Solanum sambiranense D'Arcy & Rakot., Fl. Madag., Fam. 176: 123. 1994.

Knapp, Sandra & Vorontsova, Maria S., 2016, A revision of the " African Non-Spiny " Clade of Solanum L. (Solanum sections Afrosolanum Bitter, Benderianum Bitter, Lemurisolanum Bitter, Lyciosolanum Bitter, Macronesiotes Bitter, and Quadrangulare Bitter: Solanaceae), PhytoKeys 66, pp. 1-142 : 67-69

Solanum sambiranense D'Arcy & Rakot., Fl. Madag., Fam. 176: 123. 1994. Figures 1D , 2A , 23

Type.

Madagascar. Antsiranana: vallée du Sambirano, Sep 1909, J. Perrier de la Bâthie 2324 (lectotype, designated here: P [P00352331]; isolectotypes: P [P00352332], MO [MO-150889]) .

Description.

Liana to 20 m high in canopy. Stems flattened to terete, glabrous or evenly pubescent with dendritic uniseriate trichomes to 0.1 mm long, glabrescent; new growth densely pubescent with dendritic trichomes. Bark of older stems longitudinally ridged, brown to almost white. Sympodial units plurifoliate, the leaves not geminate, somewhat clustered towards tips of branches or on short shoots. Leaves simple, 5-8 (10) cm long, 2.5-4 (5) cm wide, elliptic to obovate, membranous to chartaceous (occasionally thick-chartaceous on older branches), concolorous to weakly discolorous, glabrous with occasional short-branched dendritic trichomes along the midvein or sparsely pubescent on both surfaces with uniseriate dendritic to somewhat echinoid trichomes 0.2-0.5 mm mm long on the veins and lamina, these much denser at the axil of midrib and major veins forming tangled tufts (domatia); major veins 5-7 pairs, spreading at ca. 45° to the midvein and forming loops, the finer venation a prominent network of fine brown veins usually visible on both surfaces in dry material; base attenuate; margins entire; apex acute to acuminate; petiole 1-2(2.5) cm long, glabrous or densely dendritic pubescent with trichomes like those on the stem, pubescence of petiole denser than that of stem. Inflorescences terminal at the apex of short slender lateral branches, 3-6.5 cm long, unbranched or furcate, with 3-10 flowers, usually glabrous, sometimes finely pubescent with dendritic trichomes like those of the stem; peduncle 1-3 cm long; pedicels 1-2.5 cm long, apically dilated, drying ridged, usually glabrous, sometimes evenly pubescent like the rachis, articulated 0-0.5 mm from base; pedicel scars irregularly spaced 1.5-4 mm apart. Buds ellipsoid, the corolla exserted ca. halfway from calyx tube but not exserted beyond the tips of the calyx lobes before anthesis. Flowers 5-merous, apparently all perfect. Calyx tube ca. 2 mm long, an open cup, the lobes 4-10 mm long, 4-8 mm wide at base, uneven in size, deltate, acute at the tips, usually glabrous, sometimes evenly dendritic-pubescent like the rachis. Corolla 2-3.2 cm in diameter, violet or dark purple with a darker midvein, stellate, lobed almost to base, the lobes 10-13 mm long, 3-5 mm wide, ovate to linear, glabrous adaxially, usually glabrous abaxially or sometimes dendritic-pubescent like the rachis, densely papillate on the tips and margins. Stamens equal; filament tube ca. 1 mm; free portion of the filaments ca. 1.5 mm long, glabrous; anthers ca. 3.5 mm long, 1-1.5 mm wide, ellipsoid, not tightly connivent, smooth abaxially, poricidal at the tips, the pores much smaller than anther apices, ca. 0.4 mm in diameter, not lengthening with age. Ovary conical, glabrous; style ca. 9 mm long, protruding ca. 2 mm beyond the anthers, curved, glabrous; stigma capitate, dark, the surface smooth. Fruit an ovoid berry, ca. 0.9 cm long, 0.8 cm in diameter (immature), apically pointed, the pericarp thin, glabrous, drying black, but mature colour not known; fruiting pedicels 2.3-3 cm long, ca. 1 mm diameter at base, spreading, ridged; fruiting calyx lobes strongly accrescent, increasing to 1 cm long, sometimes extending further than the developing fruit, spreading (immature fruit only). Seeds not known from mature fruit.

