Abstract
As part of an ongoing treatment of species of the Brevantherum clade of Solanum, a new species from the Atlantic Forest of Brazil was discovered and is described here. Solanum helix Giacomin & Stehmann sp. nov. is a species well represented in herbaria that has been overlooked for almost two centuries. It has a unique expanded non-inflated fruiting calyx that resembles a propeller and that is not found in any unarmed species of Solanum. This discovery highlights the importance of continued herbarium and field work in hyperdiverse ecosystems, such as the Atlantic Forest in South America. Taxonomic affinities are discussed and images, as well as mapped distribution, are given. A key to closely related species for NE Brazil is also provided.
Keywords:
seasonal forests; forest fragmentation; taxonomy; indument; herbaria
Introduction
Among the ten most diverse genera of flowering plants, the economically important genus Solanum L. harbors crops such as the potato and the tomato (Humphreys & Linder 2009Humphreys AM, Linder HP. 2009. Concept versus data in delimitation of plant genera. Taxon 58: 1054-1074. doi: 10.1002/tax.584002
https://doi.org/10.1002/tax.584002...
; Michelangeli et al. 2019Michelangeli FA, Goldenberg R, Almeda F, et al. 2019. Nomenclatural novelties in Miconia (Melastomataceae: Miconieae). Brittonia 71: 82-121. doi: 10.1007/s12228-018-9546-0
https://doi.org/10.1007/s12228-018-9546-...
). Despite its cosmopolitan distribution, at least 75% of its species are native to the Neotropics (Nee 1999Nee M. 1999. Synopsis of Solanum in the new world. In: Nee M, Simon DE, Lester RN, Jessop JP (eds.). Solanaceae IV: Advances in biology and utilization. Richmond, Royal Botanic Gardens Kew. p. 285-333.; Solanaceae Source 2022Solanaceae Source 2022. Solanaceae Source. https://solanaceaesource.myspecies.info/. 17 May 2022.
https://solanaceaesource.myspecies.info/...
). Within the Neotropics, most of the 11 to 14 recognized lineages of the genus (Särkinen et al. 2013Särkinen T, Bohs L, Olmstead RG, Knapp S. 2013. A phylogenetic framework for evolutionary study of the nightshades (Solanaceae): A dated 1000-tip tree. BMC Evolutionary Biology 13: 214. doi: 10.1186/1471-2148-13-214
https://doi.org/10.1186/1471-2148-13-214...
; Gagnon et al. 2022Gagnon E, Hilgenhof R, Orejuela A, et al. 2022. Phylogenomic discordance suggests polytomies along the backbone of the large genus Solanum. American Journal of Botany 109: 580-601. doi: 10.1002/ajb2.1827
https://doi.org/10.1002/ajb2.1827...
) have a circum-Amazonian distribution, with centers of diversity in the Andes or in eastern Brazil (e.g. Whalen 1983Whalen MD. 1983. Centers of diversity, sympatry, and historical biogeography in the tropical plant genus Solanum. The Biologist 65: 78-95.; Knapp 2002aKnapp S. 2002a. Assessing patterns of plant endemism in neotropical uplands. Botanical Review 68: 22-37. doi: 10.1663/0006-8101(2002)068[0022:APOPEI]2.0.CO;2
https://doi.org/10.1663/0006-8101(2002)0...
).
The Solanum centers of diversity in eastern Brazil are all associated with the Atlantic rainforest (Knapp 2002aKnapp S. 2002a. Assessing patterns of plant endemism in neotropical uplands. Botanical Review 68: 22-37. doi: 10.1663/0006-8101(2002)068[0022:APOPEI]2.0.CO;2
https://doi.org/10.1663/0006-8101(2002)0...
; BFG 2021BFG ‒ The Brazil Flora Group. 2021. Flora do Brasil 2020. Rio de Janeiro, Jardim Botânico do Rio de Janeiro.), a phytogeographic domain known by its astonishing rates of plant diversity and endemism (Stehmann et al. 2009Stehmann JR, Forzza RC, Salino A, Sobral M, Costa DP, Kamino LY (eds.). 2009. Plantas da Floresta Atlântica. Rio de Janeiro, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro.; https://www.conservation.org/priorities/biodiversity-hotspots), but also by a history of devastation and expansion of urban centers (Dean 1996Dean W. 1996. A ferro e fogo: A história e devastação da Mata Atlântica brasileira. São Paulo, Companhia das Letras.; Ribeiro et al. 2009Ribeiro MC, Metzger JP, Martensen AC, Ponzoni FJ, Hirota MM. 2009. The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation. Biological Conservation 142: 1141-1153. doi: 10.1016/j.biocon.2009.02.021
https://doi.org/10.1016/j.biocon.2009.02...
). Although only an estimated 12 to 16% of its native vegetation remains (Ribeiro et al. 2009Ribeiro MC, Metzger JP, Martensen AC, Ponzoni FJ, Hirota MM. 2009. The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation. Biological Conservation 142: 1141-1153. doi: 10.1016/j.biocon.2009.02.021
https://doi.org/10.1016/j.biocon.2009.02...
; Rezende et al. 2018Rezende CL, Scarano FR, Assad ED, et al. 2018. From hotspot to hopespot: An opportunity for the Brazilian Atlantic Forest. Perspectives in Ecology and Conservation 16: 208-214. doi: 10.1016/j.pecon.2018.10.002
https://doi.org/10.1016/j.pecon.2018.10....
), most recent species discoveries within Solanum in Brazil are associated with the domain, and undoubtedly more species remain to be collected and described (e.g. Giacomin et al. 2013Giacomin LL, Bohs L, Stehmann JR. 2013. Two new species from the Brevantherum clade of Solanum (Solanaceae) from eastern Brazil. Journal of the Botanical Research Institute of Texas 7: 95-107.; Giacomin & Stehmann 2014Giacomin LL, Stehmann JR. 2014. Three new species of Solanum (Brevantherum Clade) endemic to the Brazilian Atlantic Forest. PhytoKeys 38: 69-87. doi: 10.3897/phytokeys.38.7055
https://doi.org/10.3897/phytokeys.38.705...
