Nicotiana knightiana is recorded for the first time for the flora of Chile. A new species of Nicotiana, endemic to the coast of the Coquimbo region is described and illustrated. Molecular analysis placed the new species within the N. sect. Paniculatae, as sister to N. cordifolia, an endemic to Juan Fernandez islands. The new species can be considered critically endangered (CR) according to the IUCN categories due to its restricted and fragmented distribution, small population number, and the threat that urbanization and mining activities represent for the conservation of the biodiversity of the area.

Coquimbo, endemism, exotic species, Nicotianoidae, systematics, taxonomy

Nicotiana L. is one of the largest genera in the Solanaceae with 75 recognised species (Clarkson et al. 2017) including the important crop plant Nicotiana tabacum L. Nicotiana is naturally distributed in America and Australia, with one species from south-west Africa (Hunziker 2001). Evidence of homoploidy and polyploidy showed that hybridization has been a major driver of speciation in the genus (Clarkson et al. 2010).

Since Reiche’s (1903) treatment, no modern revision of Nicotiana in Chile has been published. According to the last catalogue of the flora of Chile (Rodriguez et al. 2018), the country is home to 12 native accepted species of Nicotiana distributed from Arica y Parinacota region to Magallanes region and Juan Fernandez Archipelago, and two introduced species, Nicotiana tabacum, in Juan Fernandez and Easter Island, and Nicotiana glauca Graham in North and Central Chile. In his monograph of the genus, Goodspeed (1954) provided a taxonomic classification in which he recognised three subgenera further divided into 14 sections. Most of his sections have been confirmed as monophyletic by molecular analyses (Aoki and Ito 2000; Chase et al. 2003; Clarkson et al. 2004; Mehmood et al. 2020). Two Chilean species are included in Nicotiana sect. Paniculatae Goodsp.: the endemics Nicotiana cordifolia Phil. found in Juan Fernandez Archipelago (Philippi 1856) and Nicotiana solanifolia Walp., that grows between Tarapacá and Coquimbo regions (Walpers 1844) and has been traditionally used in the economic and cultural life of the Atacama coastal communities (Ballester et al. 2016). According to Goodspeed (1954), N. sect. Paniculatae share cordate-ovate leaves, evenly spaced along the stem, a long and narrow cylindrical thyrse with thickened central axis, a calyx with regular, broadly triangular teeth, a short and distinct tube proper with a several times longer throat, a greenish to yellowish corolla, stamens of almost equal length, filaments curving immediately above their insertion (except N. cordifolia and N. raimondii J. F. Macbr.), and anthers bending towards the stigma.

The aim of the present work is to record Nicotiana knightiana Goodsp. for the first time for the flora of Chile and describe a new species of Nicotiana endemic to Chile, determining its phylogenetic position and conservation status.

We could not find any described species of Nicotiana for Chile that matched the morphology of the plants from Elqui river and Fuerte Lambert. A specimen matching the morphology of the species from Elqui river was found at SGO, collected in 2021 in the city of Huasco Bajo, Atacama, approx. 160 km north of La Serena. Plants from Elqui river are 2 m-long, somewhat ineffectively rooted, with branching short perennial shrubs, a pale yellow-green corolla, a dark green limb and eglandular indumentum (Fig. 2, Fig. 3C-D). This species was identified as N. knightiana, a member of Nicotiana sect. Paniculatae known from coastal southern Peru. Two geo-referenced and misidentified observations of N. knightiana in Chile are available on iNaturalist, one from November 2018 in the proximity of our collection site (https://www.inaturalist.org/observations/19777218) and one from May 2021 at approx. 6 km southwards (https://www.inaturalist.org/observations/80390445) (Fig. 1). A specimen matching the morphology of the species from Fuerte Lambert was found at EIF, collected in 2006 in the whereabouts of Chungungo, Coquimbo, aprox 50 km north of Fuerte Lambert. Plants from Fuerte Lambert are perennial, rupicolous shrubs, with glandular indumentum, a characteristic congested inflorescence, and small, yellow flowers with an almost glabrous corolla (Fig. 3A-B, Fig. 4). Both species have capsules that produce a large number of seeds but the ones of N. knightiana are more rounded in shape compared to those of the new species (Fig. 5).

Figure 2. 

Nicotiana knightiana (L. Santilli 210323) A habit B inflorescence C detail of lignified horizontal stem D adaxial and abaxial side of a leaf E frontal view of a flower showing limb area F lateral view of a flower. Scale bars: 1 cm.

Figure 3. 

