Solanum imamense Dunal, Prodr. [A.P. de Candolle] 13(1): 85. 1852.

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 : 40-42

Solanum imamense Dunal, Prodr. [A.P. de Candolle] 13(1): 85. 1852. Figures 1B , 2B , 11

Solanum imamense Dunal var. grandiflorum Dunal, in DC., Prodr. 13(1): 85. 1852. Type. Madagascar. Antananarivo: "in rupibus provinciae Emirnae [Imerina] Madagascariensis" 1833, W. Bojer s.n. (holotype: G-DC [G00144980]; isotypes: W [W0000604], K [K000212345]).

Solanum ankazobe D’Arcy & Rakot., Fl. Madag. Fam. 176: 67. 1994. Type. Madagascar. Antananarivo: Bois sabloneux secs, Ambongo, entre Andranomavo et Itampitso, Sep 1905, J. Perrier de la Bâthie 9615 (holotype: P [P00349380]; isotype: MO [MO-150887]).

Type.

Madagascar. Antananarivo:"croit sur les rocher escarpées dans le d’Imamou”, 1839, W. Bojer s.n. (holotype: G-DC [G00144901]) .

Description.

Shrub or liana, 3-4(+) m tall. Stems flexuous, flattened to terete, sparsely to densely pubescent with densely to loosely branched dendritic trichomes 0.2-0.3 (0.5) mm long, glabrescent; new growth sparsely to more commonly densely pubescent with uniseriate dendritic trichomes to 0.5 mm long, these often drying golden or golden reddish in herbarium specimens; bark of older stems longitudinally ridged, light grey. Sympodial units plurifoliate, the leaves not geminate, on short shoots or somewhat clustered towards tips of branches. Leaves simple, 2.5-5(7) cm long, 1.5-3(4) cm wide, ovate, membranous to chartaceous, discolorous, pubescent on both surfaces with uniseriate dendritic trichomes to 0.5 mm long, sometimes slightly longer and somewhat denser in the axils of the main veins with the midrib; major veins 4-7 pairs, spreading at ca. 60° to the midvein and forming loops, the finer venation often visible; base attenuate or truncate to weakly cordate; margins entire; apex acute to acuminate; petiole slender, 0.5-1.5(2) cm long, pubescent with dendritic trichomes like those of the new growth and leaves. Inflorescences terminal, at the apex of slender terminal or lateral branches, 3-7(10) cm long, furcate (sometimes unbranched), with (4)7-13 flowers, pubescent with dendritic trichomes like those of stems and leaves; peduncle 0.5-2.5 cm long; pedicels 1.1-1.7 cm long, apically dilated, pubescent with trichomes as on the young stem, articulated less than 1 mm from base and tiny pegs; pedicel scars irregularly spaced 1-4 mm apart. Buds ovoid to ellipsoid, the corolla only about halfway exserted from the corolla tube before anthesis. Flowers 5-merous, apparently all perfect. Calyx tube 2-3 mm long, conical, the lobes 3-5 (7.5) mm long, 1-1.5 mm wide at base, deltate to linear, acute at the tips, unequal in size, tearing at the sinuses by ca. 1 mm, densely pubescent with dendritic trichomes like those on the rachis. Corolla 2-3 cm in diameter, violet or purple, lobed almost to base, the lobes 10-15 mm long, 2-6 mm wide, narrowly deltate to linear, puberulous adaxially, minutely pubescent abaxially with dendritic trichomes, these larger at the tips and margins. Stamens equal; filament tube ca. 1 mm long; free portion of the filaments 1-2 mm long, glabrous; anthers 4-5(6) mm long, ca. 2 mm wide, broadly ellipsoid, not connivent, smooth abaxially with some papillae near the pores, 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 10-13 mm long, protruding 3-5(7) mm above the anthers, laterally flattened, curved, glabrous; stigma clavate to capitate, dark, the surface smooth. Fruit a globose to elongate pyriform berry, ca. 3 cm long, 1.2-1.6 cm in diameter, apically rounded or the distal portion pointed and elongate, dark purple when mature, the pericarp thin, glabrous; fruiting pedicels 1-2.5 cm long, up to 1.5 mm diameter at base, pendulous, flexible, ridged; fruiting calyx slightly accrescent, the lobes becoming wider and forming a spreading cup around the fruit. Seeds 20-30 per berry, 4-4.5 mm long, 3-3.5 mm wide, flattened reniform, yellowish brown, the surfaces minutely pitted, the testal cells pentagonal or sinuate in outline, the lateral walls with hair-like projections to 0.1 mm long.

Distribution

(Figure 12 ). Endemic to Madagascar, with a broad distribution range in the west, the south, and on the high central plateau; in the provinces of Mahajanaga, Antananarivo, and Toliara.