; Knapp et al. 2015Knapp S, Stehmann JR, Giacomin LL. 2015. New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae) in Brazil. PhytoKeys 47: 9076. doi: 10.3897/phytokeys.47.9076
https://doi.org/10.3897/phytokeys.47.907...
; Gouvêa & Stehmann 2016Gouvêa YF, Stehmann JR. 2016. Two new species of the Solanum asterophorum species group (Solanum subg. Leptostemonum, Solanaceae) from the Brazilian Atlantic Forest. Phytotaxa 288: 120-130. doi: 10.11646/phytotaxa.288.2.2
https://doi.org/10.11646/phytotaxa.288.2...
; Sampaio & Agra 2016Sampaio VS, Agra MF. 2016. Solanum knappiae sp. nov. (Solanaceae) from the Atlantic Forest of northeastern Brazil. Nordic Journal of Botany 34: 395-399. doi: 10.1111/njb.01102
https://doi.org/10.1111/njb.01102...
; Stehmann & Moreira 2016Stehmann JR, Moreira NC. 2016. Solanum lagoense (Solanaceae, Geminata clade), a new species from Lagoa Santa, Minas Gerais State, Brazil. PhytoKeys 61: 15-25. doi: 10.3897/phytokeys.61.7258
https://doi.org/10.3897/phytokeys.61.725...
; Gouvêa et al. 2018Gouvêa YF, Giacomin LL, Stehmann JR. 2018. A sticky and heavily armed new species of Solanum (Solanum subg. Leptostemonum, Solanaceae) from eastern Brazil. PhytoKeys 111: 103-118. doi: 10.3897/phytokeys.111.28595
https://doi.org/10.3897/phytokeys.111.28...
; 2020Gouvêa YF, de Paula LFA, Stehmann JR, Giacomin LL. 2020. Solanum hydroides (Solanaceae): A prickly novelty from the land of the sugar loaves, central Brazilian Atlantic Forest. PhytoKeys 139: 63-76. doi: 10.3897/phytokeys.139.46635
https://doi.org/10.3897/phytokeys.139.46...
).
The Brevantherum clade is one of the main recognized lineages of Solanum (Weese & Bohs 2007Weese TL, Bohs L. 2007. A three-gene phylogeny of the genus Solanum (Solanaceae). Systematic Botany 32: 445-463. doi: 10.1600/036364407781179671
https://doi.org/10.1600/0363644077811796...
; Gagnon et al. 2022Gagnon E, Hilgenhof R, Orejuela A, et al. 2022. Phylogenomic discordance suggests polytomies along the backbone of the large genus Solanum. American Journal of Botany 109: 580-601. doi: 10.1002/ajb2.1827
https://doi.org/10.1002/ajb2.1827...
), with a wide distribution from the southern United States to Argentina, with a few invasive species in the Old World tropics (Roe 1972Roe KE. 1972. A revision of Solanum section Brevantherum (Solanaceae). Brittonia 24: 239-278. doi: 10.2307/2805665
https://doi.org/10.2307/2805665...
; Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.). The clade, which contains 95 described species and at least eight undescribed taxa, is somewhat heterogeneous morphologically. Within the Brevantherum clade, at least four main groups are phylogenetically supported (Gagnon et al. 2022Gagnon E, Hilgenhof R, Orejuela A, et al. 2022. Phylogenomic discordance suggests polytomies along the backbone of the large genus Solanum. American Journal of Botany 109: 580-601. doi: 10.1002/ajb2.1827
https://doi.org/10.1002/ajb2.1827...
): i) the Solanum trachytrichium Bitter species group, comprised of two small herbaceous species from Brazil and Argentina with unbranched trichomes, marked geminate sympodial units and leaf-opposed inflorescences (treated in Knapp et al. 2015Knapp S, Stehmann JR, Giacomin LL. 2015. New species, additions and a key to the Brazilian species of the Geminata clade of Solanum L. (Solanaceae) in Brazil. PhytoKeys 47: 9076. doi: 10.3897/phytokeys.47.9076
https://doi.org/10.3897/phytokeys.47.907...
), ii) section Gonatotrichum Bitter, with eight species, comprised of small widespread invasive weeds with explosive fruits (treated in Stern et al. 2013Stern S, Bohs L, Giacomin L, Stehmann J, Knapp S. 2013. A revision of Solanum section Gonatotrichum. Systematic Botany 38: 471-496. doi: 10.1600/036364413X666624
https://doi.org/10.1600/036364413X666624...
), iii) the Solanum inornatum Witasek species group, with four species, a group of montane herbs from southeastern Brazil with few seeded fruits (ca. 10) and very large seeds (treated in Giacomin & Stehmann 2014Giacomin LL, Stehmann JR. 2014. Three new species of Solanum (Brevantherum Clade) endemic to the Brazilian Atlantic Forest. PhytoKeys 38: 69-87. doi: 10.3897/phytokeys.38.7055
https://doi.org/10.3897/phytokeys.38.705...
), and iv) a group of shrubs to trees characterized by an indument of stellate trichomes and lateral or terminal inflorescences [“stellate subclade” in Giacomin (2015)Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.], where 80 of the 95 described species lie.
As part of an ongoing effort to list and monograph species belonging to the Brevantherum clade of Solanum (Giacomin, unpub. data), an overlooked undescribed species was identified occurring in seasonal forests of the Brazilian Atlantic Forest domain. The species is part of the “stellate subclade” of Giacomin (2015)Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil. and have considerable material available in herbaria as its first collection dates from almost two centuries ago. Its phylogenetic affinities, morphological characters, ecology, and conservation status are discussed below.
