Four new non-spiny Solanum (Solanaceae) species from South America

Abstract Four new species of “non-spiny” Solanum from South America are described. Solanum longifilamentum Särkinen & P.Gonzáles, sp. nov. (Morelloid clade) is widespread from Ecuador to Bolivia and is most similar to Solanum macrotonum Dunal from Central and northern South America. Solanum antisuyo Särkinen & S.Knapp, sp. nov. (Morelloid clade) is found on the eastern Andean slopes in Ecuador, Peru and Bolivia and is most similar to the widespread lower elevation species Solanum polytrichostylum Bitter. Solanum arenicola Särkinen & P.Gonzáles, sp. nov. (Morelloid clade) is found in low elevation habitats on the eastern Andean slopes and in Amazonia of Peru and Bolivia and is most similar to the higher elevation species Solanum aloysiifolium Dunal of Bolivia and Argentina. Solanum mariae Särkinen & S.Knapp, sp. nov. (Potato clade) is endemic to Cajamarca Department in Peru, and is most similar to the widespread Solanum caripense Dunal. Complete descriptions, distributions and preliminary conservation assessments of all new species are given.


Introduction
Solanum is one of the largest of fl owering plant genera (Frodin 2004) and its centre of diversity is in South America . Th e Andes are a hot-spot for Solanum diversity and Solanum is one of the most species-rich vascular plant genera in the Andes (Jørgensen et al. 2011). In Peru alone 272 species of Solanum occur, of which 83 are currently listed as endemic (Knapp et al. 2006;Särkinen et al., in review). Many new species continue to be described (e.g., Anderson et al. 2006;Stern and Bohs 2010;Knapp 2010 a,b;Farrugia and Bohs 2010;Tepe et al. 2012;Särkinen et al. 2013) from the Andean region, discovered both in the fi eld and in the herbarium. Solanum comprises 13 major clades of which the spiny solanum clade corresponding to subgenus Leptostemonum is the largest . Th e "non-spiny" solanums are distributed amongst a series of monophyletic groups, some of which have been treated recently (e.g., Knapp , 2013Tepe et al. 2011) while others are in the process of revision. Traditional sectional names for groups of non-spiny solanums are still in wide use, but many of these groups are very diff erent in circumscription to these traditional concepts. Stern et al. (2011) provided an assessment of the clades of spiny solanums in the New World, but the "non-spiny" solanums have not been similarly treated.
We here describe four new species that came to light on recent fi eld work as part of a project investigating the distributional ranges of Solanaceae in this megadiverse region. Descriptions are based on fi eld work and examination of herbarium specimens from 20 herbaria (BH, BM, COL, CORD, CPUN, DUKE, E, F, GH, GOET, HUSA, HUT, K, MO, MOL, NY, S, UDBC, US, USM). All specimens are cited in the text and full data are provided in the supplemental fi le and on Solanaceae Source (http://www.solanaceaesource.org).

