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Artabotrys from peninsular ailand 67
New species and new records of Artabotrys
(Annonaceae) from peninsular Thailand
Junhao Chen1, Wichan Eiadthong2,†
1 Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, 259569, Singapore 2 Faculty of Forestry,
Kasetsart University, Bangkhen campus, Jattujak, Bangkok, ailand
Corresponding author: Junhao Chen (patrickjunhao@gmail.com)
Academic editor: omas L.P. Couvreur|Received 3 March 2020|Accepted 20 April 2020|Published 17 June2020
Citation: Chen J, Eiadthong W (2020) New species and new records of Artabotrys (Annonaceae) from peninsular
ailand. PhytoKeys 151: 67–81. https://doi.org/10.3897/phytokeys.151.51643
Abstract
Two new species of Artabotrys (Annonaceae) are described from peninsular ailand. Artabotrys longi-
petalus J.Chen & Eiadthong, sp. nov., is unique among Artabotrys species in ailand in having linear
petals, relatively long ower pedicels and sessile monocarps. Artabotrys insurae J.Chen & Eiadthong, sp.
no v., resembles Artabotrys uniorus (Gri.) Craib, but can be distinguished by its oblique leaf base, at
petal blades, apiculate anther connective apex and the presence of a monocarp stipe. In addition, two new
records for the Flora of ailand are reported, viz. Artabotrys crassifolius Hook.f. & omson and Art-
abotrys pleurocarpus Maingay ex Hook.f. & omson; both species are so far only known from peninsular
ailand. A key to the 20 species of Artabotrys in ailand is provided.
Keywords
Annonaceae, Artabotrys, new records, new species, peninsular ailand
Introduction
Artabotrys R.Br. (Annonaceae) is a palaeotropical genus of woody climbers that in-
habits tropical rain forests and seasonally dry forests. e genus comprises over 100
species, with the majority occurring in Asia, ca. 30 species in Africa, and one species in
Northern Australia (Chen et al. 2018). e presence of specialised inorescence hooks
that assist climbing distinguishes Artabotrys from other Annonaceae climbers. A recent
† Deceased
PhytoKeys 151: 67–81 (2020)
doi: 10.3897/phytokeys.151.51643
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Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
68
molecular phylogenetic study (Chen et al. 2019) revealed that the genus consists of
an early-divergent grade (EDG) of two African species, and a main Artabotrys clade
(MAC) comprising an Asian clade sister to an African clade. Artabotrys possess trimer-
ous owers, with a whorl of sepals and two whorls of petals. e outer and inner petals
are generally similar in size whereas the sepals are much smaller than the petals. MAC
species are characterised by petals with a distinct upper blade and a basal concave claw,
and an elaborate rim between the inner petal blade and claw which enables the inner
petals to cohere tightly over the reproductive organs (Chen et al. 2020). Conversely,
EDG species lack a projecting rim on the inner petals, with one species (A. brachypeta-
lus Benth.) entirely lacking the distinction between petal blade and claw (Chen et al.
2020). e owers of Artabotrys are hermaphroditic, with many stamens and few to
many unfused carpels. Each carpel has two ovules on a basal placenta. After fertilisa-
tion, these carpels develop into free monocarps that are sessile or borne on short stipes.
Herbarium specimens are easily assigned to Artabotrys if the diagnostic inorescence
hooks are present. e inorescence is sometimes only slightly recurved, however; in rare
cases, it does not manifest as a hook (Fig. 1A). e inorescence hook is peculiar with
regard to its morphology and ontogeny, which are discussed in great detail in Posluszny
and Fisher (2000). e hook formation involves successive development of two hook
leaves (hook leaf 1, HL1 followed by hook leaf 2, HL2), attening and curving of the
inorescence away from the main shoot, and curving of the inorescence back towards
the main shoot. Uneven tissue expansion displaces HL1 to the distal position and HL2 to
the proximal position (gs 23, 24 in Posluszny and Fisher 2000). e oral bud in the
axil of HL2 is in fact the original apical meristem. e denition of the peduncle, which
is usually the distance between the rst-formed lower bract and the twig, is contentious
in Artabotrys because the rst-formed bract (HL1) is not in the lowest (proximal) posi-
tion. Here, we regard the entire hook (curved axis from HL1 to twig) as the peduncle
but it should be noted that its morphology is highly variable within a species, becoming
woody as it clasps onto a twig or not manifest as a hook at all as mentioned earlier. Fur-
ther higher-order branching of the hook inorescence may occur, resulting in the forma-
tion of lateral branches, which are dened as the axes between the hook and the base of
the last pedicel (Fig. 1B). e inorescence lateral branches may be condensed (Fig. 1A,
2F) or elongate (Fig. 1B). Although the genus is easily recognised, identication at the
species level is not as straightforward. Petal morphology is sometimes useful (especially
for fresh material), but a suite of more subtle characters are often needed for the identi-
cation of herbarium specimens. e characters of taxonomic utility in Artabotrys include
indumentum on lower leaf surface (erect vs. appressed), leaf base (cuneate vs. decurrent
on petiole vs. rounded vs. oblique), pedicel length, sepal size, petal size and shape, anther
connective apex (apiculate vs. truncate), number of carpels per ower, number of mono-
carps per fruit, monocarp apex, monocarp stipe length and monocarp size.
