Solanum stellaticalycinum M. A. Cueva, Treviño & D. Sotomayor, 2025

Cueva Manchego, Marco A., Treviño, Italo F., Sotomayor, Diego A., Villalba, María I. & Knapp, Sandra, 2025, Solanum stellaticalycinum, a new simple-leaved species of the Pteroidea clade from Peru (Potato Clade, Solanum, Solanaceae), PhytoKeys 266, pp. 117-128 : 117-128

Solanum stellaticalycinum M. A. Cueva, Treviño & D. Sotomayor sp. nov.

Figs 1 , 2 , 3

Diagnosis.

Solanum stellaticalycinum differs from all other species of the Pteroidea clade in its calyx with narrow linear lobes and corolla with narrow lanceolate lobes with elongate, acuminate apices that are spreading at anthesis. It differs from the sympatric S. anceps Ruiz & Pav. in its larger flowers and fruits on pendent rather than erect pedicels, and from S. mite Ruiz & Pav. and S. conicum Ruiz & Pav. in its simple, rather than deeply pinnatifid, leaves.

Type.

Peru • Pasco: Prov. Oxapampa, Distrito de Huancabamba, Parque Nacional Yanachaga-Chemillén, Sector Abra Yanachaga, camino hacia parcela , 10°22'48"S, 75°27'45.25"W, 2,880 m, 2 Oct 2009, M. Cueva, A. Monteagudo, A. Peña, J. Mateo, R. Rivera & V. Peña 645 ( holotype: HUSA [acc. # 10917]; isotypes: USM [acc. # 253156], HOXA, MO [ MO-4348867 , acc. # 7105417], HUT) .

Description.

Erect, single-stemmed herbs or subshrubs, 0.4–2 m tall. Stems 0.4–1.3 cm in diameter, terete; young growth minutely papillose glandular; internodes 0.7–1.2 cm long, brownish green, pubescent with whitish gray 7-8 - celled simple uniseriate trichomes 0.5–0.7 mm long; older internodes 1.3–2.7 cm long, glabrous or glabrescent, dark brownish green. Sympodial units unifoliate. Leaves simple, entire; blades 7–10 cm long, 1.6–4.3 cm wide, elliptic to ovate, membranous, discolorous, both surfaces glabrous or with a few simple uniseriate trichomes ca. 0.5 mm long along the veins and minutely papillate with tiny glandular hairs; adaxial surface dark green and shiny (dark brown when dry); abaxial surface pale green or with purple veins (yellowish brown when dry); principal veins 9–10 pairs, slightly raised on the abaxial surface; base cuneate to attenuate; margins entire; apex acute to acuminate; petioles 0.4–1.2 cm long, green or purple, glabrous, with tiny papillae like those of the stems and leaves. Inflorescences axillary scorpioid cymes, (7 –) 10–25 mm long, with 4–13 flowers generally inserted in the distal 1 / 3 of the axis, 1–4 flowers open at a time; peduncle 6–17 mm long, dark purple, shiny, glabrous or glabrescent, with papillate trichomes like those of stems and leaves; pedicels 10–14 (– 16) mm long at anthesis, ca. 0.8 mm in diameter at the base widening to ca. 2 mm in diameter at the apex, dark purple, glabrous or with some dispersed simple uniseriate trichomes like those of the stems and leaves, articulated at the base, deflexed at maturity so the flowers face downwards; pedicel scars slightly raised, closely spaced. Buds tapering-ellipsoid, enclosed within the linear calyx lobes. Flowers 5 - merous, cosexual. Calyx with the tube obconical, ca. 2 mm long, 3–3.4 mm in diameter, dark purple, shiny, glabrous or sparsely white-pubescent with 6-7 - celled simple uniseriate trichomes up to 0.4 mm long and some tiny papillae, the lobes (2 –) 3.5–4.5 mm long and 0.5 mm wide, linear to narrowly triangular, dark purple with white or green margins, glabrescent with whitish 6-7 - celled simple uniseriate hairs abaxially, brown-glandular papillae on the proximal half and extending towards the distal portion of the calyx tube adaxially. Corolla 17–20 mm in diameter at anthesis, deeply stellate, divided almost to the base, the lobes 8–11.5 mm long, ca. 2 mm wide, lanceolate, spreading at anthesis, membranous, white with dark purple spots, the margins puberulent with 1-3 - celled simple uniseriate hairs, less than 0.2 mm long, both surfaces glabrous, the apex elongate-acuminate. Stamens equal; filament tube minute; free portion of the filaments ca. 1.5 mm long, glabrous, white; anthers 3–4 mm long, 1.5–2 mm wide, oblong to oblong-ellipsoid, yellow, poricidal at the tips, the pores introrse, lengthening to slits with age. Ovary conical ca. 5 mm long and 1 mm in diameter, glabrous; style 6–6.5 mm long, ca. 0.5 mm in diameter, exserted 2.5–3.5 mm beyond the anthers, white, straight, densely pubescent in the basal half with 1-3 - celled simple uniseriate hairs up to 0.2 mm long; stigma ca. 0.5 mm long, capitate and slightly bilobed, white, the surface minutely papillose. Fruit an ovoid-conical berry, 1.3–2.1 (– 2.7) cm long, 0.9–1.3 (– 1.7) cm in diameter, yellowish green, the pericarp shiny, smooth or slightly rugose; fruiting pedicels 1.7–1.8 cm long, deflexed to pendent, the calyx persistent, the lobes 3–4 mm long, linear to narrowly triangular. Seeds 18–27 per berry, ovoid-reniform, ca. 3 mm long, 2.5 mm wide, brownish green, the testal cells deeply sinuate, with anticlinal walls ca. 10 µm in thickness; stone cells absent. Chromosome number: not known.

