Pothos boyceanus (Araceae), a new species from the Western Ghats, India

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Taiwania 65(2): 114‒118, 2020
DOI: 10.6165/tai.2020.65.114
114
Pothos boyceanus (Araceae), a new species from the Western Ghats, India
Gopalaprabhu RAJKUMAR, Thankappan SHAJU, Ahammed NAZARUDEEN*, Raveendranpillai PRAKASHKUMAR
Plant Systematics and Evolutionary Science Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Palode,
Thiruvananthapuram 695 562, Kerala, India.
*Corresponding author’s email: drnazru@gmail.com
(Manuscript received 5 November 2019; Accepted 5 February 2020; Online published 17 February 2020)
ABSTRACT: Pothos boyceanus sp. nov. (Araceae) of the subgenus Allopothos (sensu Schott, 1855) has been discovered from the
evergreen forests of Valara in Idukki district of Kerala, India. The species has a close affinity with Pothos crassipedunculatus
Sivadasan, Mohanan & Sathishkumar, but differs in a set of characters including the presence of a ligule, long winged petiole,
asymmetric lamina, long single cataphyll, slender peduncle, presence of a stipe, long cylindric spadix with a lorate spathe equal to
the length of spadix and 1˗3 seeded ovate berry ripening milky white at base and light violet towards tip.
KEY WORDS: Allopothos, Araceae, India, Kerala, new species, Pothos, Pothos boyceanus, Western Ghats.
INTRODUCTION
The genus Pothos L. with about 75 species
represents the climbing aroids, mostly distributed in the
Madagascar to Indo-Malaysian region, with lesser
representation in China (north to Hubei), Western
Oceania (east to Vanuatu), and Australia from south to
eastern Queensland and eastern New South Wales
(Mayo et al., 1997; Hay, 1995; Boyce and Hay, 2001; Li
and Boyce, 2010). The genus was originally erected by
Linnaeus (1753) and was subsequently refined into its
present conceptualization by Schott (1832, 1853, 1855,
1860) who established two subgenera, Pothos
(‘Eupothos’) and Allopothos based on the branching
pattern, leaf shape and inflorescence position. Engler
(1905) further subdivided Schott’s subgenera (calling
them sections) into seven series based on inflorescence
and flowering shoot characters.
Based on our field studies and a perusal of literature
(Hooker, 1894; Karthikeyan et al., 1989; Sivadasan et al.,
1989; Pandurangan and Nair, 1994; Sasikala and
Reemakumari, 2013), it is stated that there are 11 species
and two varieties in the genus Pothos in India, of which
six species including five endemic are represented in the
Western Ghats region (Nayar, 2014); in Kerala, there are
five species including four endemics (Nayar et al., 2006;
Robi et al., 2008).
During floristic explorations, the authors have
observed a species of Pothos from the evergreen forests
of Valara, in Idukki district, Kerala, India which on
detailed taxonomic evaluation has proved distinct and do
not match with any of the hitherto described species. It
has a close affinity with Pothos crassipedunculatus
Sivadasan et al. but differs with a set of characters
including presence of a ligule, long winged petiole,
asymmetric lamina, long single cataphyll, slender
peduncle, presence of a stipe, long cylindric spadix with
a lorate spathe equal to the length of spadix and ovoid,
1‒3 seeded berry ripening milky white at base and light
violet towards tip.
The present species belongs to the subgenus
Allopothos (sensu Schott, 1855) due to the presence of
the characteristic terminal inflorescence, stipitate spadix,
canaliculate and sheathing petiole with a geniculum at
the tip, just below the leaf blade. The closely related
species Pothos crassipedunculatus is compared with the
new species in Table 1. Including the present species, the
genus Pothos is represented by 12 species and two
varieties in India.
A description of the new species is provided along
with a photo plate and drawing for easy identification.
The voucher specimens including holotype and paratype
are deposited in TBGT and the isotype is placed in MH.
