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A new species and a revised record in Namibian Barleria (Acanthaceae)
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A new species and a revised record in
Namibian Barleria (Acanthaceae)
Iain Darbyshire, Erin A. Tripp & Kyle
G. Dexter
Kew Bulletin
Official Journal of the Royal Botanic
Gardens, Kew
ISSN 0075-5974
Kew Bull
DOI 10.1007/s12225-012-9393-1
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KEW BULLETIN VOL. 67: 1 Y 8 (2012)
ISSN: 0075-5974 (print)
ISSN: 1874-933X (electronic)
A new species and a revised record in Namibian Barleria
(Acanthaceae)
Iain Darbyshire1, Erin A. Tripp2 & Kyle G. Dexter3
Summary. Barleria grootbergensis I. Darbysh. & E. A. Tripp is described from the Grootberg Pass in Kunene Region,
Namibia. Its affinities within Barleria sect. Somalia are discussed. A second taxon, named as Barleria galpinii C. B.
Clarke in the Prodromus einer Flora von SüdwestAfrika, is reassessed and found to be referable to B. pseudosomalia I.
Darbysh., a species previously known only from central Tanzania. A revised checklist to the Barleria of Namibia is
presented.
Key Words. Africa, checklist, conservation, Grootberg, section Fissimura, section Somalia, taxonomy.
Introduction
The genus Barleria L. (Acanthaceae: Acanthoideae:
Barlerieae sensu McDade et al. 2008) comprises 250 –
300 species. It is largely palaeotropical in distribution,
with centres of diversity in the dry woodlands, wooded
grasslands and rocky terrain of eastern and southern
Africa (Balkwill & Balkwill 1997, 1998; Darbyshire
2010). In Namibia, the genus was most recently
treated by Meyer (1968) for the Prodromus einer Flora
von SüdwestAfrika, where 22 species were recorded.
Craven (1999), in her checklist of Namibian plants,
added three further species: B. ameliae A. Meeuse,
B. megalosiphon Mildbr. (= B. capitata Klotzsch) and
B. papillosa T. Anderson. The former two were
omitted from Meyer’s account as they are restricted
in Namibia to the Caprivi Strip and so fall outside the
remit of the Prodromus. The latter is a rare species
only recently recorded in Namibia (e.g. Kolberg &
Tholkes HK1742, 22 Oct. 2005, Karasburg District; K!,
WIND). Of these 25 species, 10 (40%) are either
endemic or near-endemic to Namibia (Appendix 1).
Such a high rate of endemism is not unusual for the
genus in Africa, where many species are highly
restricted in range and often rare (Balkwill & Balkwill
1998). Indeed, neighbouring Angola records over
50% endemism in Barleria.
Whilst conducting fieldwork in Namibia in March
2009, specifically targeting Acanthaceae, two of the
authors (E. A. T. & K. G. D.) came across a distinctive
Barleria in flower on scree near the Grootberg Pass.
The specimen did not key out in Meyer’s (1968)
account and a thorough search across the genus
confirmed that it did not match any currently
described species of Barleria. It was subsequently
collected in fruit in August 2011 by E. A. T and K. G. D.,
together with H. Hasheela and L. Lanyeni of the
National Botanical Research Institute of Namibia
(NBRI). This species is formally described in the first
section of this paper as Barleria grootbergensis I. Darbysh.
& E. A. Tripp.
The second section of the paper corrects an
identification error in Meyer’s account of the Namibian Barleria. A disjunct population of the rare
B. pseudosomalia I. Darbysh., previously thought endemic to Tanzania, is recorded in Namibia for the first
time. A revised and annotated checklist to Barleria is
presented in Appendix 1. The present research
contributes to our ongoing revision of Acanthaceae
in Namibia, in collaboration with E. Kwembeya at
NBRI.
