Brachystephanus jaundensis ssp. nimbae
|Scientific Name:||Brachystephanus jaundensis Lindau ssp. nimbae (Heine) I.Darbysh.|
Brachystephanus nimbae Heine
|Taxonomic Source(s):||Champluvier, D. and Darbyshire, I. 2009. A revision of the genera Brachystephanus and Oreacanthus (Acanthaceae) in tropical Africa. Systematics & Geography of Plants 79: 115-192.|
|Taxonomic Notes:||Specimens from Mt Kupe, Cameroon, were previously assigned to this taxon, but are now considered to belong to Brachystephanus jaundensis Lindau subsp. jaundensis (see Champluvier and Darbyshire 2009). B. jaundensis Lindau subsp. nimbae (Heine) I.Darbysh. is therefore no longer considered to occur in Cameroon.
Subsp. nimbae occurs in Upper Guinea, west of the Dahomey interval, at submontane altitudes between 540-1500 m, whereas B. jaundensis Lindau subsp. nemoralis (S.Moore) I.Darbysh. occurs in the Congo Basin and is a lowland plant. Despite the large disjunction in distribution between these two taxa they are remarkably similar. The only truly diagnostic character appears to be the minor difference in corolla indumentum. In addition, subsp. nimbae often has shorter inflorescences and longer bracts, calyx lobes and anthers than subsp. nemoralis but there is some overlap in all these characters (Champluvier and Darbyshire 2009).
|Identification information:||Perennial herb or sub-shrub, 10-180 cm tall.|
|Red List Category & Criteria:||Vulnerable B2ab(iii,v) ver 3.1|
Brachystephanus jaundensis subsp. nimbae is a perennial herb or sub-shrub that grows in submontane forest and forest margins, often in wet rocky areas such as streamsides and by waterfalls. It has been recorded from seven localities spanning from south-east Guinea to Ghana (Western and west-central Africa). It appears to be rare and has not been found at other seemingly suitable sites in Upper Guinea such as Mts Loma and Simandou, despite intensive collecting there. The major ongoing threat is habitat loss and degradation due to forest clearance for agriculture, and iron-ore mining activities in the Nimba Mountains. Urban expansion and building of roads, and small-scale logging and wood harvesting for charcoal and timber also threaten its habitat.
Since the previous assessment in Cheek et al. (2004) several new sites in the Guinean Nimba Mountains and one at Mt Béro have been found, and it is no longer considered to occur in Cameroon (see taxonomic notes). Its estimated extent of occurrence (EOO) is 54,070 km2 (Least Concern under criterion B1), based on the assumption that it still occurs at all known historical localities. Its estimated area of occupancy (AOO) of 56 km2 is a minimum value, but, in view of its restricted submontane habitat, is unlikely to exceed the Vulnerable (VU) threshold of 2,000 km2 even if new sites continue to be found. There are eight threat-based locations, an observed continuing decline in the area and quality of its habitat, and an inferred continuing decline in number of mature individuals; it is therefore assessed as VU under criterion B2ab(iii,v).
Further research is needed on its population size, distribution and trends, particularly field surveys to establish if it is still extant at historical localities.
|Previously published Red List assessments:|
|Range Description:||Brachystephanus jaundenis subsp. nimbae has been recorded from seven localities across Upper Guinea (Western and west-central Africa): Djiban (close to Macenta); Ziama Massif; between Lamineta village and Hogna kwele (Mts Béro) (all in Guinea); Nimba Mountains (Guinean and Liberian portions); Bosumkese Forest Reserve; Amedzofe (both in Ghana); Mt Tonkoui (Côte d'Ivoire). Based on the assumption that it still occurs at all known historical localities, the EOO is estimated as 54,070 km2 with a minimum AOO of 56 km2.|
Native:Côte d'Ivoire; Ghana; Guinea; Liberia
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No quantitative population data are available for this taxon. It is known from 20 herbarium specimen collections dating from 1949–2012. The most recent collections are from the Guinean Nimba Mountains and Mts Béro (2008–2012). The collections from the other sites are all much older (1949–1969). At one site in the northern end of the Guinean Nimba Mountains it is described as 'locally common' by the collector.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Brachystephanus jaundensis subsp. nimbae grows in submontane forest and forest margins, often in wet rocky areas such as streamsides and by waterfalls (Champluvier and Darbyshire 2009); recorded at 540–1,500 m altitude.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||There is no use/trade information for this species.|
The major ongoing threat is habitat loss and degradation due to forest clearance for agriculture, and mining activities. Urban expansion and building of roads, and small-scale logging and wood harvesting for charcoal and timber also threaten its habitat.
