Solanum oxapampense S. Knapp, 2010

Knapp, Sandra, 2010, New species of Solanum (Solanaceae) from Peru and Ecuador, PhytoKeys 1, pp. 33-52 : 39-41

Solanum oxapampense S. Knapp sp.nov. Fig. 4

Latin

Species nova Solano verecundo M. Nee similis, sed foliis coriaceis superne nitidibus, subtus valde pubescentibus, trichomatibus peltatis, differt.

Type.

Peru: Pasco: Prov. Oxapampa, Oxapampa-Villa Rica road, 7 km from road head, 2120 m, 10°36'S, 75°20'W, 4 January 1984, D.N. Smith & J. Albán 5558 (holotype: USM! [USM-123391]; isotypes: MO! [MO- 5784802], NY! [NY00723838]).

Description.

Treelet to small tree, 2.5-9 (-18) m tall, branching in the upper part of the stems. Stems densely pubescent with persistent short-stalked peltate trichomes 0.2-0.4 mm in diameter, the rays 20-30, fused for almost their entire length, the midpoint absent, the trichome center dark reddish brown; new growth densely pubescent with peltate trichomes like those of the stems, drying pale beige. Bark of older stems pale brownish tan from the persistent trichomes. Sympodial units plurifoliate, the branching dichasial. Leaves simple, 6.5-16 cm long, 2-5 cm wide, narrowly elliptic, coriaceous, strongly discolorous, the upper surfaces glabrous and shiny, dark green when fresh, drying dark olive green, the lower surfaces densely pubescent with short-stalked peltate trichomes to 0.5 mm in diameter with>20 rays, subtended by a dense layer of tangled sessile echinoid trichomes ca. 0.1 mm long, the lamina not visible; primary veins 16-20 pairs, deeply impressed above, densely covered by pubescence beneath; base acute; margins entire, revolute; apex acute to acuminate; petioles 0.6-2 cm long, densely pubescent with peltate trichomes like those of the stems and leaf undersurfaces. Inflorescences terminal, 8-15 cm long, many times branched, with 60+ flowers, densely pubescent with peltate trichomes like those of the stems; peduncle 3-6 cm long; pedicels 5-8 mm long, ca. 1.5 mm in diameter at the base, ca.2 mm in diameter at the apex, stout, nodding at anthesis, densely pubescent like the inflorescence axes, articulated at the base; pedicel scars closely and more or less regularly spaced ca. 1 mm apart. Buds globose, the corolla exserted about halfway from the calyx tube just before anthesis. Flowers all perfect, 5-merous. Calyx tube 1.5-2 mm long, cup-shaped, narrowing gradually to the pedicel, the lobes 1.5-2 mm long, deltate, densely pubescent abaxially with peltate trichomes like those of the inflorescence rhachis, the adaxial surface sparsely pubescent with sessile echinoid trichomes. Corolla 1.2-1.5 cm in diameter, white, stellate, lobed ca. ¾ of the way to the base, the lobes 6-7 mm long, 4-4.5 mm wide, reflexed at anthesis, the tips and margins densely pubescent on the abaxial surface with peltate trichomes with>20 rays like those of the inflorescence, the adaxial surface glabrous, the tips and margins with a few sessile echinoid trichomes. Filament tube 0.5-1 mm long, the free portion of the filaments 1-1.5 mm long, glabrous, with tiny projections ca. 0.5 mm long on edge of tube between each filament; anthers 3-4 mm long, 1-1.5 mm wide, ellipsoidal, loosely connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary densely pubescent with multangulate to echinoid trichomes; style 9-9.5 mm long, densely pubescent along its entire length with multangulate to echinoid trichomes with 4-30 rays ca. 0.2 mm long; stigma capitate, the surface minutely papillose, bright green in fresh plants. Fruit a globose berry, 0.6-0.7 cm in diameter, green when ripe, the pericarp thin, not shiny, unevenly pubescent with multangulate or echinoid trichomes with rays of many varying lengths, appearing scurfy; fruiting pedicels 1-1.1 cm long, ca. 1.5 mm in diameter at the base, woody, more or less erect. Seeds 40-50 per berry, 0.9-1 mm long, 0.9-1 mm wide, flattened-reniform, reddish or golden brown, the surfaces minutely pitted, the testal cells elongate.

