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Hydnophytum puffii (Rubiaceae: Psychotrieae), a new ant-plant from Sabah, Malaysian Borneo


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Background – Hydnophytum puffii Y.W.Low, Sugau & K.M.Wong, a linear-leaved epiphytic ant-plant is described as new from Borneo using morphological characters based on specimens preserved in the Sandakan and Singapore Herbaria. This new species is so far known only from Sabah, Malaysia. Methods – This study is based on herbarium materials and field observations in Sabah. Conventional herbarium techniques were applied for taxonomy, while the IUCN conservation status was assessed using GeoCAT. Results – Hydnophytum puffii is closely related to H. angustifolium Merr. but differs in having glabrous young twigs, 4–5 pairs of leaf secondary veins on the lower leaf surface, a corolla tube that is densely covered with translucent hairs inside the throat around the anthers, and prolate mature fruits. This new taxon is the only species in Borneo to have linear leaves as the other two taxa, namely H. coriaceum Becc. and H. formicarum Jack have broad elliptic leaves.
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Plant Ecology and Evolution 149 (1): 123–130, 2016
Hydnophytum pufi (Rubiaceae: Psychotrieae),
a new ant-plant from Sabah, Malaysian Borneo
Yee Wen Low1,*, John B. Sugau2 & Khoon Meng Wong1
1Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, 259569 Singapore
2Forest Research Centre, Sabah Forestry Department, P.O. Box 1407, 90715 Sandakan, Sabah, Malaysia
*Author for correspondence:
The peculiar rubiaceous ant-plants in subtribe Hydnophyti-
nae C.R.Huxley & Jebb (Psychotrieae) includes ve genera,
namely, Anthorrhiza C.R.Huxley & Jebb, Hydnophytum
Jack, Myrmecodia Jack, Myrmephytum Becc., and Squamel-
laria Becc., with a geographical distribution from Southeast
Asia to the northern parts of Queensland (Australia) and ex-
tending to the Fiji Islands (Huxley & Jebb 1991a). Most of
the genera have been revised in a series (Jebb 1991, Huxley &
Jebb 1991b, 1991c, 1991d), except for Hydnophytum which
was reported to be in progress (Huxley 1993). Meanwhile,
Forster (2001) described a new species, H. ferrugineum
P.I.Forst., for Australia that is distinct from H. moseleyanum
Becc., and Wistuba et al. (2014) described H. caminiferum
Wistuba, U.Zimm., Gronem. & Marwinski for New Guinea
that is distinct from H. vaccinifolium P.Royen.
Hydnophytum is the most diverse of all the genera rec-
ognised for Hydnophytinae, with an estimated 90 species
occurring from the Indo-Malaya region extending to Aus-
tralasia (Huxley & Jebb 1991a, Govaerts et al. 2014). The
phylogenetic placement of Hydnophytum, while clearly in-
cluded within the Psychotrieae, is as yet uncertain in terms
of denite generic afnities, especially with regard to with
the genus Psychotria L. In the studies of Nepokroeff et al.
(1999), Andersson (2002), Barrabé et al. (2014) and Raza-
mandimbison et al. (2014), Hydnophytum and its close al-
lies (including Anthorrhiza, Myrmecodia, Myrmephytum,
and Squamellaria) form a well-supported ‘Indo-Pacic’ sub-
clade included within one of the Psychotria complex lin-
eages, named the ‘Pacic clade’ or the ‘Pacic Psychotria
clade’. But as acknowledged by Razamandimbison et al.
(2014), there is as yet no unequivocal support for including
this alliance into a broadly circumscribed genus Psycho-
tria because the major lineages are only partially resolved.
Meanwhile, there are clearly denable morphological syna-
pomorphies for the subclade comprising the Hydnophytinae
(including axillary inorescences and a swollen stem with
anastomosing channels developing internally) coupled with
an epiphytic habit that are not present in the other lineages
in Psychotria and its close afliates that typically have ter-
minal inorescences, stem not modied, and shrub, tree, and
liana habit. We therefore continue to recognise the ve Hyd-
nophytinae genera in the sense of Huxley & Jebb (1991a)
as distinct from Psychotria, while awaiting further molecular
phylogenetic resolution that may appear with a more com-
prehensive taxon sampling and other markers.
