Solanum achorum S. Stern, 2010

Stern, Stephen & Bohs, Lynn, 2010, Two new species of Solanum (Solanaceae) from the Amotape-Huancabamba Zone of southern Ecuador and northern Peru, PhytoKeys 1, pp. 33-65 : 36-37

Solanum achorum S. Stern sp. nov. Figs 3 4

Latin

Solano megaspermo Agra et S. velutino Dunal affinis sed a S. megaspermo inflorescentiis paucifloribus et seminibus parvioris, a S. velutino calycibus parvioris differt.

Type.

Peru: Amazonas: Prov. Chachapoyas, road from Leimebamba to Chachapoyas, about 15 km N of Leimebamba along Río Utcubamba, 6°37'39"S, 77°48'44"W, 2050 m, 13 December 2007 (fl, fr), S. Stern et al. 129 (holotype: USM!; isotypes: BM001016783!, HAO! [destroyed], NY00986767!, UT!).

Description.

Erect to scandent shrub, 1-3 m tall. Stems armed with recurved, tan to orange roselike prickles to 2.5 mm in length, the base 2-3 × 0.5-1 mm, sparsely to moderately pubescent with rusty, porrect-stellate hairs, the stalks nearly absent to 0.2 mm, multiseriate, the rays 5-10, 0.2-0.3 mm, unicellular to multicellular, the midpoints nearly absent. Flowering portions of stem consisting of plurifoliate sympodial units, the leaves apparently not geminate. Leaves simple, the blades 6-20 × 2.5-11 cm, elliptic to ovate, chartaceous, discolorous, adaxially dark green, abaxially whitish green, the adaxial surface sparsely stellate-pubescent with hairs like those of the stem, the abaxial surface moderately to densely stellate-pubescent with hairs like those of the stem but white and with midpoints often gland-tipped, these mixed with multicellular, uniseriate glandular hairs 0.3-0.6 mm long; venation pinnate, the secondary veins 4-5 on both sides of the midvein, the midrib abaxially occasionally with sparse recurved spines like those of the stem; base obtuse, often asymmetrical; margin entire; apex acute; petioles 0.5-3 cm, moderately pubescent with hairs like those of the stem, occasionally armed with sparse recurved spines. Inflorescences 2-15 (20) cm, 2-5-branched, with 4-12 flowers, the plants andromonoecious, specifically androgynoecious ( Walker and Whelan 1991), with hermaphroditic flowers at the base of the inflorescence and occasionally with staminate flowers at the tip, the axes moderately to densely pubescent with hairs like those of the stem; peduncle 1-3 cm; rachis 3-5 cm; pedicels 4-15 mm in flower, 10-25 mm in fruit, erect, spaced 3-5 mm apart, articulated at the base. Calyx 3-6 mm long, the tube 1-3 mm, the lobes 2-4 × 1-2.5 mm, triangular, moderately to densely pubescent with hairs like those of the stem; fruiting calyx not accrescent, not completely covering the fruit. Corolla 2-3.5 cm in diameter, stellate with little to no interpetalar tissue, chartaceous to membranaceous, white, the tube 2-4 mm long, the lobes 10-15 × 3-5 mm, narrowly triangular-ovate, often reflexed, acute at apices, densely pubescent abaxially with white stellate hairs like those of the stem, glabrous to sparsely pubescent adaxially. Stamens 6-10 mm; filaments to 1 mm long, glabrous; anthers 6-10 mm × 1-2 mm, attenuate, connivent, yellow, the base cordate to obtuse, the apex acute to obtuse, the pores apical, not opening into slits. Ovary moderately pubescent with stellate hairs; style in functionally male flowers 3-6 × 0.5-1.5 mm, not exserted beyond stamens; style in hermaphroditic flowers 8-12 × 0.5-1.5 mm, exerted beyond stamens, cylindrical, moderately pubescent with stellate hairs; stigma 1.5-2 mm wide, capitate. Fruit a berry, 1.5-2 cm in diameter, globose, obtuse at apex, green and often mottled with white, often turning brown while still on plant, drying brown, moderately pubescent when young with gland-tipped stellate hairs like those of the stem but with rays often fused, these mixed with short simple glandular hairs, becoming glabrous to sparsely pubescent when mature. Seeds 25-50 per fruit, reniform, brown, rugose, 3-5 × 1.5-3.5 mm, the margin flattened with a swollen center.

Distribution.

Known from northern Peru in Depts. Amazonas and Cajamarca and southern Ecuador in Prov. Zamora-Chinchipe in disturbed open places in montane tropical forest, 700-2100 m in elevation.

Ecology.

Flowering specimens were collected in December; fruiting specimens were collected in July, October, and December.

Etymology.

The name Solanum achorum is derived from the Greek " achoros" meaning “homeless.” This name was chosen because of disagreement as to which group within Solanum subg. Leptostemonum this species belongs.

