Solanum sessilantherum 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 : 125-128

Solanum sessilantherum Gouvêa & Stehmann , sp. nov. ( Fig. 3A–E )

Type:— BRAZIL. Rio de Janeiro: Campos dos Goytacazes, Espera Feliz , 21°50’47”S, 41°36’29”W, 22 m, 15 May 2015 (fl, fr), Gouvêa & Falcão 188 (holotype: BHCB! [ BHCB038227 ]; isotypes: [ BM, RB]) .

Diagnosis:— Solanum sessilantherum is similar to S. asterophorum , from which it can be distinguished by its pedicels straight or nearly so buds are erect to patent (vs. pedicels curved downward keeping the buds facing down), inflorescences with armed axes and unpaired pedicel insertion points when mature (vs. inflorescences with unarmed axes, congested, always with paired pedicel insertion points), inconspicuous filaments giving the anthers a sessile appearance (vs. conspicuous filaments).

Description:—Shrubs up to 2 m, branched, erect. The initial vegetative growth is monopodial, with solitary leaves arranged in a 2/5 phyllotaxic spiral to the onset of the flowering, when it becomes sympodial. Young stems terete, densely to moderate stellate-tomentose near the apical meristem, becoming sparsely stellate-puberulent downward on the stem; the trichomes hyaline to brownish, porrect, apparently sessile to subsessile, rarely short-stalked, the stalks less than 0.1 mm long, the rays 4–8(10), 1-celled, the midpoints poorly developed, often apparently absent, 1-celled, and some small, subsessile, glandular trichomes usually present on youngest portion of the stem (hardly observable in poorly preserved material); moderately armed, the prickles recurved, 1.3–5.8 mm long, 1.0– 4.5 mm wide at base, flattened, stramineous at base usually becoming ferruginous towards the apex, with stellate trichomes like those of the stems, and some small, subsessile, glandular ones at base; bark of older stems glabrescent, dark green to dark brown to blackened. Sympodial units difoliate, geminate, anisophyllous. Leaves lobed, coriaceous, shiny, slightly discolor, dark green to dark brown above when dried, and dark brown to grayish brown beneath (with a metallic appearance); the adaxial surface sparsely to moderately stellate-tomentose, the lamina always visible, the trichomes porrect, sessile to subsessile, the stalks less than 0.1 mm long, the rays (3)4–8(11), 1-celled, the midpoints 1-celled, poorly developed, often apparently absent; the 7–8(11)-rayed trichomes are usually somewhat brownish, multiradiate and denser along the veins, but less frequent than the hyaline, porrect, 4–6-rayed tricomes on the rest of the leaf surface; the abaxial surface moderately stellate-tomentose, the lamina always visible, the trichomes porrect, sessile to short-stalked, the stalks to 0.1 mm long, the rays 4–8, 1-celled, the midpoint 1-celled, very poorly developed, often apparently absent, with some trichomes somewhat brownish, the distribution pattern related to the number of rays and coloration described for the adaxial surface is weaker or absent; both major and minor leaves with the same vestiture pattern; armed along the midrib and the primary veins above, and usually only on the midrib beneath, the prickles straight and flattened; major leaves with 6–10 pairs of primary veins, blades elliptic to obovate, 12.5–22.5 cm long, 5.9–12.5 cm wide, the apex acute to acuminate, the base cuneate, slightly decurrent, generally asymmetric, shallowly to deeply lobed, the lobes deltate, (1)2–6 on each side, to 2 cm long and 3.2 cm at base, the prickles (0)13–23 above, (1)6–11 beneath, 2.5–9.0 mm long, 0.6–3.1 mm wide at base; petiole 1.2–2.5 cm, moderately stellate-tomentose with trichomes like those of the stems, the prickles 0–5; minor leaves with 5–6 pairs of primary veins, blades elliptic, 5.1–8.1 cm long, 2.4–5.1 cm wide, the apex acuminate to rounded, the base cuneate, symmetric or asymmetric, entire to shallowly lobed, the lobes