image) E outer and inner leaves on adaxial surfaces, showing indumentum, venation, and margin shapes F inflorescence G calyx (dissected) H bracts I capsule with persistent calyx J capsule (crumbling) K habit (stoloniferous after anthesis) Photographed by De-Ming He.