Synsepalum chimanimani S.Rokni & I.Darbysh., 2019

Rokni, Saba, Wursten, Bart & Darbyshire, Iain, 2019, Synsepalum chimanimani (Sapotaceae), a new species from the Chimanimani Mountains of Mozambique and Zimbabwe, with notes on the botanical importance of this area, PhytoKeys 133, pp. 115-132 : 117-120

Synsepalum chimanimani S.Rokni & I.Darbysh. sp. nov. Figures 1 A–K , 2

Tulestea kaessneri sensu Aubréville in Adansonia Sér. 2, 12(2): 191-192 (1972), pro parte quoad Wild, Goldsmith & Müller 6645, non (Engl.) Aubrév. sensu stricto.

Afrosersalisia kaessneri sensu Kupicha in Flora Zambesiaca 7(1): 217 (1983), pro parte quoad spec. ex Mozambique & Zimbabwe, non (Engl.) J.H.Hemsl.

Synsepalum kaessneri sensu Pennington in Gen. Sapotac.: 249 (1991), pro parte, non (Engl.) T.D.Penn. sensu stricto.

Synsepalum muelleri sensu Burrows et al. in Trees & Shrubs Mozambique: 744 (2018), pro parte - photographs and reference to distribution in Haroni-Makurupini Forest; non (Kupicha) T.D.Penn.

Synsepalum sp. aff. S. kaessneri (Engl.) T.D.Penn., Hyde et al. in Flora of Mozambique (2019).

Type.

MOZAMBIQUE. Manica Province: Magorogodo hills, Zomba Community, 19°54'28"S, 33°11'4"E, c. 559 m alt., fl. and fr. 28 October 2013, B.T. Wursten BW897 (holotype: BR!, BR0000020700003)].

Diagnosis.

This species differs from Synsepalum kaessneri (Engl.) T.D.Penn. in the generally smaller (7.9-12.6 x 1.7-3.4 cm versus 9.8-16.7 x 2.8-5.2 cm) narrowly elliptic leaves with a long and narrow acuminate tip versus oblanceolate leaves with a short and broad acuminate tip (see illustration, Fig. 1E, L ); flowers sessile or almost so with pedicels less than 1 mm long (extending to 2 mm long in fruit) versus flowers stalked with pedicels 1-3 mm long (extending to 3-5 mm in fruit); shorter corolla tube (0.75-0.8 mm long versus 1.2 mm long) and shorter (1.45-1.5 mm versus 1.8-1.9 mm), broadly ovate versus ovate corolla lobes; anthers with elliptic thecae with a minute, inconspicuous point at the apex of the connective versus arrow-head shaped anthers with oblong thecae with a conspicuous apiculate apex to the connective. Table 1 shows the distinguishing characters between the two species.

It has previously been confused with Synsepalum muelleri (Kupicha) T.D.Penn. but is easily separated by the very faint secondary venation and no visible tertiary venation versus clearly visible secondary and reticulate tertiary venation; no stipules versus persistent subulate stipules 2-7 mm long; whitish-green flowers with a very short corolla tube and wide-spreading lobes versus white tubular flowers with the tube markedly longer than the lobes; corollas less than 2.5 mm long versus 7-10 mm long; exerted stamens versus included stamens; minute staminodes versus no staminodes; fruit 1-1.3 cm long with a very short (0.5 mm long) style versus larger fruit 2-3 cm long with a 5-7 mm long persistent style; glabrous fruit except for hairs at the tip around the base of the style versus fruit covered with rust-coloured hairs.

Description.