deltate, 0–3 on each side, the prickles (0)1–3 above and (0)3–7 beneath, 2.3–6.6 mm long, 1.0– 1.8 mm wide at base; petiole 0.7–2.0 cm, sparsely stellate-puberulent to moderately stellate-tomentose with stellate trichomes like those of the stems, the prickles 0–3. Inflorescences an reduced monochasial cyme, unbranched, apparently lateral, leaf-opposed to subopposite, the inflorescence axis (peduncle plus rachis) sparsely to moderately stellate-puberulent, with trichomes like those of the stem, usually armed, 0–7 prickles, the peduncle nearly absent to 1.7 cm, the rachis to 1.9 cm, straight, the pedicel insertion points generally unequally spaced, 1.5 to 6.2 mm apart, unpaired, if paired only at the tip of the rachis, with (1)2–7 flowers, 1–2 flowers open at same time; pedicels straight or nearly so, keeping the flower buds erect to patent, 10.4–22 mm long in open flowers, distally geniculate at athesis, articulated at base, armed, moderately to sparsely stellate-tomentose, with trichomes like those of the stems. Flowers 5-merous, perfect, rarely short-styled. Calyx tube conical, 3.4–5.8 mm long, sparsely to densely armed, the prickles 0–35, usually dorsiventrally flattened and adpressed when dry, swollen at base when fresh, moderately to densely stellate-tomentose, with trichomes like those of the adaxial surface of leaves, the lobes foliaceous, narrowly oblong, elliptic or lanceolate (often varying in the same flower), the apex acuminate to rounded, 2–9(–12.5) mm long, often unequal in length, 1.8–3.5 mm wide. Corolla 2.4–2.9 cm in diameter, white, stellate, the interpetalar tissue well-developed and wavy, lobed for 1/2 to 2/3 of its length, the lobes 7.8–9.0 mm length, 7.6–9.8 mm wide, rounded to deltoid, apiculate at apex, the tips of the lobes reflexed at anthesis, moderately to densely stellate-tomentose abaxially, the trichomes hyaline to brownish, porrect to multiangulate, sessile to subsessile, the rays 4–12, tortuous, the midpoint poorly developed, sometimes with multiradiate, multi-rayed trichomes (more than 12 rays) at the tip of the lobes, the adaxial surface moderate to densely stellate-tomentose at apex, becoming gradually less dense towards the base, the basal half glabrous or nearly so, the trichomes are like those of the abaxial surface, strongly misshapen. Stamens equal, with the filament tube 1.1–1.7 mm long, the free portion of the filaments very reduced, up to 0.5 mm long; anthers apparently sessile with basal lobes embedded into the basal portion of the corolla tube, widely lanceolate, narrowed towards the apex, sagittate at base, connivent, poricidal dehiscence at the tips, 7.1–9.0 mm length, 1.8–2.8 mm wide. Ovary short-cylindrical, convex at apex, with some small glandular trichomes; style 10.1–11.4 mm, white, cylindrical and gently curved in long-styled flowers; 5.0– 6.4 mm, straight in short-styled flowers; with some stellate trichomes at base; stigma 0.8–1.17 mm long, sometimes bilobed at apex, green, with a papillose surface. Fruit an obloid to transversely ellipsoid berry, 9.7–12.8 mm length, 14.0– 17.6 mm wide; fruiting pedicels 14–25 mm long, 0–3 prickles; fruiting calyx accrescent, truncate at base (slightly concave at center in fresh material), covering 1 / 3 – 1 / 4 of the mature fruit, the lobes 4.0– 7.5 mm length, (4.7) 7.8–11.5 mm wide at base; the pericarp smooth, glabrous, green to dark green with the apex pale green to whitish at maturity. Seeds 40–70 per berry, 4.1–5.0 mm long, 3.2–3.7 mm wide, flattened, reniform, stramineous at the edge, brown at the center.

Distribution and habitat:—Currently Solanum sessilantherum is only known from two localities, the Parque Estadual do Desengano and a nearby forest fragment, in the northern region of the Rio de Janeiro State ( Fig. 2 ). It occurs at the edge of wet forest fragments, usually in moist soil under indirect light; from 20–450 m elevation.

