Columnea rubromarginata J. L. Clark & Clavijo, 2025

Clark, John L., Ballesteros, Sofía & Clavijo, Laura, 2025, Columnea rubromarginata (Gesneriaceae), a new species from the western Andean slopes of Colombia and Ecuador, PhytoKeys 268, pp. 201-210 : 201-210

Columnea rubromarginata J. L. Clark & Clavijo sp. nov.

Fig. 1

Type.

Colombia • Chocó, municipio San José del Palmar, western slopes of the Cordillera Occidental, Reserva Chococito , 4°52'45.99"N, 76°15'38.18"W, 800–950 m alt., 12 Aug. 2024 (fl. & imm. fr.), John L. Clark, Esteban Barco, Cristhian Cardona, Camila Davila, Jeison Pineda, Catalina Delgado, Sofía Ballesteros, Nelson Salinas & Laura Clavijo 19345 ( holotype: COL; isotypes: CUVC, G, HUA, JAUM, MO, NY, SEL! [barcode: SEL 095528 ], US) .

Diagnosis.

Vegetatively similar to Columnea purpurimarginata L. P. Kvist & L. E. Skog by the conspicuous, broad submarginal dark red band on the undersurface of the blades, but C. rubromarginata differs in having a red corolla tube with a yellow limb (vs. yellow corolla tube with white limb and red striations in C. purpurimarginata ) and linear calyx lobes nearly equaling the corolla tube (vs. broadly ovate, short calyx lobes covering only the base of the corolla tube).

Description.

Epiphytic or climbing herb to subshrub. Stem scandent, branched, terete in cross-section, 3.0– 6.5 mm diam., herbaceous to subwoody, green to yellow green, sparsely pilose at the base and densely pilose toward the apex, trichomes white, 2.0–3.0 mm long; internodes 1.5–3.2 cm long. Leaves opposite and anisophyllous; petiole of the larger leaf 0.3–0.7 cm long, terete, strigose, with multicellular, white trichomes, 2.0–3.0 mm long, becoming slightly hirsute when dry; larger blade oblanceolate, 13.5–27.0 × 3.5–7.6 cm, coriaceous, green adaxially, green abaxially with a dark red marginal band 2.0– 7.3 mm wide, apex acuminate, dark red abaxially, base oblique and rounded, margin sparsely serrate, sparsely to densely pilose on upper and lower surfaces with multicellular, branched, whitish trichomes, margin and the apex with dark red trichomes, blades with 8–13 pairs of secondary veins; smaller blade sessile linear to lanceolate, 1.7–2.0 × 0.8–0.9 cm, 2–3 pairs of main lateral veins, often caducous. Inflorescence reduced to 1–3 axillary single axillary flowers; peduncles absent; bracts 7.5–10.0 × 1.0– 1.7 mm, green with red apex, lanceolate, apex acuminate, base truncate, margin entire, both surfaces with multicellular, branched, whitish trichomes; pedicel erect 18–40 mm long, green, pilose, with multicellular, branched, transparent trichomes. Calyx lobes 5, fused basally for 1.9–2.5 mm, equal in length, mostly red on outer surface and green on inner surface, sometimes with the base green on outer and inner surfaces, 27.0–31.4 × 2.0– 2.9 mm, persistent in fruit, secondary venation suppressed, linear, apex attenuate, base truncate, margin entire for basal half, with 4–8 teeth per side along the apical half, pilose on upper and lower surfaces with multicellular, branched, whitish trichomes. Corolla tubular, 34.0–39.0 mm long; tube erect relative to calyx, 6.3–6.5 mm wide at the middle, dark red and densely pilose with white branched trichomes, nectary chamber 4.0–7.0 × 3.0–5.0 mm, tube narrowed above the nectary chamber, throat 4.3–5.2 mm diam., limb yellow on inside and red with yellow margins on outside, corolla with 5 equal-sized lobes, 2.4–4.5 × 2.0–4.0 mm, straight, elliptic, apex rounded, margin entire, densely pilose abaxially, with white multicellular trichomes. Androecium of 4 didynamous stamens, filaments 23.0–32.0 mm long, adnate to the corolla tube for 3.5–5.5 mm, glabrous, staminode absent; anthers oblong, coherent, dehiscing by longitudinal slits, 2.2–2.5 × 2.4–2.6 mm. Gynoecium with a single-dorsal lobed nectary gland, ca. 2 mm long, glabrous; ovary superior, ca. 4.9 × 2.6 mm, ovate, sparsely pilose; style included, ca. 27 mm long, glabrous; stigma bilobed. Fruit a globose berry, 7.7–15.0 × 6.5–10.0 mm, ovoid, green, pilose with translucid trichomes; seeds elongate, fusiform, and brown, < 1 mm long.

