Solanum filirhachis Giacomin & Stehmann, 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 : 9

Solanum filirhachis Giacomin & Stehmann sp. nov. Figures 1E, F, 6

Diagnosis.

Differs from the sympatric Solanum campaniforme Roem. & Schultes in its deep forest habitat, leaves with ruffled margins, flowers less than 1 cm in diameter, pedicels with a constriction at the distal end that are swollen in fruit, and few seeds.

Type.

Brazil. Espírito Santo: Mun. Santa Teresa, Comunidade de Santo Antônio, Propriedade do Sr. Boza, fragmento de floresta ombrófila densa após plantação de eucalipto, à direita da entrada, descendo o vale, 19°54'32"S, 40°35'26"W, 740 m, 8 Jun 2012 (fl, fr), L.L. Giacomin, L. Bohs, Y.F. Gouvêa & F.Z. Saiter 1854 (holotype: BHCB [2 sheet holotype: sheet 1 (fl) BHCB019056; sheet 2 (fr) BHCB019057]; isotypes: BM, MBML, NY, RB).

Description.

Erect shrubs to small trees, up to 3 m tall, normally branching close to the apex, the upper stems ascendant; young stems terete, glabrous; new growth brownish, glabrous. Bark of older stems turning pale greyish brown, glabrous, not exfoliating. Sympodial units difoliate, mostly geminate, with leaves not differing in shape or size. Leaves simple, 4.6-15.9 cm long, 1.3-4.9 cm wide, narrowly elliptic, membranous to chartaceous, slightly discolorous when dry, the adaxial surface glabrous, dark green and somewhat shiny in live plants, the abaxial surface sparsely pubescent with simple uniseriate 7-12-celled trichomes to 1 mm long in tufts in the primary vein axils, occasionally extending to the midrib; primary veins 5-9 pairs, yellowish green, discretely raised above, raised beneath; base attenuate to acute, slightly decurrent onto the petiole, sometimes asymmetric; margins entire, slightly undulate (ruffled) and revolute, apex long-attenuate to acuminate; petioles 1-9 mm long, glabrous. Inflorescences 3.5 to 26 cm long, opposite the leaves or internodal, unbranched, slender and very delicate, with 18-60 flowers, but bearing normally with 4-10 flowers at a time, glabrous; peduncle 1.8-3.8 cm long; pedicels 7-18 mm long, ca. 0.4 mm in diam. at the base, ca. 0.9 mm in diameter at the apex, with a constriction at the receptacle, articulated at base, unevenly spaced 1.7 to 10 mm apart. Buds globose, the corolla completely exserted from the calyx tube before anthesis. Flowers all perfect, 5-merous. Calyx tube to 1 mm long, conical, the lobes ca. 0.2 mm long, ca. 1.5 mm wide, acuminate and somwewhat keeled, papillose adaxially, glabrous abaxially. Corolla 6-8 mm in diameter, normally whitish purple adaxially, light purple abaxially, stellate, membranous, lobed more than ¾ the way to the base, the lobes 4-5 mm long, 1-1.7 mm wide, spreading at anthesis and becoming reflexed in older flowers, deltate to lanceolate, glabrous on both surfaces, minutely papillose at tips and margins. Stamens 2.5-3 mm long; filament tube ca. 0.3 mm long, the free portion of the filaments up to 0.2 mm long, equal in length or slightly unequal, and when so, two filaments slightly longer (barely visible in dried material), glabrous; anthers 2-2.5 mm long, 1.2-1.5 mm wide, ellipsoid, slightly connivent, yellow, poricidal at the tips the pores directed introrsely, elongating to longitudinal slits with age. Ovary glabrous; style 4-6 mm long, white, straight, glabrous, the stigma light grayish green, capitate. Fruit a globose berry 1-1.5 cm in diameter, dull green at maturity, with irregular black spots (Figure 1F) drying grayish brown, the pericarp glabrous, not shiny; fruiting pedicels 2.0-2.4 cm long, clearly obconical, ca. 0.5 mm in diam. at the base, widening markedly towards the apex to ca. 2.5 mm in diam.; calyx lobes in fruit ca. 1.5 mm long, commonly broken off in dried fruiting material. Seeds 20-25 per berry, 2.5-4.5 mm long, 2-3.3 mm wide, ovoid-reniform to somewhat flattened towards the margins, light to dark brown, the surface irregularly pitted, the testal cells undulate.

Distribution.

Restricted to the state of Espírito Santo (Figure 7), in south-eastern Brazil. Collections are known from the central and northern parts of the state, from both sides of the Rio Doce.

