Research Article |
Corresponding author: Lei Wu ( wuleiibk@163.com ) Academic editor: Yasen Mutafchiev
© 2021 Zhao-Jie Wen, Yun-Fen Huang, Yan-Hua Hu, Khang Sinh Nguyen, Lei Wu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wen Z-J, Huang Y-F, Hu Y-H, Nguyen KS, Wu L (2021) Spiradiclis detianensis (Rubiaceae, Ophiorrhizeae), a new species from southwestern Guangxi, China. PhytoKeys 184: 103-110. https://doi.org/10.3897/phytokeys.184.69886
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A new species of Rubiaceae, Spiradiclis detianensis is described from a limestone karst area of southwestern China. This new species is morphologically similar to S. cordata and S. spathulata. All of them have rosetted habit and long peduncles, but it differs from the former by the cuneate leaf bases (vs. basally cordate) and much longer corolla tubes (1.8–2.2 cm long vs. ca. 5 mm long), and from the latter mainly by its tubular-funnel shaped corolla (vs. slenderly salver shaped), 4.5–6.8 (vs. 1.5–2) mm in diam, inside throat and corolla densely puberulent (vs. glabrous except a ring of long hairs at the middle). It also resembles to S. tubiflora, but differs clearly by its subrosulate habit (vs. procumbent to creeping), longer leaf blades (7.0–10.5 cm vs. 0.5–2.5 cm) and longer corolla tubes (18–22 mm vs. 14–16 mm). At same time, color photos, illustrations, detailed descriptions and conservation status of the new species are provided.
China, Guangxi, limestone, Rubiaceae, taxonomy
Spiradiclis Blume is a morphological complex genus of Ophiorrhizeae (Rubiaceae). It is usually distinguished from its relatives by the subglobose or linear-oblong capsules with two or four twisted or straight valves when matured (
There are approximate 58 species of Spiradiclis, distributed in southeastern Asia and concentrated in southwestern China and northeastern India (
Most representatives have a narrow habitat and prefer to grow at wet places on hill slopes or entrances of caves in limestone areas. During a field investigation to the neighboring regions between China and Vietnam in 2013, the second author came across a peculiar population of Rubiaceae. According to its calciphile habitat and rosetted habit, it is easy to associate with Spiradiclis. However, the flower shape of this population is very different from that of the known species of the genus. Its corollas are tubular-funnel shaped, with 1.8–2.2 cm long tubes, sharply shrunken near base, 4.5–6.8 mm in diam. at throat and 1.8–2.5 mm in diam. near the base, while the corollas of the genus are usually very short or slender. Hence, we revisited this population and collected its capsules. Their subglobose shape and dehiscence with 4 valves clearly indicate this population represents a species of the genus Spiradiclis. After careful comparisons with relevant literatures and examining specimens in herbaria, we found that our plant is most similar to S. cordata H.S. Lo & W.L. Sha and S. spathulata X.X. Chen & C.C. Huang, two species of subgenusSinospiradiclis, but it can be distinguished from the former by the cuneate leaf bases and much longer corolla tubes, and from the latter by its tubular-funnel shaped corolla and without a villous ring inside corolla. We conclude that this population represents an undescribed species and formally treat it here.
Materials are deposited at the herbarium of Forest Plants in Central South University of Forestry and Technology (
China. Guangxi: Daxin county, Shuolong town, Detian village, 22°52'N, 106°43'E, elevation 650–750 m, 30 March 2018 (fl.), Zhao-Jie Wen & Guang-Fu Mou 18033001 (holotype:
The new species is similar to Spiradiclis cordata and S. tubiflora, but it differs from the former mainly by the cuneate leaf base (vs. cordate) and much longer corolla tubes (1.8–2.2 cm long vs. ca. 5 mm long), and from the latter by its subrosulate habit (vs. procumbent to creeping), longer and wider leaf blades (7.0–10.5 × 2.0–3.5 cm vs. 0.5–2.5 × 0.4–1.5 cm), more secondary veins (7–10 pairs vs. 3–5 pairs) and longer corolla tubes (18–22 mm vs. 14–16 mm).