In Guinea the Ziama Massif, Mts. Béro and Djiban (Macenta) locations are under threat because of forest clearance for shifting agriculture and production of charcoal, although the rugged terrain and remoteness of upland areas of the Ziama Massif, and the fact that it is within a biosphere reserve, has provided some protection. The whole area within the Ziama biosphere reserve was forested originally, but primary forest now remains only in the remote upland parts of the south-west, next to the Liberian border. Most of the remainder is now secondary forest (Robertson 2001, Brugiere and Kormos 2009). The record for Djiban dates from 1949 and lacks precise locality information, but Djiban is the name of one of the hills or mountains close to the town of Macenta. The human population of Macenta has grown hugely since 1949, due to both internal population growth and an influx of refugees over the last 20 years or so. This has resulted in deforestation in the vicinity due to urban expansion and agricultural expansion into upland areas. Much of the remaining forest has been degraded, mainly because of the increased collection of wood for charcoal and timber (UNEP 2000). Given the age of the record and the proximity of Djiban to Macenta, B. jaundensis subsp. nimbae may no longer be extant at this location.
The main threat to the two locations in the Nimba Mountains is from iron-ore mining activities; deposits on the Guinean side have yet to be exploited, but trial mines and associated infrastructure have clearly already impacted habitat both within and around the edges of the mining concession (visible from GoogleEarth), and secondary impacts from open-cast mining are a future threat to the sites in the Mount Nimba Strict Nature Reserve. In the southern part of the mountains in Liberia about 6,000 ha have been drastically affected by the building of roads, wells, mine-shafts, workshops and townships. In particular, the removal of hundreds of square metres of soil over large areas has led to streams throughout the area becoming polluted with heavy-metal tainted run-off (Robertson 2001). The records for the sites in the East Nimba Nature Reserve all date from the 1960's, around the time when the mine was starting operations, and it is not known if it is still extant at this location. Recommencement of iron-ore mining operations here (currently stopped due to the low price of iron-ore) would threaten any remaining sites.
Much of the original lowland and submontane forests in Côte d'Ivoire have been destroyed or degraded since B. jaundensis subsp. nimbae was last recorded here in 1959, and deforestation rates are still extremely high (Poorter et al. 2004). The Mont Tonkoui location is close to the major city of Man, and the submontane forests here are threatened by clearance for agriculture - from GoogleEarth patches of cleared forest are visible on the slopes.
In Ghana good quality forest exists mainly as isolated fragments within reserves. The forests around the tourist destination of Amedzofe in Ghana receive no official or other protection. This is a highly populated area and, apart from Mount Gemi, most of the area has been cultivated at one time or another and the vegetation is mostly not original – a few very small remnants of the original primary forest are left. The building of the dam on the Volta river in the 1960's displaced tens of thousands of people and the relocation of these people put much pressure on forest habitat in areas such as Amedzofe. A main motorway recently built (opened 2011) on the Ho-Hohoe road also erased much vegetation on the sides of the old road (Dowsett-Lemaire and Dowsett 2011). The record for Amedzofe dates from 1959 – if the taxon is still present here (for example in forest on Mount Gemi or other remnants) expansion of shifting agriculture into more upland areas and increasing demand for fuel wood and timber threaten any remaining sites at this location.
Although Bosumkese Forest Reserve is protected in theory, it is degraded and poor quality (Hawthorne and Abu-Juam 1995). The record for this location dates from 1958 – if this taxon occurred on Bosumkese Hill, which is a Sacred Forest within the reserve, this may have offered some protection. Steep slopes on hills are also less likely to be impacted due to the difficulty of logging for timber (Hawthorne and Abu-Juam 1995). There is a massive open-cast gold mine close to edge of the reserve, although it has not yet encroached into the reserve. There are however indirect threats to forest habitat here due to displacement of people and increased pressure for farmland and other natural resources such as timber and charcoal.
No specific conservation measures or management plan are in place for B. jaundensis subsp. nimbae. Survey of current known populations may provide a greater understanding of its specific habitat requirements and so where it is most likely to be found in future, as well as establishing whether it is still extant at historical localities.
Sites within the Mount Nimba Strict Nature Reserve, East Nimba Nature Reserve, and Massif du Ziama Classified Forest (which was declared a Biosphere Reserve in 1980) are protected to some extent, although there are still threats to habitat here (see threats section). There are 23 villages in and on the margins of the Ziama reserve and the town of Sérédou, on its eastern edge. The reserve is divided into two main management zones, the protection zone (60,000 ha) and the production zone. Although there is a management plan, it is not known to what extent it is being followed in the exploitation of the production zone, nor whether or how much illegal exploitation is taking place. Encroachment by shifting agriculturalists and by refugees is also a problem (Robertson 2001). It has been proposed that it should given national park status (the highest level of protection) which could improve management and protection (Brugiere and Kormos 2009).
Most Classified Forests in Guinea are severely degraded due to farming activities, although remote and submontane forests such as Mts. Béro Classified Forest have suffered much less than lowland forests due to their relative inaccessibility (Brugiere and Kormos 2009).
Bosumkese Forest Reserve is in a poor condition (Hawthorne and Abu-Juam 1995) and we have little up-to date information on whether Mont Tonkoui Classified Forest is well protected and managed in reality, or what specific threats to this species' habitat there may be. Further research is needed on threats to localities outside of Guinea.
|Citation:||Rokni, S. 2017. Brachystephanus jaundensis ssp. nimbae. The IUCN Red List of Threatened Species 2017: e.T45407A92479199.Downloaded on 19 November 2017.|
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