Research Article |
Corresponding author: Junhao Chen ( onchidium@gmail.com ) Academic editor: Thomas L.P. Couvreur
© 2020 Junhao Chen, Wichan Eiadthong.
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:
Chen J, Eiadthong W (2020) New species and new records of Artabotrys (Annonaceae) from peninsular Thailand. PhytoKeys 151: 67-81. https://doi.org/10.3897/phytokeys.151.51643
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Two new species of Artabotrys (Annonaceae) are described from peninsular Thailand. Artabotrys longipetalus J.Chen & Eiadthong, sp. nov., is unique among Artabotrys species in Thailand in having linear petals, relatively long flower pedicels and sessile monocarps. Artabotrys insurae J.Chen & Eiadthong, sp. nov., resembles Artabotrys uniflorus (Griff.) Craib, but can be distinguished by its oblique leaf base, flat petal blades, apiculate anther connective apex and the presence of a monocarp stipe. In addition, two new records for the Flora of Thailand are reported, viz. Artabotrys crassifolius Hook.f. & Thomson and Artabotrys pleurocarpus Maingay ex Hook.f. & Thomson; both species are so far only known from peninsular Thailand. A key to the 20 species of Artabotrys in Thailand is provided.
Annonaceae, Artabotrys, new records, new species, peninsular Thailand
Artabotrys R.Br. (Annonaceae) is a palaeotropical genus of woody climbers that inhabits tropical rain forests and seasonally dry forests. The genus comprises over 100 species, with the majority occurring in Asia, ca. 30 species in Africa, and one species in Northern Australia (
Herbarium specimens are easily assigned to Artabotrys if the diagnostic inflorescence hooks are present. The inflorescence is sometimes only slightly recurved, however; in rare cases, it does not manifest as a hook (Fig.
A Artabotrys hexapetalus, with condensed lateral inflorescence branches borne on a peduncle that barely resembles a hook B Artabotrys suaveolens, with elongate lateral inflorescence branches (LIf) borne on a conspicuously hooked peduncle. HF1: Hook leaf 1; HF2: Hook leaf 2 (H. Sauquet HS164). Photos: A J. Chen B T.L.P. Couvreur.
Although Thailand is considered to be well known botanically, there remains an upward trend in the number of plant species described from Thailand (
The material studied include herbarium specimens of Artabotrys from Thailand and neighbouring regions housed in various herbaria (A, BK, BKF, L, PSU, QBG and SING) and digital images of specimens (especially types) from JSTOR Global Plants (https://plants.jstor.org/) and other online herbarium databases viz. AAU (https://www.aubot.dk/search_form.php), BM (https://data.nhm.ac.uk/dataset/collection-specimens), E (https://data.rbge.org.uk/search/herbarium), K (https://apps.kew.org/herbcat/navigator.do), L (https://bioportal.naturalis.nl) and P (https://science.mnhn.fr/institution/mnhn/collection/p/item/search). All specimens cited in this paper have been seen. All measurements were taken from herbarium specimens.
The conservation status of the new species was assessed using the criteria stipulated in the IUCN Red List (
Distinct from A. tipuliferus I.M.Turner & Utteridge (Fig.
A, B Artabotrys longipetalus sp. nov. A habit and inflorescence (T. Insura 57) B flowers, showing linear petals with acute apex (T. Insura 57) C, D Artabotrys tipuliferus C flowers, showing short flower pedicel and linear petals (S. Phusomsaeng 272) D fruit, showing short fruit pedicel and stipitate monocarps (T. Insura 56) E, F Artabotrys multiflorus E flowers, showing lanceolate petals with acute to obtuse apex F hooked inflorescence with many flowers. Photos: A, B, D T. Insura C Royal Botanic Garden Edinburgh E, F P. Chalermglin.
Peninsular Thailand. Surat Thani Province: Ban Na San District, Tai Rom Yen National Park, Dat Fa Waterfall, 730 m elev., 25 February 2006, S. Gardner ST2374 (holotype: BKF [SN 198209]; isotypes: BKF [SN 198210], QBG [SN 49402]).