Borneo is the third-largest island in the world, and it is
included within the phytogeographical region called Malesia
(Zollinger 1857, van Steenis 1950a) that is immensely rich
All rights reserved. © 2016 Botanic Garden Meise and Royal Botanical Society of Belgium ISSN 2032-3921
BackgroundHydnophytum pufi Y.W.Low, Sugau & K.M.Wong, a linear-leaved epiphytic ant-plant
is described as new from Borneo using morphological characters based on specimens preserved in the
Sandakan and Singapore Herbaria. This new species is so far known only from Sabah, Malaysia.
Methods This study is based on herbarium materials and eld observations in Sabah. Conventional
herbarium techniques were applied for taxonomy, while the IUCN conservation status was assessed using
Results Hydnophytum pufi is closely related to H. angustifolium Merr. but differs in having glabrous
young twigs, 4–5 pairs of leaf secondary veins on the lower leaf surface, a corolla tube that is densely
covered with translucent hairs inside the throat around the anthers, and prolate mature fruits. This new
taxon is the only species in Borneo to have linear leaves as the other two taxa, namely H. coriaceum Becc.
and H. formicarum Jack have broad elliptic leaves.
Key words – Borneo, conservation status, Hydnophytum, Malaysia, new species, Psychotrieae, Rubiaceae,
Pl. Ecol. Evol. 149 (1), 2016
in plant life, with a ora estimated to include 42,000 seed
plant species (Roos 1993). Located on the easternmost part
of the Southeast Asian continental shelf called the Sunda
Shelf, Borneo is also the largest island in West Malesia, and
the richest in plant life compared to other Sunda Shelf is-
lands (Wong 1998, Wong 2011). The total vascular ora
of Borneo is estimated between 9,000 (Merrill 1921) and
15,000 species (Merrill 1950, Raes et al. 2009), with many
more new to science still being discovered (recent examples
include Buerki et al. 2013, Wong & Boyce 2014, Utteridge et
al. 2014, Wong et al. 2014, Wong & Low 2015, Joffre et al.
2015, Low et al. 2015, Wong et al. 2015). The northern part
of Borneo, with an area of about 74,000 km2 is occupied by
the Malaysian state of Sabah, home to Mount Kinabalu, the
highest mountain in Borneo and a cradle of plant diversity
with over 5,000 vascular plants estimated there alone (Bea-
man & Anderson 2004), where new taxa are still being dis-
covered (Wong & van der Ent 2014, Chen et al. 2014, Peng
et al. 2015). However, this botanical haven is vulnerable to
deforestation, due to exploitation for timber or clearing for
oil palm plantation agriculture in past decades (White 2008).
A recent study by Bryan et al. (2013) shows that almost 80%
of the land surface of Sabah and Sarawak combined was
subjected to high-impact logging or clearing operation dur-
ing 1990–2009, an alarming gure considering the biologi-
cal wealth in these territories. Although Sabah is considered
botanically well collected since colonial times (van Steenis
1950b, Wong 1995), it is still without a comprehensive ora
account, fuelling concerns that new species may even go ex-
tinct before being documented.
Merrill (1921) in his bibliographic checklist of Bornean
plants enumerated two species of Hydnophytum, namely
H. coriaceum Becc. and H. formicarum Jack. Later, an at-
tempt to update Merrill’s checklist by Masamune (1942) also
listed the same species. The latter is a widespread species
with two varieties recorded for Borneo, viz., H. formicarum
var. borneense (Becc.) Becc. and H. formicarum var. lucidum
Becc. (Merrill 1921, Masamune 1942). Puff & Wong (1993)
in their survey of Bornean Rubiaceae provided an up-to-date
information of the genera occurring in Borneo and listed
Hydnophytum with two taxa, and indicated as well the pos-
sibility of novelties to be discovered. More recently, an up-
dated checklist for Borneo compiled by Kew (Govaerts et al.
