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A remarkable range disjunction recorded in Metarungia pubinervia ( Acanthaceae )



Summary The first occurrence of the genus Metarungia Baden (Acanthaceae) in west Africa is recorded with the discovery of an isolated population of the widespread eastern African taxon M. pubinervia (T. Anderson) Baden in eastern Nigeria. The conservation status of this species is discussed.
A remarkable range disjunction recorded in Metarungia pubinervia
Iain Darbyshire
, Kaj Vollesen
& Hazel M. Chapman
Summary. The rst occurrence of the genus Metarungia Baden (Acanthaceae) in west Africa is recorded with the
discovery of an isolated population of the widespread eastern African taxon M. pubinervia (T. Anderson) Baden in
eastern Nigeria. The conservation status of this species is discussed.
Key Words. Acanthaceae, Afromontane, Gashaka Gumti, Metarungia pubinervia, Nigeria.
Whilst conducting ecological survey work within the
Gashaka Gumti National Park and surrounding high-
lands of Saurdauna Province, Taraba State, Nigeria in
November 2002, one of the authors (H.M.C.) collect-
ed a spectacular owering Acanthaceous shrub from
the remote Leinde Fadale Forest at c. 1600 m altitude.
The specimen (H. M. Chapman 24) was subsequently
brought to Kew for identication and was found to be
referable to the genus Metarungia Baden, previously
known only from three species in eastern and
southern Africa (Baden 1981, under the illegitimate
name Macrorungia C. B. Clarke). In view of the large
disjunction in distribution, it was assumed that the
Nigerian material would prove to represent a new
species, although it was noted that the owering
material closely resembled the widespread east African
taxon M. pubinervia (T. Anderson) Baden, and it
readily keyed to that species in the revision of the
genus (Baden ibid.). Further collections, including
fruiting material, were requested and a second site
visit was made in December 2003, where further
owering and mature fruiting specimens were collect-
ed (H. M. Chapman 561). More detailed comparison
of this material with M. pubinervia found the Nigerian
gatherings to be inseparable from the east African
material, with all measurements falling well within the
range recorded for M. pubinervia by Baden (ibid.).
Metarungia pubinervia was previously recorded over a
broad distribution in eastern and southeastern Africa,
from montane southern Sudan and southwestern
Ethiopia, through the east African mountain chains
and south to southern Zimbabwe and Mozambique
where it was also recorded from major river catch-
ments. Its westernmost extent was along the mountains
bordering the Albertine Rift in eastern Congo-Kinshasa
and Burundi (see Baden 1981, Fig. 1). The Nigerian
population therefore represents a western range ex-
pansion of approximately 1200 km.
On the western fringes of its east African range,
Metarungia pubinervia is often associated with mid-
altitude (1000 1200 m alt.) forest typical of the
Congo Basin, with dominant trees including Pterygota,
Newtonia and Pseudospondias, whilst particularly in the
SE part of its range it extends to lower altitudes within
riverine forest. However, through much of its east
African range it is most commonly associated with
various montane and submontane evergreen forest
assemblages up to 2000 m alt. Its distribution there-
fore falls largely within the Afromontane phytocho-
rion, a well-dened archipelago-like oristic region
well represented in the mountain chains of east Africa
and the Cameroon Highlands (White 1978,1981,
1983). Range disjunctions of Afromontane taxa be-
tween these two montane regions are well docu-
mented and rather plentiful; for example Sebsebe
et al. (2006) traced 12 species which occur in the
highlands of Ethiopia and Cameroon but were absent
in the intervening lowlands. Many of these are
common Afromontane trees and shrubs, such as
Agarista salicifolia G. Don (Ericaceae), Bersama abyssinica
Fresen. (Melianthaceae), Nuxia congesta R. Br. ex Fresen.
(Buddlejaceae) and Schefflera abyssinica (Hochst. ex A.
Rich.) Harms (Araliaceae). However, some herbaceous
taxa display a similar trend; for example Sebsebe et al.
Accepted for publication October 2008.
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
KEW BULLETIN VOL. 63: 613615 (2008)
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2008
(ibid.) noted Moraea schimperi (Hochst.) Pic. Serm.
