Solanum riojense Bitter, Repert. Spec. Nov. Regni Veg. 11: 481. 1913.

Knapp, Sandra, Saerkinen, Tiina & Barboza, Gloria E., 2023, A revision of the South American species of the Morelloid clade (Solanum L., Solanaceae), PhytoKeys 231, pp. 1-342 : 1

48. Solanum riojense Bitter, Repert. Spec. Nov. Regni Veg. 11: 481. 1913.

Figs 146 , 147

Solanum andicola C.V.Morton, Revis. Argentine Sp. Solanum 75. 1976. Type. Argentina. Tucumán: Dpto Tafí del Valle, Paso del Infiernillo, 3,000 m, 18 Feb 1924, S. Venturi 7776 (holotype: US [00027450, acc. # 1549026]).

Type.

Argentina. La Rioja: [Dpto. Vinchina], al pie del Peñón, Cordillera de la Rioja, G. Hieronymus & G. Niederlein 233 (lectotype, designated by Morton 1976, pg. 79: CORD [CORD00004290]) .

Description.

Small herbs from a woody rhizomatous base, 0.1-0.2 m high, the branches usually spreading. Stems terete, moderately pubescent with white eglandular 2-6-celled simple uniseriate trichomes to 0.5 mm long, these usually curled and somewhat tangled; new growth moderately to densely pubescent with tangled white eglandular simple uniseriate trichomes like those of the stems, these denser along the veins; bark of older stems glabrescent, pale greenish brown. Sympodial units plurifoliate, the leaves not geminate. Leaves simple and shallowly toothed, the blades 1.8-4.5 cm long, 0.8-2.4 cm wide, elliptic, widest at the middle, somewhat thick and coriaceous or fleshy, concolorous, very variable in size on individual plants; adaxial and abaxial surfaces sparsely and evenly pubescent with curled white eglandular simple uniseriate trichomes like the stems to 0.5 mm long or glabrous with only a few trichomes along the veins; principal veins 3-4(6) pairs, sparsely pubescent on both surfaces; base attenuate; margins shallowly toothed along entire length or less teeth only present near the base, the teeth 3-5 mm long, 4-6 mm wide, with rounded or pointed tips; apex acute or occasionally bluntly rounded; petiole absent to minute (ca. 0.1 mm), sparsely pubescent with curled white eglandular simple uniseriate trichomes ca. 0.5 mm long like those of the stems. Inflorescences terminal, unbranched, 1-2.5(3) cm long, with 5-7 flowers clustered at the tips, sparsely tangled white-pubescent like the stems and leaves; peduncle 0.8-2.3 cm long; pedicels 0.8-1.1 cm long, ca. 0.5 mm in diameter at the base, 2-2.5 mm in diameter at the base, strongly tapering, spreading at anthesis, sparsely pubescent with tangled white eglandular trichomes like those of the stems and rest of the inflorescence, articulated at the base; pedicel scars evenly spaced 1-3 mm apart. Buds broadly ellipsoid, the corolla ca. halfway exserted from the calyx tube before anthesis, the style often emerging from the unopened flowers in bud. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1.5-2.5 mm long, conical, the lobes 2.5-3 mm long, broadly deltate with rounded tips, sparsely pubescent with tangled white eglandular trichomes to 0.5 mm long. Corolla 1.8-2 cm in diameter, white or pale lavender adaxially, purple abaxially, with a greenish yellow central star or eye, stellate, lobed halfway to 2/3 of the way to the base, the lobes 5-6 mm long, 3.5-5 mm wide, spreading at anthesis, adaxially glabrous, abaxially pubescent where exposed in bud with curled and tangled white eglandular simple uniseriate trichomes 0.5-0.75 mm long, these denser at tips and margins. Stamens equal; filament tube minute; free portion of the filaments ca. 0.5 mm long, sparsely pubescent with tangled weak simple uniseriate trichomes adaxially; anthers 3.5-4.5 mm long, 1.5-2 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 10-11 mm long, straight, exserted beyond the anther cone, moderately pubescent with transparent uniseriate papillae and trichomes in the lower half within the anther tube; stigma capitate and usually somewhat bilobed, the surface minutely papillate. Fruit a globose berry, 0.8-1.1 cm in diameter, mature colour not known, the pericarp thin, matte, opaque, glabrous; fruiting pedicels 1.3-1.5 cm long, ca. 0.5 mm in diameter at the base, ca. 2.5 mm in diameter at the apex, deflexed, somewhat woody, not persistent; fruiting calyx not accrescent, appressed to the berry surface or slightly reflexed, not enlarging from size in flower. Seeds ca. 20 per berry, 2.5-3 mm long, ca. 2.5 mm wide, flattened and teardrop shaped, reddish brown, the surfaces minutely pitted, the testal cells deeply sinuate in outline. Stone cells absent (Barboza 3253) or 4-10 per berry, 2-2.5 mm in diameter, pale cream. Chromosome number: n = 12 ( Moyetta et al. 2013, voucher Barboza et al. 3253, as S. echegarayi ).