Distribution

(Fig. 4 ). Solanum stellaticalycinum is endemic to the Department of Pasco (Prov. Oxapampa) in Peru. All specimens have been collected in the Yanachaga-Chemillén National Park and surrounding areas (Fig. 4 ), in the sectors of Abra Yanachaga, San Alberto and Chacos.

Ecology and habitat.

Solanum stellaticalycinum grows as a single stemmed herb (Figs 1 A , 2 A ) in the understory of primary montane forests, often close to the somewhat open borders of rural paths, between 2,399 and 3,000 m elevation. Plants have been collected in flower between August and November (Fig. 1 A ), and fruiting specimens in April and October. It is likely that these plants bloom irregularly all year round, as do many other solanums from similar habitats.

Etymology.

The species epithet refers to the shape of the calyx, which is like a star (see Figs 1 , 2 ). This character is not present in any other species of the Pteroidea clade.

Preliminary conservation status

( IUCN 2022). Solanum stellaticalycinum is here assigned a preliminary threat status of Endangered (EN), using the criteria B 1 ab (i, iii). It is only known from three localities, and the known range (EOO) is approximately 111.9 km 2. It is likely that this species is distributed along the entire extension of the Yanachaga range, which occurs within the Yanachaga-Chemillén National Park, an area protected by the Peruvian government. It possible however, that in the future, the area of occupancy of this species will shrink in response to habitat modification resulting from human activities in buffer zone areas of the park.

Additional specimens examined

( paratypes). Peru • Pasco: Prov. Oxapampa: Dist. Oxapampa, Yanachaga-Chemillén National Park, San Alberto sector, surroundings of Refugio el Cedro , 2483 m, 10°32'43.3"S, 75°21'29.5"W, 26–27 Apr 2009, M. Cueva & R. Rivera 614 ( USM) ; New highway between Oxapampa-Bosque Shollet-Villa Rica , 2399 m, 25 Oct 2013, M. Cueva & S. Smith 1700 ( HUSA) ; • Dist. Huancabamba, Abra Yanachaga, Yanachaga-Chemillén National Park , 2900–3000 m, 10°22'46"S, 75°27'43"W, 23 Nov 2004, A. Monteagudo, A. Peña, J. Perea, R. Francis, J. L. Mateo & E. Becerra 7840 ( BM [ BM 015735503 ], HOXA [acc. # 00012525], USM, HUT, AMAZ, MOL, MO [ MO-2265895 , acc. # 6217980]) ; • Dist. Huancabamba, Abra Yanachaga, Yanachaga-Chemillén National Park , 2930 m, 10°22'46.3"S, 75°27'42.9"W, 03 Aug 2005, E. Ortiz & R. Francis 735 ( HOXA [acc. # 00018108], USM, MO [ MO-1662368 , acc. # 4824338]) .