Materials & Methods
Herbarium specimens and, where available, photographs of living plants were studied using standard
herbarium practices. As only a few mature flowers
were available for Barleria grootbergensis, the measurements of corolla lobes, staminal filaments and staminodes are based on a single dissection. Prior to
dissection, flowers were soaked in Aerosol OT 5%
solution; all other measurements were made on dry
material. Pollen and leaf material of the new taxon
were studied using scanning electron microscopy
(SEM). Structures were sputter coated with gold using
Accepted for publication May 2012.
1
Herbarium, Royal Botanic Gardens, Kew, Richmond( Surrey TW9 3AB, UK. e-mail: i.darbyshire@kew.org
2
Rancho Santa Ana Botanic Garden, 1500 N. College Ave., Claremont( California 91711, USA.
3
Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, UK.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Author's personal copy
KEW BULLETIN VOL. 67(3)
a PELCO SC-7 Auto Sputter Coater and then examined using an International Scientific Instruments DS130 / WB-6 SEM.
Terminology in the description largely follows that
applied to Barleria in Balkwill & Balkwill (1997). The
species conservation assessments follow the Categories
and Criteria of IUCN (2001).
1. A new species in Barleria sect. Somalia
Barleria grootbergensis I. Darbysh. & E. A. Tripp sp.
nov. resembling B. lancifolia T. Anderson but differing
in the more congested, spiciform yellow-green inflorescences with the calyces largely hidden within the
suberect bracts during anthesis; the longer bracteoles
and the longer glandular inflorescence indumentum
that is more dense on the bracts. Type: Namibia, W of
Grootberg Pass, Tripp & Dexter 828 (holotype RSA!;
isotypes K!, NY!, WIND!).
http://www.ipni.org/urn:lsid:ipni.org:names:77120498-1
Shrub to 100 cm tall. Mature stems densely whitevelutinous, the trichomes minute, declinate, interspersed with occasional longer appressed trichomes;
uppermost internodes patent glandular-pubescent.
Leaves ovate or lanceolate, 3.8 – 5.3 × 1.4 – 2 cm, base
cuneate, apex acute or attenuate, lateral veins 4 pairs;
leaf buds densely white-strigulose but mature leaves
soon glabrescent except for sparse strigose trichomes
along the margin, midrib and lateral veins beneath,
some trichomes ‘anvil-shaped’ (i.e. biramous with one
long arm and one short arm), uppermost leaf pairs
also glandular-pubescent; cystoliths conspicuous on
both surfaces without magnification, sessile glands
visible on upper surfaces with magnification; petiole
to 6 mm long. Inflorescences short dense terminal spikes
3.5 – 5 cm long, of a series of subsessile single-flowered
opposite cymules; bracts, bracteoles and calyces pale
yellow-green, densely glandular-pubescent throughout; bracts caducous in fruit, elliptic (excluding larger
basal leaf-like pair), 18 – 22 × 5.5 – 8 mm, apex acute
or subattenuate; bracteoles narrowly elliptic or oblanceolate-elliptic, 15.5 – 20 × 2.5 – 5 mm, held erect and
± equalling the calyx, apex acute. Calyx 4-lobed;
abaxial lobe elliptic, 17 – 18.5 × 7 – 8 mm, base
cuneate, apex shallowly notched for up to 2.5 mm,
surface with 5 – 7 prominent subparallel veins;
posticous lobe elliptic, 17.5 – 20 × 6.5 – 7 mm, apex
acute or shortly attenuate; lateral lobes lanceolate,
± 11 × 2 mm, margin hyaline. Corolla pale purple with
whitish throat and tube, 48 – 52 mm long, with sparse
mixed glandular and eglandular trichomes on the
lateral lobes externally; tube 25 – 28 mm long,
unexpanded basal portion of the tube ± 3 – 4 mm in
diam., gradually expanded above attachment point of
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
stamens to ± 6 – 6.5 mm in diam. at the mouth; lobes
in ‘4 + 1’ arrangement, abaxial lobe offset by 9 mm
from the remaining lobes, broadly obovate, 17.5 ×
14.5 mm; lateral lobes elliptic-obovate, 17 × 13 mm;
adaxial lobes elliptic-obovate, 18.5 × 9.5 mm. Stamens
attached 7 mm from base of corolla tube; filaments
31 mm long, minutely pubescent at the base; anthers
4 mm long; lateral staminodes to 1.5 mm long,
flattened and triangular, minutely pubescent, antherodes absent; adaxial staminode minute. Pollen trizonocolporate, globose in equatorial view, 3-lobed in polar
view, with coarse deep reticulation of the interapertural and polar exine. Ovary 4 mm long, distal portion
densely mixed glandular- and eglandular-puberulous;
style 35 – 43 mm long, glabrous; stigma linear, 2.5 –
2.8 mm long, curved. Capsule 13 – 16 × 6 – 7 mm,
including prominent beak 4 – 6 mm long, beaked
portion covered with short glandular and/or
eglandular trichomes, fertile portion glabrous;
seeds c. 5 – 6 × 4 – 5 [very few seen], covered in
non-mucilaginous, crisped hygroscopic trichomes.