(Iridaceae)andScadoxus multiflorus (Martyn) Raf.
(Amaryllidaceae). Within the Acanthaceae this distribu-
tion has previously been noted in, for example,
Dicliptera laxata C. B. Clarke and Mimulopsis solmsii
Schweinf., both of which are widespread in the east
African mountains and in the Cameroon Highlands.
Two points are however worthy of note with regard to
the Metarungia disjunction. The rst is the apparent
lack of evolutionary divergence (at least based upon
morphological evidence) of the highly isolated
Nigerian population. This is unusual in the Acanthaceae
in which regional differences are often evident within
taxa, even on a considerably smaller scale than the
current disjunction. More remarkable still is the
apparent absence of this species from suitable habitats
in the intervening area, most notably in neighbouring
forests of Chappal Waddi and the remainder of the
Cameroon Highlands (as dened by Cheek et al. 2004)
where signicant areas of evergreen forest at a similar
altitude to Leinde Fadale (c. 1600 1700 m) remain
extant. With large, showy red owers and often a
colonial ecology, populations of this species are unlikely
to be overlooked. As evidenced by the Nigerian
population, this species appears to have a regular
annual owering period during the drier season
(November December), a period in which much
collecting has been carried out in the adjacent
mountains of Cameroon over recent decades. There-
fore, although it may yet be discovered in the more
remote parts of that country, it is almost certainly
absent from the well-known mountain regions (Mt
Cameroon, the Kupe-Bakossi-Mwanenguba complex
and the Bamenda Highlands). In contrast, the majority
of Afromontane taxa displaying a similar range disjunc-
tion are widely recorded and locally common in both
eastern Africa and the Cameroon Highlands, often with
scattered satellite populations in the intervening Congo
Basin or Angola (White 1981). The species with
perhaps the closest distribution pattern to that of
Metarungia pubinervia is the Afromontane tree Apodytes
dimidiata E. Mey. ex Arn. (Icacinaceae), which is
widespread and common in montane east Africa but
is known in the Cameroon Highlands from only ve
records, three of which are from Nigeria; it was rst
recorded in the well-collected Bamenda Highlands of
Cameroon as recently as 2004 (Cheek 2004).
Not only does this represent a new species record
for west Africa but also a new generic record.
However, Metarungia is morphologically very close to
the genus Anisotes Nees, which is recorded in west
Africa with two species in Cameroon and one species
in Guinea-Conakry. The only signicant diagnostic
character for the two genera lies in the dehiscence of
the capsule, the placenta of Metarungia rising elasti-
cally at dehiscence, that of Anisotes remaining attached
to the wall of the capsule (Baden 1981). This
character has arisen independently in several unrelat-
ed groups within the Acanthaceae and has previously
been found to be of insufcient consistency to
maintain the separation of Peristrophe Nees from
Dicliptera Juss. (Darbyshire & Vollesen 2007)and
Rungia Nees from Justicia L. (Vollesen in prep.). It is
therefore likely that future analysis of Metarungia will
result in its reduction to synonymy within Anisotes,an
approach already adopted by Heine (1966).
In both Anisotes and Metarungia, the large, brightly
coloured corollas are almost certainly bird-pollinated,
although direct pollination studies are yet to be
conducted on these groups. It is envisaged that future
observations of the Nigerian population of M. pubiner-
via will further enlighten our understanding of this
pollination mechanism.
Metarungia pubinervia (T. Anderson)Baden (1984:638).
DISTRIBUTION. Montane regions of eastern and south-
eastern Africa (Ethiopia, Uganda, Kenya, Burundi,
eastern Congo-Kinshasa, Tanzania, Mozambique,
Malawi, Zambia and Zimbabwe); eastern Nigeria.
NIGERIA. Saurdauna Province: Gashaka Gumti National
Park, Leinde Fadale forest, . 7 Nov. 2002, H. M.
Chapman 24 (K!, UCI); idem,. & fr. 29 Dec. 2003, H.
