Solanum woodii Saerkinen & S.Knapp, 2016

Saerkinen, Tiina & Knapp, Sandra, 2016, Two new non-spiny Solanum (Solanaceae) from the Gran Chaco Americano and a key for the herbaceous glandular-pubescent solanums from the region, PhytoKeys 74, pp. 19-33 : 24-28

Solanum woodii Saerkinen & S.Knapp sp. nov. Fig. 3

Diagnosis.

Similar to Solanum tweedianum Hook., but differing in having shorter calyx lobes in flower (1.2-2.1 mm) and fruit (2.0-3.5 mm) and broadly ovoid anthers, and to Solanum physalifolium Rusby but differing in having long-triangular calyx lobes, shorter filaments 0.1-0.4 mm long, and broadly ovoid anthers.

Type.

Bolivia. Santa Cruz: Prov. Valle Grande, pasando el puente Santa Rosa, a 78 km desde Serrano hacia Valle Grande , 18°42.483'S, 64°17.585'W, 1169 m, 4 Apr 2003 (fl,fr), J.R.I. Wood 19616 (holotype: LPB) .

Description.

Decumbent, slender annual (fide labels) herb to 30-40 cm. Stems 1.0-5.0 mm in diameter, terete, much branching, pale yellow or greenish beige, glabrescent; new growth densely pubescent with spreading translucent 5-8-celled simple uniseriate glandular trichomes c. 0.5 mm long, some to 1 mm. Sympodial units difoliate, not geminate. Leaves simple, (2.3-)4.5-8.0 cm long, (1.5-)2.2-4.3 cm wide, elliptic to ovate, thin-membranous; adaxial surface moderately pubescent with spreading hairs as on stem evenly spaced along lamina and veins; abaxial surface more densely pubescent along veins; major veins 5-7 pairs; base attenuate to decurrent; margins entire to shallowly and unevenly toothed, the lobes narrow; apex acute; petiole 0.8-4.5 cm long, sparsely pubescent with simple 5-8-celled uniseriate trichomes like those of the stems. Inflorescences 1.5-3.0 cm long, simple, opposite the leaves, with (2-)3-7 flowers, sparsely pubescent with simple 5-8-celled uniseriate trichomes like those of the stems; peduncle 0.9-1.8 cm long, ca. 0.3 mm in diameter at the apex and ca. 0.5 mm in diameter at the base; pedicels spaced 0-1 mm apart, 0.7-1.1 cm long, ca. 0.2 mm in diameter at the base and ca. 0.3 mm in diameter at the apex, straight and spreading at anthesis, articulated at the base. Buds ovoid, white, the corolla strongly exerted from the calyx before anthesis, exceeding the lobes by up to two times their length. Flowers 5-merous, all perfect. Calyx tube 0.6-0.7 mm long, the lobes 1.2-2.1 mm long, 0.8-1.0 mm wide, ovate to elliptic in outline with acute apices, somewhat spreading at anthesis, sparsely pubescent with simple 5-8-celled uniseriate glandular trichomes like those of the stems. Corolla 1.0-1.5 cm in diameter, white with a greenish-purple central star at the base, stellate, lobed to the middle, the lobes 4.0-6.0 mm long, 2.0-3.0 mm wide, reflexed at anthesis, sparsely pubescent abaxially with very short 1-2-celled simple uniseriate eglandular trichomes. Stamens equal; filament tube ca. 0.5 mm long; free portion of the filaments 0.1-0.4 mm long, adaxially pubescent with 4-7-celled uniseriate eglandular trichomes; anthers (2.5-)3.0-3.8 mm long, 1.2-1.4 mm wide at base, ca. 0.5 mm at tip, tapering and narrowly triangular to triangular in outline, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary globose, glabrous; style 4.5-5.0 mm long, exerted 1.5-2.0 mm beyond the anther cone, curved at the very tip, densely pubescent with 2-3-celled simple uniseriate trichomes in the basal 1/3 where included in the anther cone; stigma minutely capitate, the surface papillate. Fruit a globose berry, 5-9 mm in diameter, green (immature), the pericarp thick and shiny; fruiting pedicels 0.7-1.0 cm long, ca. 0.5 mm in diameter at the base, ca. 0.6 mm in diameter at the apex, spaced 0-1 mm apart, spreading to recurved; fruiting calyx tube ca. 1 mm long, the lobes 2.0-3.5 mm long, spreading to reflexed. Seeds 15-30 per berry, 1.6-2 mm long, 1-1.5 mm wide, flattened, teardrop-shaped with a subapical hilum, yellow, the surface minutely pitted, the testal cells pentagonal in outline with the lateral cell walls elongate and the seeds from mature fruits appearing hairy. Stone cells absent.

Distribution

(Figure 4 ). Endemic to Bolivia in the Departments of Chuquisaca and Santa Cruz, growing in Chaco and Chaco forests of inter-Andean valleys, in dry Chaco woodlands on sandy and clay soils near water sources, rivers and in moist depressions in partial or full shade; between 300-1,800 m elevation.

Ecology.

Flowering and fruiting during the wet season from January-April.

Etymology.

