Solanum sousae S. Knapp, 2010

Knapp, Sandra, 2013, A revision of the Dulcamaroid Clade of Solanum L. (Solanaceae), PhytoKeys 22, pp. 1-432 : 245-248

37. Solanum sousae S. Knapp , PLoS ONE 5(5): e10502. 2010 Figure 91

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˚45'N, 94˚11'W, 1600-1800m, 16-18 Jul 1986, Solanum Maya J. 3602 (holotype: MEXU [MEXU-932219]).

Description.

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(+) cm long, 1-5 cm wide, 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; petioles 1-4 cm long, glabrous or pubescent like the adjacent stem, twining. 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 long, 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. Buds narrowly ellipsoid, the corolla strongly exserted from the calyx tube. Flowers all perfect, 5-merous. Calyx tube 1.5-2 mm long, 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 rotate-stellate, lobed 1/2 to 3/4 of the way to the base, the lobes 5-8 mm long, ca. 4 mm wide, planar or slightly cupped at anthesis, densely pubescent-papillate with minute simple trichomes abaxially, glabrous adaxially. Filament tube minute, free portion of the filaments unequal, with 3 filaments 1-1.5 mm long and 2 filaments 1-5-2 mm long, pubescent near the base adaxially with tangled, simple uniseriate trichomes ca. 0.5 mm; anthers 2.5-3 mm long, 1-1.5 mm wide, ellipsoid, 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 long 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 long, ca. 1.5 mm in diameter, woody and pendent. Seeds>50 per berry, ca. 2.5 mm long, ca. 2 mm wide, flattened reniform, golden brown, the testal surface minutely pitted. Chromosome number: not known.

Distribution

( Figure 92 ). Solanum sousae is known only from southern Mexico in the states of Puebla, Oaxaca and Veracruz from 1600-1900 m.

Ecology.

Occurs in mesophyllous forests and oak-pine- Liquidambar L. ( Hamamelidaceae ) forests on steep slopes with rich soils.

Conservation status.

Near Threatened (NT); EOO <100,000 km2 (possible NT) and AOO <10,000 km2 (LC), with few populations. See Moat (2007) for explanation of measurements.

Discussion.

Solanum sousae is superficially similar to Solanum pyrifolium of Hispaniola, but differs from that species in its more broadly triangular inflorescence outline, minute calyx lobes without thickened margins, anthers borne on unequal filaments and in its lack of a prominent submarginal leaf vein. The leaf pubescence of the two species is very similar, but Solanum sousae is in general more densely pubescent on the new growth and abaxial corolla surfaces. Solanum sousae differs from the more common and sympatric Solanum dulcamaroides in its white flowers, generally simple pubescence (versus more commonly dendritic in Solanum 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 Solanum 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.

Specimens examined.

Mexico. Oaxaca: San Miguel Chimalapa, Cerro La Culebra, al N del Cerro Guayabitos, ca. 6 km linea recta al NO de Benito Juarez, ca. 42 km en linea recta al N de San Pedro Tapanatepec, 1600 m, 16 Jul 1986, Maya J. 3602 (MEXU); Santa María Chimalapa, Cerro de los Pavos, al N de Cerro Guayabitos y al O del Rio Portemonedas, ca. 47 km en linea recta al N de San Pedro Tapanatepec, 22 Sep 1986, Maya J. 3938 (MEXU); Puebla: Atempan, Puente Viejo, 1900 m, 8 Jul 1986, Ventura A. 22129 (MEXU); Veracruz: Mun. Jalacingo, Agua Cruz, 1600 m, 5 May 1970, Ventura A. 1022 (NY).

Figures

Figure 91. Solanum sousae S. Knapp. (A-D drawn from Ventura 2212, E from Maya J. 3938). Originally published in Knapp (2010). Illustration by Bobbi Angell.

Figure 92. Distribution of Solanum sousae S. Knapp.