Tuesday, June 19, 2018

[Botany • 2018] Talbotiella cheekii (Leguminosae: Detarioideae) • A New Tree Species from Guinea

Talbotiella cheekii Burgt

in van der Burgt, Molmou, Diallo, et al., 2018.

Talbotiella cheekii Burgt, a new tree species from Guinea, is described and illustrated. It is a tree to 24 m high, with a stem diameter to 83 cm, and occurs in forest dominated by tree species of the Leguminosae subfamily Detarioideae, on rocky stream banks and rocky hill slopes, at an altitude of 100 – 600 m. It is estimated that 1600 – 2400 mature trees have been seen, in about twelve forest patches; more trees may be present in places not yet visited. One of the localities of the new species is situated at only 46 km northeast of the centre of the capital Conakry and 6 km northeast of the town centre of Coyah, part of the Conakry urban agglomeration. Its distribution is 1400 km further west from the previous westernmost distribution of the genus. The current extent of occurrence is 166 km2. Talbotiella cheekii is here assessed as Endangered (EN) following IUCN Red List categories.

Key Words: Conservation, Endangered species, West Africa 

Fig. 3 Talbotiella cheekii Burgt.
 A branch with inflorescences; B leaf upper surface; C infructescence with three fruits; D leaflet lower surface showing two glands; E stipule; F auriculate stipule; G flower.

 A, E, G from Burgt 2087; B, D, F from Burgt 2065; C from Molmou 988. drawn by Xander van der Burgt.

Fig. 1. Talbotiella cheekii Burgt.
A two flowers; B twig with inflorescences; C infructescence with two fruits; D leaves.

 A – B from Burgt 2087; C from Molmou 988; D from Burgt 2065. 
PHOTOS: A, B, D Xander van der Burgt; C Martin Cheek.

Talbotiella cheekii Burgt sp. nov.

Recognition: Talbotiella cheekii is morphologically similar to T. batesii Baker f. The pedicels of T. cheekii are pink to red, 9 – 24 mm long; the bracteoles are 8 – 15 × 0.7 – 1.5 mm (the pedicels of T. batesii are white, 4 – 10.5 mm long; the bracteoles are 6 – 8.5 × 1.1 – 2.5 mm). The ovary of T. cheekii is reddish green to dark red, and glabrous with only the edges densely hairy (the ovary of T. batesii is pale pink, and densely hairy). The pod of T. cheekii is glabrous, the sutures sparsely hairy (the pod of T. batesii has the surfaces and suture moderately puberulous). The leaflet apex of T. cheekii is rounded to slightly emarginate (the leaflet apex of T. batesii is acute).

DISTRIBUTIONGuinea (Map 1). Talbotiella cheekii occurs on the sandstone plateau in the northern part of Coyah Préfecture. Its distribution just extends into Dubreka and Kindia Préfectures.

Etymology: Talbotiella cheekii is named after Dr Martin Cheek, Head of the Africa & Madagascar Team in the Identification and Naming Department of the Royal Botanic Gardens, Kew. The new species was discovered thanks to his long-standing commitment to the study of African plants. He has been studying the flora of Guinea on field expeditions since 2005, supported the restoration of the National Herbarium of Guinea, and described a new genus and four new species from the country (Cheek & Burgt 2010; Cheek & Haba 2016a, 2016b; Cheek & Williams 2016; Cheek et al. 2016). He is also involved in the designation of new protected areas in Guinea as part of Kew’s Tropical Important Plant Areas (TIPAs) Project (Darbyshire et al. 2017) and is supervising a Darwin Initiative-funded project on rare plant species conservation in the country.

Vernacular Name: Linsonyi (from Burgt 2084); Meni (from Molmou 988); Wonkifong wouri khorohoi (from Burgt 2097), translated as the “Tree with hard wood from Wonkifong”. This last name was proposed by the people of Malassi village when the trees were shown to them. All three names are in the Susu language.

Talbotiella cheekii is characterised by the long pedicels, pink to red in colour, the long and narrow bracteoles, the glabrous pod (only the margin sometimes has a few hairs) and the rounded to slightly emarginate leaflet apex. Apart from this, the leaves and leaflets of T. cheekii and T. batesii are more or less similar; both species have 9 – 14 pairs of leaflets per leaf. Of all previously described Talbotiella species, T. cheekii is morphologically most similar to T. batesii. This is remarkable, because T. batesii is the easternmost species of Talbotiella, occurring in southeast Cameroon, northeast Gabon and north Congo (Brazzaville), at 2900 to 3100 km distance from T. cheekii, the westernmost species. A molecular analysis might show, however, that T. cheekii is more closely related to a different species, for example to T. gentii from Ghana, geographically the nearest of the eight existing Talbotiella species.

Two more plant species from the Leguminosae family have been newly discovered in Guinea in recent years: Eriosema triformum Burgt (Burgt et al. 2012), a pyrophytic herb with unifoliolate leaves, from submontane grassland, endemic to the Pic de Fon area in the Simandou Range, and Gilbertiodendron tonkolili Burgt & Estrella (Estrella et al. 2012), a tree from well-drained sandy and/or rocky soils on river banks and forest patches, first discovered in Sierra Leone, and later found to occur also in Guinea (e.g. the specimens Cheek 16172, 16583 and 16614; all in HNG and K).

Xander M. van der Burgt, Denise Molmou, Almamy Diallo, Gbamon Konomou, Pepe M. Haba and Sékou Magassouba. 2018. Talbotiella cheekii (Leguminosae: Detarioideae), A New Tree Species from Guinea. Kew Bulletin.  73:26. DOI: 10.1007/s12225-018-9755-4

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