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Rhododendron Loranthiflorum (Ericaceae) from mainland New Guinea. a distributional record and new subspecies

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W.  TAKEUCHI 
W.  TAKEUCHI 
W.  TAKEUCHI 
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Abstract and Figures

Rhododendron loranthiflorum was previously regarded as an archipelagic endemic, with known stations in the Solomon Islands and New Britain. An exploratory survey of the Lakekamu Basin has now established the plant's presence on the southern side of the New Guinea mainland. The Lakekamu provenance represents a geographical disjunction distinguishable as a separate subspecies, and is formally described as subsp. lakekamuensis.
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333EDIN B. J. BOT. 57 (3 ): 333–337 ( 2000 )
RHODODENDRON LORANTHIFLORUM
(ERICACEAE ) FROM MAINLAND NEW GUINEA. A
DISTRIBUTIONAL RECORD AND NEW SUBSPECIES
W. TAKEUCHI*
Rhododendron loranthiflorum was previously regarded as an archipelagic endemic, with
known stations in the Solomon Islands and New Britain. An exploratory survey of the
Lakekamu Basin has now established the plant’s presence on the southern side of the
New Guinea mainland. The Lakekamu provenance represents a geographical
disjunction distinguishable as a separate subspecies, and is formally described as
subsp. lakekamuensis.
Keywords. Botanical survey, Papuasia, Vireya.
INTRODUCTION
The Lakekamu basin ranks among Papua New Guinea’s ( PNG) largest and most
unspoiled wilderness areas. It is regarded by multiagency assessment as one of the
16 terrestrial unknowns within PNG and is also included on site portfolios of the
highest-value biodiversity localities (Sekhran & Miller, 1995). In 1996, an expedition-
ary survey established biological baselines for future initiatives within the Lakekamu
drainage. Although the botanical findings were disseminated in earlier publications
(Takeuchi & Kulang, 1998; Takeuchi, 1999), new taxa continue to be identified from
the survey’s collections. The present article reports on the most recent novelty to be
separated from the botanical vouchers.
Rhododendron loranthiflorum Sleumer subsp. lakekamuensis W.N. Takeuchi, subsp.
nov. Fig. 1.
ARhododendron loranthiflorum subsp. loranthiflorum corolla tubo usque 37mm longo
et stylo fere usque ad apicem lepidoto differt.
Type: Papua New Guinea, Gulf Province, Lakekamu, east branch of the Avi Avi
River, 31 x 1996 (fl., fr.), W. Takeuchi & J. Kulang 11503 (holo. LAE; iso. A, BRIT,
E, K, L, NY ).
Perched epiphytic shrub. Branchlets numerous, subapical diam. 2–3mm, obliquely
ascending, gnarled, nodose, distally compressed and glaucous, pulverulent to the
naked eye, older intervals terete and pale brown, periderm brittle, cracking and
exfoliating in flakes; indument orange-brown or pale reddish-brown squamu-
late, ±lax, eventually falling, peltately fixed, the marginal zone hyaline, irregular,
not or hardly stelliform. Leaves usually 3–5-pseudowhorled, infrequently opposite,
* Botanical Research Institute of Texas, c/o PNG Forest Research Institute, Lae, Papua New Guinea.
W. TAKEUCHI334
FIG. 1. Rhododendron loranthiflorum subsp. lakekamuensis. (A) vegetative habit, (B) flower-
ing habit, (C) branchlet with fruit cluster, (D) corolla at anthesis (calyx not shown), (E) inset
detail of exterior corolline indument, (F ) stigma and the distal stylar indument. Scale bars:
A–C, 5cm; D, 10mm; E–F, 1mm. All drawn from the type by N. H. S. Howcroft.
spreading, firm or coriaceous, adaxially dark green, abaxially yellow-green, distinctly
bichromatic with drying: turning gray-olivaceous above, brunneous beneath; blades
always broadest above the middle, oblanceolate or more often obovate, 35–65×
RHODODENDRON LORANTHIFLORUM FROM MAINLAND NEW GUINEA 335
19–44mm, rounded or retuse at the apex, margins reflexed, base cuneate; ventral
surfaces at first lepidote, also with minute papillate-dendriform hairs in costal chan-
nels, the scales mostly caducous, hairs persisting or not, dorsal side shallowly foveo-
late, squamules rotund, seated within the depressions, orange-brown, subentire or
lacerate, generally persistent; venation pinnatiform, laterals 3–6, obliquely diverging,
hardly or not at all visible, reticulum obscure; petioles 3–11mm long, adaxially plane
and narrowly canaliculate, convex beneath, indument like the branchlets.