Figs 1 – 3.
DISTRIBUTION. NW Namibia; known only from the type
locality.
SPECIMENS EXAMINED. NAMIBIA. Kunene Region (Kaokoland): just W of Grootberg Pass on [road] C40,
19°50'20.2"S, 14°07'12.5"W, fl. 22 March 2010, Tripp &
Dexter 828 (holotype RSA; isotypes K, NY, WIND); same
location, fr. 18 Aug. 2011, Tripp & Dexter (with
Hasheela & Lanyeni) 1963 (CAS, K, MO, NY, RSA,
US, WIND).
HABITAT. Growing on rocky slopes including loose
scree close to the road; 1400 m alt.
CONSERVATION STATUS. This species is currently known
from a single locality, where it is very localised. Less
than 15 plants were seen in the vicinity; however we
should note that population size was not assessed in an
exhaustive manner. Based on current data, it is
apparently highly restricted in its range, having not
been collected previously despite being found along
one of the main roads between the popular Skeleton
Coast and Etosha Pan. However, much of the mountainous region to the north and south of the road over the
Grootberg Pass is inaccessible by vehicle and has
probably never been botanised. Satellite imagery available on Google Earth (http://www.google. co.uk/intl/
en_uk/earth/index.html) suggests that there are
extensive areas of potentially suitable habitat for Barleria
grootbergensis in this region. Furthermore, there appears
to be little threat to the only known population given
that the area is generally not heavily travelled. The only
habitation in the immediate vicinity is that of a small
eco-lodge, which is owned and operated by the
Grootberg Conservancy and thus unlikely to significantly impact the population in a negative manner. Whilst
this species must currently be considered Data Defi-
Author's personal copy
A NEW SPECIES AND A REVISED RECORD IN NAMIBIAN BARLERIA
Fig. 1. Barleria grootbergensis A habit; B mature stem indumentum, including fine detail; C inflorescence; D bract, with detail of
indumentum; E bracteoles (positioned outer left and outer right) and dissected calyx with posticous lobe to the left; F dissected
corolla with androecium; G anther; H pistil. From Tripp & Dexter 828. DRAWN BY JULIET WILLIAMSON.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Author's personal copy
KEW BULLETIN VOL. 67(3)
Fig. 2. Barleria grootbergensis in the field: A, B flowering plants; C fruiting spike; D detail of fruits.
cient (DD) (IUCN 2001) pending further survey work,
it may ultimately prove to be unthreatened.
NOTES. The minute white-velutinous indumentum on
the mature stems, the densely glandular inflorescence
indumentum and the general facies of the flowers place
this species close to Barleria lancifolia T. Anderson, a
species that is widespread and common in Namibia.
B. grootbergensis is, however, easily separable from
B. lancifolia by its dense terminal spikes with the calyces
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
PHOTOS BY E. TRIPP.
largely hidden within the ± erect yellow-green bracts
and bracteoles, the latter subequal in length to the
calyces. In B. lancifolia, the cymules are more distantly
spaced along the axis, at least in the lower portion of
the inflorescence where the bracts are foliaceous.