Although ailand is considered to be well known botanically, there remains an
upward trend in the number of plant species described from ailand (Middleton et al.
2019). is is also the case for Annonaceae, particularly in peninsular ailand where
new Annonaceae species are continuously added to the baseline of 39 species listed in
Craib (1925). Over the past ve years, for instance, an Alphonsea species (Turner and
Artabotrys from peninsular ailand 69
Figure 1. A Artabotrys hexapetalus, with condensed lateral inorescence branches borne on a peduncle
that barely resembles a hook B Artabotrys suaveolens, with elongate lateral inorescence 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.
Utteridge 2017), two Artabotrys species (Turner and Utteridge 2015; Chen et al. 2018),
a Meiogyne species (Johnson et al. 2019), two Mitrephora species (Damthongdee et al.
2019; Saunders and Chalermglin 2019) and two Xylopia species (Johnson and Murray
2019) were recently reported as new to science and narrowly distributed in peninsular
ailand and/or northern Peninsular Malaysia. During the preparation of a revision of
Artabotrys for the Flora of ailand, two new species and two new records from penin-
sular ailand are discovered and reported here, bringing the total number of species
recognised for ailand to 20 (including the commonly cultivated A. hexapetalus (L.f.)
Bhandari). A key to the 20 species of Artabotrys in ailand is provided.
Material and methods
e material studied include herbarium specimens of Artabotrys from ailand 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.
e conservation status of the new species was assessed using the criteria stipulated
in the IUCN Red List (IUCN 2012). e extent of occurrence (EOO) and area of oc-
cupancy (AOO) of each new species were calculated with the default 2 km2 grid using
GeoCAT (Bachman et al. 2011; http://geocat.kew.org). e abbreviations used in the
conservation assessments follow IUCN (2012).
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
70
New species descriptions
Artabotrys longipetalus J.Chen & Eiadthong, sp. nov.
urn:lsid:ipni.org:names:77209924-1
Fig. 2A, B
Diagnosis. Distinct from A. tipuliferus I.M.Turner & Utteridge (Fig. 2C, D), the
only other Artabotrys species in ailand with linear petals, by its relatively long ower
pedicels (8–16 mm long vs. 2–4 mm long) and sessile (vs. stipitate) monocarps. Simi-
lar to A. multiorus C.E.C.Fisch. (Fig. 2E, F) but distinguished by its chartaceous (vs.
coriaceous) leaves, acute (vs. obtuse to acute) petal apex and linear (vs. narrowly lan-
ceolate) petals, specically its longer and narrower outer petals (35–45 mm long, blade
1–2mm wide vs. 18–30 mm long, blade 3–5 mm wide) and inner petals (32–40 mm
long, blade 1–1.5 mm wide vs. 18–27 mm long, blade 2–4 mm wide).
Type. P T. Surat ani 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]).
Description. Climbers, to ca. 10 m tall. Twigs drying light brown to brownish black,
glabrous, epidermis non-aky. 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 ush above,
prominent below; secondary veins 7–12 pairs per leaf, raised to ush above and below;
tertiary venation reticulate, visible on both surfaces; petiole 2–8 mm long, 1–1.5 mm
in diameter, glabrous. Inorescences 1–15-owered, 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, 1.5–2mm
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 gla-
brous 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, lin-
ear, 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. 0.5mm
long, cylindrical. Fruit of up to 8 monocarps borne on a glabrous pedicel 19–22mm 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.