Indumentum of the leaves A, B Nicotiana rupicola with glandular hairs (N. Lavandero 1011) C, D Nicotiana knightiana with eglandular hairs (L. Santilli 210323).

Figure 4. 

Nicotiana rupicola (N. Lavandero 1011) A habitat B habit C inflorescence D adaxial and abaxial side of a leaf E frontal view of a flower showing limb area F detail of indumentum G lateral view of a flower. Scale bars: 1 cm.

Figure 5. 

Fruits and seeds A, C Nicotiana knightiana (L. Santilli 210323) B, D Nicotiana rupicola (N. Lavandero 1011).

Molecular phylogenetic analyses

The concatenated DNA matrix contained 4427 nucleotide characters (1554 matK, 1074 ndhF, 932 trnL-trnF and 867 trnS-trnG), representing 60 ingroup and 2 outgroup accessions. Both BI and ML analyses yielded congruent topologies. The topology of the phylogenetic tree constructed in this study is congruent with the clades found by Clarkson et al. (2004) (Fig. 6). Overall, the support given by Bayesian posterior probabilities are higher than bootstrap values given by ML analyses. Nicotiana sections Tomentosae Goodsp. (PP = 1, BS = 88), Undulatae Goodsp. (PP = 1, BS = 95), Paniculatae (PP = 1, BS = 87), Trigonophyllae Goodsp. (PP = 1, BS = 100), Petunioides G.Don (PP = 1, BS = 100), Alatae Goodsp. (PP = 1, BS = 96), Repandae Goodsp. (PP = 1, BS = 100), Noctiflorae Goodsp. (PP = 1, BS = 100), and Suaveolentes Goodsp. (PP = 0.94, BS = 60) all form monophyletic groups with moderate to high supporting values.

Figure 6. 

Phylogeny of Nicotiana resulting from Maximum Likelihood analysis of the plastid regions matK, rps16, trnS-trnG and trnL-trnF. Numbers above and below the branches represent the Posterior probabilities from the BI analysis and bootstrap values from the ML analysis, respectively. The species whose sequences were obtained in the present study are highlighted in bold, while section Paniculatae including N. rustica is highlighted in grey.

Section Paniculatae, including N. rustica, forms a well-supported clade (PP = 1.0, BS = 87). Relationships among the clades largely reflect Clarkson et al. (2004), including the position of the section Paniculatae as sister to section Undulatae and together as sister to the rest of the genus excluding section Tomentosae. The new species falls within section Paniculatae as sister to N. cordifolia (PP = 0.99, BS = 89), and together they form a clade with N. solanifolia (PP = 1, BS = 100). This clade is sister to a clade including the rest of section Paniculatae (PP = 0.92, BS = 66). Nicotiana knightiana and N. paniculata are closely related species (PP = 0.98, BS = 63) and form a clade with N. rustica (PP = 1, BS = 100). The species collected in the mouth of Río Elqui, and identified as N. knightiana, falls as sister to N. knightiana sequenced in Clarkson et al. (2004) with moderate support (PP < 0.5, BS = 62). A base-by-base comparison of the sequences of N. knightiana from Clarkson et al. (2004) and N. knightiana from this study, show that they are identical, while they present differences at 6 nucleotide positions (3 from trnS-trnG and 3 from matK regions) with N. paniculata.

Taxonomic treatment

 Nicotiana knightiana Goodsp., Univ. Calif. Publ. Bot. 18: 139, pls. 11, 12b (1938).

Figures 2, 3C–D, 5A–C, 7

Type

Peru. Dept. Arequipa, Prov. Islay, near Mollendo, 40 m, 16 November 1935 (fl, fr), Y. Mexia 04161 (holotype: UC [UC448735 photo!]; isotypes: MO, NA, NY).

Figure 7. 

Illustration of Nicotiana knightiana A entire branch B frontal view of a flower C lateral view of a flower D schematic drawing of a longitudinal section of a flower E seed. Scales: 5 cm (A); 0.5 cm (B); 1 cm (C, D); 0,5 mm (E). Santilli 210323 (SGO).