M. Chapman 561 (BR!, CAS!, K!, UCI, WAG!).
CONSERVATION STATUS. This species is widely distributed
in eastern and southeastern Africa where it can be
locally common and it is represented by numerous
collections in the Kew herbarium. Therefore, although
habitat destruction and degradation continue to occur
in parts of its range, it cannot be considered globally
threatened and is assessed as of Least Concern (LC)
under IUCN (2001) criteria. On a national level, the
single site in Nigeria, Leinde Fadale, is a small montane
forest patch of approximately 8 km
, lying just beyond
the boundary of the Gashaka Gumti National Park. It is
locally abundant here in one small area at c. 1600
1670 m alt., forming an almost monotypic understorey.
This forest is rather remote and is currently
undisturbed, but as it lies outside the boundary of the
formally protected National Park, it is vulnerable to
future agricultural encroachment. The presence of this
nationally scarce species could be used to support the
possible future extension of the boundary of the park
to incorporate this important forest remnant. If the
high diversity and high numbers of endemic and/or
scarce taxa recorded in the adjacent montane regions
of Cameroon are indicative, it is quite likely that the
discovery of Metarungia pubinervia here will be followed
by further equally interesting botanical nds during the
on-going ecological research programme in the
Gashaka Gumti region.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2008
Research in the Gashaka Gumti National Park was
supported by Flora and Fauna International, in
collaboration with the University of Canterbury and
the North of England Zoological Society. We thank
Martin Cheek for valuable input, and thank two
anonymous reviewers for comments on an earlier
draft of this manuscript.
Baden, C. (1981). The genus Macrorungia (Acanthaceae),
a taxonomic revision. Nordic J. Bot. 1: 143 153.
____ (1984). Metarungia, a valid name for Macrorungia
auctt. (Acanthaceae). Kew Bull. 39: 638.
Cheek, M. (2004). Vegetation. In: Y. Harvey, B. J. Pollard,
I. Darbyshire, J.-M. Onana & M. Cheek (eds.), The
Plants of Bali Ngemba Forest Reserve, Cameroon. A
Conservation Checklist. Royal Botanic Gardens, Kew.
____, Pollard, B. J., Darbyshire, I., Onana, J.-M. & Wild,
C. (2004). The Plants of Kupe, Mwanenguba and
the Bakossi Mountains, Cameroon. A Conservation
Checklist. Royal Botanic Gardens, Kew.
Darbyshire, I. & Vollesen, K. (2007). The transfer of
the genus Peristrophe to Dicliptera (Acanthaceae), with
a new species described from eastern Africa. Kew
Bull. 62: 119 128.
Heine, H. (1966). Acanthacées. Flora of Gabon 13.
Muséum National dHistoire Naturelle, Paris.
IUCN (2001). IUCN Red List Categories and Criteria:
Version 3.1. IUCN Species Survival Commission,
IUCN, Gland, Switzerland and Cambridge, U.K.
Sebsebe Demissew, Friis, I., Nordal, I. & Bürger, A.-M.
(2006). Disjunctions in the African ora as seen
from the ora of Ethiopia and Eritrea. In: S. A.
Ghazanfar & H. J. Beentje (eds.), Taxonomy and
Ecology of African Plants, their Conservation and
Sustainable Use, pp. 247 258. Royal Botanic
Gardens, Kew.
White, F. (1978). The Afromontane region. In: M. J. A.
Werger (ed.), Biogeography and Ecology of South-
ern Africa. pp. 463 513. W. Junk, The Hague,
____ (1981). The history of the Afromontane archipelago
and the scientic need for its conservation. Afr. J.
Ecol. 19: 33 54.
____ (1983). UNESCO/AETFAT/UNSO Vegetation
Map of Africa & A descriptive memoir to accompa-
ny the UNESCO/AETFAT/UNSO Vegetation Map
of Africa. UNESCO, Paris.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2008
... This is fascinating, considering that mountains sharing similar species and flora assemblies can be separated by thousands of kilometers of inhospitable habitat (White 1981). Metarungia pubinveria is a prime exemplar: until 2008, this species had only been recorded in the montane regions of East Africa; its discovery in a single forest in the highlands of eastern Nigeria represented a range disjunction of some 1200km and the first, and so far, only record of this species and genus in West Africa (Darbyshire et al. 2008). ...