Ecology and habitat.

Open dry forest and forest edges; often growing on rocks; 900-1000 m.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2014). Least Concern (LC). EOO 165,095 km2 (LC), AOO 40 km2 (EN). In common with other members of the ANS clade in Madagascar, Solanum imamense has a relatively wide distribution, resulting in an EOO indicating lack of immediate conservation concern. The paucity of collections, indicative of local rarity, coupled with the ongoing habitat threats in Madagascar, however, do indicate monitoring and further collection to assess local and regional rarity is necessary.

Discussion.

Solanum imamense is a fairly common liana or shrub with shallowly cordate or truncate leaves clustered towards tips of branches, large (to 3 cm in diameter) violet or purple flowers, and large anthers 4-5 mm long. The pubescence of den dritic trichomes up to 0.3-0.5 mm long is visible with the naked eye on the petioles, pedicels, inflorescences and abaxial sides of the leaves (Figs 1B , 2B ).

Solanum imamense is morphologically similar and possibly closely related to Solanum betroka from southern Madagascar and Solanum sambiranense from northern Madagascar, and perhaps also the rare and poorly known Solanum ivohibe from the province of Fianarantsoa. Solanum imamense differs from Solanum betroka in its inflorescences with 7-13 (versus 1-3) flowers, larger floral parts, and leaves that are always entire (versus leaves that are frequently lobed). Solanum imamense can be distinguished from Solanum sambiranense by its ovate leaves 2.5-5 cm long (versus elliptic to obovate leaves 5-10 cm long) and looser dendritic trichomes 0.2-0.5 mm (versus less than 0.1 mm) long. Solanum imamense differs from Solanum ivohibe by its ovate leaves less than 5 cm long (versus elliptic to obovate leaves 5-7 cm long), cordate to short attenuate (versus long attenuate) leaf base, and calyx lobes more than 2 mm (versus less than 2 mm) long.

Solanum imamense has a broad ecological profile occurring occasionally in dry to mesic parts of the island in the western, central, and southern ecoregions ( Humbert 1955; Faramalala 1988, 1995). In the southern part of its distribution range it is sympatric with Solanum betroka and in the northern part of the range with Solanum sambiranense .

Solanum imamense var. grandiflorum was accepted by Bitter (1917) but synonymised with Solanum imamense by D’Arcy and Rakotozafy (1994). It differs from the type variety by flower size and pubescence density, but the variation in both characters is continuous. The type specimens of both were collected by W. Bojer in central Madagascar. Solanum ankazobe was described on the basis of three collections, and was distinguished by its small leaves, smaller calyx tube, irregular tearing of the calyx and wider ovary. The type collection of Solanum ankazobe (Perrier de la Bâthie 9615) has leaves that fall within the range of variation in Solanum imamense , while other specimens cited have smaller floral parts (Perrier de la Bâthie 9577 and 9579). We consider these specimens to fall within the range of variation represented in Solanum imamense and treat Solanum ankazobe as a synonym.

Selected specimens examined.

Madagascar. Antananarivo: Antananarivo-Nord, Tananarive, environs de Tananarive (Anositavo), 22 Apr 1928, Decary 6276 (K, MO, P); Manerinerina, Tampoketsa d’Ankazobe, 3 Jan 1942, Decary 17170 MO, (P); Betafo, s.d., Perrier de la Bâthie 9574 (MO, P); Ankazobe, Manankazo, Tangeotseha entre Ihopa et Behibotra, Dec 1925, Perrier de la Bâthie 16830 (P) . Mahajanga: Marovoay, Anjiafitatra, près du MontTsialondraina ( Boïna), Nov 1901, Perrier de la Bâthie 1332 (MO, P); Ambongo, entre Andranomavo et Itampitso, Sep 1905, Perrier de la Bâthie 9615 (MO, P) . Toliara: Amboasary-Sud, Amboahangy, bassin supérieur du Mandrare (Sud-Est), Mont Amboahangy prés d’Esira, 25 Nov 1928, Humbert 6812 (MO, P); Sakaraha, forêt d’Analafanja au N du Fiherenana, Mar 1934, Humbert 14290 (P); Atsimo-Andrefana, Behetaheta, district et commume rural Beroroha, Fokotany, Beronono-Makay, 17 Jan 2010, Rakotovao et al. 5128 (MO); Bekily , Ampandrandava, entre Bekily et Tsivory, 1943, Seyrig 156 (MO, 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 11. Solanum imamense Dunal. Flowering branch (based on Baron 1754). Adapted from D'Arcy and Rakotozafy (1994) with permission of Museum National d'Histoire Naturelle.

Figure 12. Distribution of Solanum imamense Dunal.