Research Article |
Corresponding author: Li-Min Lu ( liminlu@ibcas.ac.cn ) Academic editor: Anna Trias-Blasi
© 2021 Romer Narindra Rabarijaona, Valisoa Louisicaël Rafaralahy, Charles Rakotovao, Rindra Manasoa Ranaivoson, Bing Liu, Zhi-Duan Chen, Jun Wen, Li-Min Lu.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Rabarijaona RN, Rafaralahy VL, Rakotovao C, Ranaivoson RM, Liu B, Chen Z-D, Wen J, Lu L-M (2021) Cyphostemma calcarium, a new species of Vitaceae from the Ankarana Special Reserve, Madagascar. PhytoKeys 180: 73-80. https://doi.org/10.3897/phytokeys.180.69194
|
Cyphostemma calcarium Rabarij & L.M.Lu, sp. nov., is herein described as a new species found on limestone outcrops in northern Madagascar. Its diagnostic morphological characteristics were compared to the species occurring in the Ankarana Special Reserve. We present detailed descriptions, illustrations, distribution map, and a preliminary conservation assessment of the species. An identification key to all known species of Cyphostemma from the Ankarana Special Reserve is also provided.
Ankarana, Cyphostemma, Cyphostemma calcarium, Madagascar, Vitaceae
The genus Cyphostemma (Planch.) Alston contains ca. 200 species, representing the second largest genus following Cissus within the grape family, Vitaceae (
In Madagascar, Cyphostemma consists of ca. 25 species and displays substantial morphological diversity (
Since Cyphostemma species were reported to exhibit distinct morphotypes during their vegetative and flowering stages, we conducted an in-depth morphological investigation of all 25 described Cyphostemma species from Madagascar. Of the eight species of Cyphostemma in the Ankarana Special Reserve (Fig.
Morphological comparison of four shrubby tendril-less species of Cyphostemma in the Ankarana Special Reserve, Madagascar.
Taxon | Habit | Stipule | Branch and leaf | Leaf architecture | Flower colour | Style length (mm) | Fruit |
---|---|---|---|---|---|---|---|
C. ankaranense Desc. | suberect or prostrate | ovate to widely triangular, 12–25 × 6–10 mm | glabrous | bi-ternate to bi-pinnate | reddish | ± 0.7 | ellipsoid; 5–7 × 4–5.5 mm |
C. caerulans Desc. | prostrate | ± falcate, 10–15 × 2.5–3.5 mm | glabrous | bi-pinnate | yellowish | ± 1.5 | globose or subglobose; 6.5–9 mm in diameter |
C. rutilans Desc. | erect | triangular; up to ca. 5 × 3 mm | glabrous | 3-foliolate | reddish | ± 1.5 | ellipsoid; 6–8 × 5–6 mm |
C. calcarium Rabarij & L.M.Lu | erect | triangular to ± falcate; 4–5 × 1.5–2.5 mm | pubescent | 3-foliolate, central leaflet often dropped | reddish | ± 2.5 | ellipsoid; 9–12 × 5–7 mm |
The morphological description is based on measurements of dried specimens, supplemented by photos of mature living plants collected from the field. Herbarium specimens and digital images of the most closely-related species to the new described species were examined from the following herbaria: K, P, PE, and TAN. Protologues of type specimens were gathered from
Cyphostemma calcarium is most closely comparable to C. rutilans Desc. in morphology. It differs from the latter in having distinct pubescent branches (vs. branches entirely glabrous in C. rutilans); leaves minutely puberulous and shiny on the adaxial surface, abaxial surface densely whitish pubescent to velvety particularly on the veins (vs. leaves entirely glabrous and shiny on both sides in C. rutilans); and leaflets broadly oblong or elliptic, base cuneate (vs. leaflets narrowly ovate, base subcordate in C. rutilans). Seeds of C. calcarium are ellipsoid in outline, 7–7.5 × 3–3.5 mm, surface rugose to ± muricate (vs. seeds globose, 5–6.5 mm in diameter, surface strongly rugose in C. rutilans).
Comparison of two shrubby Cyphostemma species with 3-foliolate leaves in the Ankarana Special Reserve A–E Cyphostemma calcarium sp. nov. A branches showing puberulent leaves and infructescence B–E seed morphology from Rakotovao C. et al. 6376 (Dorsal, ventral, lateral, and cross-section presented from left to right) F–J Cyphostemma rutilans Desc. F branches with glabrous leaves and inflorescence G–J seed morphology from Bardot-Vaucoulon M. 817 (Dorsal, ventral, lateral, and cross-section presented from left to right). Photos by Rakotovao Charles, Missouri Botanical Garden (A); Billiet Frieda, Meise Botanic Garden (F). The red arrow indicates an extra layer of endotestal sclereids covering the ventral infolds. Scale bars: 1 mm
Madagascar. Antsiranana: Diana, Ankarana Special Reserve, Tsingy Rary, 12°56'24.00"S, 49°07'04"E, 97 m, 16 May 2013, Rakotovao C. et al. 6376 (holotype: TAN!).
