Solanum dillonii S. Knapp, 2010

Knapp, Sandra, 2010, New species of Solanum (Solanaceae) from Peru and Ecuador, PhytoKeys 1, pp. 33-52 : 37-39

Solanum dillonii S. Knapp sp. nov. Fig. 3

Latin

Species nova Solano ripario Ruiz & Pav. similis, sed trichomatibus multangulatis vel echinatis longistipitatis, foliis ad basibus acutis, floribus violaceis, differt.

Type.

Peru: Cajamarca: Prov. Celendin, on road from Celendin to Balsas, east of pass on descent to Balsas, 2002 m, 6°52.13S, 78°30.91W, 12 December 2007, S. Stern, E. Tepe, S. Leiva & M. Zapata 119 (holotype: USM!; isotypes: BM! [BM001016881], HAO†, NY! [NY 00986687], UT!).

Description.

Shrub or small tree, 4-8 m tall, branching in the upper part of the stems. Stems densely pubescent with multangulate to echinoid trichomes on multiseriate stalks 0.5-1 mm long, the rays> 12, 0.2-0.3 mm long, glabrescent; new growth densely pubescent with multangulate to echinoid trichomes on multiseriate stalks 0.5-1 mm long like those of the stems, greyish white. Bark of older stems reddish brown. Sympodial units plurifoliate, the branching dichasial. Leaves simple, 12-30 cm long, 4.5-16 cm wide, elliptic to broadly elliptic, discolorous, the upper surfaces evenly and moderately pubescent with 1-3-rayed sessile stellate trichomes, the rays 0.3-1 mm long, the trichome bases bulbous, the lamina clearly visible, the lower surfaces densely pubescent with of multangulate to echinoid trichomes on multiseriate stalks 0.5-1.5 mm long, the rays 10-16, to 1 mm long, these mixed with porrect-stellate trichomes with 8-10 rays on multiseriate stalks to 1 mm long, and sessile echinoid trichomes with weak rays to 0.3 mm long, the lamina not visible; primary veins 9-11 pairs, the veins drying yellowish green above, not visible beneath; base acute; margins entire, plane; apex acute; petioles 1.5-3 cm long, densely pubescent with multangulate to echinoid trichomes like those of the stems and leaf undersurfaces. Inflorescences terminal, 15-20 cm long, many times branched, with 100+ flowers, densely pubescent with multangulate trichomes of many sizes, the largest to 0.l8 mm in diameter, on multiseriate stalks to 1.5 mm, some smaller and sessile; peduncle 7-10 cm long; pedicels 7-9 mm long, ca. 2 mm in diameter at the base, 2.5-3 mm in diameter at the apex, stout, nodding at anthesis, densely pubescent like the inflorescence axes, articulated at the base; pedicel scars closely spaced ca. 1 mm apart. Buds globose, the corolla scarcely exserted from the calyx tube before anthesis. Flowers all perfect, 5-merous. Calyx tube 3-3.5 mm long, cup-shaped, narrowing gradually to the pedicel, the lobes 2.5-3 mm long, deltate, densely pubescent abaxially with multangulate to echinoid trichomes like those of the inflorescence rhachis, these more sessile distally, the adaxial surface sparsely pubescent with sessile echinoid trichomes. Corolla 1.3-1.5 cm in diameter, purple, stellate, lobed ca. ¾ of the way to the base, the lobes 6-7 mm long, 3.5-4.5 mm wide, reflexed or spreading at anthesis, the tips and margins densely pubescent on the abaxial surface with sessile or short-stalked multangulate to echinoid trichomes with>10 rays like those of the inflorescence, the adaxial surface glabrous or with a few echinoid trichomes near the apex on the midvein. Filament tube minute, the free portion of the filaments 2.5-3 mm long, glabrous; anthers 3-3.5 mm long, ca. 1 mm wide, ellipsoidal, loosely connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary densely pubescent with multangulate trichomes; style 9-9.5 mm long, sparsely pubescent along its entire length with multangulate trichomes with 4-8 rays; stigma clavate, the surface minutely papillose. Fruit a globose berry, 1-1.5 cm in diameter, dark green when ripe, the pericarp thin, not shiny, unevenly pubescent with sessile or short-stalked multangulate trichomes with rays of many varying lengths, the longest rays ca. 1 mm long; fruiting pedicels 1.2-1.5 cm long, ca. 3 mm in diameter at the base, woody, more or less erect. Seeds>200 per berry, 1.5-2 mm long, 1-1.5 mm wide, flattened-reniform, reddish or golden brown, the surfaces minutely pitted.

Distribution.

Southern Ecuador (Prov. Loja) and northern Peru (Dept. Cajamarca), in the Amotape-Huancabamba phytogeographic zone (see Weigend 2002, 2004) ( Fig. 2 ).

Ecology.

Tropical moist forest along the western slopes of the Andes and the valley of the Río Marañon, from 1500-2200 m. Often found along roads and small streams in secondary situations.

