Solanum psilophyllum Stehmann & Giacomin, 2015

Knapp, Sandra, Stehmann, Joao Renato & Giacomin, Leandro L., 2015, New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae) in Brazil, PhytoKeys 47, pp. 1-48 : 13-14

Solanum psilophyllum Stehmann & Giacomin sp. nov. Figure 8C, D, E, 12

Diagnosis.

Like Solanum evonymoides Sendtn. but differing in smaller flowers, inflorescences that are unbranched or branch only once near the base, pedicels with a constriction at the apex just below the calyx lobes and ovoid-reniform seeds.

Type.

Brazil. Minas Gerais: Mun. Mariana, Mina de Fazendão, em mata, próximo à ferrovia, 20°08'43.7"S, 43°24'48.4"W, 875 m, 29 Jul 2008 (fl, fr), L.L. Giacomin, J.R. Stehmann, S.G. Resende & F. Pena 186 (holotype: BHCB [BHCB019054]; isotypes: BHCB [BHCB019055], BM, NY, RB).

Description.

Treelet to 4 m, rhizomatous with underground stems; young stems terete, glabrous; new growth completely glabrous, occasionally minutely papillate; bark of older stems greenish brown, slightly winged from the leaf bases. Sympodial units difoliate, geminate; leaves of a pair differing in size but not usually in shape. Leaves simple, the major leaves 10-15(-25) cm long, 4-13 cm wide, elliptic to narrowly elliptic, occasionally wider in the distal third and narrowly obovate, membranous, glabrous on both surfaces, the abaxial surface often drying paler than the adaxial surface; primary veins 8-11 pairs, drying somewhat lighter than the lamina; base attenuate, somewhat oblique; margins entire; apex acute, the tip somewhat blunt; petiole 1.5-2 cm long, glabrous; minor leaves 6-8 cm long, 2-3 cm wide, differing from the majors only in size and sometimes not present in dried specimens. Inflorescences 0.2-2 cm long, opposite the leaves or appearing to arise from the leaf axils, unbranched, but apparently sometimes with 2 inflorescences from one axil and appearing branched (Giacomin et al. 186), with 5-8 flowers, glabrous; peduncle 0.1-2 cm; pedicles 1.2-1.5 cm long, ca. 0.5 mm in diameter at the base, ca. 1.5 mm in diameter at the swollen apex with a marked constriction just below the calyx lobes, slender and expanding distally, spreading or pendant at anthesis, glabrous, articulated at the base; pedicel scars 0.5 -1 mm apart, more congested in the distal part of the inflorescence. Buds obovoid, the corolla strongly exserted from the calyx tube before anthesis. Flowers 5-merous, perfect. Calyx with the tube 0.5-1 mm long, broadly conical, the lobes 1-1.5 mm long, deltate to triangular, reflexed at anthesis, glabrous. Corolla 1.2-1.4 cm in diameter, white, stellate, lobed 1/2 to 2/3 of the way to the base, the lobes ca. 5 mm long, 2.5 mm wide, spread at anthesis, glabrous with the tips minutely papillate. Stamens 3.5-4 mm long; filament tube ca. 0.5 mm long, the free portion of the filaments ca. 0.5 mm long, glabrous; anthers 2.5-3 mm long, ca. 1 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 5-6 mm long, glabrous; stigma not expanded, blunt, the surface minutely papillate. Fruit a globose berry, 1-1.3 cm in diameter, green, the pericarp not markedly shiny, thick; fruiting pedicels 1.5-1.7 cm long, ca. 1 mm in diameter at the base, 2.5-3 mm and expanded at the apex, woody and pendant; calyx lobes in fruit not markedly expanding, but distinctly differentiated from the enlarged pedicel apex. Seeds not known.

Distribution.

In the south-eastern part of the state of Minas Gerais, in islands of forest ( capões) associated with iron or quartzite formations in the Iron Quadrangle and Serra do Cipó regions, in the southern limit of Espinhaço mountain range (Figure 13).

Ecology.

Solanum psilophyllum grows in the forest understory on thin soils associated with iron-rich or quartzite formations, at elevations from 800-900 m.

Phenology.

Flowering specimens have been collected throughout the year; fruits have only been seen on the type specimen, collected in July. It is probable that this species flowers and fruits sporadically throughout the year.

Etymology.

Named for its completely glabrous leaves (from the Greek psilos smooth or bare, phyllos leaf).

Preliminary conservation status ( IUCN 2014).

Critically Endangered (CR) B1, 2 a, b(ii, iii, iv); EOO 26 km2 (CR); AOO 16 km2 (EN). Solanum psilophyllum is known from only two localities and its habitat is under severe pressure from mining and frequent forest fires (see Notes). The population from which the type specimen was collected, close to a private railroad, has already been destroyed. Although the area of occupancy would suggest a status of Endangered we consider the extreme threats to these populations coupled with the habitat specifity of members of the Geminata clade (see above) warrant a status of Critically Endangered.One of the known collections might be from a protected area (PARNA Serra do Cipó), although not stated on the specimen label (Campos & Belisário CFSC-13505) but appears to be from a roadside, subject to occasional fire.