Distribution

(Figure 24 ). Endemic to northwestern and north-central Madagascar in the provinces of Mahajanga and Antsiranana.

Ecology and habitat.

Dry to subhumid woodland on limestone; 500-1500 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2014). Least Concern (LC). EOO 109,250 km2 (LC), AOO 40 km2 (EN). In common with other members of the ANS clade in Madagascar, Solanum sambiranense has a relatively wide distribution, resulting in an EOO indicating lack of immediate conservation concern. The paucity of collections, indicative of local rarity, however, coupled with the ongoing habitat threats in Madagascar, does indicate monitoring and further collection to assess local and regional rarity is necessary.

Discussion.

Solanum sambiranense is a large-leaved liana (Figure 2A ) with very large showy flowers (Figure 1D ) endemic to the northern half of Madagascar. It has long petioles, long attenuate leaf bases, prominent tufts of tangled trichomes in the axils of the midrib and main leaf veins beneath (domatia, see Fig. 23 ), inflorescences with 3-10 flowers and foliaceous calyx lobes up to 6 mm in flower, often expanding past the developing fruit. Prior to the description of Solanum sambiranense in 1994 collections of this species were thought to belong to the similarly dendritic-pubescent Solanum imamense .

Solanum sambiranense is similar to Solanum imamense and Solanum betroka and could potentially also be confused with Solanum ivohibe . Solanum sambiranense can be distinguished from Solanum imamense by its elliptic to obovate (versus ovate) leaves 5-10 cm (versus 2.5-5 cm) long, and glabrescent leaf surface with dendritic trichomes below 0.1 mm long (versus densely pubescent leaves with indumentum reaching 0.2-0.5 mm in length). The distribution of Solanum sambiranense and Solanum imamense overlaps in north-central Madagascar even though Solanum imamense occupies drier areas further south. Solanum sambiranense differs from Solanum betroka by its inflorescences with 3-10 (versus 1-3) flowers, calyx lobes 4-6 mm (versus 2-3 mm) long, and leaves 5-10 cm (versus under 5 cm) long with attenuate (versus cuneate to truncate) leaf bases. Solanum sambiranense is morphologically similar to and potentially confusable with Solanum betroka : both have a clearly visible brown fine venation network, green brown leaves on herbarium specimens, membranous glabrescent leaves without thick indumentum, and a similar habit. Typical representatives of the southern Solanum betroka and northern Solanum sambiranense are clearly distinct but specimens from the centre of Madagascar are more difficult to determine; the two species occupy distinct ecological niches with Solanum betroka restricted to the more arid south. Solanum sambiranense can be distinguished from Solanum ivohibe by its inflorescences with 3-10 (versus 10-16) flowers, and calyx lobes 4-6 mm long tearing for up to 2 mm (versus calyx lobes 0.8-2 mm long tearing for up to 1mm); Solanum sambiranense also occurs further north than the only known locality of Solanum ivohibe in Fianarantsoa.

The distribution of Solanum sambiranense spans northern and northwestern Madagascar, from locations with more dry and seasonal climatic conditions than the wet eastern rainforests, warmer climate than the High Plateau, and more moisture than the south. Larger-leaved forms predominate towards the north and east as habitats get more humid.

D’Arcy and Rakotozafy (1994) state that Solanum sambiranense differs from other species thought to be related to it by its prominent domatia. These are dense tangled tufts of dendritic trichomes in Solanum sambiranense ; no domatia are seen in Solanum betroka , but some increased trichome density in the leaf axils has been observed in Solanum imamense (Baron 1754). All specimens of Solanum sambiranense have membranous leaves except Perrier de la Bâthie 13022 with membranous leaves on young shoots that become thick chartaceous on main branches. Grevé 241 differs from the typical Solanum sambiranense by its densely pubescent leaves, but with foliaceous calyx lobes clearly belongs to it.