Material and methods
The description presented is based on field observations and examination of herbarium specimens, considering the following collections were visited (acronyms from Index Herbariorum, http://sweetgum.nybg.org/ih/): ALCB, ASE, BHCB, CEPEC, EAC, HST (non-indexed), HSTM, HUEFS, HURB, IPA, JPB, K, MBM, MO, NY, PEUFR, RB and UFP. Besides the examined material, images of types from related species were visualized on the Global Plants website (https://plants.jstor.org), especially from BR, M, G and P herbaria. Measurements presented were mostly taken from dried material in the case of vegetative characters and rehydrated or material preserved in 70% alcohol in the case of reproductive characters. The terms used in the descriptions are based on Radford et al. (1974Radford AE, Dickinson WC, Massey JR, Bell CR. 1974. Vascular Plant Systematics. 1st. edn. New York, Harper & Row.) and Roe (1971Roe KE. 1971. Terminology of hairs in the genus Solanum. Taxon 20: 501-508. doi: 10.2307/1218251
https://doi.org/10.2307/1218251...
) , the latter being applied mostly for the trichome terminology; for the definition and typology of sympodial units see Knapp (2002b)Knapp S. 2002b. Solanum section Geminata (G. Don) Walpers (Solanaceae). Flora Neotropica 84: 405. and the conservation status was assessed using IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2022IUCN ‒ Standards and Petitions Committee 2022. Guidelines for Using the IUCN Red List Categories and Criteria. https://www.iucnredlist.org/resources/redlistguidelines. 15 May 2022.
https://www.iucnredlist.org/resources/re...
). Extent of Occurrence (EOO) and Area of Occupancy (AOO) were calculated using the GeoCat tool (Bachman et al. 2011Bachman S, Moat J, Hill A, de la Torre J, Scott B. 2011. Supporting red list threat assessments with GeoCAT: Geospatial conservation assessment tool. ZooKeys 150: 117-126. doi: 10.3897/zookeys.150.2109
https://doi.org/10.3897/zookeys.150.2109...
) available at http://geocat.kew.org using the standard 2 km2 cell width for AOO calculation. The listed examined material is given as a supplementary file (Supplementary materialSearchable XLS file of all specimens examined of Solanum helix Giacomin & Stehmann.), as a .xls spreadsheet. A key to all species of the Cordovense species group (sensu Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.) occurring in NE Brazil is presented after the treatment [the Northeast political region of Brazil encompasses the following states: Alagoas (AL), Bahia (BA), Ceará (CE), Maranhão (MA), Paraíba (PB), Pernambuco (PE), Piauí (PI), Rio Grande do Norte (RN) and Sergipe (SE)]. For the morphological definition of the Cordovense species group, see Giacomin (2015)Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.. To identify main groups within Solanum, the multiaccess available at http://www.xper3.com/xper3GeneratedFiles/publish/identification/3646482090706093198/mkey.html should be consulted.
Results
Taxonomy
Solanum helix Giacomin & Stehmann, sp. nov. (Figs. 1, 2, 3)
Holotype specimen (sheet one) of Solanum helix Giacomin & Stehmann (L.L. Giacomin et al. 2000, BHCB19123). Reproduced with permission of BHCB Herbarium, Universidade Federal de Minas de Gerais.
Solanum helix Giacomin & Stehmann and related species. A. Sympodial units. B. Inflorescence architecture. C. Flower and buds. D. Abaxial fruiting calyx with trichome details. E. Fruit with unique spreading calyx. F. S. anisocladum Giacomin & Stehmann, with fruit detail in the upper left corner. G. S. didymum Dunal, with fruit detail in the upper right corner. Photos: A, B, C, D, E, F = L. L. Giacomin; G = J. D. Tovar.
Known distribution of Solanum helix Giacomin & Stehmann (circles). States abbreviations shown: AL (Alagoas), BA (Bahia), CE (Ceará), DF (Distrito Federal), ES (Espírito Santo), GO (Goiás), MA (Maranhão), MG (Minas Gerais), PB (Paraíba) PE (Pernambuco), PI (Piauí), SE (Sergipe), SP (São Paulo), TO (Tocantins), RJ (Rio de Janeiro) and RN (Rio Grande do Norte).
urn:lsid:ipni.org:names:77322646-1
Type: BRASIL. Bahia: Mun. Santa Teresinha, Serra da Jibóia, estrada não pavimentada que leva ao topo da serra, nas torres de transmissão, passando pelo povoado de Pedra Branca, fragmento de floresta estacional marginal a estrada, 12°50'52''S, 39°28'50''W, 700 m, 6 November 2013 (fl, fr), L.L. Giacomin, L. Bohs, S. Knapp & L.C. Marinho 2000 (Holotype: BHCB [2 sheet holotype: sheet 1 (fl) BHCB019123, sheet 2 (fr) BHCB019124]! (Isotypes: BM!, HUEFS000109618!, NY02240756!, UT!).
Diagnosis:Solanum helix is similar to S. didymum Dunal and S. anisocladum Giacomin & Stehmann, but can be easily distinguished from both by its abaxial leaf surfaces with mostly stalked porrect-stellate trichomes with midpoints shorter than lateral rays and stalks uniform in length, giving it a unique appearance of a uniform “canopy”, while a variety of trichomes, both sessile and stalked, with midpoints longer than the rays are observed in the other two species. The calyx of S. helix is also unique: it does not become inflated and accrescent in fruit like that of S. didymum and S. anisocladum, but instead the deltate lobes become spreading and very elongated (oblong), giving it a characteristic aspect at maturity, resembling a propeller (Fig. 2E).
