Solanum ivohibe D'Arcy & Rakot., Fl. Madag., Fam. 176: 97. 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 : 43-47

Solanum ivohibe D'Arcy & Rakot., Fl. Madag., Fam. 176: 97. 1994. Figure 13

Type.

Madagascar. Fianarantsoa: Razafinarakoto, Antambohobe, Ivohibe , 28 Nov 1951, Reserves Naturelles 3516 (lectotype, designated here: P [P00349043]; isolectotypes: P [P00349042], TAN) .

Description.

Straggling shrub or occasionally a liana, ca. 2.5 m tall. Stems long and flexuous, ridged, glabrous except youngest stems unevenly pubescent; trichomes densely dendritic to echinoid, most only to 0.2 mm long, with 10-15 highly congested branches each; main stems 2-4 mm in diameter, glabrous; bark longitudinally ridged, almost white; leaf scars prominent stumps almost overlapping to 2.5 cm apart. Sympodial units plurifoliate, the leaves not geminate, the leaves clustered at tips of branches and on short shoots. Leaves simple, 5-7 cm long, 2-2.5 cm wide, elliptic to obovate, membranous, wrinkled in herbarium specimens, concolorous, glabrous on both sides except for occasional simple or dendritic trichomes ca. 3 mm long with poorly developed branches, some more densely branched dendritic trichomes on the abaxial side of the midvein; midvein raised abaxially and flat adaxially; major veins 5-6 pairs, spreading at ca. 60° to the midvein, the finer venation brown, fine and faint, with tufts of minute dendritic trichomes with few branches (domatia) in the junction between the midvein and major veins abaxially; base long-attenuate; margin entire, mostly glabrous with occasional simple or sparsely dendritic trichomes becoming more frequent towards the apex; apex acute; petiole 1-2.5 cm long, slender, flexuous, ridged, glabrous or with occasional dendritic trichomes like those on the stem;. Inflorescences terminal, at the apex of branches or short shoots, 4-5 cm long, furcate, with 10-16 flowers; peduncle 2-2.7(5) cm long; peduncle and rachis glabrous or with occasional dendritic trichomes like those on the stem; pedicels 1-2.2 cm long, apically dilated with gradual transition between the pedicel and the calyx, articulated 0-0.5 mm from base, glabrous, the pedicel scars small stumps almost overlapping to 4 mm apart. Buds ellipsoid, the corolla long-exserted from the calyx tube before anthesis. Flowers 5-merous, apparently all perfect. Calyx tube ca. 1.5 mm long, broadly cup-shaped, the lobes 0.8-2 mm long, 1-1.5 mm wide at base, deltate, acute to obtuse at the tips, glabrous with tufts of dendritic trichomes at the tips. Corolla 1-2 cm in diameter, violet, stellate, lobed almost to base, the lobes 5-10 mm long, 2-4 mm wide, narrowly ovate, glabrous in the centre of both surfaces with small simple papillate trichomes denser and longer on the margins and tip, the tips of the lobes enlarged and knob-like, perhaps fleshy in live plants. Stamens equal; filament tube ca. 1 mm; free portion of the filaments less than 1 mm long, glabrous; anthers 3.5-4 mm long, ca. 1-1.5 mm wide, broadly ellipsoid, free and clearly separated from one another, smooth abaxially, poricidal at the tips; the pores much smaller than anther apices, ca. 0.3 mm in diameter, not lengthening with age. Ovary conical, glabrous; style 0.8-1 cm long, protruding 3-4 mm above the anthers, slender, curved, glabrous; stigma capitate or distinctly bi-lobed, dark, minutely papillose. Fruit and seeds not known.

Distribution

(Figure 14 ). Endemic to Madgascar in the Ivohibe and Andringitra areas of Fianarantsoa province.

Ecology and habitat.

Riparian and secondary montane forests from approximately 800 to1200 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2014). Endangered (EN B1a, b iii). EOO 950 km2 (EN), AOO 12 km2 (EN). Known collections of Solanum ivohibe are currently not sufficient to document its range of occurence with any degree of confidence, but its occurrence in the fragmented wet forests of eastern Madagascar and the paucity of collections leads us to give it a preliminary status that indicates conservation concern.