2014) included an additional species, Hydnophytum bornea-
num Becc., apart from the two taxa listed by Merrill (1921)
and Masamune (1942). A review of all the literature perti-
nent to the Bornean Hydnophytum taxa was carried out and
revealed that ‘Hydnophytum borneanum Becc.’ in the Kew
Checklist (Govaerts et al. 2014) was in fact a typographical
error for the accepted name Hydnophytum horneanum Becc.,
a native of Fiji (Beccari 1885). As such, only two species
of Hydnophytum have been enumerated for Borneo, namely
Hydnophytum coriaceum and H. formicarum.
In 1992, a peculiar Hydnophytum with distinctive linear
leaves was collected at around 600 m a.s.l. from Gunung
Tingkar (K.M.Wong et al. WKM 2244), one of the least bo-
tanically explored areas in Sabah (van der Ent et al. 2014).
The vegetation where the specimen was collected is low-
land forest over ultramac soils, with tall trees over 50 m
dominated by members of the Dipterocarpaceae and closed
canopy (Fox & Tan 1971, Whitmore 1984, van der Ent et al.
2014). This geological environment is well-documented as
habouring endemic species (Whittaker 1954). The Gunung
Tingkar material is distinct from all known Hydnophytum
species enumerated from Borneo that typically have broad-
elliptic leaves. The present paper claries the identity of this
unusual Hydnophytum, as more herbarium materials, particu-
larly owering and fruiting materials, of this peculiar taxon
have been accumulated over time, enabling a full description
and illustration as provided here.
This research was conducted based on dried herbarium mate-
rials preserved in BRUN, KLU, SAN, SAR, SING and SNP
(herbarium acronyms used in this study follow Thiers contin-
uously updated). Conventional methods of herbarium taxon-
omy were applied. Type images were examined at JSTOR®
Global Plants (, as well as other vir-
tual herbaria available online such as FI, K, L, NY, P, US. In
an effort to locate the missing syntypes of H. angustifolium
Merr., special assistance was requested from curatorial col-
leagues at A, B, BM, BO, F, G, GH, K, NY, PNH, SING, and
UC, to search for relevant herbarium sheets systematically in
their collections. Botanical terms used in this study largely
follows Beentje (2012), and denition of types of tropical
rain forests follows Whitmore (1984).
The IUCN conservation status of Hydnophytum pufi
was assessed using the Criterion B of the IUCN Red List
(IUCN 2012). The extent of occurrence (EOO) and the area
of occupancy (AOO) were calculated using GeoCAT (Bach-
man et al. 2011). Data used for the assessment here are based
on herbarium records represented in SAN and SING.
In Borneo, there are only two genera of the rubiaceous ant-
plants ever recorded, namely Hydnophytum and Myrmecodia
(Merrill 1921, Masamune 1942, Puff & Wong 1993). Mean-
while, Anthorrhiza is exclusive to southeastern New Guinea
(Huxley & Jebb 1991b); Myrmephytum is restricted to the
Philippines, Sulawesi, and the Bird’s Head Peninsula (north-
west New Guinea) (Huxley & Jebb 1991c); and Squamel-
laria is conned to the eastern Fijian Islands (Jebb 1991).
Although there is a possiblity that Myrmephytum could occur
in Borneo, that genus is the only one in Hydnophytinae with
blue 6-lobed corolla, whereas the Gunung Tingkar taxon has
a white 4-lobed corolla. Generally, Hydnophytum differs
from Myrmecodia in having (i) several branching stems aris-
ing from the top part of the tuber, (ii) smooth stems without
alveoli and tubers rarely with spines present (iii) sessile in-
orescences often appearing as a pair of fertile mounds, (iv)
2-lobed stigmas, and (v) two pyrenes. In contrast, Myrmeco-
dia has (i) typically solitary unbranched stems arising from
the top part of the tuber, (ii) spiny stems and tubers with al-
veoli present along the stem, (iii) inorescences sunken into
alveoli, (iv) 4–8-lobed stigmas, and (v) 4–8 pyrenes. Based
on these characters, the Gunung Tingkar taxon clearly be-
longs to Hydnophytum.