Inflorescence strictly terminal, fasciculate, umbelliform; perulae lanceolate-ovate,
c.2–3mm long, densely lepidote, fugacious. Flowers 2–7 together; bracteoles linear,
c.5–6mm long, marginate; pedicels 10–12mm at anthesis, red, very sparsely squamul-
ate; calyx±densely lepidote, truncate, margin undulate and fimbriate; corolla white,
tube isometrical, cylindrical, to 37×3mm, exterior surfaces orbicular-lepidote,
internally provided with papillate hairs on the lower part, limb glabrous, pentamer-
ous, lobes acute or rounded, c.7mm long, reflexed at anthesis; stamens 10, filaments
slender, indument like the inner corolla tube, the hairs sparse towards the throat,
anthers oblong, c.2mm long, inappendiculate; disk hirtellous; gynoecium entirely
yellow-green, ovary densely lepidote and also with coarse patent hairs; style in the
lower half with indument like the ovary, exclusively squamate near the summit,
exserted 4–5mm from the throat at anthesis, stigma capitate-turbinate, glabrous.
Fruits linear-cylindric, to 60×3mm, 5-sulcate, dark reddish-brown, sparsely provided
with an indument of mixed scales and hairs; style persistent, to c.35mm long, stigma
5-lobulate; fruiting pedicel to 17mm long.
Distribution and habitat. Thus far known only from the type locality, in the ecotone
between lowland alluvial forest and the Lakekamu foothill zone. The plant occurs
infrequently in the upper canopies of mature forest stands.
The type collection keys directly to Rhododendron loranthiflorum, a species previously
regarded as endemic to New Britain and the Solomon Islands ( Fig. 2; Sleumer, 1960,
1966, 1973). While otherwise comparable in aspect to the nominate taxon, the novelty
is distinguishable by its geographic separation, the longer corolla tube to 37mm
length, and the style exclusively lepidote in the upper intervals. The species was
previously characterized as having corolla tubes 20–25mm long and styles exclusively
hairy toward the stigma. Subspecies lakekamuensis also has petalline lobes which are
mostly acute and closely reflexed at anthesis; the archipelagic provenances in the
Bismarcks and Solomons have a salverform corolla with the segments ovate-oblong
and spreading.
Rhododendron species are generally associated with montane environments, so in
this sense the new subspecies is ecologically atypical. The type collection was obtained
at 175m elevation in warm perhumid forest from the Papuan lowlands; a habitat
not ordinarily regarded as ericaceous. Although R. loranthiflorum had been pre-
viously recorded from low elevations, the Lakekamu occurrence is notable for its
apparent linkage to elevational anomalies in other taxa. During the 1996 survey,
montane genera such as Dimorphanthera,Levieria,Myrsine (Rapanea), and
W. TAKEUCHI336
FI G . 2. Geographic distribution of Rhododendron loranthiflorum: solid circles, documented
localities for the species; arrow, type locality for subsp. lakekamuensis; main diagram, New
Guinea and nearby areas; dislocated inset at lower left, Solomon Islands.
Zygogynum were seen descending to the contact with the Lakekamu alluvial-coastal
plain ( Takeuchi & Kulang, 1998). Individual species such as Elaeocarpus blepharoc-
eras Schltr. and Ternstroemia britteniana F.Muell., previously thought to be of strictly
montane assignment, were also documented far below their previously known limits.
The new distributional station for Rhododendron loranthiflorum is thus part of a
wider permutation involving the apparent displacement of an entire montane assem-
blage to the Papuan lowland environment, where the nonconforming elements now
coexist in disparate combination with the conventional lowland flora. This concat-
enation of normally allopatric species is arguably attributable to past Quaternary
adjustments in vegetation zones managing to persist because of the exception-
ally high rainfalls in the basin, which present measurement places at c.5000mm
(Mack, 1998).
ACKNOWLEDGEMENTS
My participation on the Lakekamu survey was made possible by Conservation
International. Principal funding for my studies in Papuasian botany was previously
provided by the Liz Claiborne and Art Artenberg Foundation, and more recently
by the John D. and Catherine T. MacArthur Foundation. The PNG Forest Research
Institute and Lae Herbarium assisted with logistical and facilities support.