Discussion.

Solanum ivohibe is a slender forest shrub with almost glabrous leaves on decurrent long petioles, prominent domatia on leaf undersides (Fig. 13 inset), inflorescences with a long peduncle and 10-16 flowers. It seems likely that Solanum ivohibe can grow as a liana. The very few collections suggest it grows along streams in mid-elevation mesic to wet secondary forests in the underexplored and exceptionally diverse area around Andringitra National Park ( Lewis et al. 1996).

Within Madagascar Solanum ivohibe is most similar to Solanum sambiranense , and to some extent also with Solanum imamense and Solanum betroka . Solanum ivohibe can be distinguished from Solanum sambiranense by its inflorescence bearing 10-16 (versus 3-10) flowers, calyx lobes 0.8-2 mm long tearing for up to 1 mm (versus calyx lobes 4-6 mm long tearing for up to 2 mm), and minute versus larger tufts of trichomes (domatia) in the axils of the veins and midrib of the lower leaf surfaces; it also occurs further south than the distribution range of Solanum sambiranense . Solanum ivohibe is sympatric with Solanum imamense and Solanum betroka ; it differs from these two species by its long-decurrent (versus cuneate) leaf bases, larger leaves (> 5 cm long versus shorter than 5 cm), smaller calyx, and calyx lobes <2 mm long (versus usually> 2 mm long). D’Arcy and Rakotozafy (1994) considered Solanum ivohibe to be a relative of the Mayotte endemic Solanum macrothyrsum but with smaller leaves and inflorescences; it shares features with both Solanum macrothyrsum and Solanum sambiranense . The anthers of Solanum ivohibe are longer than those Solanum macrothyrsum (3.5-4 mm versus 2.5-3 mm), the calyx lobes are somewhat longer (0.8-2 mm versus under 0.5 mm) and more deeply divided.

Solanum ivohibe appears to occupy a somewhat higher elevation, higher moisture, and more closed canopy environment than the similar species Solanum betroka in the arid south, Solanum sambiranense in fairly dry north-west, and Solanum imamense in mesic niches, and the distribution range of Solanum ivohibe does not overlap with these species. Solanum ivohibe apprears to be sympatric with Solanum madagascariense around Andringitra National Park and the surrounding forests although Solanum madagascariense occurs in wetter forest.

The species concept of Solanum ivohibe adopted here has little in common with that of D’Arcy and Rakotozafy (1994). The protologue lists five collections of Solanum ivohibe and places the species in section Lemurisolanum . In our view, two of the cited collections represent other taxa: Humbert 13429 (P00349045, from Ankazondrana), that was used for the illustration in the original description, belongs to our circumscription of Solanum madagascariense and Peltier & Peltier 980 (P00349044, from Toamasina) belongs to our circumscription of Solanum humblotii . The type specimen, however, represents a distinct taxon and we recognise Solanum ivohibe here, with a narrow circumscription encompassing the type and two other collections (one cited by D’Arcy and Rakotozafy [1994]) from very near the type locality.

The protologue of Solanum ivohibe cites a holotype at P. There are in fact two duplicates, one of which (P00349043) is clearly marked as such in D’Arcy’s handwriting; we select this specimen here as the lectotype of Solanum ivohibe .

Specimens examined.

Madagascar. Fianarantsoa: Ambalavao, Andringitra, edge of Zomandao River , 15 Nov 2010, Rakotonasolo & Cribb RNF - 1674 (K); District d’Ivohibe R.N.V., 28 Nov 1951, Réserves Naturelles Madagascar 3523 - RN (P) .

Figures

Figure 13. Solanum ivohibe D'Arcy & Rakot. A Flowering branch B Tufts of trichomes in vein axils on leaf undersides (domatia) (based on Humbert 13429). Adapted from D'Arcy and Rakotozafy (1994) with permission of Museum National d'Histoire Naturelle.

Figure 14. Distribution of Solanum ivohibe D'Arcy & Rakot.