Taxonomic treatment
The Morelloid clade Th e Morelloid clade is one of the larger monophyletic groups of "non-spiny" solanums, and contains the type of the genus (Solanum nigrum L., a European hexaploid species). Th e clade comprises fi ve groups, four of which only have a few species (e.g., section Campanulisolanum Bitter, Barboza 2005). Th e largest group of species (ca. 52 species) are those related to S. nigrum that are often referred to as section Solanum. Members of this group occur worldwide with a centre of diversity in the Andes. Th is large group of species is morphologically relatively homogenous and is distinguished by its herbaceous habit, infl orescences usually positioned along the internodes, small fl owers and fruits, and the usual possession of stone cells in the fruits (Bitter 1911). Stone cell aggregates are small, seed-like structures that are usually spherical (rather than fl attened as are the seeds) and can most easily be seen in pressed specimens through the fruit wall. Although some studies have been done to clarify the taxonomy of the Old World and North American species (Edmonds 1977(Edmonds , 1978Schilling 1981), monographic treatment of the entire section is needed to aid species identifi cation and to clarify synonymy for the ca. 580 published names for these taxa. Th is is especially the case for South America, where most species diversity within the section lies (Edmonds 1972; Barboza et al. 2013), and where many taxa remain to be re-circumscribed and new species described. Recent work towards a taxonomic revision of this complex group has resulted in the description of two new species in this group Manoko et al. 2013), both of which had previously been subsumed within other widespread taxa. Th e three species described here were similarly considered as part of poorly understood widespread taxa, but fi eld and herbarium studies have shown them to be distinct. Description. Delicate herb to small subshrub, woody at base, 20-100 cm tall, single stemmed or occasionally branching at the base. Stems 2-4 mm in diameter at the base, terete to ridged, often purple-tinged, sparsely pubescent with appressed 1-2-celled simple uniseriate trichomes ca. 0.2 mm long. Sympodial units difoliate, not geminate. Leaves simple, 2.5-12.0 cm long, 1.0-4.0 cm wide, ovate-lanceolate; adaxial surface glabrous; abaxial surface with appressed 1-2-celled simple uniseriate trichomes like those of the stem along the veins; primary veins 4-8 pairs; base cuneate to attenuate, slightly unequal and oblique; margins entire; apex acuminate; petiole 0.5-1.0 cm long, sparsely pubescent with simple uniseriate trichomes like those of the stems and leaves, especially on young growth. Infl orescences lateral and internodal, 1.5-3.0 cm long, simple, with 3-5(6) fl owers often all apparently arising from the same place, sparsely pubescent with simple uniseriate trichomes like those of the stems and leaves; peduncle 1.0-1.5 cm long, often tinged with purple; pedicels 0.5-0.6 cm long, ca. 0.4 mm in diameter at the base and 0.5 mm at apex, straight and spreading at anthesis, articulated at the base; pedicel scars closely spaced a maximum of 1 mm apart. Buds conical, white, occasionally purple-tinged towards the base, the corolla strongly exerted from the calyx tube long before anthesis. Flowers 5-merous, all perfect; calyx tube ca. 1.5-2.0 mm long, the lobes 1.0-1.5 mm long, deltate to traingular with acute apices, slightly refl exed at anthesis, sparsely pubescent with simple uniseriate trichomes like those of the stems and leaves; corolla 5-6 mm in diameter, stellate, whitewith a yellow, purple or black central star at the base, lobed 2/3 to nearly to the base, the lobes ca. 3.0-3.5 mm long, 1.5-2.0 mm wide, strongly refl exed at anthesis, later spreading, purple towards tips, densely pubescent abaxially with 1-2-celled simple uniseriate trichomes, these usually shorter than the trichomes of the stems and leaves; fi lament tube 1.0-1.2 mm long, pubescent with a few scattered 3-5-celled trichomes at the base adaxially; free portion of the fi laments ca. 1.1-1.4 mm long, pubescent like the tube; anthers (1.7-)3.0-3.4 mm long, 0.8-0.9 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age; ovary globose, glabrous; style 3.5-4 mm long, exerted only to 0.5-1.0 mm beyond the anther cone, densely pubescent in lower ¼ with 2-3-celled simple uniseriate trichomes; stigma globose, minutely papillate, pale yellow in live plants. Fruit a globose berry, 6-7 mm in diameter, green at maturity or green and turning purplish black when ripe, the surface shiny; fruiting peduncle same as in fl ower; fruiting pedicels 1.0-1.2 cm long, ca. 0.6 mm in diameter at the base, 0.9 mm at apex, spreading; fruiting calyx lobes 1.8-3.5 mm long, spreading, the tips refl exed. Seeds 35-45 per berry, c. 1.2 mm long, c. 1.1 mm wide, concave-reniform, narrower at one end, brownish orange, the sub-lateral hilum positioned towards the narrower end of the seed, the testal cells pentagonal in outline; stone cells few per fruit. Distribution. Ecuador, Peru, and Bolivia on the eastern slopes of the Andes growing in mid-elevation montane forests in moist areas, along roadsides, often amongst mosses and small herbs, associated with Ericaceae and Asteraceae shrubs and herbs, Lauraceae, Alnus acuminata Kunth , Cecropia (Urticaceae), Clusia (Clusiaceae), Fuchsia (Onagraceae), Hedyosmum (Chloranthaceae), Weinmannia (Cunoniaceae), Miconia (Melstomataceae), and tree ferns; between (800-) 1,000-2,800 (-3,500) m elevation.

