Tropicos | Name - Dolichos nimbaensis Schnell

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Threat. pl. LGMN > Dolichos nimbaensis

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Dolichos nimbaensis Schnell

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Project Name Data (Last Modified On 4/19/2022)

Acceptance : Accepted

Taxon Profile (Last Modified On 5/31/2022)

Description: Erect or ascending herb 0,2–1,5 m tall with slender stems, angular, striate, or subcylindrical, softly pubescent.

Sous-arbrisseau traînant puis redressé atteignant 1,5 m de hauteur, à tiges grêles peu ou non ramifiées, pubescentes, anguleuses. Feuilles trifoliolées avec des stipules de 15 mm de longeur élargies à la base, aiguës, striées longitudinallement ; folioles de formes variables, le plus souvent ovales, lancéolées, aiguës au sommet, arrondies à la base, les latérales auriculées ou non, limbes latéraux d'environ 6 cm de longeur sur 2 cm de largeur sans l'auricule. Racèmes terminaux ou axillaires dressés de 8 à 12 cm de longeur, pubescents, fleurs mauve bleuté ou pourpre de 6 à 10 mm de longeur avec un pédicelle de 2 à 3 mm s'allongeant à la fructification. Gousses similaires aux autres espèces.

Habitus: Herb

Phenology: Flowers have been observed in June, September, October, November, and December.

Habitat: Highland savannas, at altitudes between 700 and 1,600 m in the Nimba mountains.

Distribution: Guinée, Liberia, Côte d'Ivoire

Distribution Note: The species is endemic to the Nimba Mountains, occurring in the three countries Guinea, Liberia, and Côte d'Ivoire; it is known from 32 collections made between 1937 and 2017. Six collections belonging to Dolichos nimbaensis were excluded for several reasons. No locality information is provided for three collections (Scaetta #3254, Bequaert #41, and Schnell #16432) and the only locality for three historical collections (de Wilde #872, Jaeger #4696, Schnell #6257) is "Mont Nimba", which is imprecise. Four older collections (Glanville #4, Adames #188, Thomas #234, and #6481) in the Kew herbarium are placed far away in the west of Sierra Leone at low elevations. Looking at other numbers from the same collectors they are indeed from the western lowlands of Sierra Leone. The species is not known in between the two areas on mountains, nor in the lowland. One of the specimens (Thomas #6481) was recently determined as Dolichos dinklagei. The flowers of another one (Adames #188) are described as purple, from the other three the colour is not known. On Nimba, the flowers of D. nimbaensis are always yellow with orange/red, whereas the flower color of the related and more widespread D. nimbaensis is usually describes as purple or blue. The three remaining Sierra Leone specimens that are still considered as D. nimbaensis are very likely to be represent another species, and are, for this reason, not considered in this assessment. Moreover, the single occurrence on Pic the Fon is an observation in 2002 by J.-L. Holié, with no specimen collected. Nevertheless, the species is not mentioned from Pic de Fon in recent grey literature. It is likely that this observation is mistaken for D. tonkouiensis, which is known to occur and has already been collected from Pic de Fon. For this reason, we excluded this occurrence from this assessment. Finally, we did not consider a doubtful, un-vouchered field observation (Sidibe) made in forest Bossou because the species is otherwise known from the high savannas of the Nimba Mountains areas. Two additional collections from Cameroon (Pasquet #86 and Villiers #965) were likewise not retained for our assessment because examination of the specimens indicated that they likely do not belong to this species. Therefore, we consider D. nimbaensis as endemic to the Nimba Mountains.

More literature: Adam, J.-G. 1971. Flore descriptive des Monts Nimba (2e partie). Mémoires du Muséum National d'Histoire Naturelle. Nouvelle Série. Série B, Botanique. 22: 1-372.

Complexe: Nimba

Zones Clés de Biodiversité: Monts Nimba (GIN9), Nimba Mountains (LBR12), Réserve Intégrale des Monts Nimba (CIV14)

Conservation assessment (Last Modified On 5/31/2022)

Red List Category: Endangered

Status of Conservation Assessment: Submitted to Red List

Date of assessment: 15 December 2021

Assessment rationale: Dolichos nimbaensis is a herb endemic to the Nimba Mountains, where it occurs in the three countries of Guinea, Liberia, and Côte d'Ivoire. It is known from 32 collections made between 1937 and 2017. Six collections were excluded for several reasons (see Geographic Range section). The 26 remaining collections represent 17 occurrences and one or two subpopulations. Considering the presence of suitable habitats, which are still significant in the Nimba Mountains, we do not regard any of these occurrences as extirpated. Based on a 2 × 2 km grid cell size, the AOO is estimated at 44 km2, below the upper threshold of the Endangered (EN) category under subcriterion B2, and its extent of occurrence (EOO) has been calculated as 62 km2, below the upper threshold of the Critically Endangered category under subcriterion B1. The species is known from two protected areas: the Mount Nimba Strict Nature Reserve in Guinea and Ivory Coast, and the East Nimba National Park in Liberia. However, in Nimba Mountains in Liberia, a former iron ore mining operation has impacted habitat quality. The only known occurrence in Liberian Nimba represents one location. In Guinea, the development of infrastructure for a mining concession has impacted the extent and habitat quality and is expected to lead to the disappearance of at least two occurrences. The occurrences located within the mining concession represent another location. Occurrences located in the Guinea portion of the Word Heritage Site are not considered as threatened and represent another location. Finally, the occurrence located in the Ivorian part of the Nimba range is not considered as threatened and represents another location. As a consequence, the 17 occurrences represent four locations (sensu IUCN 2019) with regard to the most serious plausible threat (mining activities). We infer a past, current, and future continuing decline in the extent and quality of its habitat. We also predict a future decline in its EOO, its AOO, its number of occurrences, and the number of mature individuals. Dolichos nimbaensis is therefore assessed as EN B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v).

Disclaimer: This assessment was prepared on 15 December 2021. The map proposed below is only based on the specimens available on Tropicos, therefore, may not correspond to the information provided in the assessment rationale.

Conservation measures: Dolichos nimbaensis is known from two protected areas: the Mount Nimba Strict Nature Reserve in Guinea and Côte d'Ivoire, and the East Nimba National Park in Liberia. However, since the species is threatened by mining activities various conservation measures should be considered. First, it should be regarded as an HCV1 species (High Conservation Value), and as a consequence should be included in the management plan of the industrial concessions within which it occurs. Second, it should be included in the list of protected species in Guinea, Liberia, and Côte d'Ivoire, and the degradation or loss of its habitat must therefore be avoided. Third, ex situ conservation should be tested, both within the countries where it occurs, and internationally. Finally, a public awareness campaign must be conducted targeting industrial companies and other private actors, NGOs, scientific institutions, and the different governments to ensure that D. nimbaensis is taken into consideration when decisions are made that could impact its conservation.