Description: Shrubs, up to 4 m, apical branches pendant, young stems with a markedly uniform golden-ochraceous indumentum, densely covered by 8-rayed short-stalked porrect-stellate trichomes, up to 1 mm diameter, with a ca. 0.5 mm multiseriate stalk and a one-celled midpoint much shorter than the rays (old growth glabrescent, with a few remnant trichomes). Bark of older stems yellowish-brown, delicately fissured, with remaining trichome bases. Sympodial units 1─2-foliate, not geminate. Leaves entire, petioles sulcate, 2─4 mm long, blades 5.2-14.3 × 1.7─5.5 cm, narrowly elliptic to lanceolate, sometimes oblong, chartaceous, strongly discolorous when dried, pale green to brown above, pale yellow to green beneath, the adaxial surface slightly bullate, along the blade densely to sparsely covered with three types of trichomes: unbranched 1─2-celled eglandular trichomes ca. 0.5 mm long, small unbranched glandular capitate trichomes with less than 0.5 mm, a single-celled base and single-celled glandular head, and less frequent 4─8 rayed sessile to short-stalked porrect-stellate trichomes with a midpoint usually as long as the rays; the blade surface always visible abaxially (not entirely covered by the trichomes), usually with porrect-stellate trichomes only in the midrib, these more densely packed, the abaxial surface densely covered with 8-rayed short- to long-stalked porrect-stellate trichomes, stalks from 0.5 to 1 mm, midpoint always shorter than the rays, forming a very uniform indumentum on the blade and midrib, with only a few unbranched glandular-capitate trichomes observed underneath the stellate “canopy”, with the blade surface barely visible (almost completely covered by the trichomes), midrib and secondary veins slightly impressed above, raised beneath, the secondaries in 4─6 pairs, ascending, base cordate to rounded, sometimes asymmetric, apex acute to acuminate (acumen, when present, ca. 1.5 cm long), margins entire, slightly revolute. Inflorescence 1.5─3.5 cm long, lateral or more often subopposite the leaves, unbranched cyme, 4─15 flowered, but usually bearing 1─4 flowers at a time, densely covered with trichomes like those of the stem, subsessile or with peduncles up to 4 mm, pedicels 1─1.7 cm long, widening towards the apex (from 0.5 at base to 1 mm at the apex), articulated at base, unevenly spaced from 1 to 4 mm apart. Buds obovoid, with the corolla completely covered by the calyx lobes at anthesis. Flowers all perfect, 5-merous. Calyx tube 1─2 mm long, conical, the lobes 4─5 mm long, 2─2.5 mm wide at base, lanceolate, the abaxial surface densely covered by porrect-stellate trichomes like those of the stem, adaxially with a more a sparse indumentum of mixed sessile 1-celled unbranched eglandular trichomes, sessile to short-stalked porrect stellate trichomes with 4─8 rays and a midpoint as long as the rays, and uniseriate multicellular unbranched glandular trichomes usually at the margins and apex. Corolla white, without colored stripes, stellate, 10─12 mm in diameter, membranous, lobed up to – the way to the base, tube 1─1.5 mm long, lobes 3─5 mm long, ca. 3 mm wide at base, abaxial surface covered by sessile and short-stalked porrect-stellate trichomes, with 4─8 rays and midpoint shorter than the rays, glabrous adaxially, with the apex minutely papillose. Stamens 3─3.5 mm long, filament tube ca. 0.4 mm, the free portion ca 0.8─1 mm long, equal in length, anthers 2─2.5 × 0.8─1 mm, ellipsoid, slightly connivent, yellow, poricidal at the tips, the pores directed introrsely, elongating to longitudinal slits with age. Ovary glabrous, style 4.5─5 mm long, glabrous, stigma clavate, green when fresh. Fruit a globose berry, 5─8 mm in diameter, whitish at maturity, shiny, drying dull brown, glabrous (fruiting pedicels reaching 1.7─2.1 cm long, expanded distally (i.e. obconical), ca. 0.8 mm in diameter at base, ca. 1.5 mm at apex, calyx lobes in fruit very elongated and spreading, appearing propeller-shaped, the lobes reaching 9─12 × 3─3.5 mm. Seeds 6─10 per fruit, 3─3.5 × 2─2.5 mm, flattened, reniform, golden-yellow, surface irregularly pitted, with undulate anticlinal cell walls, margins not flattened.
Etymology: The epithet helix is applied as a noun in apposition and represents a Latin and English word for spiral or coil. Its usage in English also applies to a propeller of a boat or plane, to which the fruiting calyx is similar, with its spreading lobes (see Fig. 2E).
Distribution, habitat, and phenology:Solanum helix is known from the states of Alagoas, Bahia, Pernambuco and Sergipe in northeastern Brazil (Fig. 3), in seasonal forests, ranging from sea level (ca. 90 m) to mid-elevations (900 m). It is found in secondary to preserved forests. The known fertile specimens were collected throughout the year.
Preliminary conservation status:Solanum helix has an estimated EOO of 93,179 Km2 [Least Concern (LC)] and AOO of 96 Km2 [Endangered (EN)]. Even though the AOO could allow its assignment in the Endangered category, the species is widely distributed, occurring in a broad elevational range in seasonal forests. Monitoring is recommended, nevertheless, as it is a locally rare species in a very fragmented landscape, and seasonally dry forests associated with the Atlantic Forest domain are usually neglected and have fewer dedicated protected areas when compared to more wet formations (Teixeira et al. 2021Teixeira LP, Lughadha EN, Silva MVC, Moro MF. 2021. How much of the Caatinga is legally protected? An analysis of temporal and geographical coverage of protected areas in the Brazilian semiarid region. Acta Botanica Brasilica 35: 473-485. doi: 10.1590/0102-33062020abb0492
https://doi.org/10.1590/0102-33062020abb...
). The species is known from only one protected area in Pernambuco state (Reserva Ecológica de Dois Irmãos).
