Ternstroemia cameroonensis Cheek, 2017

Cheek, M., Tchiengue, B. & Tacham, W. N., 2017, Ternstroemia cameroonensis (Ternstroemiaceae), a new medicinally important species of montane tree, nearly extinct in the Highlands of Cameroon, Blumea 62 (1), pp. 53-57 : 54-56

Ternstroemia cameroonensis Cheek , sp. nov. — Fig. 1

Ternstroemia polypetala sensu Letouzey ( Letouzey (1977) 6; Cheek in Cheek et al. (2000) 165; Cheek (2000a)).

Ternstroemia sp. nov. Cheek (Cheek & Onana (2011) 8, f. 4; Onana (2011) 147; (2013) 208).

Similar to Ternstroemia polypetala Melch. but differs in the shorter pedicel length ( 8–13 mm long at anthesis, not 20–30 mm), the bracts which are opposite or nearly opposite, immediately adjacent to the calyx, 2 times broader than long, apex rounded (not alternate, clearly separated from each other by 1–8 mm, the most distal usually inserted several mm below the calyx, usually triangular and as long as broad,or longer);venation of mature leaves not reticulate, lacking visible quaternary nerves (not finely reticulate with conspicuous quaternary nerves); androecium in female flowers uniseriate (not multiseriate), stamens lacking an apiculus (not with a long conspicuous apiculus). — Type: Letouzey 13380 ( holotype K; isotypes BM, L L.2400388, P n.v., YA, Wood CTFT, Montpellier), Cameroon ( South West Region ), ‘de la route de Baranka ( 2400 m) à la Chefferie de Fossimondi ( 1700 m) sur le mas- sif de Bamboutos, à 25 km au Nord-Ouest de Dschang’, fl. fr. 29 Nov. 1974 .

Etymology. Cameroonensis signifying from Cameroon, which holds the only global location for this species.

Monoecious tree 10–15 m tall ( Letouzey 13380), glabrous. Crown hemispherical, trunk up to 40 cm diam at 1.5 m from the ground, rough, red-brown, with raised pustules; slash thick, white-cream, oxidising red-brown or pink. Branches and branchlets curving upwards and terminating in clusters of leaves, developing according to Aubréville’s crown model ( Tomlinson 1987), that is with ‘Terminalia-branching’; leafy branchlets terete, 2–3.5 mm diam, drying dull grey-brown and cracking in oblongs, often covered by crustose lichens; leafscars horseshoe-shaped, pale glossy brown, slightly raised, c. 1 by 1 mm. New shoots probably arising in wet season (June– October), of two types: 1) extension shoots (mainly vegetative, arising laterally from below the established plagiotropic main axes and arching below and then overtopping them; and 2) main shoots, a continuation of the established main axis.

1 Extension shoots (seen in Tchiengue s.n. collected in May) lack nodes in the proximal 35–50 mm; the subsequent four internodes are (4–) 9–10 mm long, with 1/3 phyllotaxy (each leaf making a third of a circle from the previous). Usually sterile in the season in which they are produced, occasionally the basal node subtends a flower.

2 Main shoots with two stages in one season: a) the proximal 2–8 nodes (c. 2–9 mm long, internodes 1–2 mm long), producing small (‘prophylls’), highly caducous reduced leaves falling before anthesis, oblanceolate 0.9–2.4 by 0.4–0.8 mm, each subtending 1-flowered inflorescences; b) the distal part of the shoots lacking flowers, with a ro- sette (internode lengths nil) of (3–)7–9(–12) larger, spirally inserted leaves that persist for 1–2 years.

