Drymonia mexicana Clavijo & J.L. Clark, 2021

Clavijo, Laura, Ramírez-Roa, Angélica & Clark, John L., 2021, DRYMONIA MEXICANA (GESNERIACEAE), A NEW ENDEMIC SPECIES FROM VERACRUZ (MEXICO) Laura Clavijo, J. Bot. Res. Inst. Texas 15 (1), pp. 59-65 : 60-63

Drymonia mexicana Clavijo & J.L. Clark , sp. nov.

( Figs. 1 & 2 ).

TYPE: MEXICO. VERACRUZ: Mpio. San Andrés Tuxtla, EstaciÓn de BiologÍa Tropical Los Tuxtlas, Lote 71,“Pedregal” Selva alta perennifolia ,18°34’- 18°36’N 95°04’- 95°09’W, 500 m, 1Aug 1986 (fl), G.Ibarra-M, L. González G., A. Ambros A., S.Sinaca C. 2990 (HOLOTYPE: MEXU!; ISOTYPE: US!).

Differs from its congeners by the combination of narrow leaves and large corollas;leaves glabrous adaxially;bracts light green, widely ovate and entire; calyx cream to light green with ovate lobes;and flowers campanulate,with slightly ventrally recurved tube and purple limb.

Facultative epiphytic herb or subshrub. Stem scandent, branched, sometimes with adventitious roots, subquadrangular in cross-section, green, bark papyraceous, strigillose to glabrescent (more so at base); internodes 2.9–34.0 mm long. Leaves opposite, decussate, clustered apically, equal to subequal in a pair; petiole 3.7–19.0 mm, terete in cross-section, strigillose to glabrescent, usually with enations at base; blade elliptic to oblanceolate, 1.81–7.93 × 1.0–2.91 cm, coriaceous, apex acuminate, base attenuate to cuneate, symmetrical, margin entire, light green and usually drying brown-reddish abaxially, strigillose to glabrescent abaxially, glabrous adaxially, (3–)4 pairs of primary lateral veins, slightly visible on both sides, strigillose to glabrescent, higher order of venation not evident. Inflorescence axillary, reduced from a pair-flowered cyme, 1–3 flowers per axil. Flowers subtended by a pair of bracts, 7.1–11.5 × 3.5–6.8 mm, light green, widely ovate, apex acuminate, margin entire, strigillose at the base abaxially; pedicel 7–19.3 mm long, green, strigillose. Calyx cream to light green, membranous to coriaceous, persistent in fruit, venation not evident when live, reticulate when dry; calyx lobes 5, 4 nearly equal, ovate, apex acute, base cordate, margin entire, glabrous, but sometimes strigillose at the base abaxially, glabrous adaxially; ventral and lateral lobes 14.8–32.0(–38) × 10.6–25.0(–28.5) mm, dorsal lobe ca. 21.4 × 15.0 mm. Corolla zygomorphic, campanulate, 50.0–70.0(–80) mm long; tube slightly ventrally recurved, oblique relative to calyx, 35.5–70.0 mm long, 10.4–17.0 mm wide at the middle, 12.7–21.7 mm toward the throat, white suffused with purple and glabrescent to strigillose outside, white with longitudinal purple lines, particularly toward the throat inside; throat purple and glabrescent to strigillose outside, purple with glandular trichomes dorsally inside; corolla lobes 5, subequal, purple, spreading, apices rounded, margin slightly erose, glabrescent abaxially, glabrous adaxially, 6.2–9.3 × 6.0–12.6 mm, ventral lobe slightly larger than the others. Androecium of 4 didynamous stamens; filaments included, 27–50 mm long, glabrescent, coiling after anthesis, staminode absent; anthers oblong, dehiscent by a basal pore that develops into a longitudinal slit. Gynoecium with a single dorsal nectary gland; ovary superior and ovate, pilose; style included, pilose with few scattered glandular trichomes, 19.8–37 mm long; stigma clavate. Fruit a bivalved fleshy capsule, dehiscent into two reflexed valves, 18.0–21.6 × 17.3–22.2 mm, globose, yellow to orange, strigose; seeds numerous, 1.02–1.17 × 0.27–0.37 mm, black.

Distribution and habitat.— Drymonia mexicana is endemic to the Gulf of Mexico coastal state of Veracruz. All collections of Drymonia mexicana are from higher elevations (500 to 1350 m) of the Sierra de los Tuxtlas (Tuxtlas Mountains) and the Sierra de Santa Martha in the municipalities (municipios) of Catemaco, San Andrés Tuxtla and Soteapan. These forests are described by collectors as selva alta perennifolia (evergreen high forest) or bosque mesÓfilo de montaña (cloud forest). An additional population could be represented in a remanent tract of forest located 10–15 km east of the Sierra de Santa Martha range in San Martin on the border of the municipalities of Pajapan and Mecayapan (ca. 6–10 km northwest of the city of Pajapan), but no collections of D.mexicana are currently known from this locality.

Drymonia mexicana is distinguished from other congeners from Mexico by the combination of narrow leaves (rarely exceed 3 cm wide) with large corollas (up to 70 mm long); leaves with (3–)4 pairs of primary lateral veins, and adaxial surface glabrous ( Fig. 1A ); bracts light green, widely ovate and entire ( Fig. 1D ); calyx cream to light green, with ovate lobes ( Fig. 1 ); and campanulate flowers, with slightly ventral recurved tube and purple limb ( Fig. 1 , Fig. 2C ). Among the species of Drymonia in Mexico, D. mexicana is more similar to D. oinocrophylla due to their relatively small leaves (<12 cm long and 6 cm wide), with fewer pairs of primary lateral veins (3–5), and entire to subentire margins. However, they can be differentiated by the strigillose indument toward the apex of the branches in D.mexicana (vs. pilose in D. oinocrophylla), the leaves glabrous adaxially and light green abaxially in D. mexicana (vs. strigose and purplish-red in D. oinocrophylla), the bracts widely ovate and light green in D. mexicana (vs. lanceolate and red in D. oinocrophylla), the calyx lobes ovate in D. mexicana (vs. lanceolate in D. oinocrophylla), and the corolla 50–70 mm long with purple limb in D.mexicana (vs. 30–40 mm long with cream, sometimes suffused with pink, limb in D. oinocrophylla).