Conservation status.

According to the IUCN Red List Categories ( IUCN 2010) Solanum achorum is classified as VU- B2a+B2biii; D2 (Vulnerable). The extent of occupancy is estimated to be approximately 30,000 km2 with less than 10 collected locations. The conservation status of Solanum achorum is similar to that of Solanum rubicaule with respect to the potential of more unidentified specimens in herbaria, more specimens as a result of increased collecting efforts, and the difficulty of assessing future habitat as deforestation continues.

Specimens examined.

Ecuador: Zamora-Chinchipe: Cantón Chinchipe, Parroquía Zumba, Quebrada Tarrangamí, near cabin of Sandy León, W of Escuela Byron Jiménez, just S of Las Pircas, region of Guaramizal, 4°46'50"S, 79°12'33"W, 2000 m, 29 March 2005 (fr), L.Bohs et al. 3356 (LOJA, QCA, QCNE, UT); same locality, same date (fr), L.Bohs et al. 3358 (QCNE, UT); Cantón Valladolid, Parroquía Vallodolid, road between Valladolid and El Porvenir del Carmen, ca. 3 km from Valladolid en route to Tapala, 1600-1650 m, 4°33'27"S, 79°07'50"W, 1 April 2005 (fl), L.Bohs et al. 3380 (QCNE, UT); road between Zumba and Amaluza, 8-10 km W of Zumba, 1500-1700 m, 4°50'07"S, 79°09'50"W, 31 March 2005 (fl, fr), L.Bohs et al. 3367 (QCNE, LOJA, UT); along road between Zumba and Vilcabamba, 57.9 km N of Zumba, 9.2 km S of Santa Ana, 6.3 km N of Palanda, 4°36'39"S, 79°07'42"W, 1243 m, 28 July 2004 (fr), T.Croat 92480 (BM). Peru: Cajamarca: Prov. San Ignacio, Dist. San José de Lourdes, caserio Rumichina, limité con caserio Naranjos, 5°54'04"S, 78°36'09"W, 1811 m, 24 June 2006 (fr), J.Perea & V.Flores 2407 (BM); Prov. San Ignacio, Dist. San José de Lourdes, bosque alrededor de la comunidad, 5°06'16"S, 78°51'11"W, 1860 m, 10 October 2006 (fr), J.Perea & V.Flores 2799 (BM); Prov. San Ignacio, approximately km 115 on road from Jaen to San Ignacio, east side of hills dividing San Ignacio and Rio Chinchipe, 5°06'53"S, 78°59'16"W, 711 m, 17 December 2007 (fl, fr), S. Stern et al. 177 (BM, NY, USM, UT).

Discussion.

The plurifoliate sympodial units, ferruginous to reddish tomentum with stellate-glandular hairs, and large berries with large seeds and a pubescent exocarp identify Solanum achorum as a member of Solanum sect. Erythrotrichum . Additionally, parsimony analyses of sequence data from three molecular markers (nuclear ITS and waxy or GBSSI and chloroplast trnT-F) place Solanum achorum in this section; however, the relationships within the group are incompletely resolved due to a lack of taxon sampling and require further study (S. Stern and L. Bohs, unpub. data). The inflorescence structure of Solanum achorum , being branched with both hermaphroditic and staminate flowers, would place it in Agra’s (2008) subsect. Rhytidoandrum Agra; however, this relationship has not been tested phylogenetically using molecular data.

Of the 23 species of sect. Erythrotrichum that Agra (2008) recognized, only three occur in Peru, with one species, Solanum urubambaense Agra, endemic to southern Peru in the area around Cuzco. Solanum achorum can be distinguished from the two members of sect. Erythrotrichum occurring in northern Peru and southern Ecuador by a number of characters. It shares a similar vegetative appearance with Solanum megaspermum Agra, especially regarding habit, pubescence, and leaf shape; however, Solanum megaspermum has more robust inflorescences (> 30 flowers vs. 4-12 flowers in Solanum achorum ) and larger seeds (5-5.5 × 2-3 mm vs. 3-5 × 1.5-3.5 mm in Solanum achorum ). Solanum achorum also shares many characteristics with Solanum velutinum Dunal, including a scandent habit, similar pubescence, and similar-sized white corollas, but Solanum achorum has a branched inflorescence that can reach 20 cm versus inflorescences to 6 cm long in Solanum velutinum . The calyx lobes in Solanum achorum are 2-4 mm in length and not foliaceous while those of Solanum velutinum are commonly over 10 mm long and foliaceous.

Figures

Figure 3. Isotype of Solanum achorum S. Stern [Stern et al. 129 (UT)].

Figure 4. Photos of type collection of Solanum achorum S. Stern. A Hermaphroditic flower and buds. B Functionally male flower; note the absence of exserted style. C Inflorescence and immature fruits. Scale bars = 1 cm.