The bracts in the upper portion of the inflorescence in B. lancifolia are greatly reduced and
proportionally narrowed (though remaining green)
and are more spreading than in B. grootbergensis. The
Author's personal copy
A NEW SPECIES AND A REVISED RECORD IN NAMIBIAN BARLERIA
Fig. 3. SEM images of Barleria grootbergensis: A pollen, apertural view (taken at × 770); B pollen, polar view (taken at × 770); C
adaxial leaf surface showing linear, subepidermal cystoliths, stomata, and sessile, patelliform glands (taken at × 100). IMAGES BY E. TRIPP.
calyces of B. lancifolia are also always clearly exposed
(see Fig. 4). The bracteoles in B. lancifolia are
generally shorter than the calyx and ≤ 15 mm in length
in single-flowered cymules (the lower cymules of the
inflorescence are often 3-flowered). Finally, the glandular trichomes of the inflorescence in B. grootbergensis are
Fig. 4. Barleria lancifolia, showing inflorescence form for comparison with B. grootbergensis: A Kombat, between Otavi and
Grootfontein, Namibia; B Hwale River, Zimbabwe; C 108 km S of Opuwo en route to Sesfontein on C43, Namibia. A collected as
Tripp & Dexter 781, C collected as Tripp & Dexter 857. PHOTOS A, C, BY E. TRIPP, B BY B. WURSTEN.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Author's personal copy
KEW BULLETIN VOL. 67(3)
somewhat longer and more dense (particularly on the
bracts) than those of B. lancifolia.
The combination of prominently beaked, twoseeded capsules (Fig. 2D), three staminodes lacking
antherodes, linear stigmas, absence of spines and nonstellate indumenta place Barleria grootbergensis within
section Somalia of Barleria with confidence (Balkwill &
Balkwill 1997; Darbyshire 2009).
2. A revised record in Namibian Barleria
Meyer (1968) recorded Barleria galpinii C. B. Clarke
in NE Namibia from dense bushland at Andara
Mission Station on the Okavango River, based upon
de Winter & Wiss 4250. This species is otherwise
restricted to rocky hillslopes in NE South Africa and
SE Botswana. Meyer did, however, note some
differences in leaf and calyx shape compared to
typical B. galpinii. Mandy-Jane Balkwill later re-
determined the K duplicate of this specimen as the
more widespread B. mackenii Hook. f. However, on reexamining this collection whilst working on the
treatment of B. mackenii for Flora Zambesiaca, one of
us (I. D.) noted that the stigma in this specimen is
capitate. This not only immediately rules out both
B. galpinii and B. mackenii, but also places the
collection in a different section of the genus. Both
B. galpinii and B. mackenii have linear stigmas, as do
all other species in sect. Somalia. Further investigation
found that in vegetative, calyx and gross floral
morphology, the de Winter & Wiss specimen is inseparable from B. pseudosomalia I. Darbysh. of sect. Fissimura.
This species was only recently described as new and
endemic to the dry foothills of the Eastern Arc
Mountains in central Tanzania (Darbyshire 2010). Only
one well-preserved corolla is available on the de Winter
& Wiss specimen (WIND sheet), and no dissection was
made. As such, it is possible that there are minor
Fig. 5. Barleria pseudosomalia: A habit; B detail of young stem indumentum at leaf node; C calyx, anterior view, with subtending
bracteoles; D dissected corolla with androecium; E staminodes; F dehiscing capsule; G seed. A drawn from a combination of Bidgood
et al. 1001 and Lovett & Congdon 2476; B, F & G from Bidgood et al. 1001, C from Congdon 193, D & E from Lovett & Congdon
2476. DRAWN BY ANDREW BROWN.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Author's personal copy
A NEW SPECIES AND A REVISED RECORD IN NAMIBIAN BARLERIA
differences in, for example, anther size and staminode
length. However, despite this possibility, and despite the
disjunction in distribution, we have little doubt that the
Namibian and Tanzanian plants are conspecific.