... The conservation importance of Afromontane habitats should be stressed, since these areas harbour relict populations, endemics, and often-when one takes the time to look-species new to science (White 1981, Kahindo et al. 2007, Darbyshire et al. 2008, Branch and Bayliss 2009, Taylor et al. 2012, McDonald and Daniels 2012. Kahindo et al. (2007) argue for a greater emphasis of genetics in conservation planning for Afromontane species because the identification of genetically distinct, but possibly cryptic, lineages has a number of points relevant to their protection: (1) the extent of biodiversity is not truly appreciated until phylogenetic analyses are conducted; ...
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The montane forests of Africa represent some of the Earth's most diverse and threatened ecosystems. In particular, those in West Africa have received comparatively little attention from scientists in terms of understanding the ecology and biodiversity of their species. This thesis wishes to understand genetic and ecological factors that underpin the long-term survival of selected tree species (Cordia millenii, Entandrophragma angolense, Lovoa trichilioides) in the montane forests of the Mambilla Plateau, Nigeria. The results obtained here provide a strong foundation for future work that wishes to preserve the diverse forests of this region.
... It is also unexpected because one would not predict from the pre-existing data on the genus that such a new species would be so biogeographically and climatically disjunct from its congeners in the Libreville area of Gabon (see under Pseudohydrosme ebo above). However, examples of even more dramatically unexpected African range extensions have occurred recently such as the westward extension by 2,400 km of the genus Ternstroemia Mutis ex L.f., of Talbotiella Baker by 1,400 km, and of the genus Metarungia Baden by 1,200 km, or in the other direction, eastwards, 1,500 km in Mischogyne Exell (Cheek et al., 2019;Van der Burgt et al., 2018;Darbyshire, Vollesen & Chapman, 2008;Gosline, Marshall & Larridon, 2019 respectively). Such discoveries underline how incomplete our knowledge of the geography of African plant genera remains. ...
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This is the first revision in more than 100 years of the African genus Pseudohydrosme , formerly considered endemic to Gabon. Closely related to Anchomanes , Pseudohydrosme is distinct from Anchomanes because of its 2-3-locular ovary (vs. unilocular), peduncle concealed by cataphylls at anthesis and far shorter than the spathe (vs. exposed, far exceeding the spathe), stipitate fruits and viviparous (asexually reproductive) roots (vs. sessile, roots non-viviparous), lack of laticifers (vs. laticifers present) and differences in spadix: spathe proportions and presentation. However, it is possible that a well sampled molecular phylogenetic analysis might show that one of these genera is nested inside the other. In this case the synonymisation of Pseudohydrosme will be required. Three species, one new to science, are recognised, in two sections. Although doubt has previously been cast on the value of recognising Pseudohydrosme buettneri , of Gabon, it is here accepted and maintained as a distinct species in the monotypic section, Zyganthera . However, it is considered to be probably globally extinct. Pseudohydrosme gabunensis , type species of the genus, also Gabonese but probably extending to Congo, is maintained in Sect. Pseudohydrosme together with Pseudohydrosme ebo sp.nov . of the Ebo Forest, Littoral Region, Cameroon, the first addition to the genus since the nineteenth century, and which extends the range of the genus 450 km north from Gabon, into the Cross-Sanaga biogeographic area. The discovery of Pseudohydrosme ebo resulted from a series of surveys for conservation management in Cameroon, and triggered this article. All three species are morphologically characterised, their habitat and biogeography discussed, and their extinction risks are respectively assessed as Critically Endangered (Possibly Extinct), Endangered and Critically Endangered using the IUCN standard. Clearance of forest habitat for logging, followed by agriculture or urbanisation are major threats. Pseudohydrosme gabunensis may occur in a formally protected area and is also cultivated widely but infrequently in Europe, Australia and the USA for its spectacular inflorescences.