Distribution

(Fig. 148 ). Solanum riojense is endemic to the Andes of northern Argentina (Provs. Jujuy, La Rioja, Salta, Tucumán).

Ecology and habitat.

Solanum riojense grows in prepuna and puna vegetation, usually in open rocky areas, often at the edges of fields or in other disturbed areas, from 2,000 to 3,800 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 128,085 km2 [LC]; AOO = 88 km2 [EN]. Solanum riojense occurs in approximately eight locations along the eastern Andean slope and has a relatively wide distribution. It has been collected in the higher elevations of the Yungas Biosphere Reserve, but most collections are outside of protected areas.

Discussion.

Solanum riojense is a member of the Episarcophyllum clade ( Särkinen et al. 2015b), together with S. echegarayi and S. sinuatirecurvum . The identity of this species has been somewhat obscured by issues over the type specimen (see below), Barboza et al. (2013) placed it in synonymy with S. echegarayi , but Cabrera (1983) correctly identified it as distinct. It differs from S. echegarayi in the tangled, floccose pubescence of new growth (versus uniform, short erect, trichomes or absence of pubescence in S. echegarayi ) and the calyx lobes with rounded rather than sharply acute tips. Solanum riojense is similar to S. sinuatirecurvum in the floccose pubescence of new growth, but differs in having smaller flowers (1.8-2 cm in diameter versus 2-2.6 cm in diameter in S. sinuatirecurvum ) and berries (0.8-1.1 cm in diameter versus 1-1.3 cm in diameter in S. sinuatirecurvum ). The rounded calyx lobe apices of S. riojense in both flower and fruit differentiate it from S. sinuatirecurvum (with sharply pointed calyx lobe tips). Mature fruit colour of S. riojense is not known.

A specimen in CORD (CORD00012856) labelled "Echegaray 472", came to CORD from SI and undoubtably represents a mix-up of labels. The name Solanum echegarayi Hieron. was based on an un-numbered collection of Saale Echegaray from Leoncito (San Juan) that lacked pubescence (as noted by A.T. Hunziker on CORD00012858 in pencil); the protologue notes that the plant is completely glabrous and the lectotype of S. echegarayi (CORD00004197) matches the protologue. CORD00012856 has tangled white uniseriate trichomes and is therefore in conflict with the protologue.

The specimen CORD00012856 matches perfectly one of the syntypes of Solanum riojense Bitter, Hieronymus & Neiderlein 472 (CORD00004291) a similar small, high elevation species that has tangled white trichomes on all new growth and inflorescences. What appears to have happened is a complex exchange of specimens from CORD to SI, then back to CORD, with the collector and locality being copied in error to this duplicate (and that at SI) of Hieronymus & Niederlein 472. Therefore, this sheet (CORD00012856) and the corresponding sheet in SI (003309) should be considered duplicates of Hieronymus & Niederlein 472, thus isosyntypes of Solanum riojense , not type material of Solanum echegarayi .

Figures

Figure 146. Solanum riojense A habit B flower at anthesis C stamen D style with pubescence in basal half E fruit with slightly reflexed calyx lobes (A-D Cabrera et al. 21489). Illustration by V. Dudas. Previously published in Cabrera (1983: 418) and in part in Barboza et al. (2013: 244), as S. echegarayi.

Figure 147. Solanum riojense A habit B flowers at full anthesis C flower with 4 - parted corolla (A Hieronymus & Niederlein 233 [CORD 00004290], reproduced with permission of the Universidad Nacional de Cordoba B, C Barboza 3253). Photos of live plants by G. E. Barboza.

Figure 148. Distribution map of Solanum riojense.