Leaves persisting 12 months or more (sometimes seen persisting on the previous seasons stems above fruits ( Fig.1a 2), spirally inserted, alternate, simple, leathery, thickness 0.3–0.5 mm when dry, drying glossy black above, matt mid to dark brown below, elliptic, or elliptic-obovate (2.3–)5.0–7.2(–9) by (0.7–) 1.7–2.8 cm, widest point 60–65 % of the distance from the base of the blade, apex obtuse, then abruptly and shortly emarginate, less usually rounded, base gradually decurrent down the petiole as a tapering, narrow wing, sometimes reaching the stem; lateral nerves inconspicuous (7–)8–11 on each side of the midrib, brochidodromous, uniting 2–3 mm from the margin, tertiary nerves very sparse, quaternary nerves not visible; margin revolute, young leaves with up to ten patent, toothlike, short translucent, caducous, marginal glands on the proximal 1/4 length of the blade and petiole, teeth 0.1–0.2(–0.4) mm long. Petiole (0–) 2–8 mm long, flat above with a narrow wing, and concave below, glabrous. Stipules absent. Pedicels developing singly in axils of reduced highly caducous leaves (see above), at anthesis with (1–)4–9(–11) flowers on the 5–10 mm of naked stem immediately below the terminal cluster of leaves; pedicels spreading, straight, stiff, 8–12(–13) by (0.5–)1(–1.5) mm, drying more or less 3-angled, minutely papillate-verrucate, black. Bracts 2, subopposite, subequal, inserted more or less immediately below the calyx, orbicular, ovate or transversely rectangular, 0.7–1.8 by 1.5–2 mm, apex rounded to obtuse, base often with glandular areas. Flowers borne October–March ( Tacham s.n.) with male (c. 12 mm long) and female (c. 9 mm long) on different branches of the same individual ( Letouzey 13380). Sepals 5, yellow, imbricate, irregularly suborbicular, slightly concave, 2.5–3.5 by 3.5 mm, apex rounded, slightly revolute. Petals 7–8, white on inner surface, imbricate, outermost petals with outer surface pink, obovate to shortly ligulate, apex hooded. Female flowers with the petals (3.2–)6–7 by 1.8–3 mm, androecium uniseriate, the staminodes white, 30–35, forming a cylinder around the ovary; staminodes united to each other at the base and also adhering to the base of the petals ( Fig. 1f ), ligulate, flattened, 1.75–2.5 by 0.2–0.3 mm, thecae not developed, apiculus absent or in- distinct. Disc or torus (presumably nectariferous), 0.2 mm thick, surface flattened, with a ring of c. 35 small, regular depressions ( Fig. 1d ). Ovary pale yellow, ellipsoid, subverrucate 4 by 3 mm, unilocular, ovules 3–5, inserted at the apex of the axile column. Stigma subsessile, 2(–3)-lobed, forming a shallow cap or dome over the apex of the ovary, c. 2 mm diam. Male flowers with the petals c. 9 mm long by c. 2–3 mm wide; stamens 35–40, ( Fig. 1e ), more or less uniseriate, 2.8–3 mm long, dorsiven- trally flattened 0.2–0.4 mm wide, the anther thecae inserted along the two lateral margins each 1.4–1.6 mm long, united at the apex, the connective not extended as an apiculus ( Fig. 1g ); filament c. 1–1.3 mm long, shorter than the staminal por- tion. Intrastaminal disc and ovary inconspicuous. Fruit ovoid, green-orange or yellow or orange, 1.2–2.2 by 1–1.5 cm, at length dehiscing, the pericarp falling to expose the bright red 1–2(–5)-seeds. Fruiting pedicel accrescent, c. 22 by 0.2 cm, sepals accrescent, ovate to orbicular-elliptic, concave, c. 0.5 by 0.5 cm, pericarp fleshy, c. 3 mm thick, styles persistent, flat, appressed to pericarp, c. 2 by 1.5 mm in plane view, matt grey. Seeds red at fruit dehiscence, when dried bony, pink to pale brown, laterally flattened ovoid, faceted by mutual compression where more than 1 per fruit, anatropous, 6–9 by 4–6 by 3–4 mm, with a longitudinal furrow between the U-shaped embryo ends; hilum circular, depressed, subapical and lateral to the boss-like radicle extension.

Distribution & Ecology — Highlands of Cameroon, in SW and (formerly but probably now extinct) NW Regions. Upper submontane (cloud forest) and montane forest, with Nuxia congesta ( Loganiaceae ), Syzygium staudtii ( Myrtaceae ), Podocarpus milanjianus ( Podocarpaceae ), Prunus africana ( Rosaceae ) (cited on label of Letouzey 13380), Cassipourea gummiflua ( Rhizophoraceae ), Pentarrhinum abyssinicum subsp. ijimense ( Asclepiadaceae ) (collections associated with Etuge 3557), Rapanaea melanophloeos ( Primulaceae ), Schefflera sp. ( Araliaceae ) ( Tchiengue s.n.); 1900–2300 m altitude.

Vernacular names & Uses — Nkene (Bamumbu language). Medicinally much used (which has possibly contributed to its rarity) by the Mundani people of the Lebialem Highlands, e.g., for sexually transmitted diseases and as a blood tonic ( Tacham s.n.), also to address female sterility ( Tchiengue s.n.). According to Tacham et al. (2015), who list the species as Ternstroemia sp. nov., Nkene is one of 128 species used by the Mundani: “Decoction of bark is taken with milk for anemia and sickle cell. Concoction with bark of Trichilia is taken orally for pelvic inflammatory disease and infertility”.

Additional specimens. CAMEROON, North West Region , below Lake Oku , on S, Kom side, Aboh-Zitum , fr. fl. buds, 21 Nov. 1996, Etuge 3557 ( K, YA); South West Region , Lebialem Prefecture , Baranka , 2 km on road to Fossimondi, fl. fr., 15 Dec. 2013, Tacham s.n. ( K, YA 3 sheets); ibid fl. fr., May 2015, Tchiengue s.n. ( K, YA 5 sheets) .