RHODODENDRON LORANTHIFLORUM FROM MAINLAND NEW GUINEA 337
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Received 24 February 2000; accepted with revision 4 April 2000
... Individual species were found there far below their previously known lower limit. Takeuchi (2000) inferred 'the apparent displacement of an entire montane assemblage to the Papuan lowland environment…'. As Takeuchi and Kulang (1998) noted, these records are 'rather provocative and deserving of further enquiry'. ...
View
... To cover the total known distribution of each species, locality information was obtained from herbarium specimens, and supplemented with locality information from the literature (data available on request; Sleumer, 1958Sleumer, , 1973Argent & Madulid, 1995Takeuchi, 2000). Specimens from several herbaria were examined for locality information: Arnold Arboretum, Harvard University (A), Australian National Herbarium (CANB), Royal Botanic Garden Edinburgh (E), Nationaal Herbarium Nederland, Leiden, University branch (L), and the New York Botanical Garden (NY). ...
Historical biogeography of Rhododendron section Vireya and the Malesian Archipelago
Article
  • Nov 2006
  • J BIOGEOGR
Aim Vireya rhododendrons are distinctive and easily recognizable by their general form; however, they are virtually circumscribed geographically, predominantly distributed throughout the biogeographically intriguing Malesian Archipelago. Hypotheses of the evolutionary relationships of the group have been proposed but the biogeography of vireyas has not been analysed based on molecular phylogeny. Recently, the first detailed molecular phylogenetic investigation of section Vireya was completed based on cp‐ and nrDNA sequence data, therefore making this cladistic biogeographic study of vireya rhododendrons possible. Location Malesia, Australia, Solomon Islands, Taiwan, Himalayas, north Vietnam and south China. Methods Based on distribution maps, areas of endemism were determined for the biogeographic region of Malesia. Area relationships were analysed based on a recent molecular phylogeny of species in section Vireya . The method of paralogy‐free subtree analysis was applied. Results Individual distribution maps were produced for 74 species of Rhododendron section Vireya . Species clades with bootstrap support proved to be biogeographically informative. Major clades correspond to three regions: eastern Malesia, western/middle Malesia and Taiwan/north Vietnam/south China. Within eastern Malesia, Australia, New Guinea, the Bismarck Archipelago and Solomon Islands are related. In western Malesia, northern Philippines, Borneo, southern Moluccas and north and west Sulawesi are related. These areas are more distantly related to Sumatra, the Malay peninsula, Java, Bali, Palawan, Lesser Sunda islands and the southern Philippines. The position of the Himalayas is equivocal and part of a basal polytomy in the summary area cladogram. Main conclusions Two alternative hypotheses are proposed for the evolution of vireya rhododendrons based on the pattern of area relationships. The first hypothesis is that the vireyas are an old group, with ancestors present on Gondwana, rifting north in the Cretaceous. The second alternative hypothesis is that vireyas are a young group that has dispersed eastwards from India to Australia and the Solomon Islands since the current Malesian islands formed.
View
... Individual species are found there far below their previously known lower limit. Takeuchi (2000) inferred`theinferred`the apparent displacement of an entire montane assemblage to the Papuan lowland environment where the non-conforming elements now coexist in disparate combination with the conventional lowland ¯ora'. As Takeuchi & Kulang noted, these records arèrather provocative and deserving of further enquiry'. ...
Birds of paradise, biogeography and ecology in New Guinea: A review
Article
  • Jul 2001
  • J BIOGEOGR
Aim The paper reviews the biogeography and ecology of New Guinea using the birds of paradise (Paradisaeidae) as an illustrative example. Location New Guinea, the Moluccas, North‐eastern Australia. Methods Panbiogeographic analysis ( Craw et al ., 1999 ). Results The family Paradisaeidae is interpreted as the main New Guinea vicariant in Sibley & Ahlquist’s (1990) Corvinae. It has evolved mainly on the New Guinea orogen, extending, like the orogen, to the northern Moluccas and the Milne Bay islands, but not present north of it on Karkar Island or New Britain. Within the orogen, Vogelkop – Huon Peninsula disjunctions (1500 km) occur between putative sister species in Paradisaea , Astrapia and Parotia . Whatever taxonomic rank these affinities warrant, the biogeographic connection is inexplicable by ‘jump’ dispersal from the mainland, but is compatible with an accreted terrane model of New Guinea tectonics including massive lateral strike‐slip movement. This would also account for many aspects of distribution of Paradisaeidae within the New Guinea highlands, and also disjunctions between Sulawesi and the Bismarck Archipelago in the related genus Artamus . Main conclusions Birds of paradise are sedentary forest dwellers with small home ranges and are tolerant of disturbance. It is suggested that populations have been caught in the dramatic geological uplift and downwarping of different parts of New Guinea. This has led to fragmentation and juxtaposition of ranges, and determined the altitudinal range of the taxa (including altitudinal ‘anomalies’). Areas of endemism in birds of paradise include Quaternary volcanoes. In New Guinea large areas have eventually been covered by lava flows of different volcanic phases, but the living communities, including local endemics, may remain more or less in situ by constantly colonizing younger flows from adjacent older flows. In this way older life can ‘float’ on younger stratigraphy. At least five, possibly six, of the fifteen genera in subfam. Paradisaeinae are known to occur in mangrove. The ancestors of Paradisaeidae and other New Guinea bird families such as Ptilonorhynchidae probably included birds of the mangrove, beach forest and coastal hinterland which have been stranded in central Australia following marine transgressions (Ptilonorhynchidae) and uplifted in New Guinea during the Tertiary orogeny (Ptilonorhynchidae and Paradisaeidae).