Solanum longifi lamentum
Ecology. Flowering and fruiting throughout the year, with a peak of fruiting in March-July.
Etymology. Th e species is named based on its uniquely long fi laments in relation to the anthers which distinguish it from the closely related S. macrotonum.
Conservation status. Th e preliminary conservation status (IUCN 2010) of S. longifi lamentum is here considered of least concern (LC) based on the relatively large extent of the species occurrence (EOO, c. 781,800 km 2 ), although the actual area of occupancy (AOO) is small (228 km 2 ) and would merit status as endangered (EN). Many recent collections exist, indicating that populations are not in decline, and as are most members of the Morelloid clade, S. longifi lamentum is a weedy plant of disturbed areas. Discussion. Solanum longifi lamentum is most similar to S. macrotonum Bitter of Central and northern South America but these species can be distinguished based on calyx lobes (size and shape) in fl ower and fruit, anther: fi lament length ratio, and the length of the style. Solanum longifi lamentum has oblong, calyx lobes 1.0-1.5 mm long that are slightly spreading in fruit, while S. macrotonum has smaller, 0.5-1.0 mm long, triangular lobes that are tightly appressed to the mature fruit. Filaments are a minimum of half the length of anthers in S. longifi lamentum compared to S. macrotonum where fi laments are always clearly smaller in relation to anthers. Styles are exerted to only 0.5-1.0 mm beyond the anther cone in S. longifi lamentum, but extend 1.5-3.5 mm beyond the anthers in S. macrotonum. Although leaf shape is generally variable within most Solanum species, S. longifi lamentum has consistently narrower, oblonglanceolate leaves compared to the more ovate leaves of S. macrotonum. Other members of the Morelloid clade with which S. longifi lamentum could be confused include S. americanum Mill. and S. pseudoamericanum Särkinen, P. Gonzáles & S.Knapp both of which have smaller anthers c. 1.0-1.5 mm long and curved or included styles, and S. zahlbruckneri Bitter that is a larger, broadly spreading shrub up to 2 m high, with larger, violet corollas up to 2 cm in diameter.
Some infraspecifi c variation in anther size and pubescence can be noted within S. longifi lamentum. Some specimens from throughout the species range have shorter and slightly narrower anthers 1.7-2.0 mm long and 0.6-0.7 mm wide (Smith & Canne 5857; Salinas 1144; Knapp et al. 10454;Campos 5379;Cueva & Rivera 474;Gonzáles et al. 2108). Th ese specimens also have denser leaf pubescence on both surfaces, especially on young growth, and more broadly ovate leaves. Th e variation appears to correlate with environmental conditions rather than geography, where with denser pubescence and smaller anthers seem to grow in drier habitats based on herbarium specimen labels plants.