Description

Robust annual or short-lived shrub up to 3 m with many new stems at different stages of development arising from a lignified horizontal stem poorly anchored to the soil. Stems herbaceous, green, tomentose. Leaves ovate, undulate, base rounded to subcordate, apex obtuse to acute; bigger leaves 13 × 10 cm, indumentum similar to the stem but much denser on the abaxial side which confers a whitish colour, hairs simple, eglandular, pluricellular, brochidodromous venation, petioles a third or half as long as the leaves. Inflorescence a broad thyrse or lax panicle, 40 cm. Pedicels 0.5–1 cm in mature fruits, covered in glandular hairs. Calyx up to 7 mm, cylindric, tomentose, teethup to 2 mm, triangular. Corolla 20–23 mm excluding the limb (tubular part), tube proper 4 mm, throat 16 mm, pale yellow-green, covered in short, eglandular, hairs, limb bottom 3 mm wide, dark green, same indumentum as tube proper, notched into 5 lobes shorter than 1 mm. Stamens extending below the limb, 19 mm except one slightly shorter, filaments adnate to the tube proper, then free, pubescent in the proximal 6 mm, then glabrous and slightly curved, with stamens bending toward the stigma. Capsule 6–8 mm, ovoid. Seeds mainly subrotund, 0.5–0.7 mm, brown, surface reticulate. Embryo straight.

Figure 8. 

Illustration of Nicotiana rupicola A entire branch B frontal view of a flower C lateral view of a flower D schematic drawing of a longitudinal section of a flower E seed. Scales: 2 cm (A); 1 cm (C, D); 0.5 mm (E). N. Lavandero 1011 (SGO, EIF, CONC).

Distribution and habitat

Nicotiana knightiana grows naturally in the coast of southern Perú in roadsides, pastures and rocky ravines bottoms. It was found in Chile, within the city of La Serena, Coquimbo region, in the proximity of the rivermouth of Rio Elqui, and in the proximity of Avenida Los Pescadores. It was also found growing in the city of Huasco Bajo, Atacama region (Fig. 1). It grows in a dense Tessaria absinthioides (Hook. & Arn.) DC. scrub, associated with Myoporum laetum G. Forst., Phyla nodiflora (L.) Greene, Schoenoplectus californicus (C.A. Mey.) Soják, Solanum pinnatum Cav., Lycium chilense Miers ex Bertero, Sarcocornia neei (Lag.) M.A. Alonso & M.B. Crespo, Distichlis spicata (L.) Greene, Thypa angustifolia L., Ambrosia chamissonis (Less.) Greene, Nicotiana glauca and Stemodia durantifolia (L.) Sw. var. chilensis (Benth.) C.C. Cowan. It thrives in sandy soils with water table very close to the surface.

Phenology

Nicotiana knightiana is found flowering and fruiting between November and May.

Specimens examined

Perú. Arequipa: Prov. Islay, Quebrada Canyon, 5–6 km north of Mollendo, 300 m, 29 September 1938 (fl, fr) C.R. Worth & J.L. Morrison 15742 (US); 12 km southeast of Islay, 250–300 m, 28 September 1938 (fl, fr),C.R. Worth & J.L. Morrison 15724 (US). Chile. Atacama: Huasco bajo, 28 m, 16 October 2021 (fl), J.H. Macaya 1782 (SGO). Coquimbo: Prov. del Elqui, La Serena, ribera sur del Río Elqui a ca. 200 m de la desembocadura, 2 m, 23 March 2021 (fl, fr), L. Santilli 210323 (SGO); La Serena, ribera sur del Río Elqui a ca. 200 m de la desembocadura, 1 m, 24 Nov 2018 (fl, fr), A. Ryan (iNaturalist); La Serena, avenida Los Pescadores con Canto del Agua, 3 m, 26 May 2021 (fl), B.L. Bedard (iNaturalist).

 Nicotiana rupicola Santilli, De Schrevel, Lavandero & Dandois, sp. nov.

urn:lsid:ipni.org:names:77248643-1

Type

Chile. Región de Coquimbo: Prov. Elqui, Comuna de Coquimbo, Fuerte Lambert, 29°56'2.52"S, 71°20'16.46"W, 29 m, 12 November 2020 (fl, fr), N. Lavandero 1011 (holotype: SGO!; isotypes: EIF!, CONC!).

Diagnosis

Nicotiana rupicola is most similar to N. solanifolia, from which it differs by its congested panicle (vs. lax panicle), its short and glabrous corolla up to 18 mm (vs. corolla of 35–50 mm, pubescent), non-retroflexed corolla limb (vs. retroflexed corolla limb), mature capsule included or slightly exserted from calyx, 6–10 mm (vs. more than half the length excluded from calyx at maturity, 12–18 mm).