Phenology. Flowering specimens collected in February and August; fruiting speci-
mens collected in May.
Distribution and habitat. So far only known from peninsular ailand (Fig. 6).
It occurs in lowland rain forests at elevation 100–730 m, in both undisturbed and
partially disturbed sites, sometimes along ridges.
Etymology. e specic epithet reects the long petals of this species.
Artabotrys from peninsular ailand 71
Figure 2. A, B Artabotrys longipetalus sp. nov. A habit and inorescence (T. Insura 57) B owers, showing lin-
ear petals with acute apex (T. Insura 57) C, D Artabotrys tipuliferus C owers, showing short ower pedicel and
linear petals (S. Phusomsaeng 272) D fruit, showing short fruit pedicel and stipitate monocarps (T. Insura 56) E,
F Artabotrys multiorus E owers, showing lanceolate petals with acute to obtuse apex Fhooked inorescence
with many owers. Photos: A, B , D T. Insura C Royal Botanic Garden Edinburgh E, F P. Chalermglin.
Preliminary conservation status. 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 ailand.
Nevertheless, this species may become threatened with future climate change and/
or other unpredictable threats owing to its restricted AOO and few known locations.
erefore, we suggest a status of Vulnerable [VU D2].
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
72
Additional specimens examined. P T. Nakhon Si ammarat
Province: Lan Saka District, Khao Luang National Park, Karom Waterfall, 100 m elev.,
11 August 2006, T. Insura 57 (BKF). Surat ani 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).
Notes. Artabotrys longipetalus is similar to A. multiorus from Myanmar (Dawna
Range) and ailand (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 oral morphology of long,
linear, curly petals and long ower pedicels but diers 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 ower pedi-
cels (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 ai-
land and Peninsular Malaysia. Signicantly, A. longipetalus was previously confused
with A. sumatranus in Insura (2009). “Artabotrys sumatranus” in Insura (2009) consists
of mixed elements: the description and line drawing of the vegetative parts and owers
match A. longipetalus whereas the description and line drawing of the fruit match A.
tipuliferus. Apart from the short ower pedicels, A. tipuliferus can be further distin-
guished from the new species by its apiculate anther connective apex and the presence
of a monocarp stipe (ca. 1 cm long) whereas A. sumatranus is distinct from the new spe-
cies in having shorter petals (up to 15 mm long) and apiculate anther connective apex.
Artabotrys insurae J.Chen & Eiadthong, sp. nov.
urn:lsid:ipni.org:names:77209925-1
Fig. 3, 4A–C
Diagnosis. Distinct from other Artabotrys species in ailand in having oblique leaf
base and erect-pubescent lower leaf surface. Similar to A. uniorus Craib (Fig. 4D–F)
but with oblique (vs. rounded or rarely cuneate) leaf base, at (vs. three-angled) petal
blades, apiculate (vs. truncate) anther connective apex and short-stipitate (vs. sessile)
monocarps that are weakly beaked (beak ca. 1 mm long vs. 2–5 mm long).
Type. P T. Surat ani 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).
Description. Climbers, to ca. 5 m tall. Twigs drying light brown to greyish black,
sparsely to densely erect-pubescent, becoming glabrous, epidermis non-aky. Leaf lami-
nas 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 ush above, raised below; tertiary venation reticulate, visible on both
Artabotrys from peninsular ailand 73
Figure 3. Artabotrys insurae sp. nov. A habit and leaves, showing caudate to acuminate leaf apex (C. Leer-
atiwong 18-1522) B oblique leaf base and inorescence with hooked peduncle (C. Leeratiwong 18-1522)
C ower, showing oblong-ovate outer petals and oblong-elliptic inner petals (C. Leeratiwong 18-1522)
Dfruit (C. Leeratiwong 17-1116). Photos: C. Leeratiwong.
surfaces; petiole 3–10 mm long, 1–1.5 mm in diameter, erect-pubescent. Inorescenc-
es 1-owered (rarely 2-owered), 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 at,
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. 2mm long, ca.
1mm wide, oblong, anther connective apex apiculate. Carpels 10–14, ovary ca. 3 mm
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
74
Figure 4. A–C Artabotrys insurae sp. nov. A habit (T. Insura 58) B ower, showing at petal blades (T.