Climbers, to ca. 10 m tall. Twigs drying light brown to brownish black, glabrous, epidermis non-flaky. Leaf laminas 8.5–15 cm long, 2.9–7.7 cm wide, elliptic to oblong-elliptic, chartaceous, glabrous above and below; base cuneate or decurrent on petiole; apex acute to acuminate, acumen up to 5 mm long; midrib raised to flush above, prominent below; secondary veins 7–12 pairs per leaf, raised to flush above and below; tertiary venation reticulate, visible on both surfaces; petiole 2–8 mm long, 1–1.5 mm in diameter, glabrous. Inflorescences 1–15-flowered, peduncles recurved (often laterally compressed and hook-like), glabrous, lateral branches condensed, pedicels 8–16 mm long, ca. 1 mm in diameter, subglabrous. Sepals 3, free, valvate, ca. 1.5 mm long, 1.5–2 mm wide, ovate, glabrous inside, sparsely puberulent outside, apex acute, green in vivo. Petals 6, free, valvate, sparsely appressed-pubescent to glabrous on both surfaces except the glabrous base inside, membranous, greenish yellow in vivo, blade often curly, base concave. Outer petals 3, 35–45 mm long, claw 2–2.5 mm wide, blade 1–2 mm wide, linear, apex acute. Inner petals 3, 32–40 mm long, claw 1.5–2 mm wide, blade 1–1.5 mm wide, linear, apex acute. Stamens 25–35, ca. 1 mm long, ca. 1 mm wide, oblong, anther connective apex truncate. Carpels 8–10, ovary ca. 1 mm long, ca. 0.5 mm wide, stigma ca. 0.5 mm long, cylindrical. Fruit of up to 8 monocarps borne on a glabrous pedicel 19–22 mm long, ca. 4 mm in diameter. Monocarps ca. 26 mm long, 18–20 mm wide, broadly ellipsoid, rough, glabrous, apex weakly beaked (ca. 1 mm long) or rounded, sessile, colour in vivo unknown, drying brownish black, pericarp thickness unknown. Seeds not seen.
Flowering specimens collected in February and August; fruiting specimens collected in May.
So far only known from peninsular Thailand (Fig.
Etymology. The specific epithet reflects the long petals of this species.
Artabotrys longipetalus is only known from three localities, with estimated EOO and AOO of 1,165 km2 and 12 km2, respectively. All the localities are well within the boundaries of various National Parks in Thailand. Nevertheless, this species may become threatened with future climate change and/or other unpredictable threats owing to its restricted AOO and few known locations. Therefore, we suggest a status of Vulnerable [VU D2].
Peninsular Thailand. Nakhon Si Thammarat Province: Lan Saka District, Khao Luang National Park, Karom Waterfall, 100 m elev., 11 August 2006, T. Insura 57 (BKF). Surat Thani Province: Vibhavadi District, Kaeng Krung National Park, ridge ca. 2 km east of Ban Cham village, 200 m elev., 13 May 2006, S. Gardner & P. Sidisunthorn ST2731 (BKF).
Artabotrys longipetalus is similar to A. multiflorus from Myanmar (Dawna Range) and Thailand (Kanchanaburi and Tak) in having long, narrow petals and sessile monocarps with rounded to weakly beaked apex. Also comparable to the new species, A. arachnoides J.Sinclair from New Guinea shares a similar floral morphology of long, linear, curly petals and long flower pedicels but differs in its highly coriaceous leaves, larger sepals (4–5 mm long) and larger petals (50–60 mm long, 2–3 mm wide). A number of Artabotrys species also possess linear petals but have very short flower pedicels (2–4 mm long): A. speciosus Kurz from the Andaman Islands, A. sumatranus Miq. from Sumatra, Java and Borneo (Kalimantan), and A. tipuliferus from peninsular Thailand and Peninsular Malaysia. Significantly, A. longipetalus was previously confused with A. sumatranus in
Distinct from other Artabotrys species in Thailand in having oblique leaf base and erect-pubescent lower leaf surface. Similar to A. uniflorus Craib (Fig.
Peninsular Thailand. Surat Thani Province: Vibhavadi District, Khlong Yan Wildlife Sanctuary, trail from headquarters, ca. 200 m elev., 31 August 2002, D.J. Middleton et al. 1487 (holotype: BKF [SN 142020]; isotype: A).
Artabotrys insurae sp. nov. A habit and leaves, showing caudate to acuminate leaf apex (C. Leeratiwong 18-1522) B oblique leaf base and inflorescence with hooked peduncle (C. Leeratiwong 18-1522) C flower, showing oblong-ovate outer petals and oblong-elliptic inner petals (C. Leeratiwong 18-1522) D fruit (C. Leeratiwong 17-1116). Photos: C. Leeratiwong.