Small tree or shrub up to 4 m high. Bark brown and finely fissured. Branching repeatedly subterminal (" Terminalia -style") with leaves confined to branch apices. Older stems glabrous with finely fissured brownish-grey bark, young shoots, buds and petioles of young leaves with indumentum of appressed, very fine rust-coloured hairs. Hairs medifixed, less than 0.5 mm long, tips sharp. Stipules absent. Leaves with petiole 3-5 mm long, often sparsely hairy to glabrous on older leaves; lamina narrowly elliptic to rarely oblanceolate, 7.9-12.6 x 1.7-3.4 cm, apex long acuminate with a narrow rounded tip, margins entire and repand, base attenuate; midrib raised on both surfaces with striations on the midrib below, lateral veins very faint above, more distinct below, pinnate, curving towards the margin, 9-15 pairs of lateral veins, no visible tertiary venation; both surfaces finely rugose and glabrous except for sparse scattered hairs along the midrib on the lower surface, particularly on younger leaves; hairs very fine, rust-coloured, medifixed, less than 0.5 mm long, tips sharp. Flowers in clusters in leaf axils and along the branches below the leaves, small and whitish-green, sessile or almost so, pedicels less than 1 mm long (extending to 2 mm long in fruit), pedicels and external surface of calyx lobes covered with sub-appressed, medifixed, very fine rust-coloured hairs. Calyx cup-shaped, 5-lobed, lobes nearly free, imbricate, elliptic, 1.2-1.3 x 1-1.1 mm, with hyaline margins, glabrous internally. Corolla 5-merous, fused at base, tube up to 0.8 mm long, lobes involute, broadly ovate, 1.45-1.5 mm long, rounded at apex. Stamens attached at base of petals, filaments 0.6 mm long, anthers 0.9-1 mm long, the two thecae elliptic with a tiny, inconspicuous point at the apex of the connective. Staminodes minute, alternating with the petals and stamens, divided and irregularly shaped. Ovary densely hairy, with a few hairs extending onto the style, ovoid, 1mm long, style 0.5 mm long. Fruit fleshy, red when ripe, solitary, ellipsoid, 10-13 x 6-8 mm (measurements taken from dried material), with calyx and corolla persisting at base and with persistent style at apex, glabrous except for a few hairs at apex around base of style. Seed compressed-ellipsoid, 12 x 7 x 3 mm, glossy brown, with duller elliptic scar c. 5 mm wide extending the length of the seed, cotyledons large, plano-convex, endosperm absent (fide Kupicha 1983).

Distribution and ecology.

Known only from lowland, moist forests in the foothills of the southern Chimanimani mountains of Mozambique and Zimbabwe. It has been recorded from three localities: the Haroni-Makurupini Forest in Zimbabwe, and the Maronga forest (Maronga Community) and Thekeza forest (Zomba Community) in Mozambique. It occurs in the understorey of moist evergreen and semi-deciduous forests at an altitude of 305-560 m. In the Maronga Community area at the base of the Chimanimani Mountains, where this species is locally frequent, most of the area is covered by moist evergreen forest. The dominant tree here is Newtonia buchananii (Baker f.) G.C.C.Gilbert & Boutique with Maranthes goetzeniana (Engl.) Prance and Xylopia aethiopica (Dunal) A.Rich. also common. Funtumia africana (Benth.) Stapf forms a high sub-canopy along with Aporrhiza nitida Gilg, Blighia unijugata Baker, Millettia stuhlmannii Taub., Synsepalum brevipes (Baker) T.D.Penn. and Trilepisium madagascariense DC. The understorey is dominated in some areas by Drypetes arguta ( Müll. Arg.) Hutch. and other locally abundant shrubs include Rinorea convallarioides (Baker f.) Eyles, Rinorea ferruginea Engl., Tabernaemontana ventricosa Hochst. ex A.DC., Tricalysia pallens Hiern and the rare Vepris drummondii Mendonça. There are also many lianas ( Timberlake et al. 2016a).

Phenology.

Plants were collected in flower in July (buds) and October (open), and in fruit in October and December. Flowering occurs at the end of the dry season and beginning of the rainy season, the main rainy season in the Chimanimani area being from November to late March or April ( Timberlake et al. 2016b).

