Ficus sur ( Moraceae ) and Gymnanthemum coloratum ( Asteraceae : Vernonieae ) – first distribution records for Namibia

http://www.abcjournal.org doi:10.4102/abc.v45i1.1865 Background: The distribution of Ficus sur includes most of tropical Africa, but whilst this species was suspected to occur in Namibia, this has not been verified. Gymnanthemum coloratum is a tropical African savannah shrub or tree that has been recorded for Botswana, Swaziland and South Africa, but which has not previously been recorded for Namibia.


Introduction
Ficus (Family Moraceae) is a large pantropical genus with almost 800 species, of which roughly 100 are native to Africa (Burrows & Condy 2011).Most species are from subtropical and tropical regions and the plants vary from shrubs, lianas and epiphytes to large trees.Ficus is well represented in those parts of southern Africa where frost is not severe.In the Flora of southern Africa (FSA) region 28 species have been recorded (Jordaan 2003).Of these, 11 species have been reported for Namibia, 8 of which are shared with South Africa.
Ficus sur Forssk. is a round-crowned tree up to 25 m tall, occurring in a wide range of habitats including grassland, woodland, riverine forest, semi-deciduous forest and occasionally rocky outcrops.Its distribution extends from the Cape Verde Islands and Senegal in the west, Ethiopia and Yemen in the north and east, through most of tropical Africa to Zimbabwe, Mozambique and throughout eastern South Africa to the forests of the southern coastal belt and it is, together with F. burtt-davyi Hutch., the southernmost representative of Ficus in Africa (Burrows & Burrows 2003).It is also widespread in Angola (Figueiredo & Smith 2008).In the FSA region, F. sur has hitherto been recorded for Botswana, Limpopo, Mpumalanga, Swaziland, KwaZulu-Natal, Eastern Cape and Western Cape (Jordaan 2003).It is not listed in the Prodromus einer Flora von Südwestafrika (Friedrich-Holzhammer 1967).Craven (ed. 1999) listed it as a taxon for which the presence in Namibia needs verification and she mentioned a specimen from the Kaokoveld [Davies,Thompson & Miller 63 (PRE)].As references, Craven cited Van Greuning (1990) and Berg and Wiebes (1992).However, no mention regarding the presence of F. sur in Namibia could be found in the former and in the latter the taxon is merely mentioned as occurring in Namibia.Ficus sur was recently thoroughly treated by Burrows and Condy (2011).They included a map showing its distribution in Africa, but there were no records for Namibia indicated.
Gymnanthemum coloratum (Willd.)H.Rob. & B.Khan [=Vernonia colorata (Willd.)Drake subsp.colorata] is a tropical African savannah shrub or tree, with a distribution that extends from West Africa, through East Africa to southern Africa (Pope 1992).In the FSA region, G. coloratum has hitherto only been recorded and mapped for Botswana, Swaziland and South Africa, for the latter in the provinces Limpopo, Mpumalanga and KwaZulu-Natal (Herman et al. 2003;Van Wyk et al. 2011).
Expeditions to the botanically poorly explored Baynes Mountains on the southern side of the Kunene River in the Kaokoveld of north-western Namibia were undertaken by the authors in 2005 (Van Jaarsveld 2005) and 2009.The biologically rich Kaokoveld forms part of the Kaokoveld Centre of Endemism, a biogeographical region rich in restricted-range animals and plants and extending from north-western Namibia into south-western Angola (Van Wyk & Smith 2001).The expedition and subsequent visits resulted in the identification of F. sur and G. coloratum from the region, and this paper formalises the first records of these two species for Namibia.

Research methods
Specimens were collected for later verification and lodging in the herbarium of the National Botanical Research Institute, Windhoek, Namibia (WIND).Existing material in the National Herbarium, Pretoria (PRE) was examined for comparative purposes and to verify the identity of the two species documented here.Details of the specimens collected and examined are provided below.

Ethical considerations
Collecting/research permits for the study were issued by the Ministry of Environment and Tourism, Republic of Namibia.

Results
Whilst exploring the deeply dissected Slangkloof gorge through the north-central portion of the Baynes Mountains in the Kaokoveld in 2005, an unfamiliar Ficus tree (± 9 m tall) and a single unfamiliar member of the family Asteraceae (tree, ± 4 m tall) were spotted growing amongst Diospyros mespiliformis Hochst.ex A.DC. along the banks of a small perennial stream.Closer examination revealed three specimens of F. sur on the fringe of the perennial stream.All were in healthy condition, and in fruit (Figure 1     The specimen recorded here represents the first record of G. coloratum for Namibia (Figure 5), and a range extension of ± 1250 km to the west of the nearest hitherto known localities for the FSA region in northern Botswana.

Specimens examined
Ficus sur  (Burrows & Burrows 2003).The latter species has not been recorded for Namibia or South Africa.
The fact that F. sur was collected at more than one location in the Kaokoveld suggests that it is probably more widespread in suitable microhabitats.Ficus sur also occurs further north in Angola, suggesting that the Kaokoveld plants represent a cross-border outlier of the much more widespread Angolan population.
Gymnanthemum coloratum was only recorded from the one locality, and was not seen at any other sites in the Kaokoveld by the authors during expeditions to the area.The species also occurs in Angola (Figueiredo & Smith 2008), which   suggests that the Kaokoveld plant represents a cross-border outlier of the population in that country.
).Other fig trees growing in the immediate vicinity were F. bubu Warb., F. cordata Thunb., F. glumosa Delile, F. sycomorus L. subsp.gnaphalocarpa (Miq.)C.C.Berg.During a subsequent expedition to the Kaokoveld in April 2008 the authors recorded yet another location of F. sur in the Baynes Mountains.At Omavanda (south-eastern part of the Baynes Mountains), which is about 20 km to the south-east of Slangkloof, two trees as well as some seedlings were found in rock crevices just above an accessible broad rock ledge on a damp south-facing cliff (Figure 2a, 2b).Moisture draining from various spots along the cliff creates a microclimate (oasis), enabling various mesophytic plant species such as the ferns Adiantum capillus-veneris L., Christella dentata (Forssk.)Brownsey & Jermy (another first record for Source: (a and b) Photos taken by Ernst van Jaarsveld, (c) photo taken by Wessel Swanepoel

FIGURE 2 :
FIGURE 2: Ficus sur at Omavanda, Kaokoveld, Namibia: (a) young plant growing in a rock crevice with characteristic dentate leaves (April 2008), (b) a larger specimen on the cliff ledge with one of the authors, Wessel Swanepoel and uPhakamani Xaba (South African National Botanical Institute) standing next to the tree (April 2008) and (c) the same specimen as in (b), heavily utilised by Rosy-faced lovebirds damaging the growth tips (June 2012).
Distribution map prepared by Hester Steyn

FIGURE 3 :
FIGURE 3: Known distribution of Ficus sur in Namibia.

Source:
Photo taken by Wessel Swanepoel