Solanum sublentum Hiern.

Knapp, Sandra, Gouvêa, Yuri F. & Giacomin, Leandro L., 2025, A revision of the endemic Brazilian Solanum hexandrum group (Leptostemonum, Solanum, Solanaceae), PhytoKeys 253, pp. 199-259 : 199-259

6. Solanum sublentum Hiern. , Kjoeb. Vidensk. Meddel. 1877–78: 53. 1878.

Fig. 13

Solanum wettsteinianum Witasek , Denkschr. Kaiserl. Akad. Wiss. Wien, Math. - Naturwiss. Kl. 79 (advance separate): 50. 1910. Type. Brazil. São Paulo: prope “ Fazenda Bella Vista ” in districtu urbis S. Cruz ad flumen Rio Pardo, 500 m alt., Jul 1901, R. von Wettstein s. n. (lectotype, designated here: WU [acc. # 0038006]).

Type.

Brazil. Minas Gerais: Lagoa Santa , [24 Feb 1863], E. Warming s. n. (lectotype, designated here: C [ C 10019316 ]; possible isolectotype: [note date on sheet is 1866] S [acc. # S 04-2985]) .

Description.

Shrubs 1–3 m, erect or sometimes somewhat prostrate, armed. Stems terete, densely glandular-pubescent and sparsely prickly, the trichomes weak, simple uniseriate ca. 0.5 mm long with glandular tips, mixed with sparse short-stalked porrect stellate trichomes with 6–7 rays to 1 mm long, the mid-point to 1 mm long, gland-tipped or eglandular, the prickles 0.5–1.2 cm long, slightly to strongly curved and broad-based, ca. 0.5–1 cm in diameter at the base; new growth densely glandular pubescent with mixed simple and stellate trichomes like the stems; bark of older stems pale greyish-brown, somewhat glabrescent. Sympodial units difoliate, the leaves not geminate. Leaves shallowly lobed and repand, much smaller in younger branches; blades (5) 8.5–17 cm long, (3) 6–13 cm wide, ca. 1.3–1.6 times as long as wide, broadly elliptic or ovate, widest at or just below the middle, membranous, concolorous, sparsely prickly on both surfaces along the veins with straight prickles 0.3–1 cm long; adaxial surface densely pubescent with a mix of short-stalked porrect stellate trichomes with 5–7 rays ca. 1 mm long, trichomes consisting of solely unicellular or multicellular gland-tipped mid-points to 1.2 mm long (probably derived from stellate trichomes) and sessile, papillate glands composed of 4 cells; abaxial surface pubescent like the adaxial surface, but lacking the sessile papillate glands, also with delicate sessile porrect stellate trichomes with 4–5 rays ca. 0.3 mm long and mid-points shorter than the rays, these underneath the dense layer of larger short-stalked trichomes; principal veins 4–5 pairs, usually sparsely prickly on both surfaces with straight prickles to 0.9 cm long; base somewhat cordate-angular to hastate or sagittate-hastate from the basiscopically directed lowest leaf lobes, occasionally acute to abruptly attenuate, usually not decurrent on to the petiole; margins shallowly and broadly lobed, the lobes 4–5, 1–2.5 long, 2–4 cm wide, apically acute to acuminate, sometimes minutely secondarily lobed, the sinuses less than 1 / 4 of the way to the mid-rib; apex acute to acuminate; petiole (1 -) 1.5–7 cm long, prickly with straight prickles to 1 cm long, densely glandular pubescent like the stems with a mix of simple trichomes apparently consisting of unicellular or multicellular mid-points with glandular tips and sparse porrect stellate trichomes. Inflorescences internodal, 2–9 cm long, unbranched, with 3–6 flowers. but only one open at a time; axes densely glandular pubescent like the stems with a mix of unicellular and multicellular gland-tipped simple uniseriate trichomes (derived from mid-points of stellate trichomes) and sparse porrect stellate trichomes with glandular mid-points; peduncle 1.5–5 cm long; pedicels 1.2–1.5 cm long, ca. 1 mm in diameter at the base, ca. 2.5 mm in diameter at the apex (excluding trichomes), erect to spreading, densely glandular pubescent like the inflorescence axes and stems and occasionally with a few straight prickles, articulated at the base; pedicel scars more or less evenly spaced 4–5 mm apart, further apart in fruit, distally and, in young inflorescences, more tightly packed. Buds globose to ovoid, the corolla ca. halfway exerted from the calyx tube just before anthesis. Flowers 5 - merous, co-sexual or perhaps a few distal flowers short-styled and functionally staminate, the plants only weakly andromonoecious. Calyx with the tube 3.5–4 mm long, 5–6 mm in diameter, deeply to shallowly broadly cup-shaped, plicate from the fused bases of adjacent lobes, usually invaginate at the base, the lobes 7–10 mm long, 2.3–5 mm wide, long-triangular, apically acuminate, densely glandular pubescent with a mix of simple uniseriate (mid-points?) and sparse short-stalked or sessile stellate trichomes, often with a few straight prickles 0.2–1.5 mm long on the main veins abaxially. Corolla 3.5–5 cm in diameter, purple to pale violet or white, shallowly stellate, lobed ca. 1 / 4 of the way to the base, interpetalar tissue thin, glabrous, the lobes 9–12 mm long, 11–19 mm wide, spreading to slightly cupped, densely pubescent abaxially where exposed in bud with short-stalked and sessile stellate trichomes, these occasionally glandular, glabrous adaxially, but occasionally with a few minute prickles along the veins. Stamens equal; filament tube minute; free portion of the filaments 0.5–1 mm long, glabrous; anthers 8.5–9 mm long, 2.6–3 mm wide, broadly lanceolate and tapering, connivent, glabrous, yellow, abaxially swollen in the lower half (gibbous) and somewhat papillate, poricidal at the tips, the pores directed distally, not elongating to slits with age. Ovary conical, glabrous; style 14–16 mm long, glabrous, widening markedly distally; stigma clavate or broadly capitate, the surface minutely papillate. Fruit a globose berry, 1.4–2 cm in diameter, green or pale whitish-green, glabrous, the pericarp matte when dry, opaque, the berry completely enclosed in the accrescent saccate calyx; fruiting pedicel 1.6–2.5 cm long, 1–1.5 mm in diameter at the base, 3–5 mm in diameter at the apex, spreading or pendent from the weight of the fruit; fruiting calyx strongly accrescent, inflated and invaginate, exceeding the length of the berry, but not completely enclosing it, the tube 1.5–2 cm long, saccate (invaginate) at the base, the lobes 0.8–0.9 cm long, often broken in dried specimens, not overlapping, densely glandular pubescent and occasionally prickly like the calyx in flower. Seeds 80–100 per berry, ca. 2.5 mm long, ca. 2 mm wide, flattened reniform, reddish-brown when dry, the surface minutely pitted, the testal cells thick-walled and sinuate in outline. Chromosome number not known.