Discussion.

Solanum stellaticalycinum is not easily confused with any other species of Pteroidea . The flowers with linear calyx lobes alternating with the lanceolate corolla lobes (Fig. 1 D ) are unique in the clade, and unusual in Solanum overall. It shares membranous corollas, conical ovoid fruits with smooth or rugose surfaces, and ovoid reniform seeds with irregularly shaped testal cells with sinuate anticlinal walls (Fig. 3 ) with other members of the S. mite species group (sensu Knapp and Helgason 1997), where only S. anceps and S. angustialatum have simple leaves. The other six known taxa in the S. mite group ( S. conicum , S. chamaepolybotryon , S. mite , S. savanillense , S. trizygum and S. uleanum ) have compound imparipinnatifid leaves with three or more leaflets ( Knapp and Helgason 1997). Solanum anceps and S. angustialatum are morphologically similar and both differ from S. stellaticalycinum in their whitish green pedicels 4–7 mm long (versus purple pedicels 10–14 mm long, Figs 1 E , 2 B, C ), very small flowers with delate calyx lobes up to 1 mm long (versus linear calyx lobes 3.5–4.5 mm long, Figs 1 C, F , 2 ), corollas at anthesis 3–10 mm in diameter with very reflexed membranous triangular lobes 3–5 mm long (versus corolla at anthesis 17–20 mm in diameter, with extended, membranous, narrowly lanceolate lobes 8–11.5 mm long, Figs 1 C – F , 2 B, C, G and anthers ca. 2 mm long (versus 3–4 mm long in S. stellaticalycinum , Fig. 2 E ).

Solanum stellaticalycinum is also somewhat similar to the sympatric S. incurvum from the S. ternatum group (sensu Knapp and Helgason 1997). Solanum incurvum differs from S. stellaticalycinum in its calyx with deltate lobes ca. 1 mm long (versus linear lobes 3–4 mm long), a larger fleshy corolla generally 23–25 mm in diameter with triangular lobes (versus membranous corollas 10–14 mm in diameter), and in its globose smooth fruits with flattened reniform seeds (versus conical fruits with ovoid reniform seeds in S. stellaticalycinum ). Some of the examined individuals of S. anceps and S. incurvum exhibit variation regarding fruit texture and corolla consistency. Some specimens of S. anceps develop smooth ovoid fruits with only slight whitish rugosities, similar to those seen in some specimens of S. stellaticalycinum , but the pedicels are still short and erect rather than pendent, and corolla diameter does not exceed 10 mm in diameter. In some individuals of S. incurvum , the corollas can develop a membranous consistency, and fruits can be ovoid (and somewhat flattened) in the first stages of their development, but the deltate or triangular shape of both calyx and corolla lobes, as well as the flattened reniform seeds are distinctive. Morphological differences amongst the simple-leaved species of Pteroidea are summarized in Table 1 .

Figures

Figure 1. Solanum stellaticalycinum M. A. Cueva, Treviño & D. Sotomayor. A, B. Habit; C. Inflorescence; D. Flower at full anthesis; E. Floral buds; F. Fruit (M. Cueva et al. 645). Photos by M. A. Cueva.

Figure 2. Solanum stellaticalycinum. A. Habit; B. Inflorescence; C. Flower; D. Floral dissection; E. Anther detail; F. Gynoecium detail. G, H. Fruit longitudinally dissected to reveal seeds (based on M. Cueva et al. 645). Illustration by Maria I. Villalba.

Figure 3. Images of the seed coat using SEM from Solanum stellaticalycinum. A. Whole seed; B. Testal cell shape detail. Scale bar in image.

Figure 4. Distribution of Solanum stellaticalycinum. Abbreviations: Yanachaga-Chemillén National Park (PNYCH), Buffer Zone (ZA), Reserva Comunal Yanesha (RCY), Bosque de Protección San Matías San Carlos (BPSMSC).