Additional material examined (paratypes):BRAZIL.Alagoas: Mun. Murici, Bananeiras, 9°13'47’’S 35°52'78’’W, 572 m, 16 March 2002 (fr), A.M. de Carvalho et al. 7118 (CEPEC, MO, RB); Mun. Murici, Poço D’anta, ca. 16─19 km NNW of Murici by road, 9°13.530'S, 35°52.776'W, 500─600 m, 14 May 2001 (fr), W.W. Thomas et al. 12437 (CEPEC, JPB, NY, RB. Bahia: sin. loc., (fl, fr), sin. coll. (K000983206); sin. Loc., 1835 (fr), sin. coll. (K000963208); Mun. Amargosa, Serra do Timbó, Mata do Centro Sapucaia, 13°10'0''S, 39°9'0''W, 28 April 2007 (fr), J.L. Paixão et al. 1167 (CEPEC, HUEFS); Mun. Amargosa, Serra do Timbó, Área de estudos do Projeto Timbó/Centro Sapucaia, 12°52'S, 39°28'W, 750─900 m, 24 January 2007 (fr), D. Cardoso et al. 1544 (CEPEC, HUEFS); Mun. Apuarema, Concessão do Rio Tinto, 13°53'46''S, 39°41'10''W, 5 March 2013 (fr), L.Y.S. Aona et al. 2248 (RB); Mun. Castro Alves, Serra da Jibóia, 12°51'11''S, 39°28'19''W, 22 December 1992 (fl, fr), L.P. de Queiroz & T.S.N. Sena 2993 (CEPEC, HUEFS); Mun. Castro Alves, Serra da Jibóia, ca. 10 km do povoado de Pedra Branca, 12°51'11''S, 39°28'19''W, 7 May 1993 (fr), L.P. de Queiroz et al. 3164 (HUEFS); Mun. Castro Alves, Serra da Jibóia, January 1997 (fl), M. Sobral et al. 8413 (HUEFS); Mun. Castro Alves, Serra da Jibóia, 12°51'6''S, 39°28'32''W, 820 m, 10 January 1997 (fl, fr), R.M. Harley et al. 28487 (HUEFS); Mun. Conde, Fazenda do Bu, Mata da Maré, 12°2'7''S, 34°43'43''W, 24 April 1996 (fl, fr), T. Jost & H.P. Bautista 270 (HUEFS, IPA, RB); Mun. Conde, Fazenda do Bu, trilha 1 da Mata da Maré, 12°2'11’’S, 37°44'9’’W, 31 May 1995 (fr), M.C. Ferreira & L.N. Silva 717 (ALCB, IPA, MBM, RB); Mun. Conde, Fazenda do Bu, Mata da Maré, 12°2'7’’S, 37°43'43’’W, 25 October 1994 (fr), R. Marquete et al. 2072 (RB); Mun. Elísio Medrado, Serra da Jibóia, Fazenda Jequitibá, na estrada para Monte Cruzeiro, 12°52'5’’S, 39°28'47’’W, 435 m, 3 March 2001 (fr), L.P. Queiroz et al. 6481 (HUEFS); Mun. Elísio Medrado, Serra da Jibóia, 12°51'S, 39°28'W, 8 February 2011 (fr), M.L. Guedes et al. 17970 (ALCB); Mun. Entre Rios, estrada do Conde para Esplanada, 11°46'17’’S, 37°44'5’’W, 42 m, 23 January 2004 (fl), M.N.S. Stapf & B.R.N. Araújo 224 (HUEFS); Mun. Entre Rios, Estrada de Conde para Esplanada, 13,5 Km do entroncamento em direção a Esplanada, 6 February 1998 (fl, fr), M.R. Fonseca et al. 300 (INPA); Mun. Entre Rios, Imbé, 12°3'S, 38°0'W, 21 April 2010 (fl), A.V. Popovkin & J.C. Mendes 655 (HUEFS); Mun. Entre Rios, Imbé, 12°3'S, 38°0'W, 7 Oct. 2010 (fl, fr), A.V. Popovkin & J.C. Mendes 678 (HUEFS); Mun. Entre Rios, 11°56'S, 38°5'W, 4 December 2000 (fl, fr), M.L. Guedes et al. 7370 (ALCB, CEPEC); Mun. Ilhéus, on road to Vila Brasil, 10 km west of junction with BA-001, 15°06'S, 39°04'W, 10 May 1993 (fl), W.W. Thomas et al. 9845 (CEPEC, MO, NY, RB); Mun. Ilhéus, 20 km north, along road from Una to Ilhéus, 15°11'S, 39°02'W, 100 m, 23 January 1977 (fl), R.M. Harley et al. 18196 (CEPEC, E, K, MO, RB); Mun. Itanagra, Fazenda Córrego Verde, 12 January 1975 (fl, fr), E. Gusmão s.n., ALCB03787); Mun. Itanagra, road from Itanagra to Subaúma, 8 Km W of Itanagra, 50 m, 27 May 1981 (fr), S.A. Mori & B.M. Boom 14132 (CEPEC, NY); Mun. Joazeiro, 17 November 1963 (fl), A.L. Costa s.n. (ALCB03770); Mun. Mata de São João, Praia do Forte, 14 February 1987 (fr), A.J. Ribeiro et al. 190 (ALCB); Mun. Pojuca, Mariquito, 9 December 2007 (fr), C.S. Silva-Lima et al. 126 (ALCB, HUEFS); Mun. Santa Teresinha, Serra da Jibóia, 12°50'42’’S, 39°29'22’’W, 640 m, 3 April 1999 (fl, fr), L.R. Senna & F. Franca 21 (HUEFS); Mun. Santa Teresinha, Serra da Jibóia, 12°51'17’’S, 41°48'53’’W [coordinates suspicious, not included in map], 15 April 2000 (fr), B.M. da Silva 56 (HUEFS); Mun. Santa Teresinha, Serra da Jibóia, à margem da estrada da Serra da Pioneira, 12°50'S, 39°28'W, 14 February 2001 (fl, fr), A.A. Ribeiro-Filho 185 (HUEFS); Mun. Santa Teresinha, Serra da Jibóia, à margem da estrada da serra da Pioneira, 12°51'10’’S, 39°28'32’’W, 31 March 2001 (fl), M.M. da Silva et al. 512 (HUEFS); Mun. Santa Teresinha, Serra da Jibóia, 12°51'10’’S, 39°28'32"W, 31 March 2001 (fl, fr), M.M. da Silva et al. 520(HUEFS ); Mun. Santa Teresinha, Serra da Jibóia, 12°51'11’’S, 39°28'21’’W, 14 November 1986 (fl), L.P. Queiroz et al. 1079 (HUEFS); Mun. Santa Teresinha, Vila da Pedra Branca, Serra da Jibóia, estrada para torre de TV, 800─850 m, 11 June 2000 (fr), M. Alves et al. 2000 (CEPEC, RB); Mun. Santa Teresinha, 14,5 km na rod. Elísio Medrado/Sta. Teresinha, Torre da Embratel, ca. de 7 km do Distrito de Pedra Branca, Serra da Gibóia, 12°51'13’’S, 39°28'33’’W, 750 m, 24 February 2000 (fr), J.G. Jardim et al. 2828 (ALCB, CEPEC, HUEFS); Mun. Santa Teresinha, Serra da Pioneira, 3 km de P. Branca, 12°45'S, 39°32'W, 800 m, 16 May 1984 (fr), L. Noblick et al. 3210 (HUEFS); Mun. Santa Teresinha, Serra da Pioneira, 3 Km de P. Branca, 12°45'S, 39°32'W, 800 m, 6 June 1984 (fr), L. Noblick et al. 3331 (HUEFS, MO); Mun. Santo Amaro, Mata entre Santo Amaro e Cachoeira, 5 April 1962 (fl, fr), A.L. Costa s.n. (ALCB03771); Mun. São Sebastião do Passé, 12°32'28''S, 38°22'51''W, 25 March 2001 (fl), M.L. Guedes et al. 9740 (ALCB, CEPEC); Mun. Uruçuca, estrada de Itacaré para Serra Grande, pouco após km 43, ramal à direita após acesso para a cachoeira do Tijuípe, 14°23'12''S, 39°4'45''W, 5 April 2004 (fr), P. Fiaschi et al. 2262 (CEPEC). Pernambuco: Mun. Igarassu, 8 November 1887 (fl), H.N. Ridley et al. s.n. (BM000935744); Mun. Igarassu, Mata do Pezinho, 18 April 2009 (fl), E. Pessoa 83 (CEPEC, IPA); Mun. Igarassu, Mata da Piedade, 7°49'45.5''S, 34°69'35.7''W, 90 m, 21 April 2010 (fr), J.D. García G. 1487 (CEPEC, UFP); Mun. Igarassu, Usina São José, fragmento de mata com acesso posterior ao Km 10, 7°50'20''S, 34°59'43''W, 12 October 2013 (fr), L.C. Marinho et al. 490 (ALCB, CEPEC, HUEFS); Mun. Recife, Reserva Ecológica de Dois Irmãos, 11 May 1993 (fr), A.M. Miranda et al. 736 (ALCB, HST, UEC ); Mun. Recife, Mata de Dois Irmãos, 1990 (fr), M.L. Guedes 2202 (ALCB). Sergipe: Mun. Indiaroba, P.A. Sepé Tiajuru II, 11°30'44''S, 37°34'47''W, 28 February 2007 (fl), C. Gomes s.n. (ASE33264); Mun. Indiaroba, P.A. Sepé Tiajuru II, 11°30'44''S, 37°34'47''W, 25 January 2008 (fl), C. Gomes s.n. (ASE33283); Mun. Indiaroba, P.A. Sepé Tiajuru II, 11°30'44''S, 37°34'47''W, 9 September 2014 (fl, fr), R.S. Andrade 2 (ASE); Mun. Indiaroba, P.A. Sepé Tiajuru II, 11°30'44''S, 37°34'47''W, 25 November 2014 (fl), R.S. Andrade 53 (ASE); Mun. Itabaiana, Serra de Itabaiana, Margem do 1º riacho, 16 March 1983 (fr), E. Gomes 220 (ASE); Mun. Itaporanga D’Ajuda, Mata Rio Fundo, 11°04'29''S, 37°19'44''W, 7 March 2015 (fl), J.P. Santana 398 (ASE).
Discussion
As stated previously, the Brevantherum clade of Solanum is one of the main lineages recognized in many previous works that dealt with the systematics of the genus [e.g. Gagnon et al. (2022Gagnon E, Hilgenhof R, Orejuela A, et al. 2022. Phylogenomic discordance suggests polytomies along the backbone of the large genus Solanum. American Journal of Botany 109: 580-601. doi: 10.1002/ajb2.1827
https://doi.org/10.1002/ajb2.1827...
)] that congregates non-aculeate species with or without stellate trichomes. Solanum helix belongs to a group of species with porrect-stellate trichomes (and derivatives) within the Brevantherum clade of Solanum, informally named as “stellate subclade” (Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.), which is quite species-rich (ca. 80 species). Within the “stellate subclade” in Giacomin (2015)Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil., S. helix was recovered in the in the Cordovense clade [treated as S. sp. nov. (2)].
The Cordovense clade is a broadly distributed lineage with species found from Mexico to Argentina, containing part of the sect. ExtensumD’Arcy (D’Arcy 1972D’Arcy WG. 1972. Solanaceae Studies II: Typification of Subdivisions of Solanum. Annals of the Missouri Botanical Garden 59: 262-278. doi: 10.2307/2394758
https://doi.org/10.2307/2394758...