Etymology.

Named in honor of Michael O. Dillon, recently retired from the Field Museum of Natural History in Chicago, who has devoted much time and energy to the understanding of the flora of northern Peru and whose efforts collecting in the Monteseco region helped define the extent of this species' distribution.

Preliminary conservation status.

Solanum dillonii is relatively widely distributed in the Amotape-Huancabamba region, and has an EOO of 22,492 km2, giving a status of possible Near Threatened, and an AOO (with cell size of 0.04 km 2) of 10,541 km2, giving a status of Least Concern ( IUCN 2001). Using a cell size of 2 km2 gives an AOO of 28 km2, resulting in an assessment of Endangered. Given that the species is of a partially secondary nature, growing in disturbed areas and along roads, I feel the status of possibly Near Threatened is the most realistic assessment for Solanum dillonii , but more collecting with population assessment will help refine this.

Specimens examined.

Ecuador: Loja: Vilcabamba-Yangana road km 1-3, 1500-1600 m, 4°18'S, 79°14'W, 29 October 1984, P.M. Jørgensen 56267 (AAU, BM [BM001012348], QCA); ca. 7 km E of Catamayo on the road to Loja, ca. 1700 m, 3°28'S, 79°10'W, 6 February 1984, S. Knapp & J. Mallet 6258 (BH, QCA, NY [NY00829072], US). Peru: Cajamarca: Prov. Santa Cruz, Dist. Catache, upper Río Zaña valley, ca. 5 km above Monte Seco on path to Chorro Blanco, 1500-2000 m, [6°52'S, 79°05' W], 16-18 March 1986, M.O. Dillon, A. Sagástegui A., D. Dillon, P. Alcorn, J. Santisteban, S. Leiva, C. Téllez & M. Guzmán 4379 (BM [BM000849416], F [F-1993682], NY [NY00829133]); Prov. Santa Cruz, ca. 3 km por aire ENE Monteseco, 1800 m, [6°52'S, 79°05'W], 31 May 1987, J. Santisteban C. & J. Guevara B. 125 (BM, NY [NY00829131]); Prov. Celendin, Marañon River valley, Chachapoyas-Cajamarca road, 1900-2100 m, [6°51'S, 78°04'W], 28 May 1984, D.N. Smith & J. Cabanillas 7257 (MO [MO-5294201], NY [NY00829129]); Prov. Cajamarca, Dist. San Juan, 2 km before town of San Juan, on road from Casamayo to Cajamarca, km 139 about 143 km southeast of Cajamarca, 2215 m, 7°17'08"S, 78°30'91"W, S. Stern, E. Tepe, S. Leiva & M. Zapata 109 (BM [BM001016880], HAO†, NY [NY00986682], USM, UT). La Libertad: Prov. Otuzco, alrededores de Huaranchal, 2140 m, [7°41'21"S, 78°26'51"W], 6 February 1999, A. Sagástegui, S. Leiva & V. Quipuscoa 11608 (BM [BM000935134]).

Discussion.

Solanum dillonii is superficially similar to the widespread Solanum riparium Ruiz & Pav. and to the more southerly Solanum conglobatum Dunal. It differs from Solanum riparium in its violet flowers, acute leaf bases and pubescence; both stem and leaf trichomes of Solanum dillonii are very long-stalked and multangulate, while those of Solanum riparium are sessile and tend to have more rays (tending to echinoid sensu Roe 1971). Both species have some porrect-stellate trichomes on the lower leaf surfaces. Solanum riparium occurs in a wide variety of tropical and premontane forests of the eastern Andean slopes, and Solanum dillonii , while to some extent (in the Río Marañon valley) sympatric with it, is a plant of the moist to dry forests of the western Andean slopes and inter-Andean valleys in the Amotape-Huancabamba phytogeographic zone ( Weigend 2002, 2004). Solanum dillonii is the species referred to as " Solanum erianthum vel. aff." in the checklist of the Monte Seco forest fragment ( Sagástegui and Dillon 1991). Solanum dillonii has also been misidentified as Solanum conglobatum , a species of dry forests from southern Peru and Bolivia. It is similar to Solanum conglobatum , with few-rayed trichomes on the upper leaf surfaces and dense abaxial leaf pubescence, but differs from that species in having multangulate rather than porrect-stellate trichomes abaxially and in not having an accrescent calyx in fruit.

Solanum dillonii is another species endemic to the Amotape-Huancabamba phytogeographic zone ( Weigend 2002, 2004); this region has been highlighted as a center of species richness and endemism in the Geminata clade (see Knapp 2002, Stern et al. 2009) of Solanum . The area is not only home to many endemics, such as Solanum dillonii , but is a zone of considerable overlap between northern and southern taxa.

Figures

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

Figure 3. Isotype specimen of Solanum dillonii S. Knapp. (Stern et al. 119, NY [NY 00986687]). 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).