Solanum igniferum Gouvêa & Stehmann, 2016

Gouvêa, Yuri Fernandes & Stehmann, João Renato, 2016, Two new species of the Solanum asterophorum species group (Solanum subg. Leptostemonum, Solanaceae) from the Brazilian Atlantic Forest, Phytotaxa 288 (2), pp. 120-130 : 121-125

Solanum igniferum Gouvêa & Stehmann , sp. nov. ( Fig. 1A–G )

Type:— BRAZIL. Espírito Santo: São Bento de Urânia, Estrada que liga a rodovia BR-262 a São Bento de Urânia , borda de Floresta Ombrófila Densa secundária, beira de estrada, 20°27’10”S, 40°54’16”W, 979 m, 27 April 2015 (fl, fr), Gouvêa & Stehmann 164 (holotype: BHCB!-mounted in two sheets [ BHCB026909 , BHCB026910 ]; isotypes: [ BM, RB]) .

Diagnosis:— Solanum igniferum is morphologically related to S. asterophorum Martius (1838: 79) , from which it can be distinguished by the vestiture coloration, especially from the stems and adaxial leaf surface, which is composed by orange-colored to ferruginous trichomes (vs. hyaline to yellow or brownish trichomes), pedicels straight or nearly so, keeping the flower buds erect to patent (vs. pedicels curved downward keeping the flower buds facing down), and branches horizontally oriented (plagiotropic) (vs. erect branches).