Perennial herb, up to 15 cm tall; stems densely pubescent, erect or ascending, lower part rooting at nodes. Leaves subrosulate; petiole 0.8–1.7 cm long; leaf blade drying papery, obovate-lanceolate or oblong, 7.0–10.5 × 2.0–3.5 cm, obtuse or acute at apex, cuneate at base, adaxially dark green, puberulent, abaxially light green, pubescent, densely pubescent along veins at lower surface; secondary veins in 7–10 pairs; stipules persistent, pubescent, narrowly triangular, 3.2–5.7 mm long, or 2–5-lobed, lobes linear-triangular, upper part filiform. Inflorescence cymose, 2–7-flowered; peduncle 9–14 cm long, pubescent; bracts linear-triangular, 4–6 mm long, subglabrous; pedicels 0.5–5 mm long, pubescent. Flowers distylous. Calyx puberulent; hypanthium portion obconic, ca. 2 mm long; lobes triangular, 1.2–2.9 mm long, acute at apex. Corolla white to pink, tubular-funnel shaped, puberulent outside; tube 1.8–2.2 cm long, sharply enlarged at the 1/3 lower part of the corolla tube, 4.5–6.8 mm in diam. at throat, 1.8–2.5 mm in diam. near base; lobes triangular-ovate, 4.5–5.6 × 3.5–4.3 mm long. Stamens 5; anthers linear. Stigma bilobed; ovary 2-celled. Long-styled flowers: corolla tube inside with densely pubescence near base and densely puberulent above anther and on to lobes; anthers inserted near base of corolla tube, 1.9–2.3 mm long; style 1.2–1.4 cm long, puberulent; stigma inserted at between middle and throat of corolla tube, 2-lobed, lobes elliptic, 1.8–2.2 mm long. Short-styled flowers: corolla tube inside densely puberulent; anthers inserted often at or a little above middle of corolla tube, 2.6–3.3 mm long; style 1.5–3.4 mm long, glabrous; stigma near base of corolla tube, lobes ovate-triangular, 1.3–1.6 mm long. Capsules subglobose, 2.5–3.2 mm in diam., valves 4 when matured. Seeds many, angular.
. Flowering March to April, fruiting from May to July.
The specific epithet refers to the type locality, where a famous attraction, Detian Waterfall, is situated.
德天螺序草 (de-tian-luo-xu-cao in Mandarin).
Until now, only two populations of the new species have been found. They are both known from limestone hills of southern Guangxi. Plants of the new species prefer to grow at humid places at elevation range of 500‒800 m, under evergreen broad-leaved forests with tree species of Fagaceae, Lauraceae, Tiliaceae, Theaceae, Myrsinaceae, Magnoliaceae and Sapindaceae.
Spiradiclis detianensis A habit B inflorescence C leaves D, E stipule F, G short- and long-styled flower, front view H opened long- and short-styled flower, showing style and stamens I ovary, side view J infructescence, side view. S. tubiflora K habit L inflorescence. Scale bars: 1 cm (B, C, H, J, L); 2 mm (D, E, F, G, I). Photos by Z.J. Wen and L. Wu.
. During a series of field investigations at the China-Vietnam border over the past ten years (2009–2019), only three populations of Spiradiclis detianensis have been observed. One site with nearly 59 matured individuals is distributed in Detian Waterfall (type locality), while the other two sites with more than 250 and 114 individuals are in the Longzhou county and Ningming county, respectively. The habitats of the three sites are in good condition and have been rarely influenced by humans. Considering the above, the species can be assigned a status of ‘Least concern’ [LC] following the guidelines of
Our unpublished molecular data indicates that Spiradiclis detianensis shows the closest genetic relationship with S. cordata. Both species prefer to grow on limestone hills from southern Guangxi, China, and have similar habit, such as short stems, subrosulate leaves, long peduncles, heterostylous flowers, funnel-shaped corollas and subglobose capsules. However, the former can be easily distinguished from the latter mainly by its leaf blade basally cuneate (vs. basally cordate) and corolla tubes 1.8–2.2 cm long (vs. ca. 5 mm long) (more detailed comparisons are listed in Table
Morphological comparison of Spiradiclis detianensis, S. tubiflora and S. cordata Lo et W. L. Sha.