View
... papuana, yet an accession of R. loranthiflorum has recently been described from the Papuan Peninsula (Takeuchi 2000). ...
Phylogeny of Rhododendron section Vireya (Ericaceae) based on two non-coding regions of cpDNA
Article
  • Feb 2006
Section Vireya (Blume) Copel.f. is one of the most morphologically diverse groups of the genus Rhododendron. Vireyas have a unique distribution for the genus, being predominantly found throughout the Malesian Archipelago. The alpha taxonomy of section Vireya is relatively well understood and taxa are easily distinguished from other rhododendrons by their general appearance. Defining characteristics of the section the possession of seeds with tailed appendages at both ends, the twisting of capsule valves after opening, placentas that separate as thread-like structures from the central axis as the capsule opens are all subject to exceptions. Phylogenetic analyses of two cpDNA regions, psbA-trnH and trnT-trnL intergenic spacers are reported. The results of each analysis were generally congruent, with clades relating strongly to geographic areas. Section Vireya is monophyletic with the inclusion of at least one species of section Rhododendron. Only two of the seven subsections currently circumscribed are monophyletic: Malayovireya Sleumer and Siphonovireya Sleumer. ``Euvireya'', all subsections excluding the paraphyletic subsection Pseudovireya, is monophyletic and includes two major clades, one restricted to eastern Malesia and the other to the western and middle Malesia.
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Additions to the Flora of the Strickland Basin, Papua New Guinea: Fittingia Paniculata (Myrsinaceae), A New Calciphilous Species from the Southern Limestone
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  • Jun 2007
Fittingia paniculata is described from karst habitats in Papua New Guinea's Southern Fold Mts. The new species is distinguished by unusually large leaves profusely disposed in pseudowhorls (up to 21 leaves together), and by long staminate panicles.
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Ericaceae in Malesia: Vicariance biogeography, terrane tectonics and ecology
Article
  • Jul 2003
2003. Ericaceae in Malesia: vicariance biogeography, terrane tectonics and ecology. Telopea 10(1): 311–449. The Ericaceae are cosmopolitan but the main clades have well-marked centres of diversity and endemism in different parts of the world. Erica and its relatives, the heaths, are mainly in South Africa, while their sister group, Rhododendron and relatives, has centres of diversity in N Burma/SW China and New Guinea, giving an Indian Ocean affinity. The Vaccinioideae are largely Pacific-based, and epacrids are mainly in Australasia. The different centres, and trans-Indian, trans-Pacific and trans-Atlantic Ocean disjunctions all indicate origin by vicariance. The different main massings are reflected in the different distributions of the subfamilies within Malesia. With respect to plant architecture, in Rhododendron inflorescence bracts and leaves are very different. Erica and relatives with the 'ericoid' habit have similar leaves and bracts, and the individual plants may be homologous with inflorescences of Rhododendron. Furthermore, in the ericoids the 'inflorescence-plant' has also been largely sterilised, leaving shoots with mainly just bracts, and flowers restricted to distal parts of the shoot. The epacrids are also 'inflorescence-plants' with foliage comprised of 'bracts', but their sister group, the Vaccinioideae, have dimorphic foliage (leaves and bracts). In Malesian Ericaceae, the four large genera and the family as a whole have most species in the 1500–2000 m altitudinal belt, lower than is often thought and within the range of sweet potato cultivation. The same belt is also most diverse for ferns, birds-of-paradise and bowerbirds. Distribution maps of Malesian Ericaceae are presented, with related species indicated. Concentric patterns of distribution are frequent and could be attributable to evolution around shrinking seas. In New Guinea the main axial range is a composite structure, with the southern part formed by the old Australian craton and the northern and eastern parts formed from 32 tectonostratigraphic