Nothodissotis barteri (Hook.f.) Veranso-Libalah & G.Kadereit, 2019

Veranso-Libalah, Marie Claire, Lachenaud, Olivier, Stone, Robert Douglas & Kadereit, Gudrun, 2019, Nothodissotis (Melastomataceae), a new genus from Atlantic Central Africa, including the new species N. alenensis from Equatorial Guinea, PhytoKeys 118, pp. 89-103 : 92-94

Nothodissotis barteri (Hook.f.) Veranso-Libalah & G.Kadereit comb. nov. Figs 2 C–H , 3

≡ Dissotis barteri Hook.f., Fl. Trop. Afr. [Oliver et al.] 2: 454 (1871).

Lectotype (designated here).

Príncipe, 1859, Barter s.n. (K! [K000313101]; isolectotype: K! [K000313102]).

Additional specimens examined.

CAMEROON. Réserve de Faune d’Ebo, village de Ndokbaguengue, campement de Djouma, sommet après le transect “Gachaka”, 4°21.7164'N, 10°14.9694'E, 1003 m, 15 Feb. 2014 (fl.), Droissart et al. 1668 (BRLU!, MO!); Ebo forest proposed National park, Ebo Forest Research Station, Bekango trail, 13 Dec 2006 (fl.), Osborne & Emang Abwe 323 (K!). EQUATORIAL GUINEA. Inselberg Acoak Banga près de Ngong Mocomo, 1°04'N, 11°11'E, 8 Aug 1998 (fr.), Lejoly & Elad 98/77 (BRLU!); inselberg de Akoak Ebanga à 1 h du village de Ngong Mocomo, à 10 km de Nsork, 1°04'N, 11°12'E, 585 m, 31 May 2002 (fr.), Parmentier & Esono 3495 (BRLU!); ibid., 590 m, 1 Jun 2002 (fr.), Parmentier & Esono 3544 (BRLU!). GABON. rocher Fané, Efout, E of Médouneu, 5 Feb. 1968 (fl.), N. Hallé & Villiers 4952 (P05264604!); inselberg Milobo, 0°56.35'N, 10°31.31'E, 750 m, 8 Jul 2001 (st.), Ngok Banak et al. 39 (BRLU!, WAG!); ibid., 0°56.35'N, 10°30.94'E, 760 m, 26 Nov 2001 (fl. buds), Ngok Banak et al. 301 (BRLU!, WAG!); ibid., 0°56.29'N, 10°30.87'E, 770 m, 6 Dec 2001 (fl.), Ngok Banak et al. 357 (BRLU!, WAG!); c. 9 km ESE of Médouneu, Efot, inselberg Voma, 1°00.92'N, 10°54.30'E, 500 m, 24 Dec 2002 (fl.), Ngok Banak et al. 1196 (BRLU!, MO!, WAG!); ibid., 1°00.19'N, 10°54.08'E, 523 m, 26 Dec 2002 (fl. & fr.), Ngok Banak et al. 1264 (BRLU!, WAG!); Mont Mengong, inselberg au pied du village de Nzec 1, à 45 km de Mitzic vers Sam, 0°57'N, 11°17'E, 670 m, 6 Jan 2000 (fl), Parmentier & Nguema 585 (BRLU!); Mont Fene, inselberg au pied du village d’Efot, 1°00'N, 10°54'E, 15 Jan 2000 (st.), Parmentier & Nguema 650 (BRLU!); Mont Voma, inselberg au pied du village d’Efot, 1°00'N, 10°54'E, 19 Jan 2000 (fl.), Parmentier & Nguema 745 (BRLU!, WAG!); c. 28 km ESE of Médouneu, 0°55'N, 11°01'E, 500 m, 3 Feb 1986 (fl.), J.M. & B. Reitsma 1796 (WAG!). PRÍNCIPE. Infante D. Henrique, c. 215 m (c. 700 ft), 21 Dec. 1932 (fl.), Exell 652 (BR0000017285346); sommet du Pico, 30 Aug 1999 (fl.), Joffroy 202 (BRLU!); Pico Mesa, 600 m, 25 Mar. 1998 (fr.), Oliveira 546 (BRLU!); Morro Fundao, 1°37'N, 7°23'E, 370 m, 8 Oct. 1997 (fr.), Stévart & Oliveira 259 (BRLU!). Príncipe Island, summit of the Pico de Príncipe, submontane forest with many epiphytes on a ridge, 01°34'48"N, 007°23'01"E, 945 m, 16 Feb. 2018 (fl. & fr.), Stévart & Oliveira 5136 (BRLU!, MO!).

Distribution and habitat.

Nothodissotis barteri is sparsely distributed in Cameroon (Ebo forest), south-eastern Equatorial Guinea (near Nsork), northern Gabon, and Príncipe Island (Fig. 4 ). It occurs exclusively on rock outcrops at 370-1000 m elevation, mainly in low shrubby vegetation near the edge of the rocks ("manteau arbustif") where it is locally dominant, and sometimes also as isolated plants in rocky grassland dominated by Afrotrilepis pilosa (Boeck.) J.Raynal ( Cyperaceae ).

Phenology.

Flowering recorded mainly from November–February, once in August; fruits in March, May–June, August, October and December.

Conservation status.

Vulnerable [VU B2ab(iii)]. The EOO of Nothodissotis barteri is estimated to be 82,625 km2 (above the upper limit for Vulnerable status under sub-criterion B1) and its AOO to be 48 km2 (within the limit for Endangered under sub-criterion B2). The species is sparsely distributed in Cameroon, Equatorial Guinea, northern Gabon and Príncipe island, and is restricted to rocky outcrops where it occurs in low shrubby vegetation or grassland. It is known from 21 collections representing eleven subpopulations, most of which (except three on Príncipe island) lie outside protected areas. In most of its range, bushfires and agriculture (mostly pineapple plantations) represent the main threats to its habitat; planned tourism development in Príncipe is another threat. A decline in habitat extent and quality is therefore expected. The eleven subpopulations represent a total of ten locations (sensu IUCN 2012), fall ing within the limit for Vulnerable status, and the species is therefore assessed as Vulnerable under these conditions B2ab(iii).

Notes.

This species, originally described from Príncipe Island ( Hooker 1871), has since been reported from Gabon ( Jacques-Félix 1983b) and Equatorial Guinea ( Parmentier and Geerinck 2003). The collections cited above from Cameroon are the first for the country and represent an important range extension northwards.

The seeds of this species have not been described previously (e.g. Jacques-Félix 1983b). They are cochleate, c. 0.5 × 0.35 mm, and bear rounded tubercles arranged in parallel rows (Fig. 2 E–H ).

Two specimens, probably from the same field collection by Barter in 1859, are housed in K, with neither of them designated as the holo- or isotype. For this reason, we designate the specimen K000313101 as the lectotype and K000313102 as the isolectotype.

Figures

Figure 2. Digital microscope photographs of the hypanthia of Nothodissotis spp. (A-D) and SEM photographs of the seeds of N. barteri (E-H). A, B hypanthium of Nothodissotis alenensis (Parmentier & Esono 3453); cl = calyx-lobes and ia = intersepalar appendages C, D hypanthium of N. barteri (Ngok Banak 1196) E, F seeds of N. barteri in dorsal view G, H same in lateral view (Parmentier 3544).

Figure 3. Nothodissotis barteri. A habit B branches and inflorescence C leaf seen from above, and flower (petals fallen) D flower bud E blooming flower F stamens. From Droissart et al. 1668 (A, B) and Stevart & Oliveira 5136 (C-F).

Figure 4. Distribution of Nothodissotis species.