Specimens belonging to this new taxon have been identifi ed under various names, including S. macrotonum and S. nigrescens Martens & Galeotti, neither of which occur in Peru. Description. Stout herb to a shrub up to 1.5 m tall, much branching at base, the individual branches up to 1m long. Stems 2-ridged or slightly winged especially towards base, 0.4-0.6 cm in diameter, purple-coloured especially at leaf nodes, nearly glabrous, sparsely pubescent with simple uniseriate, much reduced 1-3-celled trichomes  (Knapp et al. 10399) C Woody pedicels of the infrutescence, distinct character in herbarium specimens (Knapp et al. 10401) D Ellipsoid fruits with refl exed pedicels, and the characteristic appressed calyx lobes that split into two in fruit (Knapp et al. 10435). Scale bars = 2 mm. All photos by S. Knapp. especially on the often purple coloured young growth. Sympodial units difoliate, not geminate. Leaves simple, 2-17 cm long, 1.2-8.4 cm wide, broadly ovate-lanceolate, membranous to somewhat fl eshy; adaxial and abaxial surfaces sparsely pubescent with more or less appressed 1-3-celled simple uniseriate trichomes 0.1-0.2 mm long; primary veins 7-10 pairs; base rounded, decurrent on the petiole; margins entire, often purple tinged; apex acute to acuminate; petiole 0.3-1.2 cm long, occasionally narrowly winged, sparsely pubescent with simple uniseriate trichomes like those of the stems and leaves. Infl orescences 1.4-4.0 cm long, lateral and internodal, simple or once-branched, with 5-14 fl owers arising very close together, sparsely pubescent with appressed 1-2-celled simple uniseriate trichomes similar to those on stem and leaves; peduncle 1.0-3.3 cm long, if the infl orescence branched then the peduncle rachis 0.2-0.4 cm long, short and congested; pedicels 1.0-1.2 cm long, 0.5-0.6 mm in diameter at the base tapering gradually to 1.0-1.2 mm in diameter at apex, straight and spreading at anthesis, recurving and becoming woody in fruit, not dehiscing; pedicel scars spaced 0-2 mm apart. Buds conical-ellipsoid, cream-coloured, the corolla strongly exerted from the calyx tube before anthesis. Flowers 5-merous, all perfect; calyx tube 1.5-2.0 mm long, green, the lobes 0.7-0.9 mm long, broadly deltate with rounded apices, purple coloured, sparsely pubescent with 1-celled simple uniseriate trichomes; corolla 12-24 mm in diameter, stellate, white or rarely lilac with a yellow to yellowgreen central star at the base, lobed slightly less than halfway to the base, the lobes ca. 9-15 mm long, 4-5 mm wide, spreading to refl exed at anthesis, pubescent abaxially with 1-3-celled simple uniseriate trichomes shorter than the trichomes of the stems and leaves, sparsely pubescent adaxially at base near the fi laments with 5-7-celled simple uniseriate trichomes; fi lament tube ca. 2 mm long, adaxially pubescent with 5-7-celled simple uniseriate trichomes; free portion of the fi laments ca. 2 mm long, sometimes slightly longer in two lowermost anthers at anthesis (elongating after anthesis?), pubescent like the tube; anthers ca. (2.8)3.0-3.4 mm long, 1 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age; ovary cylindrical, pubescent 2/3 from the base with 2-3-celled simple uniseriate trichomes; style 6 mm long, exerted (0.5)1-2 mm beyond the anther cone, densely pubescent up to 2/3 of the length with 2-3-celled simple uniseriate trichomes at the base; stigma globose, minutely papillate, pale yellow in live plants. Fruit an ellipsoid berry, 8-11 mm in diameter, green turning translucent green-orange when ripe (purple-black in Knapp et al. 10404 but these aff ected by pathogens?), the surface smooth and shiny when young, with relatively thick pericarp ca. 0.1 mm; fruiting peduncle woody; fruiting pedicels 11-22 mm long, purple coloured, ca. 1 mm in diameter at the base and 1.5 mm at apex, refl exed and woody in fruit, remaining on the plant after fruit drops; fruiting calyx lobes tightly appressed to the berry, purple-coloured, calyx often splitting into two larger lobes. Seeds 35-45 per berry, ca. 1.1 mm long, ca. 1.7 mm wide, concavereniform, narrower at one end, brown, the hilum positioned sub-laterally towards the narrower end, the testal cells pentagonal in outline; stone cells few per fruit.