; Nee 1999Nee M. 1999. Synopsis of Solanum in the new world. In: Nee M, Simon DE, Lester RN, Jessop JP (eds.). Solanaceae IV: Advances in biology and utilization. Richmond, Royal Botanic Gardens Kew. p. 285-333.) and many other species (ca. 18 species in total; Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.). Species assigned to the Cordovense clade in Giacomin (2015)Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil. have a quite diverse morphology of terminal to lateral inflorescences that can be unbranched, sessile, and quite small and discrete, like those observed in S. helix, to huge and many times branched, as in Solanum lantana Sendtn.. Also, some species can have accrescent fruiting calyces, but this is undoubtedly a homoplastic feature within the lineage. Despite the diverse morphology, species of the Cordovense clade share a shrubby scandent habit, are usually associated with the edge of moist forests and most are locally rare (except for S. didymum), with individuals usually found very apart from each other (Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.).
Within the Cordovense clade, S. helix most resembles S. didymum and S. anisocladum, which are also found in northeastern Brazil (Giacomin et al. 2013Giacomin LL, Bohs L, Stehmann JR. 2013. Two new species from the Brevantherum clade of Solanum (Solanaceae) from eastern Brazil. Journal of the Botanical Research Institute of Texas 7: 95-107.). Vegetatively, Solanum helix can be easily identified by the following combination of characters: sympodial units without geminate leaves and an indument on the abaxial leaf surfaces mostly composed of stalked porrect-stellate eglandular trichomes, with short midpoints and stalks roughly of the same length, giving it a very uniform and unique appearance (like a “canopy”) that is soft to the touch. In S. didymum it is quite common to find geminate leaves and the indument on the adaxial surface is quite variable, with sessile to long-stalked stellate trichomes, with at least some of the trichomes with midpoints longer than the lateral rays, and glandular or eglandular rays, often with a sticky touch. Solanum anisocladum, although also lacking geminate leaves (i.e., leaves are most solitary), has a very dense indument on the abaxial leaf surface, with short- to long-stalked porrect-stellate trichomes and midpoints longer than lateral rays that are hard and rough to the touch. Although it is possible to distinguish S. helix vegetatively, it is most easily recognized while fruiting: its fruiting calyx becomes quite elongated (with expanded lobes) and spreading and, in association with the small fruit, gives it a propeller-like aspect not found in any other species of the Cordovense clade, nor of the more inclusive Brevantherum clade (see Fig. 2E). Another species of the Cordovense clade that also occurs in northeastern Brazil is Solanum maranguapense Bitter, but it can be easily distinguished from Solanum helix by its sessile porrect-stellate trichomes on both leaf surfaces, and leaves with a much more delicate texture, somewhat membranaceous. Solanum helix is also a species from markedly seasonal forests, while S. maranguapense is mostly found in wet forests.
It is intriguing that S. helix has not been described before, given the oldest known collections are from almost 200 years ago. The two oldest collections of the species were located at Kew herbarium (K000983206 and K000983208), but they both have imprecise dates (1857 and 1835 respectively), as they are assigned to “Hooker”, but both botanists Joseph Dalton Hooker (1817-1911) and his father William Jackson Hooker (1785-1865), former directors of Kew, have never been to Brazil. These dates are likely the ones in which the specimens were incorporated into the herbarium and the collection date is expected to be earlier, therefore. Consequently, the oldest collection of the species is expected to be at least 188 years old. The oldest collection to which a precise date can be attributed is that of Ridley (BM000935744), from 1887.
In addition to the time lapse from the first records, the species is widespread in herbaria (see Suppl. MaterialSearchable XLS file of all specimens examined of Solanum helix Giacomin & Stehmann.) and has a strikingly different morphology from other species. Some specimens found in visited herbaria were labeled as Solanum gemellum Mart., a name treated currently as a synonym of S. didymum (Giacomin 2015Giacomin LL. 2015. Solanum L. clado Brevantherum (Solanaceae): Sistemática e diversidade. PhD Thesis, Universidade Federal de Minas Gerais, Brazil.; BFG 2021BFG ‒ The Brazil Flora Group. 2021. Flora do Brasil 2020. Rio de Janeiro, Jardim Botânico do Rio de Janeiro.). Species limits within what was previously treated as Solanum sect. Extensum have been misunderstood, as most species are broadly distributed but locally rare, and specimens available usually present an enormous variation within a small set of collections [for example, see comments of Nee (1999Nee M. 1999. Synopsis of Solanum in the new world. In: Nee M, Simon DE, Lester RN, Jessop JP (eds.). Solanaceae IV: Advances in biology and utilization. Richmond, Royal Botanic Gardens Kew. p. 285-333.) under Solanum extensum Bitter]. With an increasing number of collections and images available online in initiatives that aggregate herbarium databases (such as speciesLink, https://specieslink.net/, and Reflora, http://reflora.jbrj.gov.br/), it is likely that a greater diversity will be unveiled in the Cordovense clade in the future.
The discovery here of an undescribed species after many decades since its first collection highlights the importance of continued work in the field and herbaria in megadiverse ecosystems and reinforces how herbaria can be a frontier for discoveries (Bebber et al. 2010Bebber DP, Carine MA, Wood JRI, et al. 2010. Herbaria are a major frontier for species discovery. Proceedings of the National Academy of Sciences 107: 22169-22171. doi: 10.1073/pnas.1011841108
https://doi.org/10.1073/pnas.1011841108...
). The fact that S. helix is widespread in herbaria, but mostly represented in regional small collections, also reinforces the outsize contribution of these to reduce the incomplete knowledge on organism distribution (described as “Wallacean shortfall” in literature; Hortal et al. 2015Hortal J, de Bello F, Diniz-Filho JAF, Lewinsohn TM, Lobo JM, Ladle RJ. 2015. Seven shortfalls that beset large-scale knowledge of biodiversity. Annual Review of Ecology, Evolution, and Systematics 46: 523-549. doi: 10.1146/annurev-ecolsys-112414-054400
https://doi.org/10.1146/annurev-ecolsys-...
