Monstera gambensis M. Cedeño & M.A. Blanco, Webbia

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 84-85

20. Monstera gambensis M. Cedeño & M.A. Blanco, Webbia 75(1): 123–132. 2020. ( Figs. 36 , 37 )

Type: — COSTA RICA. Puntarenas Province, Golfito Cantón, Golfito, La Gamba , sendero sobre quebrada, 94 m, 27 May 2016, M. Cedeño, A.P. Karremans & I. Chinchilla 890 (holotype USJ!) .

Nomadic vine, appressed-climbing. SEEDLINGS: unknown. JUVENILE PLANTS: root climbers; appressed-climbing; stem dark green, slightly rough; internodes 3–5 cm long, 4–10 mm diam.; petioles visible (i.e., the leaves not shingling), dark green or light, slightly rough, 3–5 cm long, sheathed to base of the geniculum; petiole sheath persistent; blades more or less horizontal, not flattened to the substrate of the phorophyte, 4–7 × 3–4 cm, obovate or lanceolate, subcordate to truncate at base, acuminate at the apex, thinly coriaceous, without fenestrations. ADULT PLANTS: root climbers; stem terete, dark green, rough; internodes 1–4 cm long, 0.5–1.0 cm diam., 2–3 times longer than wide; anchor roots black and corky, 4–6 cm long, feeder roots black and semi-corky, both with black root hairs; petioles light green or whitish, rough to the geniculum, 17–22 cm long, sheathed to 2–3 cm below base of the geniculum; petiole sheath involute and persistent, the free portion slightly grooved; geniculum elongate, 0.5–1.0 cm long; blades lanceolate, attenuate at base, acuminate at the apex, subcoriaceous, 12–24 × 5–10 cm, decurrent on the geniculum (the decurrent part 0.5–1 mm wide); midrib convex to the middle of the blade abaxially, slightly rough; primary lateral veins 5–13 per side, impressed or indistinct abaxially, prominent on the underside, departing midrib at 35–45°; fenestrations (when present) one or two close to each other on the same side of the blade near its middle part; collective veins not visible; margins entire. INFLORESCENCES on ascending stems; peduncle rough throughout, 20–25 cm long; spathe unknown; spadix 7–10 × 1.3–1.6 cm, color unknown; basal sterile flowers 3–4 mm long; fertile flowers 4–5 mm long; stamens 2–4 mm long, with laminar filaments; anther 1–2 mm long; ovary prismatic, longitudinally ribbed, 2–3 × 2–3 mm; style hexagonal, 1–2 × 3–5 mm; stigma linear; berries yellow when ripe; pulp white; seeds black, 2–3 mm long.

Distribution and ecology: —Endemic to Costa Rica, where it has been found growing low on the supporting trees (ca. 2 m above ground level), in rain forest at La Gamba Biological Station, Cantón Golfito, mostly at 50–100 m, in Tropical wet forest life zones.

Phenology: —Flowering has not been observed, fruiting was recorded in May.

Discussion: —The species, a member of section Monstera , differs from other species by its rough whitish stem and petioles, its persistent entire involute petiole sheath, and entire adult leaf blade with or without fenestrations. In size it is similar to Monstera obliqua , but it is differentiated by having smaller leaves (12 × 5 vs. 35 × 14 cm), rough petiole (vs. smooth), and persistent petiole sheath (vs. deciduous). In Costa Rica, Monstera obliqua is found only in the extreme southeast of the country (Caribbean slope, Grayum 2003), while M. gambensis is known only from a single collection in La Gamba de Golfito (Pacific slope).

This species is also similar to Monstera minima but that has smaller petioles (2–6 cm), leaf blades (9–14 × 2–4 cm), and spadices (ca. 4.4 × 09– 1 cm) and is only known from the northern (Caribbean) coast of Panama and along the Pacific slope of northern Colombia, in the Chocó region ( Jácome & Croat 2002). In Costa Rica, Monstera gambensis is found in lowland tropical wet forest at elevations up to ca. 100 m. The individuals observed were climbing in undisturbed forest on small trees no more than 2.5 m high, with abundant shade in the understory.

Figures

FIGURE 36. Monstera gambensis from Golfito, Costa Rica. (A) Adult plant with non-perforated leaves. (B) Juvenile plant. M. Cedeño et al. 890 (USJ). Image from Cedeño-Fonseca et al. (2020d).

FIGURE 37. Monstera gambensis from Golfito, Costa Rica. (A) Support roots (i) and a feeding root (ii) both corky and blackened. (B) Petiole sheath margins persistent and involute in adult plants (arrow). (C) Petioles with sheath margins persisting, whitish and asperous (arrow). (D) Internodes of adult plant (arrow). (E) The shallowly channeled distal portion of the petiole (arrow). (F) Portions of either dead epidermis or epicuticular waxes that give a whitish appearance and an asperous texture to the surface of the petioles. M. Cedeño et al. 890 (USJ). Image from Cedeño-Fonseca et al. (2020d).