Ecology. Flowering and fruiting throughout the year, peak in March and June-July. Etymology. Th e species name refers to Antisuyo (also Antisuyu), Quechua, for the eastern (anti) region (suyo/suyu) of the Inca territory, that referred to the lands on the eastern Andean slopes. Th e species is most diverse along the eastern fl anks of the Andes in southern Peru, and the name is chosen to refl ect this.
Conservation status. Th e preliminary conservation status (IUCN 2010) of S. antisuyo is here considered of least concern (LC) based on the relatively large EOO (ca. 692,500 km 2 ), although the AOO (136 km 2 ) would merit listing as endangered (EN). Th e species grows readily in disturbed sites and combined with its wide range, it appears to have relatively low threat status despite the generally increasing human pressure and habitat destruction in the Andes.    Knapp et al. 10406 more, styles are always more exerted (2-4 mm versus 1-2 mm beyond the anther cone) in S. polytrichostylum. Th e two species are also ecologically somewhat distinct, with S. polytrichostylum restricted to streams and moist road sides, and S. antisuyo is found in drier areas in gravel, disturbed areas, and landslides. Other members of the Morelloid clade in Peru without glandular trichomes with which S. antisuyo could be confused include S. probolospermum Bitter that has smaller, spherical fruits, larger violet corollas that are more rotate in outline, and denser indumentum with longer 3-7-celled simple hairs, and S. pallidum Rusby (incl. S. planifurcum Bitter) that is similar to S. probolospermum but has branched rather than simple hairs.
Variation in growth form and fl ower colour can be observed in the fi eld, where individuals growing in more humid conditions grow into stout herbs to ca. 1.5 m tall, whilst individuals in drier, higher elevation habitats in rocky landslides are stunted herbs reaching only ca. 40 cm in height. Colour variation in corolla is common within Morelloids and Solanum species in general: most specimens of S. antisuyo have creamy white petals, but occasional specimens with lilac corollas are known (e.g., Särkinen et al. 4048,4049,and 4053 Diagnosis. Like Solanum aloysiifolium Dunal, but diff ering in having simple, subumbellate infl orescences, and a dense indumentum of multicellular glandular-tipped trichomes; also similar to Solanum subtusviolaceum Bitter, but diff ering in having internodal infl orescences, much reduced calyx lobes to only 0.5 mm long, corolla deeply lobed to 2/3 of the way to the base, and a more exerted style extending 2-3 mm beyond the anther cone at anthesis. Description. Herb or vigorous, weak-stemmed shrub 0.2-1.5 m tall. Stems angled, sparsely to densely pubescent with simple, translucent, uniseriate 3-8-celled trichomes 0.8-2 mm long with glandular tips; new growth densely pubescent with spreading glandular trichomes like those of the stem. Sympodial units difoliate, not geminate. Leaves simple, 2.6-13 cm long, 0.8-5 cm wide, ovate to broadly ovate, membranous; adaxial surface glabrous; abaxial surface paler or tinged with purple, sparsely pubescent with simple uniseriate trichomes like those of the stem restricted to the veins; primary veins 5-7 pairs; base acute to cuneate and decurrent on the petiole; margins variable in shape from entire to undulate to shallowly lobed; apex acute-acuminate; petiole 0.5-5.0 cm long, sparsely to densely pubescent with glandular trichomes like those of the stems. Infl orescences 2.0-3.5 cm long, lateral and internodal, simple, with 3-8(9) fl owers, sparsely to densely pubescent with spreading glandular trichomes like those of the stem; peduncle 1.0-2.4 cm long; pedicels 0.5-0.7 cm long, ca. 0.3 mm in diameter at the base and 0.4 mm at apex, straight and spreading, articulated at the base; pedicel scars unevenly spaced 1.0-2.5 mm apart. Buds ellipsoid, the