terranes or microplates. These formed independently and then docked with each other and the craton. The tectonic boundary between the craton and the accreted terranes is also an important biogeographic boundary. Many taxa have distributions linking different accreted terranes but are not on the craton. Movement and integration of island arcs and more substantial terranes has led to complex patterns of disjunction throughout Malesia, but there is an underlying parallel-arc structure, seen clearly in New Guinea. The tectonic provinces in Borneo are also reflected in the two main biogeographic tracks: Kuching-–Kinabalu and Kutei Mts./Mt. Kemul–Kinabalu, the Lupar River boundary and the Meratus Mts. centre. The islands of the Riouw Pocket (Corner 1978a) are notably surrounded by many groups which are absent there, including mangrove and Ericaceae species. However, other mangrove and coastal taxa occur along a CW Sumatra – Riouw Pocket – SW Borneo track. In Malesia, Rhododendron and Vaccinium mangrove and coastal species are mainly restricted to the west, in Sumatra–Borneo and often the Riouw Pocket; and are represented in New Guinea by related montane taxa. Van Steenis (1963, 1984) drew attention to mangroves uplifted by tectonics and the Malesian Ericaceae in general could be largely derived from mangrove forms. Rhododendron species occur as epiphytes in mangrove, and many Ericaceae occur in calcareous and saline sites. The very rapid rates of tectonic uplift occurring in New Guinea would raise a mangrove community or a coastal 'padang' to the upper montane zone in just one million years.
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Plant discoveries from PABITRA-related exploration in Papua New Guinea
Article
  • Dec 2003
AbstractUnlike many of the archipelagic stations comprising the Pacific-Asia Biodiversity Transect (PABITRA) network, the flora of Papua New Guinea (PNG) is exceedingly speciose and in a remarkable state of preservation. Sites targeted for PABITRA action in PNG are unexplored or have only very limited botanical documentation. Vegetation sampling under such a combination of circumstances is highly problematic, particularly with respect to identification of sterile material from plot enumerations. The country team has thus pursued a study plan based on intensive collection and taxonomic evaluation, conducted prior to establishment of transects. Sterile vouchers can be determined to an acceptable level of confidence when matched to fertile specimens obtained from comprehensive exploration. Substantial numbers of new taxa are being revealed by the PABITRA assessments as a collateral benefit of this procedure. The following narrative summarizes the discoveries which have resulted from ongoing investigations in poorly known environments, and discusses some implications for future floristic work in Papuasia.
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New plants from Papuasia. Novelties from the Lakekamu and Bismarck-Ramu expeditions
Article
  • Dec 1999
Two species are formally described from the 1996 survey of the Lakekamu basin. The new plants are Medinilla sapoi-riverensis (Melastomataceae) and Trichospermum stevensii (Tiliaceae). Medinilla bismarck-ramuensis is described from the 1995 biological survey of the Bismarck-Ramu tract. Taxonomic and ecological notes are provided with the diagnoses.
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Florae Malesianae praecursores XXIII. The genus Rhododendron in Malaysia
  • Jan 1960
  • 45-231
  • S Le Um Er
S LE UM ER, H. (1960). Florae Malesianae praecursores XXIII. The genus Rhododendron in Malaysia. Reinwardtia 5 (2): 45-231.
New species and noteworthy records of Rhododendron in Malesia (Ericaceae)
  • Jan 1973
  • BLUMEA
  • 357-376
  • S Le Um Er
S LE UM ER, H. (1973). New species and noteworthy records of Rhododendron in Malesia (Ericaceae). Blumea 21: 357-376.
Vegetation part 2: botanical survey
  • Jan 1998
  • 36-39
  • W Ta K Eu Ch I
  • J La N G
TA K EU CH I, W. & K U LA N G, J. (1998). Vegetation part 2: botanical survey. In: MACK, A. (ed.) A Biological Assessment of the Lakekamu Basin, Papua New Guinea. Rapid Assessment Program Working Papers 9, pp. 36-39, 105-130. Washington, DC: Conservation International.