Description:—Shrubs up to 2 m, branched, with horizontally oriented (plagiotropic) branches diverging from the top of a vertically oriented (orthotropic) stem. Young stems terete, densely stellate-tomentose; trichomes orange-colored to ferruginous, porrect, short-to long-stalked, the long ones less frequent, stalks 0.03–0.4 mm long, multiseriate, 2–4 cells wide; rays (4)6–8(10), 1-celled, unequal in length, midpoint poorly developed, 1-celled, up to ¼ of size of the rays, oblique, moderately to sparsely armed; prickles recurved, 1.8–4.5 mm long, 2.0–5.0 mm wide at base, flattened, stramineous at base becoming ferruginous towards the apex, with stellate trichomes like those of the stems and some small, subsessile, glandular ones at base, these often darkened when dry; bark of older stems glabrescent to moderately stellate-tomentose before secondary growth, dark green to dark brown. Sympodial units difoliate, geminate, anisophyllous. Leaves lobed, repand in large-leaved plants, membranaceous to chartaceous, discolor, drying green to dark brown with the vestiture giving a superficial yellowish orange-colored appearance to the adaxial suface, and grayish green to yellowish green to the abaxial surface; adaxial surface densely stellate-tomentose, epidermis always visible; trichomes porrect to antrorse, sessile to long-stalked, stalks to 2.5 mm long, multiseriate, 3–4 cells wide, rays (3)4–8, 1-celled, unequal in length, midpoints 1-celled, often straight, from ¾ to the same length of the rays, with trichomes forked, sessile to short-stalked rarely present, long trichomes more densely distributed along the midrib and primary veins, these are orange-colored to ferruginous, contrasting with the short, hyaline to stramineous ones; the abaxial surface densely stellate-tomentose, the lamina always visible, the trichomes porrect to antrorse, sessile to long-stalked, stalks to 0.24 mm long, multiseriate, 3–4 cells wide, rays 4–8, 1-celled, unequal in length, midpoint 1-celled, up to ¾ of size of the rays, with long trichomes more densely distributed along the midrib and primary veins, these less frequent than on the adaxial surface, usually ferruginous to orange-colored contrasting with the most frequent hyaline to stramineous shorter ones, both major and minor leaves with the same vestiture pattern; unarmed to moderately armed along the midrib and the primary veins on both surfaces, the prickles straight, flattened, 1.0– 7.5 mm long, 0.5–2.5 mm wide at base, 0–25 above and 0–10 beneath; major leaves with 6–9 pairs of primary veins, blades ovate to obovate, 14–22(30) cm long, 8.0–17(23) cm wide, the apex acute to obtuse, the base cuneate to subcordate, generally asymmetric, shallowly to deeply lobed, the lobes deltate, (1)2–8 on each side, to 2.5 cm long, to 6.5 cm at base; petiole 2.0– 4.5 cm, densely stellate-tomentose with stellate trichomes like those of the stems, the prickles 0–5; minor leaves with 5–6 pairs of primary veins, blades elliptic to nearly rounded, 7.0– 12 cm long, 4.0– 7.5 cm wide, the apex and base are acute to obtuse-rounded, generally symmetric, entire to shallowly lobed, the lobes deltate, 0–3 on each side, to 1 cm long, to 2.5 cm wide at base; petiole 1.0– 2.8 cm, densely stellate-tomentose with stellate trichomes like those of the stems, the prickles 0–4; the leaves of juvenile plants are large, with abundant prickles and strongly lobed, becoming smaller, and less armed and lobed in older plants. Inflorescences a reduced monochasial cyme, unbranched, apparently lateral, opposite to subopposite to the leaf, the inflorescence axis (peduncle plus rachis) densely stellate-tomentose with stellate trichomes like those of the stems, unarmed, the peduncle nearly absent to 7 mm, the rachis 1.5–20 mm, unarmed, with (4)7–15(19) flowers, pedicel insertion points spaced 0–3.8 mm apart, with the more spaced ones at proximal portion of the rachis, 1–2 flowers open at same time; pedicels straight or nearly so, keeping the flower buds erect to patent, 9.0– 16 mm long in open flowers, sometimes geniculate distally, articulated at base, unarmed, densely stellate-tomentose, the trichomes only ferruginous to orange-colored or mixed with hyaline to stramineous ones, porrect, short-to long-stalked, the stalks 0.04–0.4 mm long, multiseriate, 2–3 cells wide, the rays (6)8(11), 1-celled, unequal in length, the midpoints poorly developed, 1-celled, up to ½ of size of the rays. Flowers 5-merous, perfect, rarely heterostylous. Calyx tube conical, somewhat angular, 5.0–7.0 mm long, with 0–10 prickles, densely stellate-tomentose with trichomes like those of the pedicels, the lobes narrowly oblong, elliptic or lanceolate, 2.5–7.0(9.0) mm long, often unequal in length, 1.2–2.5(2.8) mm wide, the apices acute to rounded. Corolla 3.0– 3.8 cm in diameter, white to purplish-white, stellate, the interpetalar tissue well-developed and wavy, lobed for 1/3 to 3/5 of its length, the lobes 6.5–10.5 mm length, 7.6–14 mm wide, rounded to deltoid, apiculate at apex, the lobe tips usually cucullate and reflexed at anthesis, densely stellate-tomentose along its whole length abaxially, the trichomes usually ferruginous, porrect to multiangulate, usually misshapen, sessile to short-stalked, the rays up to 12, tortuous, the midpoint ½ to the same length of the rays, the adaxial surface densely stellate-tomentose at apex, becoming gradually less dense towards the base, the basal half glabrous or nearly so, the trichomes like those of the abaxial surface, strongly misshapen. Stamens equal, with the filament tube 1.5–2.3 mm long, the free portion of the filaments 1.0– 1.3 mm long; anthers lanceolate, narrowed towards the apex, sagittate at base, connivent, with apical poricidal dehiscence, 6.6–10.7 mm length, 1.5–2.4 mm wide. Ovary short-cylindrical, convex at apex, with some glandular trichomes; style white, cylindrical, 13.6–14.3 mm, often gently curved in long-styled flowers; 7.4–9.0 mm, straight in short-styled flowers; stellate-tomentose at base; stigma 1.0– 1.3 mm long, often bilobed at apex, green, with a papillose surface. Fruit a widely depressed ovate to spherical berry, 9.7–13 mm length, 12.3–14.5 mm wide; fruiting pedicels 2–2.4 cm long, unarmed; fruiting calyx accrescent, completely covering the fruit in its earlier stages of development, and ½–¾ of the mature fruit, the lobes 3.5–10 mm long, 5.6–8.0 mm at base; the pericarp smooth, glabrous, the exposed portion whitish (immature) becoming somewhat orange when ripe, and the portion covered by the calyx green to pale green at maturity. Seeds 40–50 per berry, 3.5–4.5 mm long, 3.1–3.4 mm wide, flattened, reniform, stramineous to pale brown.

Distribution and habitat:—Known only from southern Espírito Santo State, Brazil with most of its records concentrated in the municipality of Alfredo Chaves (São Bento de Urânia) and surroundings ( Fig. 2 ). Solanum igniferum inhabits the edges of well-preserved fragments of the Brazilian Atlantic Rainforest, at 435 to 979 m, in moist soil under indirect light.