Climbers, to ca. 5 m tall. Twigs drying light brown to greyish black, sparsely to densely erect-pubescent, becoming glabrous, epidermis non-flaky. Leaf laminas 9–19 cm long, 3.7–7.5 cm wide, oblong-elliptic to oblong-obovate, chartaceous, glabrous above except the sparsely erect-pubescent midrib and secondary veins, sparsely to densely erect-pubescent below; base oblique; apex caudate to acuminate, acumen up to 15 mm long; midrib sunken above, prominent below; secondary veins 8–13 per side, sunken to flush above, raised below; tertiary venation reticulate, visible on both surfaces; petiole 3–10 mm long, 1–1.5 mm in diameter, erect-pubescent. Inflorescences 1-flowered (rarely 2-flowered), peduncles recurved (often laterally compressed and hook-like), sparsely erect-pubescent, lateral branches condensed, pedicels 5–15 mm long, ca. 1 mm in diameter, sparsely to densely erect-pubescent. Sepals 3, free, valvate, 6–10 mm long, 5–6 mm wide, ovate, sparsely puberulent inside, densely puberulent outside, apex acute, green in vivo. Petals 6, free, valvate, sparsely to densely puberulent on both surfaces except the glabrous base inside, chartaceous, yellow in vivo, blade flat, base concave. Outer petals 3, 17–29 mm long, claw 6–8 mm wide, blade 6–12 mm wide, oblong-ovate, apex acute. Inner petals 3, 16–28 mm long, claw 4–6 mm wide, blade 3–6 mm wide, oblong-elliptic, apex acute. Stamens 20–30, ca. 2 mm long, ca. 1 mm wide, oblong, anther connective apex apiculate. Carpels 10–14, ovary ca. 3 mm long, ca. 0.5 mm wide, stigma ca. 2 mm long, cylindrical. Fruit of up to 10 monocarps borne on a subglabrous pedicel 8.5–20 mm long, 2–2.5 mm in diameter. Monocarps 23–27 mm long, 10–13 mm wide, ellipsoid, smooth, glabrous, apex weakly beaked (ca. 1 mm long), base contracted into a stipe 1.5–4 mm long, green in vivo, drying brownish black, pericarp ca. 2 mm thick. Seeds 15.5–17.8 mm long, 9.4–10.7 mm wide, 4.6–5.2 mm thick, generally smooth with wrinkled area on sides, light yellowish brown.
A–C Artabotrys insurae sp. nov. A habit (T. Insura 58) B flower, showing flat petal blades (T. Insura 58) C fruit, showing weakly beaked monocarps with distinct stipes (D.J. Middleton et al. 1487) D–F Artabotrys uniflorus D habit E flower, showing three-angled petal blades F fruit, showing strongly beaked monocarps that are sessile. Photos: A, B T. Insura C D.M. Johnson D–F P. Chalermglin.
Flowering and fruiting specimens collected in August and September. Fruiting specimens also collected in February and June.
So far only known from peninsular Thailand (Fig.
The specific epithet was given in honour of Mr Tawee Insura, whose prolific collection of Artabotrys specimens during his MSc study led to the discovery of several new species and new records for Thailand.
Artabotrys insurae is estimated to have an EOO of 15,994 km2 and an AOO of 20 km2. This species largely occurs within various Wildlife Sanctuaries, which constitute Protected Areas in Thailand. A population exists in a remnant forest adjacent to Khao Le Buddhist Temple in Songkhla; such vegetation is regarded as sacrosanct and hence would likely remain undisturbed. We suggest a status of Vulnerable [VU D2] for this species because its restricted AOO makes it susceptible to future threats such as climate change.
Peninsular Thailand. Narathiwat Province: Sukhirin District, Hala-Bala Wildlife Sanctuary, 7 September 2006, T. Insura 75 (BK, BKF). Songkhla Province: Hat Yai District, Ton Nga Chang Wildlife Sanctuary, Puangpen et al. N192 (QBG); idem, Ton Nga Chang Waterfall, 150 m elev., 2 February 1997, C. Leeratiwong s.n. (PSU); idem, 80 m elev., 12 August 2006, T. Insura 58 (BK, BKF); Sadao District, Khao Le, 150 m elev., 16 August 2018, C. Leeratiwong 18-1522 (PSU); Sadao District, Ton Nga Chang Wildlife Sanctuary, Pha Dam Ranger Station, 350 m elev., 2 June 2017, C. Leeratiwong 17-1116 (PSU).