corolla strongly exerted from the calyx tube long before anthesis. Flowers 5-merous, all perfect; calyx tube ca. 1 mm long, shallow, the lobes 0.2-0.5 mm long, triangular with acute apices, sparsely to densely pubescent with glandular trichomes like those of the stem; corolla 8-12 mm in diameter, stellate, white with a purple-yellow or yellow-green central eye at the base, lobed 2/3 to the base, the lobes ca. 3.5-4.0 mm long, 1.0-1.5 mm wide, strongly refl exed at anthesis, later spreading, densely pubescent abaxially with glandular trichomes like those of the stems, glabrous adaxially; fi lament tube 1.0-1.2 mm long; free portion of the fi laments slightly unequal in length, the lower two ca. 1.5 mm long, the upper three ca. 1.0-1.2 mm long, sparsely pubescent with simple uniseriate 1-3-celled trichomes on the side facing the ovary; anthers 3.0-4.0 mm long, 0.8-0.9 mm wide at base and 0.5-0.6 mm wide at apex, cylindrical, narrowing towards the apex, yellow, poricidal at the tips, the pores lengthening to slits with age; ovary ellipsoid, glabrous; style 4-5.7 mm long, exerted 2.0-3.0 mm beyond the anther cone, densely pubescent up to 2/3 of the length with 1-6-celled simple uniseriate trichomes, these longer at the base and becoming gradually shorter towards the middle; stigma clavate, minutely papillate. Fruit a globose berry, 3.5-7.0 mm in diameter, green, turning black when ripe; fruiting peduncle 2.0 cm long; fruiting pedicels 1.0-2.0 cm long, ca. 0.5 mm in diameter at the base and 0.6 mm at apex, strongly recurved; fruiting calyx lobes appressed to the berry, the tips not refl exed. Seeds 35-45 per berry, ca. 0.8 mm long, ca. 0.6 mm wide, fl attened-reniform, narrowing towards one end, yellow, the sub-laterally positioned hilum positioned towards the narrower end, the testal cells pentagonal in outline; stone cells few per fruit.
Distribution. In lowland Bolivia and Peru; in lowland moist rain forest in sandbanks and river margins, tree fall gaps, and in disturbed sites near housing and fi elds in open, sandy soil, with occasional records from seasonally dry semi-deciduous forests with Hura crepitans L. (Euphorbiaceae), Gallesia integrifolia (Spreng.) Harms (Phytolaccaceae), Bougainvillea modesta Heimer (Nyctaginaceae), and Anadenanthera colubrina (Vell.) Brenan (Amaranthaceae); most commonly associated with lowland rain

Discussion. Solanum arenicola can be easily distinguished from S. americanum
Mill., the only other similar Morelloid species found in lowland Amazonia; it has larger anthers which are 3.0-3.2 mm long in S. arenicola as compared to the minute anthers < 1.5 mm of S. americanum. Specimens without locality information can be easily confused with S. nigrescens M.Martens & Galeotti of Central and northern South America, S. aloysiifolium Dunal of middle to high elevation Argentina and Bolivia or S. subtusviolaceum Bitter of low to middle elevation Peru and Bolivia. Both S. arenicola and S. nigrescens have simple infl orescences, but S. arenicola diff ers in having longer anthers (3.0-3.2 mm) compared to S. nigrescens (1.5-2.2 mm) and in the possession of glandular hairs (S. nigrescens is eglandular). Th e anthers are similar in size and shape to those of S. aloysiifolium, but S. arenicola has simple infl orescences and glandular-tipped hairs, while S. aloysiifolium has branched infl orescences (sometimes many branched) and lacks glandular hairs. Solanum subtusviolaceum possesses the same dense, glandular-haired indumentum as S. arenicola, but diff ers from it in having infl orescences with the fl owers clustered near the tips positioned opposite the leaves rather than arising along the internodes, longer calyx lobes (2-3 mm versus 0.2-0.5 mm), more rotate corollas lobed only halfway to the base, and less exerted styles (to a maximum of 1 mm versus exerted to 3 mm beyond the anther cone).