Ecology:— Solanum sessilantherum is an essentially hermaphroditic species, with only few short-styled flowers being occasionally produced along its flowering period. No clear pattern related to the production of the functionally male flowers was observed. The presence of yellow poricidal anthers and field observations made by the authors suggests that buzzing bees are its main pollinators (buzz-pollination; Michener 1962; Buchmann 1983). The fruit color (green with the apex pale green to whitish), fleshiness, absence of odor and the permanent attachment of its fruits are some of the characteristics associated with dispersal by bats (chiropterochory) and birds (ornitochory) ( Van der Pijl 1972). Furthermore, S. sessilantherum has clonal reproduction as an important way of vegetative propagation.

Phenology:—Flowering specimens were observed from September to May; fruiting specimens have been collected between November and June.

Etymology:—This compound epithet is a union of the Latin terms “sessilis” and “anthera”, which means sessile and anther, respectively, and refers to the much-reduced filaments that keep the anthers embedded into receptacle, giving them a sessile appearance.

Preliminary conservation status:—Data Deficient (DD); the number of georeferenced collections (only one) and inaccurate collection details prevented the conservation status assessment. Only six collections have been made in about 38 years, four of these within the Parque Estadual do Desengano and the other two in a nearby forest fragment. This indicates that S. sessilantherum is fairly rare and further field surveys are a priority to obtain an accurate conservation status assessment.

Additional specimen examined (paratypes):— BRAZIL. Rio de Janeiro: Mun. Campos dos Goytacazes, Espera Feliz , 21°50’47”S, 41°36’29”W, 22 m, 15 May 2015 (fl, fr), Gouvêa & Falcão 187 ( BHCB) ; Mun. Santa Maria Madalena, Parque Estadual do Desengano, Fazenda Morumbeca do Imbé , na mata, 11 September1999 (fl), dos Santos 420 ( RB) ; Trilha para Morumbeca do Imbé, parte média da trilha, antes do Riacho da Morumbeca à direita, 15 June 2000 (fr), dos Santos 565 ( BHCB, RFFP) ; Alto Imbé, picada para o Cruzeiro , 350–450 m, 24 October 2012 (fl), Bandeira et al. 142 ( BHCB, RB) ; Derrubadinha , 24 Nov 1977 (fl, fr), Mautone 460 ( JPB, RB) .

Discussion:— Solanum sessilantherum differs from other species in the S. asterophorum group by having pedicels straight, or nearly, so buds are erect to patent, the stems vestiture and adaxial leaf surface with hyaline to brownish trichomes, inflorescences with armed axes and unpaired pedicel insertion points (when fully developed), and inconspicuous filaments giving the anthers a sessile appearance. Solanum sessilantherum has the typical morphology of S. asterophorum species group (see introduction), and resembles especially S. asterophorum , the more widespread, collected and morphologically variable species of the group. Vegetatively, S. sessilantherum is more similar to populations of S. asterophorum from Rio de Janeiro and some populations of Espírito Santo, sharing sparse to moderately distributed vestiture composed by sessile or, less often, short-stalked trichomes. In addition to the distinctive characters pointed out in the diagnosis, S. sessilantherum can be identified by its coriaceous leaf (vs. membranaceous to chartaceous in S. asterophorum ), and the obloid shape (vs. spheroidal to widely depressed ovate in S. asterophorum ) and size (see description) of its fruit.

Despite both S. sessilantherum and S. asterophorum occur in Rio de Janeiro State, they were not observed cooccurring in the same area. The records of S. sessilantherum are restrict to the northern region of the State, whereas the records of S. asterophorum ranges from the southern central region of Rio de Janeiro (with a gap from the northern region of Rio de Janeiro to the southern region of Espírito Santo State) to Paraíba, in northeastern Brazil.

Figures

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).

FIGURE 3. A–E. Solanum sessilantherum. A. Fertile branch. B. Developing inflorescence. C. Developed inflorescence. D. Fruits. E. Detail of a dissected flower (stamens and corolla) (All from Gouvêa & Falcão 188, BHCB). Scale bars A= 10 cm; B= 1.5 cm; C= 2 cm; D= 1.5 cm; E= 1 cm.