﻿Two new species of Drymonia (Gesneriaceae) from Northwestern South America, including the discovery of the longest flower known in the genus

﻿Abstract Two new species, Drymoniaintermedia Clavijo & J.L.Clark, sp. nov. and D.longiflora J.L.Clark & Clavijo, sp. nov. (Gesneriaceae, Columneinae), are described from the western Andean slopes of Ecuador and Colombia. The new species are similar to D.fimbriata, D.laciniosa, D.macrophylla, and D.peponifera because of the facultative epiphytic habit, deeply serrate to laciniate calyx margins, and fleshy bivalved capsules with tardily dehiscent endocarps. Leaves with brochidodromous venation, narrowly elongate corolla tube, and laciniate calyx margins differentiate D.intermedia. The longest corolla of any known Drymonia (> 6.5 cm long) differentiates D.longiflora. Digital photographs, geographic distributions, and IUCN categories are provided for the new species.


Introduction
The flowering plant family Gesneriaceae, with more than 3400 species and 150+ genera (Weber 2004;Weber et al. 2013), is in the order Lamiales. The family is divided into three subfamilies and seven tribes (Weber et al. 2013(Weber et al. , 2020, which represent monophyletic lineages (Ogutcen et al. 2021). The majority of New World members are in the subfamily Gesnerioideae and are represented by 1200+ species and 77 genera . Drymonia Mart. is classified in the tribe Gesnerieae and subtribe Columneinae (Weber et al. 2013(Weber et al. , 2020, the largest subtribe with 26+ genera and 16% (ca. 525+ spp.) of the total species' diversity in the family (Weber et al. 2013(Weber et al. , 2020. Drymonia is strongly supported as monophyletic based on molecular sequence data (Clark et al. 2015). Our preliminary DNA sequence data strongly support a clade that includes the two species described here: Drymonia intermedia Clavijo & J.L.Clark and Drymonia longiflora J.L. Clark & Clavijo. Other members of this clade include Drymonia laciniosa Wiehler, D. macrophylla (Oerst.) H.E.Moore, and D. peponifera J.L. Clark & Clavijo. Digital images are provided to differentiate the two new species from closely related congeners. Table 1 summarizes geographic distributions and diagnostic morphological characters for differentiating Drymonia fimbriata C.V. Morton, D. intermedia, D. laciniosa, D. longiflora, D. macrophylla, and D. peponifera Clark et al. 10344). Photos by J.L. Clark. 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 km 2 and AOO <500 km 2 ) 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.  Fig. 4 Diagnosis. Differs from all Drymonia by an elongate corolla that exceeds 6.5 cm in length, the longest corolla known in the genus. The subshrub habit with elongate shoots and corolla shape are similar to Drymonia macrophylla and D. peponifera. Drymonia macrophylla has a corolla that rarely exceeds 3.5 cm in length and D. peponifera has a corolla that rarely exceeds 4.5 cm in length.
Phenology. This species has been found with flowers in two periods: February to May and August to October.
Etymology. The specific epithet is in reference to the elongate corolla tube, the longest of any known species of Drymonia.
Distribution and preliminary conservation assessment. Drymonia longiflora is locally abundant in forests along the western slopes of the northern Andes in Ecuador (Provinces Carchi and Esmeraldas) and Colombia (Departments Chocó, Valle del Cauca, and Nariño). One disjunct population is documented from southern Ecuador (Province Morona-Santiago). Drymonia longiflora grows in mature shaded forests, from 150 to 900 m in elevation. We provisionally assess this new species as Vulnerable (VU), according to the IUCN Red List criteria (IUCN 2022) for limited geographic range (EOO < 20,000 km 2 and AOO <2,000 km 2 ) and associated subcriteria, including occurrence at fewer than ten locations (B2a) and continuing decline of Andean forests (B2b).
Comments. Drymonia longiflora is distinguished by the longest known corolla recorded for Drymonia (> 6.5 cm). The unbranched subwoody epiphytic or terrestrial subshrub habit and the foliage are similar to Drymonia macrophylla, D. fimbriata, and D. peponifera. All four species are vegetatively similar, but readily differentiated by corolla tube length and calyx lobes (Fig. 5C, D). The calyx lobes of Drymonia peponifera appear crispate from the reflexed and undulating lobes (Fig. 5C, D). In contrast, the calyx lobes of D. macrophylla (Fig. 3D) and D. longiflora (Fig. 4D) are flat. The margins of the calyx lobes in Drymonia longiflora are serrate to slightly laciniate, in contrast to the strongly laciniate with unbranched filiform teeth of D. fimbriata. The corolla in Drymonia longiflora exceeds 6.5 cm in length (Fig. 4D). In contrast, the corolla rarely exceeds 3.5 cm in D. macrophylla (Fig. 3D) and D. fimbriata. The corolla is less than 4.5 cm in D. peponifera (Fig. 5D). Drymonia longiflora and D. intermedia share similar shapes for corolla tubes and calyx lobes, but differ in size, with D. intermedia much smaller. A summary of diagnostic characters is provided in Table 1.
Our preliminary DNA sequence data strongly support a close relationship in a clade that includes D. intermedia, D. laciniosa, D. longiflora, D. macrophylla, and D. peponifera. This clade is defined by fleshy capsular fruits with tardily dehiscent endocarps. A photographic guide and description of fruit types is summarized in Clark and Clavijo (2022). Most Drymonia capsules have endocarps that dehisce when mature. In contrast, the clade that includes D. intermedia and D. longiflora is defined by endocarps that remain attached and surround the placentae and mass of funiculi and seeds (Figs 1B, 5B). The endocarp eventually becomes dehiscent at a later stage when it detaches from the reflexed outer layers of the fruit wall (Fig. 5B). Although we have not observed mature fruits of Drymonia longiflora, we predict that the fruit type of this species shares the same characters with closely related congeners.
Specimens examined. Colombia. Chocó: 2 km south of Las Animas on road