Solanum arenicola is one of the few morelloids known from lowland humid forests in South America. Most morelloid species grow > 2,000 m or in drier habitats along the western slope of the Andes or in the inter-Andean valleys, whilst S. arenicola is restricted to humid forests on the eastern side of the Andes below 1,200 m elevation. Currently, the species is known from central and southern Peru and from Bolivia, but it is likely that the species also occurs in adjacent areas of Brazil in the state of Rondônia, where the Río Madre de Dios and Río Beni join and cross the Brazilian border, especially considering habitat preferences of S. arenicola for disturbed, sandy soils along river banks.

The Potato clade
Within the non-spiny taxa of Solanum, the Potato clade forms a strongly supported monophyletic group ) that comprises the potatoes, tomatoes and a series of smaller groups (e.g., section Pteroidea Dunal, Knapp and Helgason 1998, Tepe et al. 2010and section Herpystichum Bitter, Tepe et al. 2011. Solanum sect. Basarthrum (Bitter) Bitter is one of these smaller groups and is distinguished by the presence of distinctive uniseriate few-celled trichomes termed bayonet hairs (sensu Seithe and Anderson 1982) and basal pedicel articulation. Th e taxonomy and reproductive biology of these species have been treated by Anderson and colleagues (Anderson 1975, 1976, 1979Anderson et al. 1991;Seithe and Anderson 1982), but new species continue to be discovered in the Andes, a centre of species diversity in the group Prohens et al. 2006). Th e new species described here is clearly a member of this group, but has unusual calyx morphology and growth form. Description. Trailing herbs, stems to 20-30 cm tall arising from woody trailing stems that root at nodes, the individual stems up to 5 m long. Stems terete, 1.5-2.5 mm in diameter, moderately to densely pubescent with spreading bayonet hairs (uniseriate, 2-celled hairs with an elongate, thicker-walled basal cell capped by a short acuminate cell) and with simple, 2-4-celled uniseriate glandular-tipped fi nger hairs c. 0.5 mm long; new growth densely pubescent with trichomes like those of the stems; bark of older stems grey-brown, smooth. Sympodial units plurifoliate, not geminate. Leaves simple, 1.4-3.5 cm long, 1.0-1.6 cm wide, ovate-lanceolate; adaxial surface moderately pubescent with bayonet hairs like those on the stems, and with simple, 2-celled uniseriate glandular-tipped hairs c. 0.3 mm long; abaxial surface more densely pubescent with trichomes like those of the upper surface; primary veins 4-6 pairs; base acute to obtuse; margins entire; apex rounded; petiole 0.5-1.2 cm long, moderately to densely pubescent with trichomes like those of the stems. Pseudostipules in pairs, simple, 5 mm long, 3 mm wide, ovate-lanceolate, tip acute, resembling leaves in shape and appearance. Infl orescences 1.5-2.7 cm long, lateral and internodal, simple, with 3-5 fl owers in the distal half, moderately to densely pubescent with spreading trichomes like those of the stems; peduncle 0.4-1.6 cm long; pedicels 0.6-0.7 cm long, ca. 0.3 mm in diameter at the base and apex, straight, curved at the tip, articulated at the base; pedicel scars spaced ca. 1 mm apart. Buds globose, the corolla only exerted from the calyx tube just before anthesis. Flowers 5-merous, all perfect; calyx tube ca. 1.5-2.0 mm long, the lobes 2.0-2.5 mm long, 1.8-2.0 mm wide, broadly deltate, with acute apices, spreading in bud and fl ower, moderately to densely pubescent; corolla 1.2-1.5 cm in diameter, shallowly stellate, white, lobed halfway to slightly less than halfway to the base, the lobes ca. 4-5 mm long and 4-5 mm wide, spreading at anthesis, moderately to densely pubescent abaxially with trichomes like those of the stem, glabrous adaxially; fi lament tube minute, glabrous; free portion of the fi laments ca. 1.0-1.2 mm long, glabrous; anthers 2.7-3.0 mm long, ca. 2.5 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age; ovary conical, glabrous; style 5-6 mm long, exerted 1.5-2.0 mm beyond the anther cone, glabrous; stigma clavate, minutely papillate, yellow-green in live plants. Fruit (immature) an ellipsoid berry, 8-9 mm