Description

Perennial shrub up to 2 m with many stems arising from a lignified horizontal stem. Stems lignified, light brown, glabrous. Leaves orbicular to ovate, flat to slightly ondulate, margins slightly revolute, base rounded to cordate, apex retuse to obtuse; bigger leaves 10 × 8.5 cm, reducing their size towards the apex, densely covered in two types of hairs in both sides: simple, straight, pluricellular, up to 1 mm long, and glandular (capitate), straight, pluricellular, 50–600 µm long, brochidodromous venation, petioles a quarter to half as long as the leaves, 0.5–2.5(–5.0) cm long. Inflorescence a compact panicle, up to 35 cm; pedicels up to 0.5 cm, same indumentum as the leaves. Calyx up to 10 mm, cylindric, same indumentum as the leaves, teeth up to 3.5 mm, triangular. Corolla 17–18 mm excluding the limb (tubular part), tube proper up 5.5–6 mm, throat up to 12 mm, yellow, glabrous, limb 4 mm wide, yellow, glabrous or with scattered hairs, notched into 5 lobes. Stamens extending below the limb, similar length; filaments adnate for the first 5 mm to the tube proper, then free, pubescent at the base, then glabrous and slightly curved, with the distal portion bending toward the stigma. Capsule 6–10 mm long, ovoid. Seeds mainly angular, laterally compressed, 0.4–0.6 mm long, dark brown, surface reticulate. Embryo unknown. Chromosome number unknown. (Fig. 3; Fig. 4B-D; Fig. 8)

Distribution and habitat

Nicotiana rupicola is endemic to Chile where it is currently known from two locations, Fuerte Lambert and Chungungo, both in the region of Coquimbo (Fig. 1). In Fuerte Lambert it grows among the rocks in a cliff near the ocean together with Alstroemeria magnifica Herb., Cistanthe grandiflora (Lindl.) Schltdl, Diplolepis boerhaviifolia (Hook. & Arn.) Liede & Rapini, Eulychnia breviflora Phil., Loasa elongata Hook. & Arn., Myrcianthes coquimbensis (Barnéoud) Landrum & Grifo, Nolana acuminata (Miers) Miers ex Dunal, N. rupicola Gaudich., N. sedifolia Poepp., Ophryosporus triangularis Meyen, Plumbago caerulea Kunth, Polyachyrus poeppigii Kuntze ex Less., Puya venusta Phil., Sicyos baderoa Hook. & Arn. var. baderoa, Solanum pinnatum Cav., Stachys pannosa Phil., In Chungungo it grows on a rocky cliff facing the ocean, together with Nolana crassulifolia Poepp. and N. sedifolia Poepp and surrounded by a scrub of Balbisia peduncularis (Lindl.) D. Don, Heliotropium stenophyllum Hook. & Arn., and Oxalis virgosa Molina.

Phenology

Nicotiana rupicola was found flowering and fruiting in November.

Etymology

The specific epithet derives from the Latin rupes (rock), and cola (dweller), alluding to rocky habitat of this species.

Additional specimens examined (paratypes)

Chile. Región de Coquimbo. Prov. Elqui, Comuna La Higuera, costa al Norte de Chungungo, 7 November 2006 (fl), N. García 3085 (EIF).

Conservation status

Nicotiana rupicola can be considered as Critically Endangered (CR) under the IUCN categories and criteria B1ab(iii); D. The criterion B1 was selected because its extent of occurrence is < 100 km² (8 km²). The criterion “a” was selected because the distribution is highly fragmented. The criterion “b(iii)” was selected because there is a projected decline in the area, extent and quality of habitat. This area is constantly threatened by the expansion of urbanization that is affecting central-north coastal Chile. One of the locations is currently found at less than 300 m from the residential area of Coquimbo and the habitat is being altered by numerous and increasing amounts of formal and informal paths and human activity (camping, garbage, etc.). Moreover, mining activities within the extent of occurrence, especially Minera Dominga, which pretends to settle between the two known localities, will more likely affect possible unknown populations and the quality of the habitat. The criterion D was selected because we observed less than 50 individuals around the two known localities.

The characters that proved to be useful to differentiate species of Nicotiana sect. Paniculatae are the type of inflorescence, the types of trichomes and distribution of the indumentum, as well as the size and colour of flowers. N. knightiana resembles most N. paniculata from which it differs on account of its shorter flowers with dark green limbs (vs. yellow) (Fig. 2E-F) . The large undulate leaves, the narrow panicles and the long throat of the flowers of N. knightiana also resemble N. solanifolia from which it can be distinguished for its smaller flowers (2–2.3 cm vs 3–5 cm respectively), eglandular indumentum (vs. glandulous) and dark green limb (vs. yellow) (Figs 2E, F, 3C, D). Nicotiana rupicola is morphologically similar to N. solanifolia from which it can be distinguished by its congested panicle (vs.lax), glabrous corolla tube (vs. hairy), its smaller flowers and no-retroflexed corolla (Fig. 4) .