Phenology.

Collected in flower in February, March, April, May, June, August, and October, and with fruits in August.

Etymology.

The epithet rubromarginata is derived from the Latin ruber (red) and marginatus (bordered or edged), referring to the distinctive dark red submarginal band on the abaxial (underside) surface of the leaves (Fig. 1 B ).

Distribution and preliminary assessment of conservation status.

The geographic distribution of Columnea rubromarginata corresponds to the Chocó Biogeographic Region, an area characterized by relatively high levels of precipitation and epiphytic diversity, between 30 and 950 m in elevation ( Gentry 1986; Pérez-Escobar et al. 2019). Columnea rubromarginata is locally abundant in the privately owned and operated Reserva Chococito in the Colombian Chocó Department along the western slopes of the Cordillera Occidental. It has also been documented along roads in the following Colombian localities along the western Andean slopes of the Cordillera Occidental: Chocó (highway Bolívar – Quibdó and Quibdó-Tutunendo) and Valle del Cauca (old highway Buenaventura – Cali). One population was also documented in the environs of Lita in northern Ecuador (Fig. 3 ).

The extent of occurrence ( EOO) is calculated as 30,769.253 km 2, corresponding to a Near Threatened status; the area of occupancy ( AOO) is calculated as 28 km 2, which is within the threshold for Endangered status under subcriterion B 2. The only known collection from Ecuador dates to 1987, prior to construction of the highway between Lita and Esmeraldas, and it is likely that this population has been extirpated. Fewer than ten collections are known, meeting subcriterion B 2 a for Vulnerable. If the Ecuadorian record is excluded from the GeoCAT analysis, the recalculated EOO is 11,805.300 km 2, corresponding to a status of Vulnerable under criterion B 1, and an AOO of 24 km 2, which falls within the threshold for Endangered under criterion B 2.

The species is threatened in Ecuador and Colombia by ongoing habitat loss and fragmentation resulting from deforestation, the expansion of agriculture (especially African palm plantations), mining and illegal logging (especially in Ecuador), and urbanization. These threats were observed by the authors between 1994 and 2022 and have led to a recent decline in the quality and extent of suitable habitat.

The preliminary IUCN category is therefore suggested as Vulnerable ( VU), based on subcriteria B 1, B 2 a, b (i, ii, iii).

Comments.

Most epiphytic species of Columnea with dorsiventral shoots have abaxial leaf surfaces with red apices or entirely red leaves. In one species, C. eubracteata Mansf. , the leaves are mostly red with green apices. Columnea rubromarginata is remarkable for its broad red band along the abaxial surface of the leaf margins (Fig. 1 B ). The only other species with a similar red marginal band is C. purpurimarginata L. P. Kvist & L. E. Skog (Fig. 2 ; see also fig. 8 in Kvist and Skog 1993), a species for which several specimens are now recognized as C. rubromarginata . Vegetatively, these two species appear nearly identical, but they are readily distinguished by their corollas and calyx lobes. In C. rubromarginata , the calyx lobes are linear, uniformly dark red, and more than 2.7 cm long, or nearly as long as the corolla tube (Fig. 1 A, C ). In contrast, in C. purpurimarginata , the calyx lobes are uniformly pale green, ovate, and less than 1 cm long, covering only the basal third of the corolla tube (Fig. 2 A, B ). Both species have elongated tubular corollas but differ in their color patterns. Columnea rubromarginata has a uniformly red corolla with a yellow limb (Fig. 1 A ), whereas C. purpurimarginata has a uniformly yellow corolla with a white limb and red striations on the corolla lobes (Fig. 2 A, C ).