Ecology.

Rare in the understory of well-preserved fragments of the sub-montane and montane Brazilian Atlantic coastal rainforest (Floresta Ombrófila Densa; IBGE 2012), normally in formations where granitic outcrops are present or close by, in elevations ranging from 200 to 750 m.

Phenology.

Fertile specimens of Solanum filirhachis are known mostly from the rainy season (from November to March), but the type collection from June indicates that the species might be fertile for a longer period. Mature fruits were observed in specimens from November and June.

Etymology.

The epithet refers to the long and slender inflorescence rachis, which is not observed in any of the Brazilian sympatric species, although a common feature in some species of the Solanum confine group from Colombia, Ecuador and Venezuela ( Knapp 2002a).

Preliminary conservation status (IUCN 2013).

Endangered (EN) B1, B2 ab (ii, iii, iv); EOO 1,136 km2 (EN); AOO 20 km2 (EN). Solanum filirhachis is currently known from only five localities, and all collections are from within private properties, where agriculture (both large and small scale) is known to occur. Despite the fact that it inhabits higher elevations that are usually harder to access and not always suitable for agriculture, we strongly recommend that further efforts to map new populations of the species should be undertaken, mainly within protected areas with similar forest types. Although the type locality of Santa Teresa in central Espirito Santo has several well preserved fragments of forest, the landscape has been rapidly transformed in the last few decades to Eucalyptus and coffee plantations, and summer vacation homes (cottages).

Notes.

Solanum filirhachis is remarkably similar to a suite of species of the Geminata clade with ruffled leaf margins (see Figure 1E) and long filiform inflorescences ( Solanum leptorhachis Bitter and Solanum nematorhachis S.Knapp from the W Andean slopes in Colombia and Ecuador and Solanum tenuiflagellatum S.Knapp of Venezuela). Knapp (2002a, 2008) treated these as members of her Solanum confine species group, all of whose members have a thin inflorescence rhachis, small flowers and leaves with ruffled (undulate) margins, although this latter character is impossible to see in herbarium specimens. Solanum filirhachis differs from those species in its distribution and in the tufts of trichomes in the abaxial leaf vein axils (domatia); other members of this morphologically similar set of species are glabrous or have fine, golden pubescence. The only Brazilian species Knapp (2002) placed in this group was Solanum stipulatum which can be easily distinguished from Solanum filirhachis by its shorter inflorescences, flowers with reflexed corolla lobes and winged stems with anisophyllous difoliate, geminate sympodial units. Solanum stipulatum is usually a shrub of watercourses, and often grows amongst rocks and is submerged in floods, while Solanum filirhachis is a slender treelet of forest understory. The relationships of the Solanum confine group have not yet been tested using molecular markers.

Another Brazilian species with which Solanum filirhachis could be confused is Solanum campaniforme that has similar (but somewhat stouter) elongate inflorescences and tufts of uniseriate trichomes in the abaxial leaf vein axils. Solanum filirhachis has leaves with ruffled margins tht normally dry pale green and smaller flowers (0.6-0.8 cm in diameter) that (at least in the type specimen) are tinged purple; Solanum campaniforme has leaves with entire, non-ruffled margins that normally dry black or brownish black and larger flowers (1.2-1.8 cm in diameter) with strongly cucullate corolla lobes.

We have designated a two sheet holotype for Solanum filirhachis in order to represent both flower and fruit in the type sheets.

Specimens examined.

BRAZIL. Espírito Santo: Mun. Águia Branca, Assentamento 16 de Abril, 18°54'25"S, 40°44'05"W, 150-200 m, 15 Mar 2006 (fl), V. Demuner et al. 1919 (MBML, BHCB); Mun. Santa Leopoldina, Colina Verde (Morro do Agudo), prop. Israel Elias Ramos (trilha da casa), 20°06'12"S, 40°26'30"W, 250-370 m, 29 Nov 2007 (fl, fr), V. Demuner et al. 4628 (MBML, BHCB); Mun. Santa Leopoldina, Pedra Branca, mata na Serra Santa Lucia, prop. Cristiano Bremencampi, 20°01'36"S, 40°29'32"W, 300-600 m, 30 Nov 2007 (fr), V. Demuner et al. 4655 (MBML, BHCB). Mun. Águia Branca, Rochedo, Trilha do Córrego, prop. Ailton Corteleti, 18°57'21"S, 40°48'05"W, 300-400 m, 19 Dec 2007 (fl, fr), V. Demuner et al. 4817 (MBML, BHCB).