Solanum sousae S. Knapp, 2010

Knapp, Sandra, 2010, Four New Vining Species of Solanum (Dulcamaroid Clade) from Montane Habitats in Tropical America, PLoS ONE 5 (5), pp. 1-8 : 6-8

Solanum sousae S. Knapp , sp. nov.

[urn:lsid:ipni.org: names:77103636-1]

Type: Mexico. Oaxaca: Mun. San Miguel Chimalapa , Cerro La Culebra , al N del Cerro Guayabitos , ca. 6 km línea recta al NO de Benito Juarez, ca. 42 km en línea recta al N de San Pedro Tapanatepec, 16 ° 459N, 94 ° 119W, 1600– 1800 m, 16–18 Jul 1986, S. Maya J. 3602 (holotype, MEXU-932219) .

Figure 5 .

Species Solano pyrifolio Lamarck similis, sed foliis aequaliter pubescentibus, lobis calycis minutis, antheris inaequalibus, differt.

Woody vine with trailing stems; stems sparsely pubescent with simple, uniseriate trichomes to 0.5 mm long, composed of 2–3 cells, the stems soon glabrescent; new growth densely pubescent with simple uniseriate trichomes, these whitish cream; bark of older stems pale greenish brown, glabrescent. Sympodial units plurifoliate. Leaves simple, 2.7–7(+) × 1–5 cm, narrowly ovate to elliptic, membranous, the upper surface glabrous to sparsely pubescent with simple, uniseriate trichomes on the lamina, more densely pubescent on the veins, the trichomes to 0.5 mm long, the undersurfaces almost glabrous to densely pubescent with simple, uniseriate trichomes to 0.5 mm long, these denser on the veins; primary veins 5–7 pairs, yellowish; base truncate to broadly acute; margins entire; apex acute to acuminate; petiole 1–4 cm, twining, glabrous or pubescent like the adjacent stem. Inflorescence 7– 10 cm long, terminal, many times branched, more or less broadly triangular in outline, with 30–40 flowers; peduncle 3–4 cm long, pubescent like the stems; pedicels 1–1.5 cm, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, nodding at anthesis, sparsely pubescent like the rest of the inflorescence, articulated near the base, leaving a small peg ca. 1 mm high, on the rhachis; pedicel scars spaced 0.1–0.5 cm apart, clustered near the tips of the inflorescence branches. Flowers all perfect, 5 merous; calyx tube 1.5–2 mm, conical, appearing striped from the thickened venation, the lobes, 0.5 mm, mere undulations on the margin of the tube, occasionally somewhat quadrate when sinus splitting, sparsely and unevenly pubescent with simple, uniseriate trichomes to 0.5 mm; corolla 1.5–2 cm in diameter, white, stellate to pentagonal stellate, lobed 1/2 to 3/4 of the way to the base, the lobes 5– 8 x ca. 4 mm, planar or slightly cupped at anthesis, densely pubescent-papillate with minute simple trichomes abaxially, glabrous adaxially; stamens with the filament tube minute, pubescent; free portion of the filaments 1.2–2 mm, very slightly unequal in some collections, pubescent near the base adaxially with tangled, simple uniseriate trichomes ca. 0.5 mm; anthers 2.5–3× 1–1.5 mm, yellow, ellipsoidal, poricidal at the tips, the pores lengthening to slits with age; ovary glabrous; style 7–9 mm, pubescent with simple uniseriate trichomes, 0.5 mm in the lower half; stigma capitate or somewhat bilobed, the surface densely papillate. Fruit a globose berry to 1.5 cm in diameter, green (immature?), the pericarp thin, matte; fruiting pedicels 1.5–1.7 cm, ca. 1.5 mm in diameter, woody and pendent. Seeds.50 per berry, ca. 2.5× 2 mm, flattened reniform, golden brown, the testal surface minutely pitted.

Distribution. Solanum sousae is known only from southern Mexico in the states of Puebla and Oaxaca, in mesophyllous forests and oak-pine- Liquidambar forests on steep slopes with rich soils, from 1600–1900 m.

Etymology. Solanum sousae is named in honour of Mario Sousa Sánchez (MEXU), whose dedication to the advance of knowledge of the Mexican flora has resulted in a whole new generation of Mexican botanists.

Preliminary conservation status. Solanum sousae is known from only three widely dispersed collections, none of which falls within a protected area. It must be considered at threat, but further collecting and observation are a priority.

Additional specimens examined. MEXICO. Oaxaca: Mpio. Santa María Chimalapa , Cerro de los Pavos , al N de Cerro Guayabitos y al O del Río Portemonedas , ca. 47 km en línea recta al N de San Pedro Tapanatepec , 16 ° 479N, 94 ° 109W, 22–23 Sep 1986, Maya J. 3938 ( MEXU). Puebla: Mpio. Atempan, Puente Viejo , 1900 m, 8 Jul 1986, Ventura A. 22129 ( MEXU) .

Solanum sousae is superficially similar to S. pyrifolium Lam. of Hispaniola, but differs from that species in its more broadly triangular inflorescence outline ( Fig. 5A ), minute calyx lobes without thickened margins ( Fig. 5B ) and in its lack of a prominent submarginal leaf vein. The leaf pubescence of the two species is very similar, but S. sousae is in general more densely pubescent on the new growth and abaxial corolla surfaces. Solanum sousae differs from the more common and sympatric S. dulcamaroides Poir. in its white flowers, generally simple pubescence (versus more commonly dendritic in S. dulcamaroides ), white rather than purple flowers, and in its anthers that are not markedly thickened and rounded abaxially.

It is likely that the juvenile leaves of S. sousae are pinnatifid, as are those of most other species in this group; young foliage is only very rarely collected and is often not associated with the flowering stems with simple leaves.

Figures

Figure 5. Solanum sousae. A) portion of stem with flowering inflorescence, B) flower, C) flower cross section, D) anthers, E) portion of stem with fruiting inflorecence. A–D drawn from Ventura 2212, E from Maya J. 3938. doi:10.1371/journal.pone.0010502.g005