A number of disjunctions in plant distributions
between East and South Africa, both at the specific
and generic level, are well documented (see e.g.
Verdcourt 1969; de Winter 1971; Thulin 1994). Most
of these are between the arid zones of the Horn of
Africa and Southwest Africa, at the extremities of the
putative Pleistocene ‘arid corridor(s)’. The disjunct
distribution of Barleria pseudosomalia is less extreme,
but could still be climate-driven. The habitats of the
two populations of B. pseudosomalia differ to some
degree, with the Tanzanian plants being recorded
from dry Brachystegia microphylla woodland and scrub,
whilst the Namibian collection is from ‘moist dense
bushland’. However, annual rainfall is similar in the
two areas (c. 400 − 600 mm p.a.). Much of the
intervening region, in SW Tanzania and Zambia, is
dominated by wetter miombo woodland assemblages with higher annual rainfall. Thus, the intervening habitat may not be suitable for B.
pseudosomalia under current climatic conditions.
A full description of Barleria pseudosomalia can be
found in the protologue (Darbyshire 2010: 377) and is
not repeated here, but the species is illustrated for the
first time in Fig. 5.
Barleria pseudosomalia I. Darbysh. (Darbyshire 2010:
377). Type: Tanzania, Mpwapwa Distr., Bidgood et al.
1001 (holotype K! sheet 1; isotypes C, CAS, DSM!, EA!,
K! sheet 2).
Barleria galpinii sensu Meyer (1968: 14), non C. B. Clarke.
DISTRIBUTION. Central Tanzania, NE Namibia.
SPECIMENS EXAMINED. TANZANIA. Mpwapwa Distr.: 2 – 3
miles on Kibakwe to Motta track, fr. 10 April 1988,
Bidgood et al. 1001 (holotype K sheet 1; isotypes DSM,
EA, K sheet 2); Rubeho Mts, Ikuyu to [Mang’aliza]
Mangalisa road, Mangalisa Mt, fl. & fr. 10 April 1988,
Congdon 193 (K); between Ikuyu and Mangalisa, fl. &
fr. 10 April 1988, Lovett & Congdon 3192 (MO). Iringa
Distr.: Iringa to Dodoma road N of Isimani, fl. 31
Jan. 1988, Lovett & Congdon 2976 (DSM, K, MO).
NAMIBIA. Okavango Native Territory, Andara Mission
Station, fl. 14 Jan. 1956, de Winter & Wiss 4250 (K,
PRE, WIND).
HABITAT. In Tanzania, recorded from dry woodland
and scrub with Brachystegia microphylla; 1200 – 1250 m
alt. In Namibia, in shade of moist dense bushland on
sandy soil; altitude unrecorded.
CONSERVATION STATUS. Assessed by Darbyshire (2010)
as IUCN (2001) category Data Deficient (DD);
the discovery of a Namibian population greatly
extends the Extent of Occurrence but this species
remains poorly known and is still clearly scarce. As
threats remain unknown, the assessment of DD is
upheld here.
Acknowledgements
Fieldwork in Namibia was supported by a U.S. National
Science Foundation grant to E. Tripp and L. McDade
(DEB-0919594). We thank Juliet Williamson and Andrew
Brown respectively for the excellent illustrations of Barleria
grootbergensis and B. pseudosomalia, and Bart Wursten for
permitting use of his photograph of Barleria lancifolia from
Zimbabwe. At the National Botanical Research Institute,
Windhoek (WIND), we thank Ezekeil Kwembeya and
Esmerialda Klaassen for facilitating the fieldwork,
Hendrina Hasheela and Leevi Lanyeni for field
assistance during the second collecting trip, and
Hendrina Hasheela for kindly checking and scanning herbarium specimens of Barleria. We thank the
Ministry of Environment and Tourism for granting
our research permits. Finally, two anonymous
reviewers are thanked for their useful comments on
an earlier draft of the manuscript.
