Drymonia intermedia Clavijo & J.L.Clark, 2022

Clark, John L. & Clavijo, Laura, 2022, Two new species of Drymonia (Gesneriaceae) from Northwestern South America, including the discovery of the longest flower known in the genus, PhytoKeys 190, pp. 1-14 : 1

Drymonia intermedia Clavijo & J.L.Clark sp. nov.

Fig. 1

Diagnosis.

Differs from all Drymonia by leaves with a submarginal collecting vein formed by the secondary venation (i.e., brochidodromous), a narrow elongate tubular corolla, and lanceolate calyx lobes with margins laciniate with unbranched filiform serrations. Similar to D. longiflora , but differs by smaller corolla tube and smaller calyx lobes. Similar to D. laciniosa , but differs by the nearly isophyllous leaves (vs. anisophyllous leaves in D. laciniosa ).

Type.

Ecuador. Esmeraldas: cantón San Lorenzo, parroquia Alto Tambo, trail from the community Durango to Rio Tululbi via trail north of highway San Lorenzo-Ibarra , forest managed by Fundacion Sirua , 1°2'50"N, 78°36'54"W, 200 m, 28 May 2008, J.L. Clark, B. Bisvicuth & J. Melton III 10442 (holotype: SEL [117454]; isotypes: MO, NY, QCNE, US).

Description.

Terrestrial, hemiepiphytic or epiphytic herb or subshrub, with scandent to horizontal shoots to 1 m long. Stems subquadrangular in cross-section, 0.3-0.5 cm in diameter, strigose to glabrate, internodes 2.5-8 cm long. Leaves opposite, decussate, usually evenly spaced and becoming clustered near apex, isophyllous or subequal in a pair; petioles 0.3-0.6 cm long, basal enations not evident, strigillose to strigose, terete in cross-section; blade elliptic to ovate, 6.5-12.2 × 2.6-5.5 cm, membranous to subcoriaceous, the base rounded to acute, sometimes oblique, the apex acuminate, the margin serrate, the upper surface glossy-green, glabrescent or strigose, the lower surface light green, glabrescent or strigillose, lateral secondary veins 5-6 pairs, prominent abaxially, strigose abaxially, forming a submarginal collecting vein (i.e., brochidodromous). Inflorescence reduced to a single axillary flower in the upper leaf axils; peduncle absent; bracts not observed. Flowers with calyx uniformly light green; lobes 5, fused at base, 4 nearly equal, the upper lobe slightly smaller and more narrow, membranous, lanceolate with an elongate acute apex, the margins laciniate with unbranched filiform teeth, the lobes covered with sparsely pilose trichomes, 1.4-1.6 × 0.2-0.3 cm. Corolla zygomorphic, tubular, elongate, 2.0-3.5 cm long, with slight spur (nectar chamber) at base, to 0.4 cm long; the corolla tube perpendicular relative to calyx, ampliate toward the limb, not contracted above, ca. 2.0 cm long, ca. 0.8 cm wide near middle, uniformly pale yellow outside, usually lighter yellow in the throat and limb, sometimes with brown spotting on lower portion of throat, the inside sparsely pilose or glandular, the outside uniformly sericeous; throat to 0.8 cm in diameter; limb with 5 spreading lobes, subequal, globose, rounded at apex, margins fimbriate, uniformly strigose abaxially and adaxially, lobes 3-5 × 4-5 mm, the lower lobe slightly larger. Androecium of 4 didynamous stamens, included; filaments 1.2-2.0 cm long, adnate to the base of the corolla tube for 2-3 mm, glabrous, coiled after anthesis; the anthers at first coherent, after anthesis separating, dehiscent by basal pores, 2-4 × 1.2-1.6 mm. Gynoecium with a single dorsal nectary gland, thick, ovate, 2-3 mm long, glabrous; the ovary superior, sericeous, green; style included, 2-3 cm long, white, puberulent; stigma stomatomorphic. Fruit a fleshy bivalved capsule, the valves green abaxially, dark maroon adaxially, at dehiscence reflexed 180°, revealing a central cone of fleshy, dark red funicular tissue covered by a thin, purple endocarp that remains attached and surrounds the placentae and mass of funiculi and seeds, and then dehisces at a later stage. Seeds numerous, initially covered by the endocarp, but immersed in the central cone of funicular tissue, each seed 0.4-0.5 × 0.2-0.3 mm, brown, subglobose, pointed at both ends, striate.