Low, Sugau & Wong, A new Hydnophytum from Borneo
The Gunung Tingkar taxon is morphologically similar to
Hydnophytum angustifolium Merr., a taxon known only from
Mindanao described based on four collections at the Manila
Herbarium (PNH), namely three unnumbered sheets by Mary
Strong Clemens from Lake Lanao, Camp Keithley, but dated
April 1906, May 1907, and June 1907; and an unnumbered
sheet by Copeland from San Ramon, Zamboanga (Merrill
1908). Merrill left Manila in 1907 for the United States, and
on his way back to Manila in 1908, he spent two months in
Europe visiting the Berlin Herbarium (B), Natural History
Museum, London (BM), Genève Herbarium (G), Florence
Herbarium (FI), Kew Herbarium (K), and Leiden Herbarium
(L) examining types of Philippine plants (Robbins 1958). It
is plausible that the unidentied Mindanao Hydnophytum
was named following his two months of research in the Eu-
ropean herbaria. The taxon, Hydnophytum angustifolium,
was published on 18 July 1908, shortly after Merrill arrived
back in Manila in April 1908. Merrill, however, did not indi-
cate a type, but as the title suggested “New Philippine plants
from the collections of Mary Strong Clemens, I”, the unnum-
bered sheets from Lake Lanao, Camp Keithley would have
to be the type material. Unfortunately, the Manila Herbarium
was destroyed during World War II (Howard 2000), and very
likely the material examined by Merrill perished when the
herbarium was razed; these sheets are certainly not present
at PNH today (L.T. Evangelista, Philippine National Her-
barium, pers. comm.). Although a good number of Philip-
pine specimens were well distributed (van Steenis-Kruseman
1950), these four sheets are not found in A, B, BM, BO,
F, FI, G, K, L, NY, P, PNH, SING, UC and US. Measure-
ments and information pertinent to Hydnophytum angustifo-
lium used for this study were based entirely on the article
published in Merrill (1908). Table 1 compares H. pufi and
H. angustifolium for a number of characters that distinguish
these two species apart.
It is worth noting that in the horticultural circles of Eu-
rope, Japan, and Taiwan, a mysterious Hydnophytum species
with linear leaves purported to have originated from Borneo
is being traded under the name “Hydnophytum perangus-
tum”. We have not specially examined materials traded under
this name, and also this unpublished name has no bearing on
the nomenclature.
Hydnophytum pufi Y.W.Low, Sugau & K.M.Wong,
sp. nov.
This species appears to be related to Hydnophytum angus-
tifolium Merr. from the Philippines, but differs in having
glabrous young twigs, 4–5 pairs of leaf secondary veins, a
corolla tube that is densely covered with translucent hairs
inside at the throat around the anthers and prolate mature
fruits. In contrast, H. angustifolium has thickly pubescent
young twigs, inconspicuous leaf secondary veins, a corolla
tube that is only sparsely hairy inside at the middle and bar-
rel-shaped mature fruits. The leaves are much narrower than
those of H. angustifolium and only approached by those of
H. ramispinum Merr. & L.M.Perry of New Guinea which,
however, has a spiny tuber. – Type: Borneo, Sabah (Malay-
sia), Tongod, Gunung Tingkar, 2000 ft [609 m] alt., 26 Aug.
1992, K.M.Wong et al. WKM 2244, owers and fruits (holo-:
SAN; iso-: L).
Tuber subglobose to slightly compressed ovoid, to 2–7 ×
3–7 cm, spineless, glabrous, surface smooth to sparsely tu-
berculate and often with entrance holes for ants at the base;
chambers complex and forming a honeycomb of chambers.