The protologue cites a holotype from P; of the two duplicates of the type collection held in Paris we here select one of these (P00352331) as the lectotype of Solanum sambiranense as it bears a note "type collection" in D’Arcy’s handwriting, while the other duplicate of Perrier de la Bâthie 2324 (P00352332) has no additional annotation.

Selected specimens examined.

Madagascar. Antsiranana: Ambanja, Sambirano, bassin supérieur du Sambirano, berges du Sambiran, 1937, Humbert 18586 (P); Ambanja , Sambirano , bassin supérieur du Sambirano: forêt de Besanatribe, 1937, Humbert 18709 (P); Antsiranana Rural , Diego-Suarez , a la limite N des collines et plateaux calcaires de l’Ankarana, s.d., Humbert 19072 (MO, P); Ambanja , Tsaratanana , Mont Tsaratanana , 14°01' S, 48°58' E Alt : 1000m, 1000 m, Dec 1912, Perrier de la Bâthie, J.M.H.A. 2580 (P); Vohemar, Dairaina, forêt de Binara, a 1370 m du point côté 779, 14 Dec 2005, Ranirison & Nusbaumer 1032 (G, K); canton de Marovato, district d’Ambanja, Réserve naturelle 4 [Tsaratanana], 12 Dec 1953, Réserves Naturelles Madagascar 5766 (MO, NY, P, TAN) . Mahajanga: Beanka, partie sud, Kinahango, 23 Nov 2011, Gautier et al. 5707 (G); Tsiampihy , district d’Antsalova, 15 Oct 1932, Léandri 297 (NY, P); Maevatanana , Mahatsinjo , au sud d’Andriba, Feb 1920, Perrier de la Bathie 13022 (P); Maevatanana , Mahatsinjo , au Nord du Tampoketsa d'Ankazobe , 1000 m, Sep 1926, Perrier de la Bâthie 17783 (P) .

Figures

Figure 1. Flowers of species in the ANS clade. A Solanum africanum Mill. (South Africa, Rebelo s. n. - no herbarium voucher) B Solanum imamense Dunal (Madagascar, Rakotavao 5128) C Solanum madagascariense Dunal (Madagascar, Vorontsova et al. 498) D Solanum sambiranense D'Arcy & Rakot. (Madagascar, Randrianasolo 580) E Solanum terminale Forssk. (Kenya, Vorontsova et al. 93) F Solanum truncicola Bitter (Madagascar, Antilahimena et al. 7846). Photo credits: A Tony Rebelo; B Charles Rakotavao; C, E Maria Vorontsova; D Richard Randrianasolo; E Patrice Antilahimena.

Figure 2. Habit and fruits of species of the ANS clade. A Habit of Solanum sambiranense D'Arcy & Rakot. (Madagascar, Randrianasolo 580) B Fruit of Solanum imamense Dunal (Madagascar, Rakotavao 5128) C Fruit of Solanum terminale Forssk., pointed form (Angola, Goyder et al. 7749) D Fruit of Solanum terminale Forssk., globose form (Tanzania, Tepe et al. 2783). Photo credits: A Richard Randrianasolo; B Charles Rakotavao; C David Goyder; D Maria Vorontsova.

Figure 23. Solanum sambiranense D'Arcy & Rakot. A Flowering branch B Flower bud C Open flower from side showing spreading corolla lobes D Open flower from above, showing terminal anther pores E Fruiting branch F Domatia on leaf abaxial surface at junction of midvein and lateral veins G Immature berry H Dendritic trichome I Simple trichome. (Based on: A Ranirison & Nusbaumer 1032; B, C Nusbaumer 860; D, E Randrianasolo 580, drawn from photograph; F-I Perrier 2580). Scale bar: A, E = 3 cm; B-D = 1.5 cm; F, G = 1 cm; H, I = 0.3 mm. Drawn by Lucy T. Smith.

Figure 24. Distribution of Solanum sambiranense D'Arcy & Rakot.