Succulent erect shrub, up to 2 m tall. Old stems swollen, succulent; bark smooth, lenticellate; branches brown to reddish, shortly pubescent. Tendrils absent. Stipules triangular to ± falcate, 4–5 × 1.5–2.5 mm, soon caducous. Leaves 3-foliolate, central leaflet often drooping, somewhat thick and fleshy when fresh, becoming coriaceous when dry, usually folded upwards along the midrib; leaflets 3–5 × 1.5–2.5 cm, broadly oblong or elliptic, base cuneate, rounded to obtuse at the apex, margin shallowly denticulate; minutely puberulous and shiny on the adaxial surface, abaxial surface densely whitish pubescent to velvety particularly on the veins; venation closely reticulate, prominent. Petioles 1.5–2.5 cm long. Petiolules equal, up to 1 cm long. Inflorescence a compound dichasium, terminal, ca. 7.5 cm long, very shortly pubescent; bracts inconspicuous; pedicels 2–4 mm. Floral buds ± 2.5 mm long, minutely puberulous or glabrescent; sepals ± 0.5 mm long; petals reddish; stamens 4, filaments cylindrical, ca. 2.2 mm long, anthers ca. 0.8 mm long; ovary glabrous, styles ± 2.5 mm long. Fruits ellipsoid, 9–12 × 5–7 mm, glabrous. Seeds broadly ellipsoid, 7–7.5 × 3–3.5 mm, rugose; base rostrate; beak conspicuous; apex revolute; rugae apex shallowly conspicuous on both surfaces; chalaza linear, sinuate, up to 6 mm long (ca. 6/7 of seed length); ventral ridge raised, elongate but widened in the middle, extending up to 6/7 of seed length; endosperm m-shaped in cross-section.
Cyphostemma calcarium sp. nov. A branches showing the inflorescence and infructescence and the bark with distinct lenticels B trichomes on the abaxial leaflet surface C flower bud constricted at the middle D flower with petals and stamens removed to show the floral disc of 4-large free glands E fruit with a persistent stigma (Illustration by Ai-Li Li; based on Rakotovao C. et al. 6376, TAN).
Flowering and fruiting around May.
The epithet of the species refers to the habitats on limestone outcrops.
It grows on limestone outcrops in northern Madagascar at an altitude of 90–300 m. (Fig.
The new species is endemic to Madagascar with distribution restricted to its type locality. It is assessed here as Critically Endangered (CR) according to the IUCN Categories and Criteria (
This species is described from materials collected by Rakotovao C. et al. in 2013. It was initially identified as Cissus pileata Desc., but it clearly belongs to Cyphostemma in having constricted flower buds and floral disks with four free glands. These characters, together with its M-shaped endosperm as viewed in cross sections of the seeds and the presence of extra layers of endotestal sclereids covering the ventral infolds in cross-section, clearly distinguish the new species from Cissus L. A summary of some diagnostic characters that differentiate this new species from other shrubby species of Cyphostemma in Ankarana Special Reserve is provided in Table
1a | Shrubby succulent plants; tendrils absent | 2 |
1b | Climbers to woody vines, sometimes tree-like; tendrils usually present | 5 |
2a | Stems erect or suberect; leaves usually 3-foliolate; flowers reddish | 3 |
2b | Stems rather prostrate; leaves pinnately arranged; flowers green to yellowish | 4 |
3a | Young stems, branches, and petioles glabrous; leaves entirely glabrous and shiny on both sides; leaflets narrowly ovate, base subcordate | C. rutilans |
3b | Young stems, branches, and petioles puberulent; leaves minutely puberulous and shiny on the adaxial surface, abaxial surface densely whitish pubescent to velvety particularly on the veins; leaflets elliptic, base cuneate | C. calcarium |
4a | Leaflets narrowly oblong-elliptic, overall with a reddish tone; stipules ovate to widely triangular, 12–25 × 6–10 mm; flowers pale green; fruits ovoid or elongate–ellipsoid, apiculate | C. ankaranense |
4b | Leaflets rhomboid, ovate or suborbicular, rather green; stipules ± falcate, lanceolate-acuminate, 10–15 × 2.5–3.5 mm; flowers yellowish; fruits globose or subglobose, not apiculate | C. caerulans |
5a | Leaves digitately arranged, 3–5-foliolate | C. glanduloso-pilosum |
5b | Leaves pinnately arranged | 6 |
6a | Trunk sub-spherical, 0.50–0.70 m diameter; bark flaking, corky to reticulately fissured; inflorescences and flowers reddish | C. pachypus |
6b | Trunk tree-like, up to 5 m tall or even taller; bark smooth, peeling, papery; inflorescences and flowers green to yellowish | 7 |
7a | Leaflets 1-pinnate, densely pubescent; petioles 4–6 cm long; inflorescences 6–10 cm, usually shorter, densely pubescent; fruits subglobose, 12–13 mm in diameter | C. macrocarpum |
7b | Leaflets 2-pinnate, glabrous; petioles 6–12 cm long; inflorescences 8–15 cm long, glabrous above, with scattered white-pubescence at the base of the nerves beneath, somewhat-like domatia; fruits ellipsoid, 10–12 × 6–7 mm | C. greveanum |
We are grateful to our collaborators from the Mention Biologie et Ecologie Végétale (MBEV)-Université d’Antananarivo, Madagascar, the curators of the Parc Botanique et Zoologique Tsimbazaza (TAN), especially Rapanarivo Solohery Jean Victor, for facilitating access to the collections, Plant Science Facility of the Institute of Botany, Chinese Academy of Sciences for their technical assistance, and Ai-Li Li for the line drawing. This study was supported by the National Natural Science Foundation of China (31870197), the International Partnership Program of CAS (151853KYSB 20190027), the Sino-Africa Joint Research Center, CAS International Research and Education Development Program (SAJC202101), and the Biological Resources Programme, CAS (KFJ-BRP-017-50). Li‐Min Lu was partially supported by the Young Elite Scientist Sponsorship Program by CAST (2018QNRC001) and the Youth Innovation Promotion Association CAS (2020080). Romer Narindra Rabarijaona was supported by CAS‐TWAS President’s Fellowship for International Ph.D. Students.