Stems several, branching, 24–57 cm long, (0.2–)0.25–0.4 cm
wide, semi-pendulous to erect; arising from the apical part of
the tuber. Stipules triangular fused and sheathing at the base,
Hydnophytum pufi Hydnophytum angustifolium
Young twig surface glabrous furfuraceous
Leaf blade, length (mm) (40–)60–94(–110) 50–100
Leaf blade, width (mm) 2.5–4(–9) 6–18
Secondary veins
on lower leaf surface 4–5 pairs Secondary veins inconspicuous
Corolla tube surface, inside Densely covered with translucent hairs at the
throat, around the anthers
Sparsely covered with translucent hairs
around the middle of the tube
Fruit shape (length × width)
(mm) Prolate (6 × 4) Barrel-shaped (10 × 4)
Restricted to northern Borneo
(Sabah: Beluran, Keningau, Lahad Datu,
Nabawan, Sandakan and Tongod)
Known only from Philippines
(Mindanao: Lake Lanao, Camp Keithley
and San Ramon, Zamboanga)
Lowland to hill kerangas or heath forest
over sedimentary rocks and forest
over ultramac geology
Table 1Comparison of morphological characteristics, distribution and habitat between Hydnophytum pufi Y.W.Low, Sugau &
K.M.Wong and H. angustifolium Merr.
Pl. Ecol. Evol. 149 (1), 2016
Figure 1 Hydnophytum pufi: A, habit and fruiting leafy branches; B, corolla (longitudinally opened with a segment removed) showing
inner surface with dense translucent hairs at the throat; C, detail of style and stigmas (note surface densely papillate); D, close-up of an open
ower (note the truncate upper margin of the hypanthium); E, close-up of a prolate fruit; F, detail of the lower side of leaf lamina showing
ve pairs of secondary veins. All drawn from Y.W.Low LYW 367 (SING) by Zainal Mustafa.
Low, Sugau & Wong, A new Hydnophytum from Borneo
c. 1.5 mm long, c. 1 mm wide, glabrous, caducous; apex
acute. Petiole inconspicuous to c. 0.9–2.5 mm long, glabrous,
terete in cross section. Leaf lamina linear, (40–)60–94(–110)
mm long, 2.5–4(–9) mm wide, thin-leathery, glabrous on
both sides; base attenuate; apex acute; margin entire; mid-
rib inconspicuous and glabrous on upper side, prominent
and glabrous on the lower side; secondary veins 4–5 pairs,
inconspicuous on upper side, faintly raised and glabrous on
lower side; tertiary venation inconspicuous on both sides. In-
orescences sessile, axillary and paired at nodes; bracts in-
conspicuous. Flowers 4-merous, heterogeneity not evident.
Calyx cupuliform, tube c. 0.6–1 mm long, glabrous on both
sides; margin lobes not present. Corolla tubular, white; tube
1.5–2 mm long, outside glabrous, inside with a band of dense
translucent hairs at the throat; aestivation valvate; lobes 4,
triangular, c. 1.5 mm long, c. 1 mm wide, outside surface
glabrous, inside hairy at the basal-most part attached to the
corolla tube; apex not uncinate. Stamens 4, alternipetalous,
inserted at the corolla throat, basixed; laments subses-
sile; anthers c. 0.5 mm long, exserted. Style c. 2.5 mm long,
densely papillate except at the basal quarter. Stigma 2-lobed,
c. 0.5 mm long, surface densely papillate, exserted above the
anthers; ovules 2. Fruit prolate, c. 6 mm × 4 mm, smooth,
eshy drupe, maturing reddish orange; locules 2. Pyrenes 2,
fusiform, broadest slightly above middle, c. 3.5 mm long, 1.7
mm wide, with a semi-transparent eshy thread at the basal
Figure 2 Hydnophytum pufi, habit of a relatively young fruiting plant, taken in Tawai Forest Reserve, Telupid, Sabah. Photographed by
Ubaldus Majawal.
Figure 3 – Distribution of Hydnophytum pufi in Sabah, indicated
by dots; (inset) Borneo, showing Brunei, Kalimantan (Indonesia)
and Sabah and Sarawak (Malaysia).
Pl. Ecol. Evol. 149 (1), 2016
end; base attenuate; apex obtuse; plano-convex in cross sec-
tion; endosperm non-ruminate. Figs 1 & 2.
Distribution and habitat – An epiphyte in lowland to hill
‘kerangas’ or heath forest over sedimentary rocks (see Whit-
more 1984 for denition of forest types) and forest over ul-
tramac geology in Sabah (g. 3). Flowering and fruiting is
recorded from June to December.