Conservation — We assess Ternstroemia cameroonensis as Critically Endangered (CR B2ab(iii)+D) according to the categories and criteria of IUCN (2012) since, despite wide- spread targeted searching over many years, only 10 mature individuals are known to survive (Criterion D). These are all at a single location (area of occupancy estimated as 4 km 2 using the IUCN-preferred grid cells of this dimension) where there are ongoing losses of the habitat due to clearance of natural vegetation for agricultural land in the immediate area ( Letouzey 1977, Tchiengue pers. obs. 1999–2015). Trees are known to have been exterminated at the type locality and at Mt Oku in the last few decades resulting in the loss of two of the three known sites for the species. Trees at the only surviving site are also threatened by wounds inflected by harvesting of bark for medicinal purposes. Tacham et al. (2015) report that the species is overexploited for sale locally and in neighbouring markets. No regeneration has been detected at this site (Tchiengue pers. obs. 2015), possibly because any seedlings that develop might be swept away by run-off down the steep slopes on which the surviving trees grow. The species has not been cultivated nor seed-banked, although we intend to rectify this. A poster depicting the species, for use in Cameroon promoting its conservation, was produced and distributed by Kew ( Cheek 2000a).

Ternstroemia polypetala in the broad sense, including the Cameroon population, as well as those of Tanzania and Malawi, was assessed as Vulnerable by Lovett & Clarke (1998), while it was assessed as Critically Endangered in Cheek et al. 2000: 74. The new species did not feature in the Red Data Book of Cameroon Flowering Plants (Onana & Cheek 2011) since by that time it was recognised to be a separate species but lacked a published name which is required by IUCN before a conservation assessment can be accepted. Ternstroemia cameroonensis (as Ternstroemia sp. nov. sensu Cheek), was listed as Data Deficient ( Onana 2013: 208).

New species from the Highlands of Cameroon Ternstroemia cameroonensis is the most recent of numerous new species to science discovered and published from the Cameroon Highlands in recent years. Most of these are also threatened with extinction due to clearance of their habitat. Others include: Allophylus ujori Cheek ( Cheek & Etuge 2009a), Ancistrocladus grandiflorus Cheek (2000b) , Brachystephanus kupeensis Champl. ( Champluvier & Darbyshire 2009), Chassalia laikomensis Cheek ( Cheek & Csiba 2000), Coffea montekupensis Stoff. ( Stoffelen et al. 1997), Coffea bakossii Cheek & Bridson ( Cheek & Bridson 2002), Cola metallica Cheek (2002) , Coleochloa domensis Muasya & D.A.Simpson ( Muasya et al. 2010), Costus kupensis Maas & H.Maas (Maas et al. 2016), Deinbollia oreophila Cheek ( Cheek & Etuge 2009b), Diospyros kupensis Gosline & Cheek (1998) ; Dovyalis cameroonensis Cheek & Ngolan (2007) , Dracaena kupensis Mwachala et al. (2007) , Impatiens etindensis Cheek & Eb.Fisch. (1999) , Impatiens frithii Cheek ( Cheek & Csiba 2002b), Isoglossa dispersa I.Darbysh. ( Darbyshire et al. 2011), Kupea martinetugei Cheek & S.A.Williams ( Cheek et al. 2003), Ledermanniella onanae Cheek (2003) , Ledermanniella pollardiana Cheek & Ameka (2008) , Mussaenda epiphytica Cheek (2009) , Myosotis cameroonensis Cheek & R.Becker (2004) , Newtonia duncanthomasii Mackinder & Cheek (2003) , Oxyanthus okuensis Cheek & Sonké (2000) , Psychotria geophylax and P. bakossiensis ( Cheek & Sonké 2005) , Psychotria moseskemei Cheek ( Cheek & Csiba 2002a), Rhaptopetalum geophylax Cheek & Gosline (in Cheek et al. 2002) and Talbotiella bakossiensis Cheek ( Mackinder et al. 2010). Most of these are en- demics of single mountains, sometimes of neighbouring peaks, and have putative sister species from lowland forest elsewhere within Cameroon or in central Africa. In rare cases the sister taxa are in the Eastern Arc Mountains of Tanzania ( Kupea ), or in the mountains of the eastern rift ( Luzula ). However, in most cases there is an absence of solid phylogenetic data to assign sister relationships.

Figures

Fig. 1 Ternstroemia cameroonensis. a1. Habit, flowering branches; a2. habit, branch with fruit and flowers; b. female flower opening; c. female flower, side view, 5 sepals, 2 petals and part of the single whorl of staminodes removed to expose the ovary and its basal disc; d. female flower, all perianth lobes and staminodes removed; e. male flower, perianth segments removed; f. innermost petal of female flower showing adnate, flattened staminodes; g. stamen of male flower; h. ovary, apical view, showing 3-lobed, shallowly domed stigma; i. ovary, detail of h. but stigma removed to show the short style; j. fruit (slightly distorted by drying); k. two appressed seeds; l. seed in longitudinal section showing the U-shaped embryo; m. seed, transverse section along lines x-x indicated in l (all: Letouzey 13380, K). — Scale bars: a1+a2 = 5 cm; b–e, j–m = 1 cm; f–i = 1 mm. — Drawn by Andrew Brown.