It is worth mentioning that N. solanifolia has been erroneously reported for the Coquimbo region based on a collection held at K (Cuming 860), which is the type of Nicotiana breviloba Jeffr., considered by Goodspeed (1954) as a synonym of N. solanifolia. Johnston (1936) considered that Cuming’s collections with collection number between 853 and 911 were obtained north of Huasco, Atacama region. This is consistent with the collection localities of the specimens of N. solanifolia revised in the present work which show that the distribution of N. solanifolia and of N. rupicola do not overlap. The southernmost collection of N. solanifolia is found at approx. 100 km north of the northernmost collection locality of N. rupicola.

Molecular analyses showed that plants from Elqui river are likely correctly identified as N. knightiana and that our initial conjectures about the phylogenetic position of N. rupicola as part of the sect. Paniculatae were confirmed (Fig. 6) . Our topology retrieves Clarkson’s et al. (2004) results of two separate clades within the sect. Paniculatae that reflect geography, one including species from Peru and one including the two endemics N. solanifolia from the North of Chile and N. cordifolia from Juan Fernández Archipelago (Fig. 6). Species of Chilean sect. Paniculatae share long tubular flowers and long-petiolate leaves. Surprisingly, N. rupicola results in being more closely related to the Juan Fernández species N. cordifolia than to the continental species Nicotiana solanifolia, despite their morphological affinity.

An important question regards whether N. knightiana has to be considered native or introduced to Chile. Either the species was never noticed or collected during the last two centuries of botanical expeditions, and presents naturally disjunct populations, being almost 1500 km apart from the closest population found in Peru, or it was recently introduced in Chile by anthropogenic means. The earliest evidence of its presence dates back to 2018 (iNaturalist) and it seems to have been established and possibly expanded to the surrounding area in sites with similar ecological conditions to the river mouth of Elqui river, such as Huasco Bajo. The production of abundant and small seeds, together with the ability of some species to grow in a broad range of open and disturbed habitats, is considered as a common adaptation that ensures high probability of dispersal and establishment. Such is the case for Nicotiana paniculata, N. glauca, and N. plumbaginifolia Viv. that are considered invasive species (Gallo et al. 2008; Gairola et al. 2016; Rodríguez-Caballero et al. 2020; Alharthi et al. 2021)

Nicotiana rupicola presents a restricted distribution limited to a small portion of the coastal area of northern Chile, where it grows on two locations on easily accessible coastal rocky cliffs at less than 300 m from urbanization. The population from Fuerte Lambert is situated in an area where urban expansion has caused major damage to the vegetation. The coastal area between Tongoy and Coquimbo is catalogued as a site of interest for the conservation of woody and succulent species due to its high diversity and rates of endemism (Squeo 2000). The area is home to various threatened species such as: Carica chilensis (Planch. ex A. DC.) Solms, Myrcianthes coquimbensis (Barnéoud) Landrum & Grifo, Porlieria chilensis I.M. Johnst. Controversially, it is an area particularly affected by intense expanding urbanization that seriously threatens the conservation of the local biodiversity. Additionally, a new mining facility and a discharge port (Minera Dominga) will be constructed within its extent of occurrence, close to its northernmost known locality. It is likely that several more individuals of N. rupicola are present in the area, since the abiotic and biotic conditions are similar to the currently known localities. None of these individuals were considered during the environmental impact assessment of the project. It is of great importance for the conservation of the species to search for more individuals and localities, and to raise the attention to much needed conservation measures for the species and the unique ecosystem where it is found.

The authors thank staff at SGO and EIF for receiving the specimens and allowing revision of specimens under their care, Sebastian Teillier for providing literature of Nicotiana, Gabriel Marianjel Donoso for his help in the field, Gisela Stotz for logistic support during fieldwork, Elisa Guzman for sharing images of the flora of the Elqui river, Matías Tobar for providing images of Nicotiana cordifolia for comparison, Nicolás García for sharing data and information about the new species, Jorge Macaya for providing a new locality for Nicotiana knightiana in Huasco Bajo and Gioconda Peralta for the support provided with molecular work (CONICYT-FONDEQUIP EQM150077). We would also like to thank Andrés Moreira-Muñoz and João Renato Stehmann for their helpful comments on the submitted manuscript. Herbarium and lab work were funded by the ANID/FONDECYT grant 1211765.