The species epithet honours John R.I. Wood who has collected extensively in central and eastern Bolivia and mentored numerous young Bolivian botanists. Material collected by John throughout his career has been the basis for the description of many new species, and here we add yet another to that long list.

Conservation status.

The preliminary IUCN ( IUCN 2014) threat status of Solanum woodii is Vulnerable (VU, B1) based on the small extent of occurrence (EOO=19,656 km2). The area of occupancy is even smaller (AOO=36 km2) and would merit status as endangered (EN), but knowing that collection densities in this part of south-central Bolivia remain low and that the collections are mainly along the sparse road network, we prefer basing our assessment on the extent rather than area of occurrence. No occurrences are known within protected areas in Bolivia thus far.

Additional specimens examined.

Bolivia. Chuquisaca: Prov. Belisario Boeto, bajando de Nuevo Mundo hacia Santa Rosa, en dirección al Rio Grande , 18°55'37"S, 64°17'07"W, 1,350 m, 2 Mar 2006 (fl,fr), J.R.I. Wood 22341 (K) . Santa Cruz: Prov. Andrés Ibáñez, 5-8 km E-SE of Comunidad Don Lorenzo, nr Quebrada Caracoré, on rd to Estancia Caracore , La Bola area, 17°50'S, 62°50'W, 310 m, 4 Jan 1996 (fl,fr), M. Nee 46692 (MO, NY) . Prov. Caballero, El Canal , a 7 km N de Saipina, 18°00'20"S, 64°36'15"W, 1,500 m, 31 Mar 1994 (fl,fr), J. Balcázar 368 (MO); cerca de Pulquina hacia el Rio Mizque , ca. 2 km antes de llegar al primer cruce de río y ca. 1 km de la comunidad Witron , 18°05'57"S, 64°25'52"W, 1,562 m, 20 Feb 2007 (fl,fr), J.R.I. Wood 22840 (K) . Prov. Cordillera, along gravel rd eastward, just E of new highway from Santa Cruz to Abapó, the turnoff 3 km N of bridge over Rio Seco , 18°63'33"S, 63°23'33"W, 510 m, 19 Apr 1998 (fl), M. Nee 49056 (MO); floodplain and adjacent upland along the Río Seco, 1.5 km NW of highway at the town of Río Seco along rd to La Florida, 18°40'S, 63°15'W, 525 m, 24 Mar 2002 (fl), M. Nee 51967 (MO). Prov. Vallegrande, steep slopes of valley of the Río Grande, on rd from Pucará to the new bridge over the Rio Grande , 10 km (by winding road) NW of Puente Santa Rosa, 18°70'00"S, 64°28'33"W, 1,500 m, 29 Jan 1994 (fl), M. Nee 44742 (MO); bajando de Pucará hacia Santa Rosa del Rio Grande , 18°14'43"S, 64°16'00"W, 1,787 m, 6 Mar 2005 (fl,fr), J.R.I. Wood 21787 (K); La Higuera, bajando de Pucará al puente de Santa Rosa, 18°42'06"S, 64°16'23"W, 1,580 m, 18 Feb 2007 (fl,fr), J.R.I. Wood 22790 (K) .

Discussion.

Solanum woodii is unusual in having tapering, somewhat cone-shaped anthers with a beak-like tip (see Fig. 1C ); this character, however, can be difficult to see in older flower with dehisced anthers. Amongst other glandular-viscid herbaceous solanums it could be confused with Solanum tweedianum and Solanum physalifolium . Solanum woodii is sympatric with Solanum tweedianum but the latter species has longer calyx lobes in flower (3.5-5(-7) mm) and fruit (>5 mm), and slightly larger ellipsoid anthers (3.0-)4.0-4.5 mm long that are rectangular in outline (equally wide along their entire length) rather than broadest at the base; the calyx of Solanum tweedianum is accrescent and completely covers the berry at maturity, while that of Solanum woodii is spreading and does not become accrescent.

The unusual anther shape in Solanum woodii resembles that of the enigmatic Solanum anomalostemon S.Knapp & M.Nee described from the dry inter-Andean valley of the Rio Apurimac in southern Peru ( Knapp and Nee 2009). Solanum anomalostemon is morphologically unique within Solanum in having cordate anthers, and was thought to belong to the Morelloid clade ( Knapp and Nee 2009). Recent molecular phylogenetic evidence, however, showed it belongs to the Mapiriense clade ( Särkinen et al. 2015c), along with a small group of species that have similar tapering anthers (see Bohs 2005). Despite the similarity in anther shape, preliminary molecular data suggest Solanum woodii is a member of the Morelloid clade rather than closely related to Solanum anomalostemon and other members of the Mapiriense clade (T. Sarkinen, unpubl. data).

Figures

Figure 1. Solanum michaelis. A Fruiting stem B Inflorescence with details of indumentum of simple, multi-cellular eglandular and glandular trichomes along the stem, calyx and corolla C Flower at full anthesis with buds D Maturing fruit (A-D Nee & Flores 54821: photos by Michael Nee).

Figure 3. Solanum woodii. A Flowering stem B Inflorescence with details of buds, calyx and corolla C Flower at full anthesis (A-B Wood 21787; C Nee et al. 51967; photos by Gwen Davis).

Figure 4. Distribution map of Solanum woodii.