TAXONOMIC TREATMENT
Pothos boyceanus G. Rajkumar, Shaju, Nazarudeen &
Prakashk., sp. nov.
Figs. 1 & 2
This species has a close affinity with Pothos
crassipedunculatus Sivadasan et al., but differs in a set
of characters including the long, sheathing slightly
winged petiole with the sheath terminating in a short
ligulate portion, asymmetric leaf blade, single long
cataphyll subtending inflorescence, slender peduncle,
long lorate spathe, long cylindric spadix with a distinct
stipe, and milky white ripe berries with light violet heads
(Table 1).
Type: INDIA. Kerala: Idukki district, Valara, ± 300
m, 13 Feb.2000, G. Rajkumar & T. Shaju, TBGT 38780,
(holotype TBGT; isotype MH).
Root climber; stem terete, unarmed, green, glabrous,
internodes 2˗3 cm long; branchlets tipped with long whip
like flagella. Heteroblasty absent, leaves coriaceous,
glabrous broadly oblong-elliptic to elliptic lanceolate, 16‒
30×5‒11 cm, tip cuspidately acuminate, base narrowed,

2020 Rajkumar et al.: Pothos boyceana (Araceae), a new species from India
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Fig. 1. Pothos boyceana sp. nov. A. Habit, flowering branch with apical flagellum. B. Single flower. C. Infructescence showing long
spathe. D. Pistil. E. Stamen. F. Tepal. Drawed by Dr. T. Shaju.

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Fig. 2. Pothos boyceanus sp. nov. A. Habit. B. Growing apex showing long flagellum. C. Inflorescence. D. Infructescence showing
long spathe.

2020 Rajkumar et al.: Pothos boyceana (Araceae), a new species from India
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Table 1. Comparative morphology of Pothos boyceanus sp. nov. versus P. crassipedunculatus Sivadasan, Mohanan & Sathishkmar
Characters P. boyceanus sp. nov. P. carssipedunculatus
Ligule Present Absent
Petiole 6‒9 (17) cm long, slightly winged 1˗2 cm long, not winged
Lamina Asymmetric, oblong elliptic, 16‒22 (30)×5‒7 (11) cm
Symmetric, oblong lanceolate, 8‒20×2‒4.5 cm
Cataphyll subtending inflorescence
Single, 8‒10 cm long 3‒4 together, 0.5‒1cm long
Spadix stipe 0.8‒1.5 cm long Absent
Spadix Cylindric, 7‒8 cm long Subcylindric, 1‒2 cm long
Spathe Lorate, 7‒8 cm long Ovate, cymbiform, 2‒2.5 cm long
Berries Ovoid oblong, 4‒
6 angled at tip, base milky
white, tip light violet when ripe
Slightly obovoid, inconspicuously 4‒
6 angled,
scarlet red throughout when ripe
acute or obtuse, margin entire, midribs prominent below,
channelled above, lateral veins more than 40 pairs, close,
irregularly parallel, nearly horizontal, obscure, looping
clear; petiole 6‒17 cm long, with geniculum (pulvinus)
at the tip, deeply canaliculate, slightly winged, wings 5‒
8(16)×0.4‒0.5 cm, extends up to 1 cm below the lamina,
narrowed to the semi amplexicaule base and truncate at
apex, with longitudinal veins. Cataphyll solitary, linear
oblong, 8×0.6 cm. Inflorescence solitary on short lateral
shoots; stipe 0.8‒1.5 cm long, glabrous, terete, thickened
towards tip; spathe green, lorate, linear oblong to linear
lanceolate, glabrous, equal to spadix in length, 7‒8×0.4‒
0.5 cm, persistent, reflexed, tip acuminate, base slightly
sheathing, margin entire, 4‒5 parallel veins on either side
of the mid vein. Flowers creamy white, compact; tepals
6; stamens 6, filaments flat, anthers bilobed, extrorse;
ovary trilocular, ovules 1‒3 in each cell, stigma small,
punctate, sessile, 3˗lobed. Berry 1‒3 seeded, ovate,
broad at base, narrow towards tip, ripening milky white
with light violet ends.
