Solanum dolichorhachis, Bitter, Repert., 2011

Tepe, EJ & Bohs, L, 2011, A revision of Solanum section Herpystichum, Systematic Botany 36 (4), pp. 1068-1087 : 1076-1077

3. SOLANUM DOLICHORHACHIS Bitter,

Repert. Spec. Nov. Regni Veg. 11: 490. 1913.

—TYPE: ECUADOR. Guayas: Balao , “in silvestris, rarium,” May 1892 (fl, fr), H. Eggers 14641 (holotype: M–M0111203 !; isotypes: A–GH00077619!, B [destroyed], L–L0403275!, LE [photo!], US –1324515!, WU!; photo of Bisotype [F neg. 2658]: G–G00080131!).

Scandent shrub or liana, climbing to 8 m or more. Stems slender, wiry-woody, glabrous to moderately pubescent with trichomes 0.1–0.2 mm long, these frequently in distinct lines along stem. Sympodial units plurifoliate. Leaves simple, the arrangement distichous, the blades 4.4–11 × 1.3–4.5 cm, 2–3 times as long as wide, ovate to elliptical, chartaceous to coriaceous to somewhat fleshy, glabrous to moderately pubescent on the midvein adaxially, glabrous abaxially; venation pinnate, with ca. 5 pairs of secondary veins, the veins sand-punctate; base oblique, sides of the lamina 3–4 mm distant on the petiole, the two sides rounded to truncate to somewhat cordate; margins entire; apex acuminate; petioles 0.2–0.6 cm, moderately pubescent adaxially, sandpunctate. Internodes 0.7–2.8 cm. Inflorescences 3–55 cmlong, unbranched, terminal to extra-axillary to nearly leaf-opposed, with 14–116 flowers (scars), the axes slender, densely pubescent; peduncle 2–5 cm; rachis 2–49 cm; pedicels 5–6 mm in flower, slender, 13–14 mm in fruit, glabrous to minutely pubescent, spaced 1.5–8 mm apart. Calyx 1.5–2 mm long, membranous, sparsely pubescent, sand-punctate, the tube ca. 1 mm long, the lobes 0.5–1 × ca. 2 mm, broadly rounded, rounded to shortly acuminate at tips; fruiting calyx not accrescent. Corolla 0.7–1 cmindiameter, 3–5 mm long, stellate, membranous, white to greenish-white, the lobes 3–4.5 × 1.5–2 mm, lanceolate, acute at tips, reflexed at maturity, glabrous adaxially, pubescent along center of petal abaxially, the margins ciliate. Stamens with filaments 0.5–1 mm long, glabrous; anthers ca. 2.5 × 1 mm. Ovary glabrous; style 3–4 × ca. 0.3 mm, clavate, glabrous; stigma capitate. Fruits (immature) 9–18 × 4–6 cm, 2–3 times as long as wide, spindle-shaped to possibly cordate, pointed at apex, the color unknown, glabrous. Seeds unknown. Figure 2C .

Habitat and Distribution— Solanum dolichorhachis occurs in the Pacific and Amazonian lowlands of Ecuador and in the Amazonian lowlands of Peru; 50–350 m in elevation. ( Fig. 5 )

Phenology— Flowering specimens have been collected in Apr. and Dec.; fruits have been collected in Apr.

Conservation Status— According to the IUCN red list categories ( IUCN 2010), S. dolichorhachis is classified as B1a+biii (critically endangered). This species is only known from five widely scattered locations, two of which are in western Ecuador, an area that continues to experience extreme habitat degradation ( Dodson and Gentry 1991). The location at Limoncocha is in the center of an oil field, continued development of which is encroaching on all sides of the 4,600 ha Reserva Biológica Limoncocha (E. J. Tepe, pers. obs.). Despite its broad distribution, only five collections of this species are known, suggesting that it occurs at low densities, and appears to have been rare even at the time of collection. The label on the type specimen notes in silvestris, rarium (and in silvis rarissimum on some of the isotypes). Solanum dolichorhachis was collected near the Laguna de Limoncocha near the Río Napo in 1974 (B. A. Drummond III 7329, MO); however, EJT was unable to relocate this species during a five day visit to the Reserva Biológica Limoncocha in 2009.