Distribution.

Endemic to the valley of the Río Huancabamba ( Río Pozuzo) in central Peru; found within the Parque Nacional Yanachaga-Chemillen ( Fig. 2 ).

Ecology.

Montane forests from 1500 to 2500 m elevation; as with many members of the Brevantherum group, often found along roadsides and in open areas.

Etymology.

Named for the valley of Oxapampa, where this species is endemic.

Preliminary conservation status.

Solanum oxapampense is known from only 4 localities, has an EOO of 198 km2 and AOO (using a cell size of 0.04) of 195 km2; giving it a status of Endangered ( IUCN 2001). If the IUCN (2001) recommended cell size is applied the AOO is reduced to 16 km2; the status remains Endangered.

Specimens examined.

Peru: Pasco: Prov. Oxapampa, Dist. Huancabamba, camino a Pozuzo, 1200-1400 m, 10°04.02S, 75°32.59W, 2 June 2004, R. Rojas, M. Huaman, A. Peña & J. Mateo 2490 (MO, NY [NY00824860], USM); Prov. Oxap ampa, Dist. Oxapampa, Parque Nacional Yanachaga-Chemillen, Sector Chacos, 2471, 10°37'S, 75°17'W, 24 January 2004, R. Vasquez, A. Monteagudo, A. Peña & R. Francis 28939 (MO, NY[NY00829065], USM); Prov. Oxapampa, Dist. Oxapampa, Oxapampa-Villa Rica road, 2300 m, 10°39.59S, 75°19.33W, 22 November 2007, E. Tepe, S. Stern, J. Mateo, M.P. Moreno, R. Rojas 2227 (BM [BM001017349], USM, UT).

Discussion.

Solanum oxapampense is a very distinctive species with its coriaceous and strongly discolorous leaves, with the upper surfaces dark green and shiny and the veins deeply impressed, and the lower surfaces densely pubescent with pale tan peltate trichomes. It is similar to Solanum verecundum M. Nee with which it is broadly sympatric, but does not apparently co-occur. Solanum verecundum is found along the eastern slopes of the Andes from Ecuador to southern Peru, Solanum oxapampense is possibly derived from it. The two species share trichomes that are peltate to some degree, small white flowers and small fruits (orange in Solanum verecundum , apparently green at maturity in Solanum oxapampense ). Solanum oxapampense differs from Solanum verecundum in its coriaceous, narrower leaves and in its pubescence, which is composed of truly peltate trichomes whose rays are fused for more than half their length and that lack midpoints. Trichomes of Solanum verecundum have rays that are only fused in the central half, near the midpoint; midpoints are always present, even if sometimes very small and nub-like.

In the original description of Solanum verecundum ( Nee 2000), the plant illustrated in Figure 1 is Smith & Albán 5558 the type specimen selected here for Solanum oxapampense , not Jaramillo et al. 13285, the type specimen of Solanum verecundum as indicated in the text of Nee (2000). Smith and Albán 5558 is the only specimen of the species here recognised as Solanum oxapampense to have been included in the original circumscription of Solanum verecundum ; an emended description of that species excluding this element is presented below and diagnostic characters separating the two are presented above.

Neither Solanum oxapampense nor Solanum verecundum would have been included in section Brevantherum by Roe (1972) due to their possession of peltate trichomes, despite the overall habit and inflorescence morphology. Nee (2000) mentioned this in the original description of Solanum verecundum (see below). Molecular data show these groups (the traditional sections Brevantherum and Lepidota (Dunal) Seithe) to be members of the same clade, defined by having ellipsoid anthers and variations on stellate trichomes (some of which have lost the rays altogether, e.g., section Gonatotrichum Bitter, see Stern and Bohs 2009).

Figures

Figure 2. Distribution of Solanum kulliwaita (circles), Solanum dillonii (triangles) and Solanum oxapampense (squares).

Figure 4. Isotype specimen of Solanum oxapampense S. Knapp. (Smith & Alban 5558 NY [NY 00723838]). Specimen image reproduced with the permission of The C. V. Starr Virtual Herbarium of The New York Botanical Garden (http: // sciweb. nybg. org / science 2 / VirtualHerbarium. asp).