Phenology.— Drymonia mexicana has been observed in flower and fruit from July through December.

Etymology.—The specific epithet is in reference to the country of Mexico where Drymonia mexicana is endemic.

Conservation and IUCN Red List category.— Drymonia mexicana is geographically limited to three populations in the Mexican state of Veracruz. More than 12% of Mexico’s native forest has been lost since the 1950s (Velázquez et al. 2002). The state of Veracruz is reported to have one of the highest rates of deforestation in Mexico (Muñiz-Castro et al. 2015; GÓmez-DÍaz et al. 2018) where more than 80% of its primary vegetation has been converted to pastures, plantations, and secondary vegetation ( Ellis et al. 2011). The Sierra de los Tuxtlas (Tuxtlas Mountains) corresponds to the range of Drymonia mexicana and is an important biodiversity hotspot. This area is represented by 2,548 species with more than 600 occurring in an area of less than 116 km 2 ( Villaseñor et al. 2018). Therefore, we provisionally assess this new species as Endangered (EN), according to the IUCN Red List criteria ( IUCN 2012) for restricted geographic range (B1 ab + B2 ab).

Additional specimens studied. MEXICO. Veracruz, Mpio. Catamaco: Cerro Egegald, N de Catemaco, carr. a Sotecomapan, 700, 16 Nov 1985 (fr), G. Castillo-C et al. 4439 (XAL!); Rancho La Chingada, 10 km al SE de Tebanca camino de Bastonal, Encinar con Liquidambar y elementos de selva alta perennifolia,22 Nov 1984 (fr), R. Cedillo-T.et al.2892 (MEXU!MO); road from Coyame to Bastonal, E of Laguna de Catemaco, 700 m, 28 Jul 1973 (fl), R.L. Dressler 4442 (PMA, SEL!, US!); Cumbres de Bastonal, 10 Jul 1978 (fl), R. Cedillo-T. et al. 3278 (MEXU!);Ejido RuÍz Cortinez,falda del Volcán San MartÍn Tuxtla,bosque mesÓfilo de montaña, 18°34’N, 95°08’W,1110 m, 1 Jul 2005 (fl), T. KrÖmer & A. Acebey 2300 (MEXU!, SEL!XAL!);Camino Bstonal a Santa Martha, 920 m, 26 Nov 1978 (fr), A. GÓmez-P.et al.5426 (XAL!); 4.8 Km E of Tebanca (4.8 km E side of Laguna de Catemaco) on road to Bastonal,740 m, 5 Jul 1980 (fl), M.Nee & B.F.Hansen 18766 (XAL!); Coyame, cerca Cerro Cochinitos, selva alta perennifolia,alterada,3 Aug 1982 (fl), T.P.Ramamoorthy et al.3892 (MEXU!,US!); Bastonal,12 Km NE de Catemaco, camino Catemaco-Tebanca, 950 m, 30 Jul 1985 (fl), S. Sinaca-Colín 154 (MEXU!); Bastonal, 10 Km NE de Tebanca, camino al poblado de Coyame, 950 m, 30 Jul 1980 (fl, fr), S. Sinaca Colín 162 (MEXU!); Cerro Buenavisata, 3 km al N de Catemaco, carr. a Sotecomapan,600 m, 25 Sep 1999 (fr), A. Torres-R. 346 (XAL!). Mpio. San Andres Tuxtla: Cerro Coyolar,al N de Catemaco, 29 May 1985 (fl), J.I.Calzada 11813 (XAL!);Arriba de Bastonal, 700 m, 29 Jul 1973 (fl), A. GÓmez-P.5136 (XAL!). Mpio. Soteapan: Ejido Santa Martha,2 km al oeste, 950 m, 15 Jul 1987 (fl), R. Acosta-P. 1695 (NY!); Cerro Platanillo, falda del cerro, Sierra Santa Martha,1350 m, 20 Dic 1978 (fr), J.L. Calzada 5092 (XAL!); Alrededores del poblado de Santa Martha, 1240 m, 20 Dic 1978 (fl, fr), R.Ortega-O. et al.1098 (XAL!); Ejido Santa Martha,1250 m, 11 Nov 1980 (fl), F. Vázquez B. 6 (XAL!);Ejido Santa Martha,1250 m, 11 Nov 1980 (fr), F. Vazquez-B.12 (F!).

Figures

FIG. 1. Drymonia mexicana Clavijo & J.L.Clark.A.Habit featuring glabrous foliage and dorsal view of the flower.B. Lateral view of flower.C.Front view of corolla.D.Lateral view of flower.(Photographic images of cultivated material:A,C,D,J.L.Clark 6282; B,Richard Dunn,without collection number).

FIG. 2. Drymonia mexicana Clavijo & J.L.Clark.A. Front view of corolla.B. Scandent habit featuring adventitious roots.C.Dorsal view of flower.D.Lateral view of flower.E.Seeds.F. Fleshy bivalved capsule.G. Lateral view of open flower featuring gynoecium.H. Lateral view of open flower featuring androecium.Illustration by Sue Blackshear.