This species is most similar to A. uniflorus from peninsular Thailand (Chumphon, Ranong, Phang-Nga and Surat Thani) in having erect-pubescent lower leaf surfaces, 1-flowered (rarely 2-flowered) inflorescences, caudate to acuminate leaf apex and relatively narrow monocarps (10–15 mm wide). Its distribution overlaps with A. uniflorus in Surat Thani. Artabotrys siamensis Miq. from Northern, Northeastern, Eastern and Southwestern Thailand is also similar in having erect-pubescent lower leaf surfaces, but is distinct due to its coriaceous leaves, cuneate leaf base, thicker petals, numerous carpels (25–29 per flower), numerous monocarps (up to 22 per fruit) and broader monocarps (15–20 mm wide).
Artabotrys pleurocarpus
Maingay ex Hook.f. & Thomson, Fl. Brit. India 1: 54 (1872). Type: Peninsular Malaysia. Malacca, 6 Feb 1868, A.C. Maingay 3261 [Kew distribution no. 34] (lectotype K [K000381010], designated in
Peninsular Malaysia and peninsular Thailand (Fig.
Peninsular Thailand. Songkhla Province: Rattaphum District, Boripat Forest Park, 4 July 1986, J.F. Maxwell 86-444 (A) [A00571911]; idem, 6 April 2006, T. Insura 61 (BK, BKF). Satun Province: Thale Ban National Park, Ton Plio Falls, open area by stream, 115 m elev., 3 June 2001, R. Pooma et al. 2004 (BKF) [SN 134816]. Trang Province: Na Yong District, Ton Pliw Waterfall, 7 April 2006, T. Insura 62 (BK, BKF); idem, 7 April 2006, T. Insura 63 (BK, BKF); idem, 7 April 2006, T. Insura 64 (BK, BKF).
This species was hitherto known from Malacca, Kedah and Perak in Peninsular Malaysia (
Artabotrys crassifolius
Hook.f. & Thomson, Fl. Brit. India 1: 54 (1872). Type: Peninsular Malaysia. Malacca, Griffith s.n. [EIC 426] (lectotype: K [K000607645], designated in
Singapore, Peninsular Malaysia, peninsular Thailand (Fig.
Peninsular Thailand. Trang Province: Palian District, Lam Plok Waterfall, ca. 20 m elev., 4 May 2010, W. Eiadthong 2010-1 (BK, BKF).
The protologue for A. crassifolius cites a specimen from Martaban in Myanmar. In addition, a regional checklist (
1 | Axillary shoots often with thorns; leaf apex retuse, truncate, rounded or mucronate (rarely acute); riparian plants | A. spinosus |
– | Axillary shoots without thorns; leaf apex acute, acuminate or caudate (rarely or never retuse, truncate, rounded or mucronate); forest plants | 2 |
2 | Young twigs erect-pubescent; leaves erect-pubescent below | 3 |
– | Young twigs appressed-pubescent, puberulent or glabrous; leaves glabrous or appressed-pubescent below | 5 |
3 | Leaves coriaceous, apex acute to acuminate (never caudate), base cuneate; petals coriaceous; carpels 25–29 per flower; monocarps up to 22 per fruit, 15–20 mm wide | A. siamensis |
– | Leaves chartaceous, apex caudate to acuminate, base rounded or oblique (rarely cuneate); petals chartaceous; carpels 10–18 per flower; monocarps up to 12 per fruit, 10–15 mm wide | 4 |
4 | Leaf base rounded, rarely cuneate; petal blades three-angled; anther connective apex truncate; monocarps sessile, apex strongly beaked (2–5 mm long) | A. uniflorus |
– | Leaf base oblique; petal blades flat; anther connective apex apiculate; monocarp base contracted into a stipe 1.5–4 mm long, apex weakly beaked (ca. 1 mm long) | A. insurae |
5 | Young twigs, flower pedicels and lower surface of sepals with a dense covering of long appressed hairs (visible with the naked eye) | A. crassifolius |
– | Young twigs, flower pedicels and lower surface of sepals glabrous or with a sparse covering of short appressed hairs (visible with hand lens) | 6 |
6 | Twigs with flaky outer layer; leaf blades 21–33 cm long, tertiary venation subscalariform; inflorescence lateral branches often elongate (up to 6 cm long) | A. byrsophyllus |