... In size and form, corollas of Metarungia are remarkably similar to those of Anisotes and it is somewhat surprising that these plants are not closely related (see below). The results presented here thus strongly suggest parallel evolution of these floral traits, likely an adaptation to passerine bird pollination (Darbyshire & al., 2009) (e.g., long and often brightly colored corollas, axillary inflorescences; Bruneau, 1997). Specifically, (Kiel & al. 174,RSA); F, Anisotes madagascariensis (Daniel & Butterwick 6736,CAS). ...
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This is the first study in Acanthaceae to provide a robust and well-sampled phylogenetic framework for the ‘justicioid’ lineage (Acanthaceae: Acanthoideae: Justicieae), a clade that includes at least 1000 species that together occupy essentially the entire distributional range of the family as a whole. Species are morphologically diverse and occupy a wide variety of habitats. Although much progress has been made in understanding phylogenetic relationships within Acanthaceae, well-sampled phylogenetic studies are lacking for ‘justicioids’. DNA sequence data from six regions for 178 accessions from across the entire lineage were used to test monophyly and validity of 17 putative genera of ‘justicioids’ on a global scale. Included among these genera is the species-rich genus Justicia for which we evaluate the current morphology-based classification with a focus on Old World taxa. Our results strongly support monophyly of New World ‘justicioids’, including all New World species of Justicia plus species assigned to at least five other smaller genera. Further, with a greatly expanded taxon sample, we confirm our earlier unexpected result that Diclipterinae are embedded within ‘justicioids.’ As traditionally circumscribed, Diclipterinae lack the morphological traits that mark ‘justicioids’ and thus had not previously been associated with that group. This study further extends this unexpected result by placing a number of Old World ‘justicioids’ in a clade that is sister to Diclipterinae. Although some genera of ‘justicioids,’ notably of Diclipterinae, are monophyletic, Justicia is grossly polyphyletic. We explore these results by examining the diagnostic utility of morphological characters for major clades with a focus on inflorescences, androecia, pollen and seeds. We further use our results as context for documenting evolutionary patterns of floral traits and pollinator relationships, as well as biogeographic patterns, across this species-rich and diverse clade.
Four species of Anisotes Nees (Acanthaceae) are described from northern and west-central Madagascar: A. hygroscopicus T. F. Daniel, Letsara & Martín-Bravo, A. perplexus T. F. Daniel, Letsara & Martín-Bravo, A. subcoriaceus T. F. Daniel, Letsara & Martín-Bravo, and A. venosus T. F. Daniel, Letsara & Martín-Bravo. A key to the six species of the genus known from Madagascar, all of them endemic to the island, is provided. Morphological features previously unknown in the genus are noted for A. hygroscopicus and A. venosus (hygroscopic trichomes on seeds), A. subcoriaceus (2-colporate, pseudocolpate pollen lacking insulae), and A. perplexus (2-pororate pollen). None of these species can be treated with certainty in any of the currently recognized sections of Anisotes. Data pertinent to the conservation status of each species are provided.
The tropical African genera Brachystephanus Nees and Oreacanthus Benth. are revised. A detailed morphological survey indicates that only a single genus is involved, the name Brachystephanus having priority. A new taxonomie treatment is therefore proposed with Brachystephanus sensu lato divided into three sections: sect. Brachystephanus, sect. Oreacanthus and sect. Pseudoreacanthus. The closely allied American genus Stenostephanus Nees is compared using both available morphological and molecular data. In the newly circumscribed Brachystephanus, 32 taxa within 22 species are presented among which six new species, two new subspecies and two new varieties are described here, together with new combinations or names for four taxa and a new status for two taxa being formalised. Keys to identification and descriptions are presented for each taxon together with notes on habitat and ecology, distribution, phytogeographical considerations and herbarium specimen citations, supported in many instances by illustrations. Pollen analysis with accompanying SE micrographs is provided for 21 taxa. The occurrence of plietesial life cycles, myrmecophily and gynomonoecy within the genus are discussed, together with a summary of the conservation significance of Brachystephanus. © 2009 National Botanic Garden of Belgium Permission for use must always be obtained from the National Botanic Garden of Belgium.