Spiradiclis detianensis | S. cordata | S. spathulata | S. tubiflora | |
---|---|---|---|---|
Habit | rosulate to subrosulate | rosulate to subrosulate | rosulate | procumbent to creeping |
Leaf blade | obovate-lanceolate or oblong, 7.0–10.5 × 2.0–3.5 cm, base cuneate, apex obtuse or acute | elliptic-ovate to elliptic-oblong, 5–13 × 2–5.5 cm, base cordate, apex obtuse to rounded | spatulate or obovate-oblanceolate, 8–13 × 2–4.5 cm, base acute to cuneate, apex obtuse to rounded | ovate to elliptic, 0.5–2.5 × 0.4–1.5 cm, base rounded to obtuse, apex acute to rounded |
Secondary vein | 7–10 pairs | 15–19 pairs | 15–25 pairs | 3–5 pairs |
petiole | 0.8–1.7 cm long | 1–7 cm long | 5–8 mm long | 0.3–1.8 cm long |
Stipule | triangular, entire or bifid | deeply 2-lobed, lobes linear | lanceolate-linear or linear | narrowly linear |
Inflorescence | cymose, one per plant, 2–7-flowered | cymose to paniculate, 1–3 per plant, many flowered | cymose, 10– to many flowered | cymose, one per plant, 2–5-flowered |
Peduncle | 9–14 cm long | 6–16 cm long | 7–12 cm long | 1.2–1.5 cm long |
Bract | linear-triangular, 4–6 mm long | linear or subulate, 2 mm long | linear-lanceolate, 3–4 mm long | subulate, 1.8–3.0 mm long |
Calyx lobe | triangular, 1.2–2.9 mm long | triangular, ca. 0.8 mm long | narrowly lanceolate, 1–1.3 mm long | triangular, 1.4–1.6 mm long |
Corolla color | Purple | White | purple-reddish | white |
Corolla tube | tubular-funnelform, sharply enlarged at the 1/3 lower part of the corolla tube, 18–22 mm long | tubular-funnelform, sharply enlarged at the middle or 1/3 upper part of the corolla tube, 5 mm long | slenderly salverform, tube 15–25 mm long | tubular-funnelform, slightly enlarged from the base to the throat, 14–16 mm long |
Corolla inside (long-styled form) | without villous ring | with villous ring at middle | with villous ring at middle | Without villous ring |
Spiradiclis detianensis is very similar to S. spathulata in morphology, since both have subrosetted habit, obovate-oblanceolate leaf blades, long peduncles and subglobose capsules, but it differs mainly by its corolla tubular-funnel shaped (vs. slenderly salver shaped), 4.5–6.8 (vs. 1.5–2) mm in diam. at the middle and densely pubescence inside corolla near base and densely puberulent above anther and onto lobes (vs. glabrous except a ring of long hairs at the middle) (more detailed comparisons are listed in Table
Spiradiclis detianensis is a distinct species in the genus Spiradiclis due to the corolla tubes 18–22 mm long and having the shape of a reversed wine bottle, with an abruptly narrowed lower third, 4.5–6.8 mm in diam. at throat, 1.8–2.5 mm in diam. near base. Until now, only one other known species, S. tubiflora L.Wu, B.M.Wang & B.Pan (
(paratypes). China. Guangxi: Longzhou county, Nonggang National Nature Reserve, 2 April 2019 (fl.), Zheng-Quan Nong nzq0004 (
The author is grateful to the curators of herbaria GSMI, IBSC KUN and PE for permission to examine specimens, and to Mr. Zheng-You Nong and Yu-Song Huang for their help in the field investigation. We also appreciate Ms. Xin-Yi Zeng for her excellent drawing. This study was supported by the Scientific Research Project of Education Department of Hunan Province (grant. no. 18B178).