Etymology – This species commemorates Prof. Dr. Chris-
tian Puff (1949–2013) of the University of Vienna (Austria),
a distinguished Rubiologist and tropical botanist, mentor and
friend, who contributed signicantly to the understanding of
Southeast Asian plants, particularly in Borneo and Thailand.
Proposed IUCN Conservation AssessmentThis spe-
cies is given an IUCN Red List Category of Vulnerable
(VU B1+2ab(iii,iv)). Hydnophytum pufi is so far recorded
only in Sabah (Borneo), and its habitat is highly threatened
by logging and clearing for oil palm plantations (White
2008). The extent of occurrence (EOO) of the species is es-
timated to be 10,998.387 km2 (which falls within the limits
20,000 km2 upper limit for VU status under the subcriterion
B1), whereas its area of occupancy (AOO) is estimated to be
28 km2 (which falls within the limits for EN status under the
subcriterion B2). This species has so far been known only
from seven localities based on herbarium specimens collect-
ed, namely Keningau (Sook Plain), Nabawan, Beluran (Ta-
wai Forest Reserve), Tongod (Gunung Tingkar), Sandakan
(Mile 81, Labuk Road), and Lahad Datu (Danum Valley and
Ulu Segama Forest Reserve). These subpopulations at seven
locations, according to the IUCN guidelines, qualify the spe-
cies as Vulnerable under condition “a” (less than or equal to
10). Considering also factors such as (i) decrease in the qual-
ity of habitat, and (ii) the number of locations, the species
qualies under condition “b”. Habitat loss is a major conser-
vation concern for the species as forest cover in Sabah has
declined tremendously (Bryan et al. 2013). Mining of copper
was active at Ranau since 1975, with the establishment of the
Mamut copper mine, but this ceased operation in 1999 (The
Star 2007). It was the only, and the last, copper mine estab-
lished in Sabah. However, the proposed status for the species
would require reassessment as more botanical surveys in Sa-
bah are being carried out.
Additional specimens examinedBorneo, Sabah (Malaysia):
Keningau, Mile 6, Sook Plain, Tulid road, kerangas forest, 4 Jun.
1965, Meijer 51704 (K n.v., SAN); Nabawan, locality unknown,
kerangas forest, 17 Jul. 2010, Suzana et al. SAN 152603 (K n.v.,
SAN); Tongod, Gunung Tingkar Forest Reserve, secondary forest,
3 Apr. 2013, Suzana et al. SAN 150236 (SAN); Beluran, Telupid,
Tawai Forest Reserve, Ultramac forest, 5 Aug. 2011, Joel et al.
SAN 153055 (SAN); Sandakan, Mile 81, Labuk Road, 14 Dec.
1971, Dewol et al. SAN 74968 (SAN); Lahad Datu, Ulu Sg. Da-
num, near Kuala Sg. Segama, 31 Aug. 1976, B.C.Stone et al. SAN
85200 (SAN); Lahad Datu, Ulu Segama Forest Reserve, Kennedy
Bay, 12 Aug. 1986, Joseph & Gambio SAN 116885 (SAN). Ma-
lay Peninsula, Peninsular Malaysia (Malaysia): Kuala Lumpur,
University of Malaya, Rimba Ilmu Botanical Garden, cultivated
[specimen originated from Sabah], 18 Apr. 2009, Y.W.Low LYW
367 [KLU, SING: barcode 0166293 and spirit material (barcode
We would like to express our appreciation of the following
colleagues who have very kindly assisted with type materi-
als and information from their institutions: Dr Anthony R.
Brach (A & GH); Dr Robert Vogt (B); Jacek Wajer and John
Hunnex (BM); Ridha Mahyuni (BO); Dr Christine J. Niez-
goda (F); Dr Laurent Gautier and Dr Martin Callmander (G);
Dr Aaron Davis and Nina Davies (K); Dr Jacquelyn Kal-
lunki and Dr Thomas A. Zanoni (NY); Dr Jeremy Barns and
Dr Luisi to T. Evangelista (PNH); Dr Andrew S. Doran (UC).