Columnea rubromarginata and C. purpurimarginata share overlapping geographic and ecological habitats. Both species are more abundant in Colombia, but the type locality for C. purpurimarginata is in Ecuador, and it has been documented several times in northern Esmeraldas during expeditions conducted between 2000 and 2022. In contrast, the type locality of C. rubromarginata is in Colombia, and this species has been documented only once in Ecuador, in 1987 ( H. Wiehler 87104).

Another vegetatively similar species is Columnea pulcherrima C. V. Morton , but in this species the marginal red band is much narrower and often absent, giving the leaves an almost uniformly green appearance or green with red apices. Additionally, the leaves of C. pulcherrima are thinner and more membranaceous compared to the thicker, more coriaceous leaf blades of C. rubromarginata .

Specimens examined.

Colombia. Choco: • road Bolivar-Quibdo, 18 km NE of Tutunendo, near Vereda 21, at Alto de Veinte, hacienda of Ruben Jaramillo, half hour walk downhill from road and farm house , 580 m, 15 Mar 1987 (fl.), H. Wiehler & GRF Expedition of 1987 8723 ( SEL, US) ; • Andagoya , 70–100 m, 20–30 Apr 1939 (fl.), E. P. Killip 35051 ( BM, US) ; • Negría, dense forest along Río San Juan , 50 m, 17 Apr 1939 (fl.), E. P. Killip 35024 ( BM, US) ; • between La Oveja and Quibdó , 1 Apr 1931 (fl.), W. A. Archer 1765 ( US) ; • Quibdó, entre Quibdó y Tutunendo, carretera a Carmen de Atrato 8.1 km de Quibdó , 110 m, 8 Aug 1982 (fr), L. Albert de Escobar et al. 2160 ( CUVC, HUA) . Valle del Cauca: • old road from Cali to Buenaventura, about 10 km beyond Queremal, on path down to Río Anchicayá , 30 Apr 1972 (fl.), H. Wiehler et al. 7289 ( SEL, US) ; • road Cali-Buenaventura, near Río Zabaletas , 2 May 1972 (fl.), H. Wiehler et al. 72140 ( SEL, US) ; • Sabaletas, km 29 of highway from Buenaventura to Cali , 25 m, 4 June 1944 (fl.), E. P. Killip & J. Cuatrecasas 38751 ( F, US) ; • Río Cajambre, San Isidro , 5–100 m, 2–5 May 1944 (fl.), J. Cuatrecasas 17354 ( F, SEL, US) ; • Río Calima, La Trojita , 5–50 m, Feb – Mar 1944 (fl.), J. Cuatrecasas 16821 ( F, US) ; • Buenaventura, Corregimiento Bajo Calima, Vereda San Isidro. km 39 of road to Bahia Malaga (under construction), zona de explotación forestal (Cartón de Colombia), Frente A 35 (Hans) , 4.033333°N, 76.96667°W, 30–50 m, 18 May 1989, D. C. Daly 6041 ( CUVC) ; • Buenaventura, margen derecha aguas abajo Río Anchicaya; por trocha que desde el pueblo San José de Anchicaya, conduce al pueblo Calle Larga , 19 m, 19 Oct 2012 (fl), A. Giraldo 7941 ( CUVC) . Ecuador. Esmeraldas: • forest near Lita , 550-650 m, 6 May 1987 (fl.), H. Wiehler 87104 ( SEL) .

Figures

Figure 1. Columnea rubromarginata J. L. Clark & Clavijo. A. Flower; B. Habit; C. Immature fruit; D. Adaxial surface of shoots showing anisophyllous leaves (A – D from J. L. Clark et al. 19345). Photos by J. L. Clark.

Figure 2. Columnea purpurimarginata L. P. Kvist & L. E. Skog. A. Flower; B. Immature fruit; C. Corolla lobes; D. Habit; E. Nectary gland (A, B from J. L. Clark et al. 17224; C – E from J. L. Clark et al. 11086). Photos by J. L. Clark.

Figure 3. Distribution map of Columnea rubromarginata indicating documented localities in Colombia and Ecuador.