Insura 58) C fruit, showing weakly beaked monocarps with distinct stipes (D.J. Middleton et al. 1487)
D–F Artabotrys uniorus D habit E ower, 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.
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 brown-
ish 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.
Phenology. Flowering and fruiting specimens collected in August and September.
Fruiting specimens also collected in February and June.
Distribution and habitat. So far only known from peninsular ailand (Fig. 6).
It occurs in lowland moist and dry forests, secondary forests and forest edges at eleva-
tion 80–200 m.
Etymology. e specic epithet was given in honour of Mr Tawee Insura, whose
prolic collection of Artabotrys specimens during his MSc study led to the discovery of
several new species and new records for ailand.
Preliminary conservation status. Artabotrys insurae is estimated to have an EOO
of 15,994 km2 and an AOO of 20 km2. is species largely occurs within various Wild-
life Sanctuaries, which constitute Protected Areas in ailand. 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.
Artabotrys from peninsular ailand 75
Additional specimens examined. P T. 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 Febru-
ary 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).
Notes. is species is most similar to A. uniorus from peninsular ailand
(Chumphon, Ranong, Phang-Nga and Surat ani) in having erect-pubescent lower
leaf surfaces, 1-owered (rarely 2-owered) inorescences, caudate to acuminate leaf
apex and relatively narrow monocarps (10–15 mm wide). Its distribution overlaps with
A. uniorus in Surat ani. Artabotrys siamensis Miq. from Northern, Northeastern,
Eastern and Southwestern ailand 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 ower), numerous monocarps (up to 22 per fruit) and
broader monocarps (15–20 mm wide).
New records for peninsular Thailand
Artabotrys pleurocarpus Maingay ex Hook.f. & omson
Fig. 5
Artabotrys pleurocarpus Maingay ex Hook.f. & omson, Fl. Brit. India 1: 54 (1872).
Type: P M. Malacca, 6 Feb 1868, A.C. Maingay 3261 [Kew
distribution no. 34] (lectotype K [K000381010], designated in Turner (2016) ex-
plicitly excluding material in packet; isolectotype BM [BM001014846]).
Distribution and habitat. Peninsular Malaysia and peninsular ailand (Fig. 6), in
lowland rain forests.
Specimens examined. P T. 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: ale 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).
Notes. is species was hitherto known from Malacca, Kedah and Perak in Penin-
sular Malaysia (Sinclair 1955). Specimens of A. pleurocarpus from peninsular ailand
were formerly misidentied as A. kurzii Hook.f. & omson or identied to genus
level; they were only recently re-identied during our preparation of the Artabotrys
treatment for the Flora of ailand. e specimens from peninsular ailand and Pen-
insular Malaysia closely match one another in leaf and fruit morphology and there can
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
76
Figure 5. Artabotrys pleurocarpus A habit and mature ower B habit and developing fruit C developing
owers on hooked inorescence D fruits, showing monocarps borne on very distinct stipes. Photos: T. Insura.
be no doubt that they are conspecic. erefore, this represents the rst record of A.
pleurocarpus in ailand. Artabotrys pleurocarpus is distinct among the ai species on
account of its fruit morphology, with relatively few monocarps (up to 9 per fruit) that
are prominently beaked (2–3 mm long), quite large (22–30 mm long, 15–20 mm wide)
and borne on a long stipe (7–10 mm long). e fruits therefore supercially resemble
those of Polyalthia species, but specimens can be easily assigned to Artabotrys if the ino-
rescence/infructescence hook is present. Although A. kurzii from Myanmar (Pegu) was
previously confused with A. pleurocarpus, it bears little resemblance to A. pleurocarpus,
diering in its obovate (vs. oblong-lanceolate to oblong-elliptic) leaves, mucronate (vs.
caudate to acuminate) leaf apex and short petioles (1–2 mm long vs. 4–6 mm long).
Artabotrys crassifolius Hook.f. & omson
Artabotrys crassifolius Hook.f. & omson, Fl. Brit. India 1: 54 (1872). Type: P-
M. Malacca, Grith s.n. [EIC 426] (lectotype: K [K000607645],
designated in Sinclair (1955)).
Artabotrys from peninsular ailand 77
Figure 6. Distributions of A. crassifolius, A. insurae, A. longipetalus and A. pleurocarpus in peninsular
ailand. Only the region in peninsular ailand is shown; adjacent areas in Peninsular Malaysia and
Myanmar are removed.