Distribution

(Fig. 14 ). Solanum sublentum is recorded to south-eastern and central Brazil, in the States of Espírito Santo, Goiás, Minas Gerais, Rio de Janeiro and São Paulo. The collection from Goiás is discontinuous from the rest of the species range (see discussion).

Ecology and habitat.

Solanum sublentum occupies primarily forest understory, edges and clearings of wet coastal and semi-deciduous forests in the Atlantic Forest domain (Mata Atlântica; Fig. 13 A, B ), as well as semi-deciduous and deciduous seasonally dry tropical forests (Fig. 13 C, D ) in ecotonal zones or within savannah matrices in the Cerrado domain. The forests where S. sublentum occurs can be associated with granite / gneiss (wet and semi-deciduous forests in coastal and sub-coastal regions) and limestone or basaltic (inland seasonally dry tropical forests in savannah matrices) outcrops, it is the only species in the group and one of the few American species of Solanum found in STDFs associated with limestone outcrops. Solanum sublentum grows both in deep soils and in rock cavities, in fissures and in small, shallow soil patches that accumulate on bare rocks (Fig. 13 D ); from sea level to 800 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2020). EOO (642,872 km 2, LC); AOO (72 km 2, EN). Solanum sublentum is known from eight localities (including the extremely disjunct occurrence in the State of Goiás), at least three of which are in protected areas (Parque Nacional Cavernas do Peruaçu, Estação Biológica de Caratinga in Minas Gerais State; Parque Municipal Sombra da Tarde in Espirito Santo State) with other collections from the mountains near Rio de Janeiro in what is now Parque Nacional da Serra dos Orgãos (e. g. “ Organ Mount ”). Even with the disjunct occurrence in Goiás excluded, S. sublentum has the largest extent of occurrence of any of the species of the S. hexandrum group. Nevertheless, due to the extreme level of habitat alteration in the region where it occurs and the paucity of recent collections (most of those used in calculating the EOO are more than a century old), we consider it of some conservation concern and suggest a preliminary status of Near Threatened, based on criteria B 2 a, b ii, iii, iv.

