Solanum arequipense Bitter, Repert. Spec. Nov. Regni Veg. 11: 204. 1912.

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

8. Solanum arequipense Bitter, Repert. Spec. Nov. Regni Veg. 11: 204. 1912.

Figs 27 , 28

Solanum furcatum Dunal var. subdentatum Nees, Nov. Act. Acad. Caes. Leop. 19, Suppl. 1: 386. 1843. Type. "Peruvia ad Arequipam, Aprili" F.J.F. Meyen s.n. (no specimens cited; no original material located). Peru. Arequipa: Prov. Arequipa, 2 km on dirt road from Cayma (northern outskits of Arequipa) to Charcani Grande, along Rio Chili; turn off from Cayma main road to 'Egasa Centrales Hidroelectricas Charcani Santuario Virgen de Chapi’; within the Egasa hydroelectrical company’s perimeter ca. 50 m from the river, 2,518 m, 25 May 2012, T. Särkinen, A. Mathews & P. Gonzáles 4099 (neotype, designated here: USM; isoneotypes: BM [BM001114853, BM001114854, BM001114856]).

Solanum furcatum Dunal var. subintegerrimum Nees, Nov. Act. Acad. Caes. Leop. 19, Suppl. 1: 386. 1843. Type. "Chile: Copiapó, Aprili; Peruvia: circa Tacoram [ Volcán Tacora], Aprili" both syntypes collected by F.J.F. Meyen s.n. (no specimens cited; no original material located). Peru. Tacna: Prov. Tarata, Río Chacavira, camino a Caro, margen derecha de Río Chacavira, 3070-3480 m, 5 Dec 1997, M.I. La Torre 1890 (neotype, designated here: USM [acc. # 159556]).

Type.

Peru. Arequipa: sin. loc., C. Seler 204 (holotype: B, destroyed [F neg. 2597]; lectotype, designated here: LE [LE00016838]) .

Description.

Subwoody shrubs 0.3-1.5 m high, the branches erect. Stems terete or somewhat angled with a wing less than 0.5 mm wide and with a few spinescent processes along the angles, sparsely pubescent with white eglandular simple uniseriate 3-7-celled trichomes 0.5-1 mm long, these appressed and antrorse or somewhat spreading; new growth densely papillate with tiny glandular (?) 1-celled papillae and densely pubescent with white eglandular simple uniseriate trichomes like those of the stems. Sympodial units difoliate, the leaves geminate or not geminate. Leaves simple or occasionally toothed, the blades 3.2-14 cm long, 1.5-6 cm wide, larger on older branches, elliptic to somewhat ovate, widest in the lower half, membranous, more or less concolorous; adaxial surfaces almost glabrous to sparsely and evenly pubescent with erect eglandular simple uniseriate 5-7-celled trichomes of varying lengths to 1 mm long, these denser on the veins; abaxial surfaces almost glabrous to sparsely and evenly pubescent with simple uniseriate trichomes like the adaxial surfaces; principal veins 5-7 pairs, more densely pubescent than the lamina; base attenuate to truncate and abruptly attenuate, winged onto the petiole; margins entire or irregularly and shallowly toothed, the teeth ca. 2 mm long, ca. 10 mm wide, if present irregular in size and shape, the sinuses rounded and reaching ca. 1/10 of the way to the midrib; apex acute to acuminate; petioles 0.5-2 cm long, the winged portion narrowing towards base. Inflorescences internodal or opposite the leaves, forked or more than once forked (e.g., Gonzáles et al. 2870) with widely diverging branches, 2-6 cm long, with 10-20 flowers in the distal half of the branches, sparsely pubescent with appressed or slightly spreading eglandular simple uniseriate trichomes to 1 mm long like those of the stems; peduncle 1.1-3 cm long; pedicels 0.5-0.8 cm long, ca. 0.5 mm in diameter at the base, ca. 0.75 mm in diameter at the apex, filiform and slightly tapering, spreading at anthesis, sparsely pubescent to nearly glabrous like the rest of the inflorescence, articulate at the base; pedicel scars regularly spaced in the distal parts of the inflorescence branches ca. 1 mm apart. Buds globose, the corolla strongly exserted from the calyx before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1-1.5 mm long, conical to slightly cup-shaped, the lobes 1-2 mm long, 0.75-1 mm wide, elongate-deltate with the tips rounded or acute, sparsely pubescent with eglandular simple uniseriate trichomes like the stems and leaves, usually drying dark greyish black. Corolla 1.5-1.6 cm in diameter, white, white tinged with violet or pale violet, with a green eye, stellate, lobed ca. halfway to the base, the lobes 4.5-5 mm long, 4-5.5 mm wide, broadly deltate, reflexed or spreading at anthesis, adaxially glabrous, abaxially densely white puberulent with white simple uniseriate trichomes ca. 0.5 mm long. Stamens equal; filament tube minute; free portion of the filaments 1-1.2 mm long, densely pubescent adaxially with tangled transparent simple uniseriate trichomes; anthers 2.5-3 mm long, 1-1.5 mm wide, broadly ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 6-9 mm long, straight (curved in bud), long- exserted from the anther cone, densely pubescent in the lower third with transparent simple uniseriate trichomes; stigma globose or small-capitate, sometimes bilobed, the surface minutely papillate. Fruit a globose berry, 0.5-0.6 cm in diameter, pale green when immature, ripening to greyish green tinged with purple when ripe, the pericarp thick, matte, opaque, glabrous; fruiting pedicels 1-1.1 cm long, 0.75-1 mm in diameter at the base and apex, not markedly woody, strongly deflexed, not persistent; fruiting calyx not markedly enlarged or accrescent, the lobes to ca. 2 mm long, strongly appressed to the berry. Seeds 12-20 per berry, ca. 2 mm long, ca. 1.5 mm wide, flattened and teardrop shaped, reddish brown, the surfaces minutely pitted, the testal cells pentagonal in outline. Stone cells 2 per berry or absent, ca. 1 mm in diameter, cream-coloured. Chromosome number: 2n = 48 ( Chiarini et al. 2017, voucher Särkinen et al. 4083, as S. furcatum ). A count of 2n = 72 was reported by Edmonds 1977, based on Hawkes et al. 4111, but we have been unable to locate this voucher to verify its identity.