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
78
Distribution and habitat. Singapore, Peninsular Malaysia, peninsular ailand (Fig.
6) and probably Myanmar (see notes), in lowland rain forests.
Specimen examined. P T. Trang Province: Palian District,
Lam Plok Waterfall, ca. 20 m elev., 4 May 2010, W. Eiadthong 2010-1 (BK, BKF).
Notes. e protologue for A. crassifolius cites a specimen from Martaban in
Myanmar. In addition, a regional checklist (Kress et al. 2003) and a forest ora
(Kurz 1877) indicate the presence of this species in Tenasserim (Taninthayi), My-
anmar. However, Turner (2015) was unable to trace the syntype or any other speci-
men of this species from Myanmar; our attempts to trace those specimens were
likewise in vain. e occurrence of A. crassifolius in Myanmar therefore requires
future verication. Artabotrys crassifolius can be distinguished from other species
in ailand as its young twigs, ower pedicels and lower surface of sepals have a
dense covering of long appressed hairs that is visible with the naked eye. In ai-
land, this species is currently known from a single gathering from Trang, which
exhibits the unique indumentum mentioned earlier and has monocarps with shape
and size matching A. crassifolius. e specimens of this gathering were previously
led as ‘Artabotrys indet’ and only recently identied for the Flora of ailand
project. Outside of ailand, A. crassifolius is widespread in Peninsular Malaysia
but restricted to the Central Catchment Nature Reserve and Bukit Timah Nature
Reserve in Singapore.
Key to Artabotrys species in Thailand
1 Axillary shoots often with thorns; leaf apex retuse, truncate, rounded or mu-
cronate (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 ower; 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 ower; monocarps up
to 12 per fruit, 10–15 mm wide .................................................................4
4 Leaf base rounded, rarely cuneate; petal blades three-angled; anther connec-
tive apex truncate; monocarps sessile, apex strongly beaked (2–5 mm long) ...
.................................................................................................. A. uniorus
– Leaf base oblique; petal blades at; anther connective apex apiculate; mono-
carp base contracted into a stipe 1.5–4 mm long, apex weakly beaked (ca.
1mm long) ...................................................................................A. insurae
Artabotrys from peninsular ailand 79
5 Young twigs, ower pedicels and lower surface of sepals with a dense covering
of long appressed hairs (visible with the naked eye) .................A. crassifolius
– Young twigs, ower pedicels and lower surface of sepals glabrous or with a
sparse covering of short appressed hairs (visible with hand lens) .................. 6
6 Twigs with aky outer layer; leaf blades 21–33 cm long, tertiary venation sub-
scalariform; inorescence 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; inorescence 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; ower 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 peti-
ole; ower 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 at, 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 ower;
monocarps up to 9 per fruit, 22–30 mm long, 15–20 mm wide, base con-
tracted into a stipe 7–10 mm long .......................................A. pleurocarpus
– Leaf apex acute to acuminate (never caudate); carpels ca. 20 per ower;
monocarps up to 17 per fruit, 18–20 mm long, 11–15 mm wide, base con-
tracted into a stipe 3–4 mm long ................................................. A.brevipes
15 Leaves membranous; monocarp apex beaked (ca. 2 mm long), base contract-
ed into a stipe 4–5 mm long; cultivated only .........................A. hexapetalus
– Leaves coriaceous; monocarp apex rounded (rarely weakly beaked), base con-
tracted into a stipe 5–12 mm long; occurs in the wild .............A. harmandii
Junhao Chen & Wichan Eiadthong / PhytoKeys 151: 67–81 (2020)
80
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; inorescences 10–20-owered; carpels 15–20 per ower;
monocarp apex rounded or weakly beaked; inhabits montane forests at 900–
1700 m ................................................................................. A. punctulatus
– Leaves coriaceous; inorescences 3–5-owered; carpels ca. 10 per ower;
monocarp apex beaked ca. 3 mm long; inhabits lowland forests ...A. venustus
19 Leaves coriaceous; petals lanceolate, apex obtuse to acute; outer petals
18–30mm long, blade 3–5 mm wide; inner petals 18–27 mm long, blade
2–4mm wide ........................................................................ A. multiorus
– 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
Acknowledgements
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 Leer-
atiwong for their advice and assistance in taking measurements of Artabotrys speci-
mens. e 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.
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