long and 6.8 mm wide when developing, with the mesocarp ca. 0.2 mm wide, green, fully enclosed in the accrescent calyx, glabrous, mature fruits not seen; fruiting peduncle 1.3-2.2 cm long; fruiting pedicels 1.8-2.3 cm long, 0.3-0.5 mm in diameter at the base and 0.5-1.8 mm at apex, refl exed 180° in fruit; fruiting calyx 8-9 mm long, 3.5-4.0 mm wide and still developing, appressed to and enclosing the entire berry, the calyx lobes spreading at the mouth of enclosing tube. Seeds 30-40 per berry, 1.2-1.5 mm long, 1.0-1.2 mm wide, fl attenedreniform, yellowish, the surfaces minutely pitted, the hilum positioned laterally in the middle, the testal cells pentagonal in outline. Distribution. Endemic to Peru; growing along north facing banks in loamy soils in along roadsides, not in full sun, associated with Lycianthes lycioides (L.) Hassl. (Solanaceae) and various grasses; only known from a single population at 2,600 m elevation from San Marcos Province in the Department of Cajamarca.
Ecology. Flowering and fruiting April-May. Etymology. Th e species is named after biologist Maria Baden who collected the fi rst specimen in Cajamarca in 2013 with the authors. Many of the collections made in our fi eld trips in Peru since 2006 would not have been made without her, and to honour the number of hours spend on plant spotting from fast moving vehicles and driving carefully through recent landslides, we name this shy and stunningly beautiful Solanum species in her honour.
Conservation status. Th e IUCN (2010) threat status of S. mariae is here considered of critically endangered (CR) based on only a few known occurrence points near Chancay in the San Marcos province, Department of Cajamarca, Peru, with AOO of 4 km 2 .
Th e species appears to have specialist habitat requirements, preferring north-facing shady cliff sides. Th e known populations are both small, and vulnerable to grazing pressures.  Discussion. Solanum mariae can be easily distinguished from other section Basarthrum species based on the large, broadly ovate and spreading calyx lobes in fl ower that become to enclose the entire fruit that are not known from any other species of the section. Further distinguishing characters include the combination of trailing stems that root along nodes, the relatively dense pubescence of long, 2-4-cellular glandulartipped fi nger hairs throughout the plant, and the strictly simple leaves. In Peru, the species is most similar to S. caripense Dunal and closely allied species, but diff ers in having simple leaves combined with the glandular-tipped fi nger hairs throughout mature plants and larger calyx lobes that are spreading in fl ower and are accrescent and enclose the fruit. Anderson and Bernardello (1991) provide a key to the members of series Caripensia Correll to which the new species clearly belongs based on morphology.
Based on the style extension well beyond anthers in the newly described species, S. mariae is likely to be self-incompatible. Style extension has been found to indicate self-incompatibility in sect. Basarthrum in previous studies (e.g., Anderson 1979).
Th e trailing growth form of the new species, where roots are formed at leaf nodes, has been observed in other members of sect. Basarthrum, as well as in the closely related sect. Anarrhichomenum Bitter (Tepe et al. 2012), whose members are distinguished from those of sect. Basarthrum by the presence of pseudostipules, winged seeds, and fruits maturing red or orange.
Th e central Andes region is a centre of diversity for Solanum sect. Basarthrum (Stern et al. 2008;Anderson 1979;Anderson et al. 2006;Särkinen et al. in prep.), and the new species described here adds to the growing list. Solanum mariae remains poorly understood based on our two collections from the single known population from the San Marcos Province of the Department of Cajamarca. No further specimens have been seen in local herbaria in Trujillo and Cajamarca. Th e locality lies within the watershed of the Río Marañón, and further fi eld work in the same watershed in the Province of San Marcos is a priority in order to increase knowledge of this rare species, including the morphology of the fully mature fruits.