), and therefore their major role in the advance of evolutionary and biogeographical studies and conservation initiatives (Ribeiro et al. 2009Ribeiro MC, Metzger JP, Martensen AC, Ponzoni FJ, Hirota MM. 2009. The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation. Biological Conservation 142: 1141-1153. doi: 10.1016/j.biocon.2009.02.021
https://doi.org/10.1016/j.biocon.2009.02...
).
The Atlantic Forest, although mostly degraded in northeastern Brazil (Ribeiro et al. 2009Ribeiro MC, Metzger JP, Martensen AC, Ponzoni FJ, Hirota MM. 2009. The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation. Biological Conservation 142: 1141-1153. doi: 10.1016/j.biocon.2009.02.021
https://doi.org/10.1016/j.biocon.2009.02...
), is a source of discoveries within its small remnants, a scenario predicted by Pimm et al. (2010Pimm SL, Jenkins CN, Joppa LN, Roberts DL, Russell GJ. 2010. How Many Endangered Species Remain to be Discovered in Brazil? Natureza & Conservação 8: 71-77. doi: 10.4322/natcon.00801011
https://doi.org/10.4322/natcon.00801011...
) and realized in the case of Solanum (e.g. Sampaio & Agra 2016Sampaio VS, Agra MF. 2016. Solanum knappiae sp. nov. (Solanaceae) from the Atlantic Forest of northeastern Brazil. Nordic Journal of Botany 34: 395-399. doi: 10.1111/njb.01102
https://doi.org/10.1111/njb.01102...
, and this paper). Nevertheless, continued work in herbaria is a task intimately associated with continued training of human resources (Bebber et al. 2014Bebber DP, Wood JRI, Barker C, Scotland RW. 2014. Author inflation masks global capacity for species discovery in flowering plants. New Phytologist 201: 700-706. doi: 10.1111/nph.12522
https://doi.org/10.1111/nph.12522...
), considering a learning curve is expected in taxonomy (Ahrends et al. 2011Ahrends A, Rahbek C, Bulling MT, et al. 2011. Conservation and the botanist effect. Biological Conservation 144: 131-140. doi: 10.1016/j.biocon.2010.08.008
https://doi.org/10.1016/j.biocon.2010.08...
), as getting acquainted with patterns of variation within groups might take time. Unfortunately, Brazil, the country that retains the greatest known plant diversity on earth (Forzza et al. 2012Forzza RC, Baumgratz JFA, Bicudo CEM, et al. 2012. New Brazilian floristic list highlights conservation challenges. BioScience 62: 39-45. doi: 10.1525/bio.2012.62.1.8
https://doi.org/10.1525/bio.2012.62.1.8...
), has faced alarmingly decreased science funding in recent years (Fernandes et al. 2017Fernandes GW, Vale MM, Overbeck GE, et al. 2017. Dismantling Brazil’s science threatens global biodiversity heritage. Perspectives in Ecology and Conservation 15: 239-243. doi: 10.1016/j.pecon.2017.07.004
https://doi.org/10.1016/j.pecon.2017.07....
). We advocate for a reversal of this trend and anticipate the discovery of many species as biodiversity studies are continuously supported, which should be done together with human resources training programs, fundamental to form a well-trained task force for the years to come.
Key to the Solanum cordovense species group (Cordovense clade of Giacomin 2015) in NE Brazil (see Materials and Methods for a geographical definition)
1. Stems, inflorescences and leaves with porrect-stellate trichomes with central rays (midpoints) notably shorter than the lateral rays ……….. 2
1’. Stems, inflorescences and leaves with at least part of the porrect-stellate trichomes with central rays (midpoints) notably longer than the lateral rays…… 3
2. Leaves usually drying dark, abaxially with mixed sessile and short stalked porrect-stellate trichomes (mostly sessile); fruiting calyx lobes deltate, only partially accrescent, adhered to the fruit, usually not longer than the fruit length, never spreading (AL, BA, CE, PE)……… Solanum maranguapense Bitter
2’. Leaves usually drying brownish yellow, abaxially with mostly short stalked porrect-stellate trichomes, with stalks roughly at the same size, forming a “canopy”; fruiting calyx lobes getting oblong, usually way longer than the mature fruit, the sepals spreading in a propeller-like aspect (AL, BA, PE, SE)……. Solanum helix Giacomin & Stehmann
3. Stems hirsute to hispid, rough to the touch in old growth, with very long stalked porrect-stellate trichomes reaching > 2 mm, all eglandular; inflorescence emergence usually associated with a change in stem growth direction (AL, BA, PE)…… Solanum anisocladum Giacomin & Stehmann
3’. Stems pubescent, not rough to the touch, with sessile or stalked porrect-stellate trichomes in various sizes, usually < 2 mm, with a glandular or eglandular midpoint; inflorescence emergence never associated with a change in stem growth direction…… 4
4. Fruiting calyx becoming inflated, somewhat plicate, usually covering the fruit at maturity (accrescent); sepals cordate (BA)…. Solanum didymum Dunal
4’. Fruiting calyx not becoming inflated, not plicate, usually not completely covering the fruit at maturity (not markedly accrescent); sepals deltate to elliptic (MA)…. Solanum cordovense Sessé & Moc.
Acknowledgements
We gratefully thank curators of cited herbaria. We are also grateful to Lucas Marinho, Sandra Knapp and Lynn Bohs for assisting fieldwork. Financial support was given to LLG and JDT by IAPT through research grant awards, CNPq (427198/2016-0, 311416/2021-7) to JRS and LLG, Synthesys+ (Project 823827) to LLG and CAPES and the Programa de Desenvolvimento da Pós-Graduação (PDPG) na Amazônia Legal through PhD and PDSE fellowships to JDT and LLG (finance code 001).
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Supplementary material
Searchable XLS file of all specimens examined of Solanum helix Giacomin & Stehmann.
Publication Dates
-
Publication in this collection
24 July 2023 -
Date of issue
2023
History
-
Received
03 Feb 2023 -
Accepted
16 May 2023