Spiradiclis yuanyangensis Y. S. Chen, L. Wu & C. Liu, 2021

Wu, Lei, Liu, Cheng, Song, Xiao-Fei & Chen, You-Sheng, 2021, Spiradiclis yuanyangensis (Rubiaceae), a new species from Yunnan, China, Phytotaxa 522 (4), pp. 294-300 : 295-296

Spiradiclis yuanyangensis Y. S. Chen, L. Wu & C. Liu , sp. nov. ( Figs 1 , 2 & 3A–K )

Type: — CHINA. Yunnan: Yuanyang County, Daping town, Jinzi river , elev. ca. 1526 m, 22°55′12” N, 103°5′59” E, 16 June 2020, Y. S. Chen et al. YY1056 (holotype CSFI 076276 ; isotype IBSC) .

Diagnoses: —This species is similar to Spiradiclis petrophila H. S. Lo (1983: 30) but differs from the latter by its pubescent stems, longer corolla tubes and short-styled corolla inside without a villous ring.

Description:—Perennial herb, up to 25 cm tall; stems pubescent, lower part procumbent, rooting at nodes, upper part ascending. Petiole 0.4–1.2 cm long, pubescent, often purple; leaf blade drying papery, elliptic or ovate-elliptic, 1.2–5.5 × 0.5–2.2 cm, acute at apex, cuneate at base, adaxially green, abaxially pale green, both surfaces pubescent, margin entire, ciliate; secondary veins in 7–12 pairs, abaxially purple; stipules triangular, 0.5–1.0 mm long, pubescent. Inflorescence cymose, several to 15-flowered; peduncles 2.5–7.5 cm long, puberulent; bracts subulate, 0.5–2.5 mm long, puberulent; pedicels 0.2–1 mm long, puberulent. Flowers distylous. Calyx puberulent; hypanthium portion obconic, 1.0– 1.5 mm long; lobes triangular, 0.3–0.8 mm long, acute at apex. Corolla white, tubular, glabrous outside; tube 4–5 mm long, sometimes slightly enlarged at base of long-styled corolla; lobes triangular-ovate, 1.8–2.2 × ca. 1 mm. Stamens 5; anthers linear. Stigma bilobed; ovary 2-celled. Long-styled flowers: corolla tube inside with densely pubescence above anthers and pilosulous at throat and sometimes onto lobes; anthers inserted at the middle of corolla tube, ca. 1 mm long; style 1.5–1.6 mm long, glabrous; stigma slightly above the throat, 2-lobed, lobes elliptic, ca. 0.5 mm long. Short-styled flowers: corolla tube inside pubescent through middle to throat and pilosulous at base of lobes; anthers slightly above the throat, ca. 0.8 mm long; style 2.5–3.5 mm long, glabrous; stigma at middle of corolla tube, lobes lanceolate, ca. 1.0 mm long. Capsules subglobose, 1.5–2.2 mm in diam., valves 4 when mature. Seeds many, angular.

Distribution and habitat: — Spiradiclis yuanyangensis is currently known from two localities in Yuanyang County, Yunnan Province, China. It grows on shady limestone cliffs by a stream at elevation between 870 m and 1500 m.

Phenology: —Flowering from March to June, fruiting from June to maybe September.

Etymology: —The specific epithet refers to the geographical distribution of the species. Chinese name is suggested as 元ḄAE序v (Yuan Yang Luo Xu Cao).

Notes: — Lo (1998) first systematically studied species of this genus from China, and two subgenera were recognized on the basis of capsule characters, viz., subgenus Spiradiclis , characterized by narrowly ellipsoid or linearoblong and twisted valves, and subgenus Sinospiradilclis, characterized by subglobose capsules and untwisted valves. According to Lo, Spiradiclis yuanyangensis belongs to subgenus Sinospiradilclis. It is morphologically most similar to S. petrophila by having perennial and herbaceous habit, long peduncles, heterostylous flowers, white and tubular corollas and subglobose capsules that with four valves when mature. But it differs from the latter mainly by the characters in the diagnosis and detailed comparison summarized in Table 1 .

Conservation status: —During our one year’s fieldwork in southeastern Yunnan, Spiradiclis yuanyangensis is currently found two localities from the type locality with no more than 150 individuals at each side in Daping Xiang, Yuanyang County, as two localities are not far apart geographically and should be considered as a single location. And it is easily disturbed because its habitats are close to the town and farmland. It is considered to be Critically Endangered (CR B1, 2a; C2a) because of its small size of only one population, which is vulnerable to human disturbance ( IUCN Standards and Petitions Subcommittee 2019).

Additional specimens examined (paratypes): — CHINA. Yunnan: Yuanyang County, Daping Xiang, Jinzihe river , 22°54′26″N, 103°06′53″E, elev. ca. 870 m, 21 June 2020, in fruiting, Cheng Liu et al. 20CS19498 ( KUN, CSFI); Daping Xiang, 22°55′15″N, 103°5′59″E, 1482 m, vouchers from the cultivated plants at the Kunming Institute of Botany , Chinese Academy of Sciences , 9 March 2021, in flowering, Cheng Liu & Ming-Jian Feng BC210313 ( KUN, CSFI) .

Figures

FIGURE 1. Illustration of Spiradiclis yuanyangensis. A: Habit. B: Leave (adaxially upper part, abaxially lower part). C: Stipule. D: Opened long-styled flower (showing style, stigma and corolla inside). E: Opened short-styled flower (showing style, stigma and corolla inside). F: Infructescence in side view. G: Capsule in side view. H: Dehiscent capsule in front view (Drawn by Hui-xian Zheng after the holotype).

FIGURE 2. Holotype of Spiradiclis yuanyangensis.

FIGURE 3. Spiradiclis yuanyangensis.A: Habitat.B–D: Habit (D). E: Leave (adaxially upper part, abaxially lower part).F: Inflorescence. G: Stem (showing indumentum).H: Long-styled flowers in side view I: Dehiscent long-styled corolla. J: Dehiscent short-styled flower.K: Infructescence and capsules in side view. S. petrophila. L: Stem (showing indumentum). M: Dehiscent long-styled corolla. N: Dehiscent short-styled flower. (scale: D 5 cm; E & F 2 cm; G-N 2 mm)