Solanum truncicola
Not known.
Solanum truncicola is endemic to the east-central region of Madagascar in Antananarivo, Fianarantsoa, and Toamasina provinces. Ti grows in humid and subhumid montane forest; (600-)1000-2000 m elevation.
Madagascar. hendramena, farafandoha (D’Arcy and Rakotozafy 1994, as S. humblotii).
Preliminary conservation status (IUCN 2014). Vulnerable (VU B1a, biii). EOO 19,845 km2 (VU), AOO 56 km2 (EN). Although Solanum truncicola has been been consistently but sparsely recorded over a coherent stretch of the eastern Malagasy rainforest from Toamasina in the northernmost part of its distribution range to the Ambalavao area in the southernmost part, the highly fragmented nature of these eastern forest habitats gives cause for conservation concern.
Solanum truncicola is a rare and unusual montane forest shrub or epiphyte. It is easily identifiable by its coriaceous leaves and long, almost linear calyx lobes which are divided to the base before the corolla begins to expand (Fig. 30A). The length of the calyx lobes (0.4-1.1 cm) in combination with the deeply stellate corollas with narrow lobes makes its flowers appear to be two overlapping stars (see Fig. 1F in Knapp and Vorontsova 2016). Petioles of S. truncicola are the shortest of all Madagascar Solanum species (1-5 mm), usually less than 1/8 of the total leaf length. The flowers can reach 3 cm in diameter, and anthers to 6 mm in length.
Misidentification of S. truncicola is not likely, even though its height, internode length, and leaf size vary spectacularly across its distribution range: leaves of the type specimen are ca. 1.5 cm long, while leaves on other collections reach 13 cm. Some large leaved forms become reminiscent of S. myrsinoides in habit and can be distinguished from S. myrsinoides by their inflorescences of 1-2 (versus 2-6) flowers and calyx lobes 0.4-1.1 cm (versus less than 0.1 cm) long.
Bitter (1917) correctly described S. truncicola as distinct from S. humblotii.
Solanum truncicola can be distinguished from S. humblotii by its petioles 0.1-0.5 cm (versus 0.6-1 cm) long, acute (versus acuminate) leaves, glabrous (versus pubescent) young stems, narrowly ovate to obovate (versus deltate to acuminate) calyx lobes, and a different overall appearance. D’Arcy and Rakotozafy (1994) included S. truncicola as a synonym of S. humblotii, perhaps because Bitter’s key only highlighted the more superficial indumentum and size differences between the two species, and the type collections were not carefully consulted. During the years that followed D’Arcy and Rakotozafy’s treatment, many specimens of S. truncicola were determined as S. humblotii; this has caused considerable confusion in herbaria. The two species occur in similar wet forest habitats but are allopatric with S. truncicola with a more southerly distribution and at higher elevations than S. humblotii.
Although the original spelling of the epithet is “truncicolum” (Bitter 1917) the word element -cola should be treated as a noun in apposition and this is a correctable error to truncicola (Article 23.5, McNeill et al. 2012).
Label details on Malcomber et al. 1353 (MO) record the pedicel and calyx as dark purple. The anthers on at least one flower of Malcomber et al. 1353 are clearly connate but distinctly free on other flowers of the same specimen and on other collections.
Bitter (1917) cited three herbaria in the protologue – G-Boiss., B and “Haussknecht” (now held in JE). We have selected the duplicate at JE as the lectotype because it bears an annotation label in Bitter’s handwriting and is a larger specimen with more flowers than that at G.