Montúfar (2000) listed S. dolichorhachis as a critically endangered species endemic to Ecuador. If the Peruvian collection is, in fact, a population of S. dolichorhachis (see below), then the species is more widespread than previously believed. Nevertheless, based on the number of collections available for this species, we believe that it is critically endangered, especially in western Ecuador where the type was collected and which has experienced tremendous habitat destruction.

Etymology— The epithet dolichorhachis refers to the long, slender inflorescences of this species.

Notes— Solanum dolichorhachis is a climbing species recognizable by the long and slender inflorescences, small stellate flowers, spindle-shaped fruits, and the simple, usually large leaves with distinctly oblique bases. This species is most similar to S. pacificum , but the wiry-woody stems, densely shortpubescent inflorescences and young stems, and oblique leaf bases set this species apart.

The label from the type collection describes the fruits as cordate (fructu cordato). It is difficult to know what Eggers saw in three dimensions based on the single fruit on the isotype at A, but Egger’s notes suggest that the fruits may have been flattened and, therefore, possibly somewhat like those of the ground-trailing species in shape (i.e. Figs. 1B–C ).

The collections of this species from eastern Ecuador differ somewhat from the type in that they have longer pubescence, darker stems that are densely sand-punctate (vs. light tan, non-punctate stems), inflorescences with less dense and coarser pubescence, and non-punctate calyces. The Peruvian collection is closer to the type in leaf shape than collections from eastern Ecuador, but the plant appears to be rather fleshy. It is possible that the two variants from the regions east of the Andes merit recognition at the species level; however, they have no unambiguous, qualitative differences and, since this species has been collected few times, there is currently insufficient material upon which to base further taxonomic decisions.

Additional Specimens Examined— ECUADOR. Los Ríos: Near Quevedo, Canton Vinces, Hacienda San José, 0°30’S 79°21’W, 50 m, 28 Oct 1934 (fl), Y. Mexia 6617 (UC, US). Sucumbíos: Limoncocha on Río Napo, 0°23′15”S 76°36′35″W, 300 m, 1 Oct 1974 (fr), B. A. Drummond III ( MO). Orellana: Parque Nacional Yasuni, Río Tiputini, al noroeste de al confluencia con el Río Tivacuno, 0°38’ S 76°30’ W, 200–300 m, 25 Apr 2002 (fl), G. Villa et al. 1461 (BM, F).

PERU. Loreto: Maynas, Indiana, Reserva Explorama, 3°28’S 72°50’W, 106 m, 9 May 1990 (fl), R. Vásquez & N. Jaramillo 13680 (MO, NY).

Figures

FIG.2. Flowers, fruits, and habit of Solanum sect.Herpystichum. A. Solanum pentaphyllum, habit and flower (from O. Haught 2551, F). B. S. dalibardiforme, habit and flower (from K. von Sneidern 3121, US). C. S. dolichorhachis, habit, flower, and immature fruit (from F. H. Eggers 14641, A).

FIG. 5. Distribution of Solanum crassinervium, S. dalibardiforme, and S. dolichorhachis.

FIG.1. Flowers fruits, and habit of Solanum sect. Herpystichum: A. Solanum limoncochaense, habit, flower, and bud. B. S. limoncochaense fruit in situ and C. in cross section (E. J. Tepe & S. Stern 2627, QCNE). D. S. trifolium flower and leaf (E. J. Tepe & S. Stern 2682, QCNE). E. S. phaseoloides habit, flower, and leaf (photo by W. H. Haber). F. S. crassinervium habit (E. J. Tepe & S. Stern 2729, QCNE), and G. flowers (S. Stern & E. J. Tepe 400, QCNE). H. S. evolvulifolium habit and flower, and I. fruit (immature) (E. J. Tepe & S. Stern 2671, QCNE). J. S. pacificum inflorescence with flowers, buds, and fruit (immature), and K. habit (E. J. Tepe et al. 2696, QCNE). L. S. loxophyllum habit, note adventitious roots at nodes, and M. older stem with inflorescences, note figure eightshaped stem (E. J. Tepe & S. Stern 2726, QCNE). Inflorescences emerge from the cleft between the two lobes of the stem.