Phenology.

This species has been collected with flowers in May and June. Specimens with fruits are only known from May.

Etymology.

The specific epithet is in reference to the intermediate shapes and sizes of the corolla and calyx between D. macrophylla , D. laciniosa , and D. longiflora .

Distribution and preliminary conservation assessment.

Drymonia intermedia is endemic to the western Andean slopes between 150 and 600 m in the Ecuadorian province of Esmeraldas. This species has not yet been found in any formally protected area in Ecuador. According to the IUCN Red List criteria ( IUCN 2022) for limited geographic range (EOO <5,000 km2 and AOO <500 km2) and associated subcriteria, including occurrence at fewer than five locations (B2a) and continuing decline of Andean forests (B2b), Drymonia intermedia should be listed in the category Endangered (EN).

Comments.

The characters that differentiate D. intermedia are intermediate between D. longiflora , D. laciniosa , and D. macrophylla . Vegetatively, D. intermedia is distinguished by a submarginal collecting vein formed from the secondary veins that curve upwards towards the leaf margin (brochidodromous venation) (Fig. 1A ). Drymonia laciniosa also has brochidodromous venation, but differs vegetatively by leaves that are anisophyllous (vs. leaves that are nearly isophyllous in D. intermedia ) (Fig. 2A ). Other closely related species, like D. macrophylla , have eucamptodromous venation that are defined by secondary veins that curve upwards, but do not form a collecting vein (Fig. 3A ). The laciniate calyx lobes of Drymonia intermedia are similar to D. laciniosa , but have unbranched filiform serrations (Fig. 1D ). In contrast, the calyx lobes of D. laciniosa are strongly laciniate with branched filiform serrations (Fig. 2B, D ). The calyx lobes shape and margin of D. intermedia are similar to D. longiflora , but are less than 2 cm long (Fig. 1D ). In contrast, the calyx lobes of D. longiflora are larger and usually exceed 2.5 cm (Fig. 4D ). The corolla in D. intermedia is less than 3.5 cm long (Fig. 1D ). In contrast, the corolla of D. longiflora is greater than 6.5 cm long (Fig. 4D ). A summary of diagnostic characters is provided in Table 1 .

Specimens examined.

Ecuador. Esmeraldas: cantón San Lorenzo, parroquia Alto Tambo, border region of Awa Indigenous Territory , entrance to the Rio Bogota community (future biological research station), near Quebrada Pambilar , 0°58'57"N, 78°35'50"W, 350-600 m, 12 Feb 2003, J.L. Clark, G. Zapata & G. Toasa 7148 (MO, QCNE, SEL, US); Esmeraldas: cantón San Lorenzo, parroquia Alto Tambo, trail from the community Durango to Rio Tululbi via trail north of highway San Lorenzo-Ibarra, forest managed by Fundación Sirua, 1°2'50"N, 78°36'54"W, 150 m, 2 Jun 2009, J.L. Clark & The 2009 Gesneriad Research Expedition Participants 11060 (QCNE, SEL, US) .

Figures

Figure 1. Drymonia intermedia Clavijo & J. L. Clark A holotype specimen B upper view of mature fruit C front view of corolla D lateral view of flower (A holotype (SEL) of J. L. Clark et al. 10442 B from J. L. Clark et al. 7148 C, D from J. L. Clark et al. 10344). Photos by J. L. Clark.

Figure 2. Drymonia laciniosa Wiehler A dorsiventral habit B immature cone-shaped fruit C front view of flower D lateral view of flower (A from J. L. Clark 1630 B from J. L. Clark et al. 9629 C from J. L. Clark et al. 10117 D from J. L. Clark et al. 12123). Photos by J. L. Clark.

Figure 3. Drymonia macrophylla (Oerst.) H. E. Moore A erect subwoody habit B mature fleshy bivalved capsule C front view of corolla D lateral view of flower (A from P. Pedraza et al. 850 B from J. L. Clark et al. 12119 C, D from J. L. Clark et al. 10044). Photo A by P. Pedraza and photos B-D by J. L. Clark.

Figure 4. Drymonia longiflora J. L. Clark & Clavijo A erect subwoody habit B mature calyx lobes C front view of corolla D lateral view of flower (A from J. L. Clark et al. 7196 B from J. L. Clark et al. 13417 C, D from J. L. Clark et al. 10343). Photos by J. L. Clark.