A justification for the amalgamation of the genus Peristrophe Nees into Dicliptera Juss. is presented. Particular attention is paid to the mechanism of capsule dehiscence and its taxonomic significance. Four new combinations are made for Dicliptera taxa occuring in the Flora of Tropical East Africa and Flora Zambesiaca regions: D. paniculata (Forssk.) I. Darbysh., D. gillilandiorum (K. Balkwill) I. Darbysh., D. decorticans (K. Balkwill) I. Darbysh. and D. serpenticola (K. Balkwill & Campb.-Young) I. Darbysh. A new species, D. brevispicata I. Darbysh., is described from Tanzania and Zambia and its taxonomic placement and conservation status are discussed. The differences between Dicliptera, under its broadened delimitation, and the closely related Hypoestes Sol. ex R. Br. are considered.
The genus Macrorungia C. B. Clarke is revised. 5 taxa have previously been proposed in the genus; the present revision recognises 3, viz. Macrorungia galpinii C. Baden sp. nov., M. longistrobus C. B. Clarke and M. pubinervia (T. Anders.) C. B. Clarke. The delimitation between Anisotes and Macrorungia is discussed. Phytogeographical and ecological aspects are discussed in relation to the phytogeog–raphical division of Africa.
The vegetation of the highest mountains in tropical Africa is so different from that of the surrounding ‘lowlands’* that it has attracted the attention of travellers and scientists since the earliest days of botanical exploration. Even to the layman, it is familiar because of the unusual growth-forms of its giant lobelias and senecios. In recent years the flora and vegetation of these high peaks have been regarded by specialists (Hauman 1955, Hedberg 1965) as sufficiently distinct to justify the recognition of a separate phytogeographical ‘Afroalpine’ Region.
The Afromontane floristic région is briefly described and examples of its complex biogeographical and evolutionary relationships are given. The origin of disjunctions of the Afromontane flora remains a matter of controversy but current hypotheses based on biogeographic and stratigraphic evidence are examined; the former are found to require some modification while the latter tend to be discordant with the facts. Evidence is presented which indicates a relatively recent southern migratory track between the mountains of East and West Africa, at least for forest trees. The implications for conservation and research arising from the complexity of the Afromontane flora and its outstanding scientific interest are discussed. La région floristique d'Afromontagne est brièvement décrite et des exemples de ses relations biogéographiques et évolutives sont données. L'origine de disjonction dans la flore d'Afromontagne reste une matière controversée mais des hypothèeses basées sur des données biogéographiques et stratigraphiques sont examinées; les premières requièrent quelques modifications alors que les secondes semblent discordantes avec les faits. Certaines évidences indiquent une voie de migration vers le Sud relativement récente entre les montagnes d'Afrique de 1'Est et de I'Ouest, tout au moins pour les arbres forestiers. Les implications pour la conservation et la recherche dues è la complexité de la flore d'Afromontagne et l'intérêt scientifique qui en découle sont discutés.
Acanthacées Flora of Gabon 13. Muséum National d IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission Disjunctions in the African flora as seen from the flora of Ethiopia and Eritrea
  • H Heine
  • Iucn
  • Gland
  • Switzerland
  • U K Cambridge
  • Sebsebe
  • Demissew
  • I Friis
  • I Nordal
  • A.-M Bürger
Heine, H. (1966). Acanthacées. Flora of Gabon 13. Muséum National d'Histoire Naturelle, Paris. IUCN (2001). IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission, IUCN, Gland, Switzerland and Cambridge, U.K. Sebsebe Demissew, Friis, I., Nordal, I. & Bürger, A.-M. (2006). Disjunctions in the African flora as seen from the flora of Ethiopia and Eritrea. In: S. A. Ghazanfar & H. J. Beentje (eds.), Taxonomy and Ecology of African Plants, their Conservation and Sustainable Use, pp. 247 – 258.
The Plants of Bali Ngemba Forest Reserve, Cameroon. A Conservation Checklist
  • M Cheek
  • M. Cheek
Cheek, M. (2004). Vegetation. In: Y. Harvey, B. J. Pollard, I. Darbyshire, J.-M. Onana & M. Cheek (eds.), The Plants of Bali Ngemba Forest Reserve, Cameroon. A Conservation Checklist. Royal Botanic Gardens, Kew.