Etymology.

The specific epithet is taken from the Chimanimani mountains to which the species is confined.

Conservation status.

Synsepalum chimanimani S.Rokni & I.Darbysh, sp. nov. has been assessed as Endangered under IUCN criterion B (EN B1ab(iii)+2ab(iii); Rokni et al. 2018, as Synsepalum sp. nov.). It is estimated to have an extent of occurrence (EOO) and area of occupancy (AOO) of only 16 km2 and is known from fewer than five locations. Although part of its population is well protected within the core zone of the Chimanimani Trans-Frontier Conservation Area (TFCA), it is threatened by extensive destruction and degradation of its forest habitat within the buffer zone of the TFCA, particularly within the Maronga and Zomba communities of Mozambique (see Discussion for further information on threats in this area).

Specimens examined.

MOZAMBIQUE. Manica Province: Magorogodo hills, Zomba Community, 19°54.467'S, 33°11.067'E, alt. c. 559 m, fl. and fr. 28 Octo ber 2013, Wursten BW897 (BR!, BR0000020700003); Survey Plot 3, Magorogodo hills, Zomba Community, alt. 548 m, st. 28 October 2013, Wursten BW887 (BR!); Sussundenga Dist., Maronga community, base of Chimanimani Mountains, Forest plot 002, 19°58.417'S, 33°5.233'E, alt. 341 m, st. 14 November 2015, Timberlake et al. 6196 (LMA!); Sussundenga Dist., Maronga community at base of Chimanimani Mountains, 19°58.928'S, 33°4.948'E, alt. 330 m, st. 17 November 2015, Timberlake et al. 6197 (K!, K001291034; LMA!); Sussundenga Dist., Chimanimani foothills, Zomba community, Thekeza Forest, 19°54.717'S, 33°11.433'E, alt. 386 m, st. 30 June 2015, Cheek 17963 (K!, K001291036); Sussundenga Dist., Chimanimani foothills, Zomba community, Last House Thekeza, 19°54.533'S, 33°11.303'E, alt. 542 m, fl. buds 2 July 2015, Cheek 18027 (K!, K001291037); Southern tip Chimanimani Mts. near Haroni-Makurupini Forest, alt. +/- 1000 ft [c. 305 m], st. 28 May 1969, Müller 1085 (SRGH!). ZIMBABWE. Manicaland Province: Chimanimani District, Haroni/Makurupini Forest, alt. 1300 ft [396 m], fr. 4 December 1964, Wild, Goldsmith & Müller 6645 (K!, K001291026; BR!, BR0000020184520; SRGH!); Chimanimani District, Makurupini-Haroni Forest, st. 22 April 1973, Mavi 1437 (K!, K001291028; SRGH!).

Figures

Figure 1. Synsepalum chimanimani (A-K) and Synsepalum kaessneri (L) A habit B stem apex with apical buds / young leaves and petioles showing indumentum C medifixed hairs on stem D abaxial leaf surface showing sparse medifixed hairs on midrib E leaf showing (faint) secondary veins F flower cluster showing bud, open flower and partially opened flower G flower, side view (hydrated) H corolla after removal of two petals and stamens (hydrated) I stamen and staminodes in situ on petal, inner face bases of neighbouring petals shown J side view of stamen and petal (staminodes omitted) K immature fruit (from photograph) L leaf (abaxial) of Synsepalum kaessneri. A, D-K drawn from B. T. Wursten BW 897 (BR 0000020700003) B, C from Timberlake et al. 6197 (K 001291035) L drawn from Magogo & Glover 280 (K). Scale bars: 1 mm (Single bar); 2 mm and 5 mm (graduated single bar); 1 cm (double bar); 5 cm (graduated double bar). Drawn by Andrew Brown, November 2018.

Figure 2. Synsepalum chimanimani A habit and leaves B, C flowering stems D flowers E immature fruit (Photographs by Bart Wursten).