Ecology:—The flowers of S. igniferum are essentially perfect and functionally hermaphrodites, however, some short-styled flowers may occur, indicating a weak type of andromonoecy. Despite this, no clear pattern was observed regarding their position in the inflorescence or flowering phase in which these functionally male flowers are produced. The anther morphology as well as field observations suggest that female bees with buzzing behavior are its primary pollinators (buzz-pollination; Michener 1962; Buchmann 1983). Its whitish to somewhat orange, fleshy, odorless, persistent fruits suggests that seed dispersal may be performed by bats (chiropterocory) and/or birds (ornitochory) ( Van der Pijl 1972). In addition to sexual reproduction, this species exhibits a strong clonal reproduction, producing several individuals around the mother plant.

Phenology:—According to data on specimens’ label and field observations, flowering starts at the beginning of the rainy season, around November, and lasts until April. Fully developed fruits were found in April.

Etymology:—The epithet igniferum is an adjective derived from the Latin ignis that means “bearing fire”; an allusion to its peculiar fire-colored vestiture.

Preliminary conservation status:— Solanum igniferum was assessed as Endangered (EN) B1; B2 a, b (ii, iii) based on its relatively restricted geographic distribution. The species is only known from two localities, occupying an area (AOO) and an extent of occurrence (EOO) of approximately 20 km ² and 145 km ², respectively, with all records outside protected areas. This region holds a considerable amount of forest remnants, most of them fragmented and located in of private properties. There is a high risk of forest suppression of these forest fragments to give place to crops, a very common local activity.

Additional specimen examined (paratypes):— BRAZIL. Espírito Santo: Mun. Alfredo Chaves, São Bento de Urânia , 14 January 1995, Hatschbach & Silva 61483 ( CEPEC, MBM, NY) ; Mun. Atílio Vivacqua, estrada de terra para a comunidade de Moitão do Sul , 21°00’11”S, 41°12’15”W, 461 m, May 2015, Gouvêa & Falcão 190 ( BHCB) ; ibid., 21°00’08”S, 41°12’15”W, 435 m, 05 June 2012, Giacomin, Bohs & Gouvêa 1845 ( BHCB, NY, RB) ; Mun. Marechal Floriano, Pedra Azul , 16 May 1999, Hatschbach et al. 69092 ( BHCB, MBM) .

Discussion:— Solanum igniferum is unique among the species of the S. asterophorum group by possessing a suite of characteristics: the vestiture composed by orange-colored to ferruginous trichomes, pedicels straight or nearly so, keeping the flower buds erect to patent, and conical calices. The disposition of the buds is easily observed in live plants, however, in herbarium sheets the pressing may influence the position of these structures and lead to a misinterpretation. Therefore, if possible, notes about this feature must be taken and recorded on the herbarium label, thus making the species identification easier.

Solanum igniferum is most similar to S. asterophorum , from which it differs by the features mentioned in the diagnosis. The ferruginous coloration of its vestiture can also be observed in some specimens of S. piluliferum Dunal (1852:265) , which is the most morphologically distinct species of the group. However, S. igniferum can be distinguished by its conical calices with the lobes narrowly oblong, elliptic or lanceolate (vs. calyx globose with calyx lobes deltate in S. piluliferum ), major leaves ovate, widely elliptic or obovate with the apex acute to obtuse (vs. major leaves elliptic, entire, with the apex acuminate in S. piluliferum ), and the markedly curved, medium-sized prickles (vs. prickles straight or nearly so, deltate and usually small in S. piluliferum ). The geographic distribution of S. igniferum and S. asterophorum are also distinct. While S. asterophorum is widely distributed in southeast and northeast Atlantic forests, S. igniferum is only known from a restricted area from Alfredo Chaves to Atílio Vivacqua municipalities, in the southern of Espírito Santo State. Although both species occur relatively near from each other (ca. 50 km) and share similar environmental preferences, they were not observed occupying the same sites so far.

Figures

FIGURE 1.A–G. Solanum igniferum. A. Fertile branch. B. Developing inflorescence.C. Developed inflorescence.D. Detail of a dissected flower (stamens and corolla). E. Fruits. F. Short-stalked trichome. G. Long-stalked trichome (A Gouvêa & Falcão 190, B–G Gouvêa & Stehmann 164, both in BHCB). Scale bars A= 10 cm; B= 1.5 cm; C= 3.5 cm; D= 90 mm; E= 1.5; F= 80 μm; G= 200 μm.

FIGURE 2. Known distribution of Solanum igniferum and Solanum sessilantherum in the states of Espírito Santo and Rio de Janeiro, southeastern Brazil (S. sessilantherum: empty circle= estimated coordinates; full circle= original coordinates).