Spiradiclis elliptica Y.M.Shui & W.H.Chen, 2022

Cai, Jia-Hua, Shui, Yu-Min, Song, Xiao-Fei & Wu, Lei, 2022, Validation of the name Spiradiclis elliptica (Rubiaceae), a new species endemic to southwestern China, Phytotaxa 545 (1), pp. 110-114 : 111-113

Spiradiclis elliptica Y.M.Shui & W.H.Chen , sp. nov. ( Figs. 1–2 ).

Type:— CHINA. Yunnan: Hekou County, Nanxi, Longyinchong , in the dense forests on the limestone slope, alt. ca. 700 m, 19 June 2003, Y.M. Shui et al. 32124 (holotype KUN, barcode 1519977, isotype IBSC, barcode 0883945) .

Diagnosis:— This species is similar to Spiradiclis petrophila H.S.Lo (1983: 30, 33) for having tubular, white and shorter than 4 mm corollas, but differs from the latter mainly by the persistent, ovate to ovate-oblong, 7–10 mm long (vs. caducous, triangular, 1.5–2 mm long) stipules, and white or sometimes pink, oblong to ovate-oblong, 3–5 mm long (vs. green, narrowly triangular, 0.3–0.8 mm long) bracts.

Description:—Perennial herb, up to 30 cm tall; stems glabrous, lower part procumbent, rooting at nodes, upper part ascending. Petiole 1–2 cm long, glabrous; leaf blade leathery, elliptic or sometimes ovate-elliptic, 3–10 × 2–4 cm, acute at apex, cuneate to rounded at base, adaxially dark green, abaxially green, both surfaces glabrous, margin entire; secondary veins in 6–10 pairs; stipules ovate to ovate-oblong, 7–10 × 6–8 mm, acute or at apex, both surfaces glabrous, persistent. Inflorescence cymose, several to 15-flowered; peduncles 2.5–7.5 cm long, glabrous; bracts white or sometimes pink, oblong to ovate-oblong, 3–5 × 1.5–2 mm, glabrous, rounded at apex; pedicels 1–2 mm long, glabrous; bracteoles ovate-oblong, 1.5–2 × 1–1.5 mm. Flowers distylous. Calyx glabrous; hypanthium portion obconic, ca. 1.2 mm long; lobes 5, broadly ovate-triangular, 0.5–0.8 × ca. 0.8 mm, acute or 2-lobed at apex. Corolla white, tubular-funnelform, glabrous outside; tube 2–3.5 mm long, sometimes slightly enlarged at base; lobes 5, ovate, 1.5–2.2 × ca. 1 mm. Stamens 5; anthers linear, ca. 0.8 mm long. Stigma bilobed; ovary 2-celled, ovules numerous. Long-styled flowers: corolla tube inside with a ring of golden hair above anthers and pilosulous at throat and sometimes onto lobes; anthers inserted a little below the middle of corolla tube; style 2.5–3.5 mm long, glabrous; stigma slightly exserted above the throat, lobes ellipsoid, ca. 0.3 mm long. Short-styled flowers: corolla tube inside sparsely pubescent and pilosulous at throat and sometimes onto lobes; stamens ca. 1.6 mm long, anthers slightly exserted above the throat of corolla tube; style 1.0– 1.5 mm long, glabrous; stigma inserted at middle of corolla tube, lobes lanceolate, ca. 0.6 mm long. Capsules subglobose, ca. 2 mm in diam., valves 4 when mature. Seeds many, angular.

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

Distribution and habitat:— Until now, Spiradiclis elliptica is known only from Hekou County and Maguan County, southeastern Yunnan Province. The individuals prefer to grow on the shady cliffs of limestone forests dominated by species of Fagaceae , Lauraceae and Magnoliaceae at an altitudinal range from 700 to 1600 m.

Etymology:— The name of the new species comes from the elliptic leaf blades.

Conservation status:— At present, only three populations (one from Maguan County and two from Hekou County) of Spiradiclis elliptica with a total of more than 300 mature individuals were observed during our investigations. All individuals discovered were from southeastern Yunnan in nature reserves, where habitats are in good condition and there are no threaten factors until now. We speculate that there are more than 2000 mature individuals in the distribution area, and the distribution area is more than 30 km 2. Thus, this species is assigned a status of Least Concern (LC) following the guidelines of IUCN (2019).

Additional specimen examined (paratypes):— CHINA. Yunnan: Hekou County, Qiaotou Town, Bozhujing Village , 22°46’N 104°22’ E, 1450 m, 5 May 2017, L. Wu & Z.J. Wen 5928 (CSFI, IBSC). Maguan County , Gulinqing, Laowangzhai, 22°43’N 103°59’ E, 1050 m, in the evergreen broad-leaved forest of the limestone hills, in fruits, 3 October 2002, Y.M. Shui, W.H. Chen & J.S. Sheng 30247 (KUN) .

Taxonomic relationships:— According to the classification of Lo (1998), Spiradiclis elliptica belongs to subgenus Sinospiradiclis due to the subglobose capsules dehiscent with 4 valves when mature. This species is distinguishable from other species of the genus mainly by its large stipule and distinctive bract. To our knowledge, the bracts of the known species of Spiradiclis are described as linear or subulate (vs. oblong to ovate-oblong in S. elliptica ), the apices of which are lanceolate or acute (vs. rounded), and the color are green (vs. white or sometimes pink).

Figures

FIGURE 1. Spiradiclis elliptica.A: Habit, B: Stipule, C: Inflorescence, D: Longitudinally dissected long-styled flower, E: Longitudinally dissected short-styled flower. Drawn from the holotype by Ming-min Chen.

FIGURE 2. Spiradiclis elliptica. A: Habitat, B: Plant and habit, C: Habit, D: Stipule, E: Inflorescence, F: Infructescence, G: Long-styled flowers and bracts (lateral view), H: Longitudinally dissected long-styled flower. Scale bars: C=2 cm, D=1 cm, E=5 mm, F=2 mm, G & H=3 mm. Photos by Lei Wu and Yu-Min Shui; Designed by Lei Wu.