This study is supported by the Singapore Botanic Gardens,
National Parks Board, Singapore, in collaboration with the
Forest Research Centre, Forestry Department, Sandakan, Sa-
bah. We are grateful to Christina Soh and Zakiah Agil (Li-
brary of Botany and Horticulture, Singapore Botanic Gar-
dens) for help and assistance with missing references; and
Susan Hick (Singapore Botanic Gardens volunteer) for assis-
tance at the Singapore Herbarium. The line drawing was pre-
pared by Zainal Mustafa; and Ubaldus Majawal provided the
habit photo of the new species used here. Lastly, we would
like to thank the reviewers, Dr Matthew Jebb (National Bo-
tanic Gardens, Glasnevin, Dublin, Ireland) and Dr Laure
Barrabé (Institut Agronomique néo-Calédonien, Nouméa,
New Caledonia), as well as the Editor-in-chief Prof. Elmar
Robbrecht for their comments which helped to improve the
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Manucript received on 7 Jan. 2015; accepted in revised version 5
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Communicating Editor: Elmar Robbrecht.
... Distribution -Borneo (Sabah, E Kalimantan). Conservation status - Low et al. (2016) assigned a status Vulnerable (VU) under criteria B1+2ab(iii,iv). At the time the taxon was considered to be endemic to Sabah. ...
... Hydnophy tum angustifolium (see Uncertain and Little Known Species) described by Merrill (1908) from the Philippines suggests a very similar facies to this species, but all the original type material is missing (see Uncertain and Little Known Species). In describing H. puffii, Low et al. (2016) contrasted the description of this later species in some detail. ...
... However, the dates of publication for these taxa -H. longi florum (1858) (2015) and The Plant List (2015), as pointed out by Low et al. (2016) 53. Squamellaria guppyana (Becc.) ...
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Hydnophytum (Psychotrieae Hydnophytinae) is revised. A key is provided, and an informal infrageneric grouping is proposed. Variation in tuber structure is discussed. Fifty-five species are recognised, of which 19 are described as new. For one species a number of varieties are also described. Forty-four species are found in New Guinea, of which 41 are endemic. The recent transfer of a number of taxa into an expanded concept of Squamellaria based on a molecular phylogeny is addressed. Three taxa of Squamellaria are included in this revision to complete the series of papers on the tuberous epiphytes of the Rubiaceae.
... and Hydnophytum spp. (Rubiaceae), have a symbiotic relationship with ants as an adaptation to the nutrientlimited environment of heath forests (Whitmore 1984;Low et al. 2016;Zoletto and Cicuzza 2022). Both Hydnophytum spp. ...
... and Myrmecodia spp. possess an enlarged stem with chambers that act as shelter for ants, in exchange for which the ants provide the plants with essential nutrients by bringing them into the chambers where the plants will then break down and absorb the nitrogen-rich debris brought by the ants through their wall linings or adventitious roots (Low et al. 2016). L. sinuosa has a mutualistic association with stingless shelter ants from the genera Crematogaster, Technomyrmex or Iridomyrmex, sheltering the latter in exchange for protection against herbivory, as well as nutrients derived from the feces of ant colonies (Zoletto and Cicuzza 2022). ...
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Ikbal IM, Din HHM, Tuah WH, Jaafar SM, Ahmad N, Sukri RS. 2023. Review: Diversity, structure, and community composition of Bornean heath forest with a focus on Brunei Darussalam. Biodiversitas 24: 2814-2829. Tropical heath forests, a unique lowland forest ecosystem with high conservation value, are increasingly threatened by disturbances. Heath forests are characterized by trees of short stature and the presence of highly acidic, sandy soils with poor nutrient content. Bornean heath forests are widely studied for their diversity, structure, and community composition and are known to support endemics of high conservation value. Environmental factors and soil properties, such as topography, water availability, and nutrient status, are known to influence tree species diversity and forest structure of Bornean forests. However, factors influencing their community composition, including the role of seedling communities in influencing heath forest communities, are still not well understood. In particular, studies of tree diversity and community composition of heath forests in Brunei Darussalam have revealed high endemism and the presence of species with high conservation value. Anthropogenic threats to Bornean heath forests highlight the urgent need for an increased understanding of these forests and prioritization of their conservation. Increased insights into the ecological preferences of heath forest species are crucial for the successful restoration of degraded heath forests. The intact forest ecosystems of Brunei could provide opportunities for further ecological research on the plant communities found in these unique forests.