Notes.

Solanum psilophyllum is the species previously called Solanum cormanthum Vell. in Lista de Especies de Flora do Brasil ( Stehmann et al. 2014). That name, however, has been of uncertain application since Sendtner (1846) listed a collection from Minas Gerais ("Caxoeira do Campo") as belonging to Solanum cormanthum , but with reservations.

Three sheets of labelled as "Solanum cormanthum Vell." in Martius’s hand in Brussels belong to this species as do presumed duplicates of this collection in F (F-680206) and G (G00016950) cited by Knapp (2008) as belonging to Solanum evonymoides Sendtn., a species now considered to only occur from coastal Bahia to northeastern Minas Gerais (see discussion of Solanum verticillatum below). Sendtner (1846) cites a collection in Martius’s herbarium from "Caxoeira do Campo, prov. Minarum, Martio floret: Martius"; this was probably collected by Claussen. One of the three of the sheets in BR (BR00000825373) is from Martius’s herbarium and is labelled "Mart. 1839." Another sheet is definitely attributed to Claussen and collected in 1835, while the third is attributed ("comm. Schüch fil. 1850") to Guilherme Schüch, the Baron of Capanema (Minas Gerais, currently the active iron mine of Capanema), who sent plants to Martius.

The Vellozo illustration of Solanum cormanthum (tab. 113, Vellozo 1831) has distinctly axillary inflorescences and is said to come from what is now the city of Rio de Janeiro ("Praedii S. Crucis"), an area of very different vegetation and soils than the iron or quartzite rich formations of Minas Gerais. We recognise Solanum cormanthum here as a synonym of Solanum lacteum , both on morphological and distributional grounds. Members of the Geminata clade are very similar morphologically and Vellozo’s plates are often distinctly suboptimal for secure identification. In view of the restricted distribution and habitat of these plants (see below) we prefer to describe this as new here rather than use Solanum cormanthum for these distinct and endangered populations.

Solanum psilophyllum has a very narrow distribution restricted to the Iron quadrangle, within areas that are today active mines, and to the Serra do Cipó region, were it was collected more than ten years ago, in forest fragments close to roadsides. The fact that no collections are known from northern areas of the Espinhaço range likely indicates that the distribution is extremely restricted to the region acround Serra do Cipó and the Iron Quadrangle. Efforts to locate new populations of this species are urgent, especially considering that most areas where it might occur are currently owned by mining companies and are subject to an intensive land use.

Solanum psilophyllum is morphologically similar to Solanum verticillatum (described here below), another completely glabrous species of the Geminata clade occurring in the states of São Paulo and Rio de Janeiro. It can be distinguished from that species by its longer calyx lobes and by the swollen distal portions of the pedicels that are markedly constricted just below the calyx lobes. In addition, the leaf texture of Solanum psilophyllum is somewhat fleshy, while leaves of Solanum verticillatum are brittle and chartaceous.

Solanum psilophyllum is also morphologically similar to Solanum lacteum from Atlantic forests in Rio de Janeiro, Espirito Santo and Minas Gerais states. It differs from that species in its larger flowers (>1 cm in diameter), longer inflorescences, elliptic rather than obelliptic leaves that do not dry a blackish brown colour and in the non-lenticellate stem. Like Solanum lacteum , Solanum psilophyllum is completely glabrous. Solanum psilophyllum has an underground stem (Figure 8C), like Solanum arboreum Dunal of northern South America and Central America (see Knapp 2002a); this characteristic may be more common in the Geminata clade than currently thought, as it is rare that the underground parts of these small shrubs are collected or even observed.

Specimens examined.

BRAZIL. Minas Gerais: Mun. Santana do Riacho, Serra do Cipó, Rodovia MG-010, Belo Horizonte a Conceição do Mato Dentro, ca. de 1.5 km antes da bifurcação para Morro do Pilar, pequeno capão da mata a direita, próximo a rodovia, 19 Nov 1993 (fl), M.T.V.A. Campos & A.J.M. Belisário CFSC-13505 (BHCB); sin. loc., 1835 (infl), P. Claussen s.n. (BR); sin. loc., 1839 (infl), P. Claussen s.n. (F); Caxoeira do Campo, Mar 1839 (infl), P. Claussen 200 (BR, G); Mun. Santana do Riacho, Serra do Cipó, ca. 400 m antes da bifurcação Morro do Pilar-Conceição do Mato Dentro, ca. 1.8 km da estrada, 2 Mar 2001 (fl), M. Groppo et al. 640 (BHCB); Mun. Catas Altas, Mina de Fazendão, próximo à area da cava, 20°07'38"S, 43°24'48"W, 970 m, 27 May 2008 (fl), S.G. Rezende et al. 2749 (BHCB); sin. loc., 1850 (infl), G. Schüch s.n. (BR).