Discussion.

Solanum sublentum is easily distinguishable from other members of this group in its markedly plicate accrescent calyces that exceed, but do not completely enclose the berries and simple, glandular pubescence with a mix of much less abundant stellate trichomes.

The majority of trichomes of S. sublentum are simple, uniseriate and unicellular or multicellular. Their shape and overall morphology suggest they are structurally analogous to mid-points of stellate trichomes without rays, like those that occur in the Acanthophora clade ( Nee 1979; Hilgenhof et al. 2023) and most members of the Gonatotrichum group of the Brevantherum clade ( Stern et al. 2013).

The single collection of S. sublentum from Goiás (Hatschbach 34747) is from Mun. Jataí, in the extreme southwest of the State. The habitat is stated as “ clareiras da mata ” (forest clearings) and the area in which it was collected was a remnant of the now very restricted Atlantic Forest. The southernmost portion of Goiás State is the original limit of the Atlantic Rainforest domain in central Brazil and an ecotonal zone with the Cerrado domain, where contiguous forested formations were found in the past (IBGE 2012). These mostly semi-deciduous forests were either considered part of the Cerrado (“ Cerradão ”) or the Atlantic Rainforest itself. They have been largely converted first to cattle farming and later to soy and corn plantations ( Oliveira 2007). No recent collections from this locality have been seen, so recollection there is a priority.

Solanum sublentum is similar to S. aciculare in possessing glandular indument and strongly accrescent, inflated and invaginate fruiting calyx lobes. The pubescence of S. sublentum is of unbranched trichomes (the bases and mid-points of modified stellate trichomes), while that of S. aciculare is of long-stalked stellate trichomes with glands on each ray tip. Prickles in S. sublentum are sparse and recurved, whereas those of S. aciculare are straight and denser especially on stems. The calyx completely covers the berry in S. aciculare (Fig. 2 H ) while, in S. sublentum , the berry is clearly visible (Fig. 13 J ).

Many different collecting dates are written on the Warming collections at C used by Hiern (1878) to describe S. sublentum . We have chosen the only sheet with both flowers and fruits (C 10010316), showing the characteristic saccate calyx in fruit of S. sublentum . The many syntype collections in Copenhagen and sent elsewhere by Hiern have a confusing panoply of dates and some may be isolectotypes, but, in the absence of unambiguous dates on these sheets, we do not recognise them as such. The sheet we here cite as a possible isolectotype at S (acc. # S 04-2985) has a label stating 1866, so it too is likely not a duplicate, but it is the only original material we have seen outside of Copenhagen.

Figures

Figure 2. Solanum aciculare A habit in open area B habit along rock face C inflorescence with bud D inflorescence with open short-styled flower E calyx at anthesis F short-styled flowers (note colour change over anthesis) G long-styled flower H mature berry with calyx removed I stem section with glandular long-stalked stellate and multangulate trichomes and straight acicular prickles (A, D, G Gouvêa 283; B, H Gouvêa 281; C, E, F, I Gouvêa 280). Photos: Yuri F. Gouvêa .

Figure 13. Solanum sublentum A habitat of arboreal restinga (coastal scrub-forest transition) forest edges B habit C habitat in seasonally dry deciduous forests D habit in rocky inselberg E stem with recurved prickles and unbranched glandular pubescence F leaf with cordate base and secondary lobing G variation in leaf bases and lobing H inflorescence I long-styled flowers showing colour polymorphism J mature berry with accrescent invaginate calyx (B, F, H – J Gouvêa & Guerrero 452; D Stehmann et al. 6370; E, G Stehmann et al. 6372). Photos: A, B, H – J Yuri F. Gouvêa C, D, E, G João R. Stehmann.

Figure 14. Distribution of S. sublentum.