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Squamellaria Becc. is revised to include three species, one of which is new (Squamellaria thekii), and one existing species (S. wilsonii) is reduced. The genus is endemic to Fiji.
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Myrmedoma Becc. is sunk into Myrmephytum Becc. on account of floral and inflorescence characters. Myrmephytum is revised to contain eight species, of which one is new and four are little known.
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The morphology and ant-association of the five genera Hydnophytum Jack, Myrmecodia Jack, Anthorrhiza Huxley & Jebb, Squamellaria Becc. and Myrmephytum Becc. are described. On the basis of shared character states in tuber cavity development and inflorescence structure these five genera are united as a subtribe, the Hydnophytinae.
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The morphology and ant-association of the five genera Hydnophytum Jack, Myrmecodia Jack, Anthorrhiza Huxley & Jebb, Squamellaria Becc. and Myrmephytum Becc. are described. On the basis of shared character states in tuber cavity development and inflorescence structure these five genera are united as a subtribe, the Hydnophytinae.
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Begonia jamilahana Y.W.Low, Joffre & Ariffin is described and illustrated here as a new species based on a collection from Ladan Hills Forest Reserve, Tutong, Brunei Darussalam. This new taxon is closely related to B. conniegeriae S.Julia & Kiew and B. papyraptera Sands, but differs in a suite of morphological characters. Begonia jamilahana is placed in Begonia section Petermannia, the largest of all the sections recognised.
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Five new species of seed plants are described: Alangium kayuniga K.M.Wong (Cornaceae), Melastoma ariffinii K.M.Wong, Melastoma ashtonii K.M.Wong, Melastoma joffrei K.M.Wong & Y.W.Low (Melastomataceae), and Lasianthus jangarunii Y.W.Low (Rubiaceae). New plant records for the ongoing Brunei floristic inventory include Planchonea valida (Blume) Blume (Lecythidaceae), Melastoma velutinosum Ridl. (Melastomataceae), and Gardenia costulata Ridl. (Rubiaceae).
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A brief introduction to research and botanical documentation of the Brunei flora, and the collaborative programme for a continuing botanical survey of the country, is given. An outline of the key biogeographical features of the Brunei area supports the premise that distinct geo-ecological enclaves occur which are special units of species richness, within which a significant level of undocumented plant diversity still exists. Jarandersonia yahyantha K.M.Wong, Joffre, Ariffin & Y.W.Low (Malvaceae), a new tree species so far only known in Brunei, is described.
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Background: Haniffia Holttum is a genus of three described species of terrestrial gingers hitherto restricted to Peninsular Thailand and various localities in Peninsular Malaysia. Results: With generic placement confirmed using nrITS, trn K and mat K plastid sequence data, Haniffia santubongensis S.Y. Wong & P.C. Boyce is described as a taxonomically novel species representing a new generic record for Borneo, to where it is endemic to Mount Santubong, Kuching Division, NW Sarawak, Malaysian Borneo. An identification key to all species is given and H. santubongensis is illustrated from living plants. Conclusion: Haniffia santubongensis is the fourth species of Haniffia so far described, and the first occurring on sandstone.
The species-rich ecological assemblages of SE Asia have been molded via both historical and ecological processes. Over both short and long timeframes, environmental inconstancy and heterogeneity play a fundamental part in shaping speciation and organismal diversity. Climate change has been important in past transformations of SE Asian ecosystems, which can bounce back, change, or go extinct. This account has brought together botanical and zoological examples, integrating palaeontological and archaeological information, as well as insights from molecular studies, to provide a synoptic look at the biogeography of SE Asia. The coming together of the sciences has enriched our understanding of the connections among landforms, ecosystems and species, the role of changes in the environment, both past and present, and how some losses brought about by anthropogenic activities could be minimized.