Distribution

(Fig. 29 ). Solanum arequipense is endemic to the slopes of the Andes in Peru (Depts. Ancash, Arequipa, Ayacucho, Cajamarca, Junín, Huancavelica, Lima, Moquegua, Puno, Tacna), occurring mostly on the western slopes of the cordillera.

Ecology and habitat.

Solanum arequipense grows in low elevation coastal ‘lomas’ formations and in open scrubby areas and along streams in higher elevation moist and cloud forests; from 200 to 4,400 m elevation.

Common names and uses.

Peru. Moquegua: hierba mora ( Núñez 6). No uses recorded.

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 255,276 km2 [LC]; AOO = 224 km2 [EN]. Solanum arequipense is widely distributed in a wide range of habitats; like most morelloid species it thrives in disturbed areas. It occurs in several protected areas in Peru (Bosque de Zarate, Lomas de Atiquipa, Parque Nacional Huascarán).

Discussion.

Solanum arequipense is morphologically very similar to S. furcatum of central Chile and adjacent Andean Argentina and has been previously confused with that species (the plate published as S. furcatum in Knapp et al. 2019:67 is S. arequipense and is here reproduced with the correct identification). The species share forked inflorescences, globose buds with styles that are often exserted prior to anthesis, and greenish purple mature fruits. Solanum arequipense differs from S. furcatum in having no or only two apical stone cells in the fruits, while S. furcatum has more than six that are easily seen though the pericarp. Both species are tetraploid (see above and description of S. furcatum ), but in analyses based on DNA sequence data the two species are not closely related ( Gagnon et al. 2022); they may share different parentage. Solanum pentlandii also has similar globose buds and exserted styles but has much shorter anthers (less than 2 mm versus 2.5-3 mm in S. arequipense ) and shiny green berries that lack stone cells. Plants of S. arequipense are generally woodier than those of S. pentlandii and occur at lower elevations. The two species are sympatric in central Peru, where S. arequipense has been collected at high elevations. Leaf lobing is usually more pronounced in S. pentlandii , but this is not consistent across the species range.

In describing Solanum arequipense , Bitter (1912b) cited a single specimen in the Berlin herbarium (F neg. 2597) that is now destroyed. We select here as lectotype the only duplicate of Seler 204 we have seen, the sheet in the Komarov Institute in St. Petersburg (LE00016838); it is indicated as a gift from Berlin and the label "Solanum (Morella) arequipense Bitt. / 1912 Bitter" is in Bitter’s handwriting.

No herbaria were cited in the protologue of the descriptions of any of the four varieties of S. furcatum described by Nees von Esenbeck (1843) from the collections of Franz Meyen’s trip around the world (1831-32). The four taxa were distinguished based on leaf shape differences, a character notoriously variable in the Morelloid clade. Nees von Esenbeck (1843) cited two collections each for three varieties, mixing plants from the distributions of S. arequipense and S. furcatum (see discussion of S. furcatum ). The only one citing a single collection was S. furcatum var. subdentatum ( Nees von Esenbeck 1843). Franz Meyen’s herbarium from his South American travels was held in B and destroyed, and we have found no duplicates of these collections (see also S. furcatum ) nor were any specimens photographed by J.F. Macbride. We have chosen to neotypify Solanum furcatum var. subdentatum with a recent collection from near the single cited locality in Peru (Arequipa, Särkinen et al. 4099). Solanum furcatum var. subintegerrimum was based on collections from Copiapó in northcentral Chile and from the area around Volcán Tacora (border of Peru and Chile); we have not seen any collections from near Copiapó of either S. furcatum or S. arequipense , so we neotypify it with a collection from near the border of Peru and Chile at high elevation (La Torre 1890, USM acc. # 159556).

Figures

Figure 27. Solanum arequipense A flowering branch B fruiting branch C detail of abaxial leaf surface D detail of adaxial leaf surface E flower bud F dissected flower G fruit (A-G Saerkinen et al. 4095). Illustration by R. Wise. Previously published in Knapp et al. (2019: 67) as S. furcatum.

Figure 28. Solanum arequipense A habit B flowering branch C flowers and buds D developing fruits (A-D Saerkinen et al. 4084). Photos by P. Gonzales.

Figure 29. Distribution map of Solanum arequipense.