Appendix 1: revised and annotated checklist
of Barleria in Namibia
We here present an update of Craven’s (1999) list of
Namibian Barleria. Synonymy is provided only where
the accepted name differs from Craven’s list and/or
from the earlier revision by Meyer (1968). Endemic
species are marked (E); near-endemics (NE).
Sect. Barleria
(1) Barleria capitata Klotzsch
Barleria megalosiphon Mildbr. synon. nov.
(2) Barleria cyanea S. Moore
(3) Barleria damarensis T. Anderson (E)
Note. The records from Angola listed by Clarke (1899)
under the synonym B. marlothii Engl. and repeated by
Makholela (2008) are erroneous and refer to a taxon
more closely allied to B. cyanea S. Moore.
(4) Barleria elegans S. Moore
(5) Barleria jubata S. Moore (E)
(6) Barleria lanceolata (Schinz) Oberm. (E)
(7) Barleria lichtensteiniana Nees
(8) Barleria macrostegia Nees
(9) Barleria meeuseana P. G. Mey. (E)
(10) Barleria merxmuelleri P. G. Mey. (E)
(11) Barleria papillosa T. Anderson (NE)
Note. This rare species is also recorded from near the
Namibian border in South Africa.
(12) Barleria rigida Nees
Note. This species and its allies are currently under
revision by F. Nyirenda and K. Balkwill (J). It is likely that
more than one taxon will be recognised in Namibia since
there is considerable morphological variation.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Author's personal copy
KEW BULLETIN VOL. 67(3)
(13) Barleria solitaria P. G. Mey. (E)
Sect. Fissimura
(14) Barleria pseudosomalia I. Darbysh.
Barleria galpinii sensu Meyer (1968: 14), non C. B. Clarke
Sect. Prionitis
(15) Barleria ameliae A. Meeuse
Barleria prionitis L. subsp. ameliae (A. Meeuse) Brummitt
& J. R. I. Wood
Note. Craven (1999) listed this taxon both as a good
species and as a subspecies of B. prionitis; for a
discussion on the appropriate taxonomic rank see
Darbyshire (2010: 415).
(16) Barleria kaloxytona Lindau (E)
(17) Barleria dinteri Oberm. (NE)
Note. there are very few records of this species from
South Africa. However, it is questionable as to whether
it is distinct from B. coriacea Oberm. of Botswana and
NE South Africa; the two might be better treated as
geographic subspecies.
(18) Barleria prionitoides Engl.
Barleria prionitis L. subsp. prionitoides (Engl.) Brummitt &
J. R. I. Wood
Note. Craven (1999) listed this taxon as endemic,
however it is also frequent in Angola.
(19) Barleria senensis Klotzsch
Sect. Somalia
(20) Barleria grootbergensis I. Darbysh. & E. A. Tripp (E)
(21) Barleria lancifolia T. Anderson
(22) Barleria lugardii C. B. Clarke
(23) Barleria mackenii Hook. f.
Barleria galpinii sensu Craven (1999: 152) quoad
Burgoyne 3273, non C. B. Clarke
(24) Barleria matopensis S. Moore
Barleria albi-pilosa Hainz synon. nov.
Note. Barleria albi-pilosa was accepted as an endemic
species by both Meyer (1968) and Craven (1999)
but this taxon is here considered to fall within the
variation of the widespread B. matopensis.
(25) Barleria violacea Hainz (E)
Note. The status of this taxon, and in particular its
relationship to Barleria matopensis, has not been fully
assessed at the present time. The type specimen of B.
violacea could be merely a depauperate form of B.
matopensis.
Sect. Stellatohirta
(26) Barleria taitensis S. Moore var. occidentalis S. Moore
Barleria rogersii sensu Meyer (1968: 17) & sensu Craven
(1999: 152).
Note. Varietal status seems inappropriate for this
geographically as well as morphologically discrete
variant of Barleria taitensis (see Darbyshire 2010: 381
for further discussion); however, the B. taitensis - B.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
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rogersii complex is currently under revision by one of us
(I. D.). As such, we here refrain from making any
taxonomic changes until that revision is complete.
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