– | Twigs usually with unbroken outer layer; leaf blades 5–20 cm long, tertiary venation reticulate; inflorescence lateral branches condensed or short (up to 2.5 cm long) | 7 |
7 | Petals cream-white in vivo, blades terete; monocarps 1–2(–5) per fruit | A. suaveolens |
– | Petals yellow, orange, beige, maroon or brown in vivo, blades not terete; monocarps 4–30 per fruit | 8 |
8 | Petals 7–14 mm long | 9 |
– | Petals 15–45 mm long | 11 |
9 | Leaves lanceolate, base oblique or rounded; flower pedicels 3–6 mm long; outer petals ovate; monocarp base contracted into a stipe ca. 4 mm long | A. oblanceolatus |
– | Leaves oblong-elliptic to oblong-obovate, base cuneate or decurrent on petiole; flower pedicels 7–10 mm long; outer petals deltoid; monocarps sessile or with base contracted into a stipe up to 2 mm long | 10 |
10 | Leaf apex acuminate to caudate; outer petal blades flat, inner petal blades spathulate; monocarp apex strongly beaked (ca. 2 mm long) | A. spathulatus |
– | Leaf apex acute; outer petal blades undulate, inner petal blades rhomboid; monocarp apex weakly beaked (less than 1 mm long) | A. tanaosriensis |
11 | Anther connective apex apiculate | 12 |
– | Anther connective apex truncate | 16 |
12 | Sepals ca. 3 mm long, ca. 2.5 mm wide; petal blades 1–2 mm wide | A. tipuliferus |
– | Sepals 5–10 mm long, 5–8 mm wide; petal blades 5–18 mm wide | 13 |
13 | Flower pedicels 5–9 mm long | 14 |
– | Flower pedicels 15–32 mm long | 15 |
14 | Leaf apex often caudate (sometimes acuminate); carpels ca. 10 per flower; monocarps up to 9 per fruit, 22–30 mm long, 15–20 mm wide, base contracted into a stipe 7–10 mm long | A. pleurocarpus |
– | Leaf apex acute to acuminate (never caudate); carpels ca. 20 per flower; monocarps up to 17 per fruit, 18–20 mm long, 11–15 mm wide, base contracted into a stipe 3–4 mm long | A. brevipes |
15 | Leaves membranous; monocarp apex beaked (ca. 2 mm long), base contracted into a stipe 4–5 mm long; cultivated only | A. hexapetalus |
– | Leaves coriaceous; monocarp apex rounded (rarely weakly beaked), base contracted into a stipe 5–12 mm long; occurs in the wild | A. harmandii |
16 | Outer petal blades 11–14 mm wide, broadly elliptic; monocarps 8–10 mm wide, apex sharply beaked ca. 5 mm long | A. oxycarpus |
– | Outer petal blades 1–7 mm wide, ovate, lanceolate or linear; monocarps 15–28 mm wide, apex rounded or beaked up to 3 mm long | 17 |
17 | Outer petals ovate; monocarp base contracted into a stipe 1–3 mm long | 18 |
– | Outer petals lanceolate or linear; monocarps sessile | 19 |
18 | Leaves chartaceous; inflorescences 10–20-flowered; carpels 15–20 per flower; monocarp apex rounded or weakly beaked; inhabits montane forests at 900–1700 m | A. punctulatus |
– | Leaves coriaceous; inflorescences 3–5-flowered; carpels ca. 10 per flower; monocarp apex beaked ca. 3 mm long; inhabits lowland forests | A. venustus |
19 | Leaves coriaceous; petals lanceolate, apex obtuse to acute; outer petals 18–30 mm long, blade 3–5 mm wide; inner petals 18–27 mm long, blade 2–4 mm wide | A. multiflorus |
– | Leaves chartaceous; petals linear, apex acute; outer petals 35–45 mm long, blade 1–2 mm wide; inner petals 32–40 mm long, blade 1–1.5 mm wide | A. longipetalus |
We thank Tawee Insura, Piya Chalermglin, Charan Leeratiwong and David Johnson for use of their photographs. We are also grateful to David Johnson and Charan Leeratiwong for their advice and assistance in taking measurements of Artabotrys specimens. The curators of A, BK, BKF, L, PSU, QBG and SING made specimens and specimen images available for study. Financial support was received from the National Parks Board (Singapore). Finally, we thank David Johnson and Timothy Utteridge for their constructive and comprehensive comments on the manuscript.