Phenology: Flowering & fruiting occurs during
January‒March.
Distribution and habitat: India, Kerala, sporadic
along the foot hills of the southern Western Ghats, near
the 4th Milestone, Valara, Idukki district; prefers rich
damp soil and dappled shade of riparian habitat at an
altitude between 300 ˗350 m asl., climbing on trees in
tropical evergreen forests, in association with
Poeciloneuron indicum Bedd., Antidesma montanum
Blume, Glycosmis macrocarpa Wight, Humboldtia
vahliana Wight, H. sanjappae Sasidh. & Sujanapal,
Polyalthia malabarica var. longipedicellata Alister et al.,
Ormosia travancorica Bedd., Ixora nigicans R.Br. ex
Wight & Arn., Myristica malabarica Lam., Villebrunea
integrifolia (Gaud.) Miq., Kunstleria keralensis
Mohanan & Nair, Smilax zeylanica L., Ochlandra
travancorica (Bedd.) Benth. ex Gamble and
Hydnocarpus macrocarpa (Bedd.) Warb.
Etymology: The specific epithet ‘boyceanus’ is
given as a mark of respect to Dr. Peter C. Boyce, who
has made remarkable contributions on the systematics of
Araceae of South East Asia.
Population structure and conservation status: The
species possess a narrow distribution in its original
habitat and exhibits a low population in its type locality.
Repeated surveys could locate only less than 100
individuals found growing scattered in a 10 km2 area
qualifying itself to get into the category of Critically
Endangered (CR) Category (B1; C2+a (i); D) as per
IUCN (2014) and therefore the species warrants urgent
conservation measures.
Notes: Pothos boyceanus belongs to the subgenus
Allopothos with petioles sheathing for much of its length,
conspicuously geniculate at the apex and inflorescences
mostly arising from below the leaf axils, or terminally on
leafy shoots. Again, the species falls under the Allopothos
super group (sensu Boyce & Hay, 2001) with their spadix
with congested flowers arranged in a dense spiral and
Pothos barberianus Schott group (sensu Boyce and Hay,
2001) in which the inflorescence is held beneath the shoot
on deflexed peduncles or on long, arching peduncles and
most of the species coming under this group is dispersed
between the Indian subcontinent and West Malesia. Pothos
atropurpurascens M. Hotta (Borneo), P. barberianus
Schott. (Sumatra, Peninsular Malaysia & Borneo), P.
brevivaginatus Alderw. (Sumatra), P. englerianus Alderw.
(Indonesia, Sumatra), P. kingii Hook.f. (Thailand and
Peninsular Malaysia), P. lancifolius Hook.f. (Peninsular
Malaysia), P. longivaginatus Alderw. (Borneo), P.
mirabilis Merr. (Borneo), P. philippinensis Engl.
(Philippines), P. salicifolius Ridl. ex Burkill & Holttum
(Peninsular Malaysia), P. volans P.C.Boyce & A.Hay
(Sarawak and Brunei Darussalam) and P. wallichii Hook.f.
(Peninsular Malaysia, Java, Borneo), Pothos thomsonianus
Schott (India), P. crassipedunculatus Sivadasan et al.
(India), P. tirunelveliensis Sasikala & Reemakumari (India)
and P. keralensis Pandur. & Nair (India) are the species
coming in this group.
ACKNOWLEDGMENTS
The authors express their sincere gratitude towards Kerala
Forest Department for granting permission to explore forests,
Deputy Director, BSI, Southern Regional Centre, Coimbatore,
for his consent to refer herbarium specimens housed at MH.
Authors express deep gratitude to Dr. Peter C. Boyce for
constructive criticism.
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