Monstera tarrazuensis Croat & M.Cedeño, Nordic J. Bot.

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 172

48. Monstera tarrazuensis Croat & M.Cedeño, Nordic J. Bot. 38(12): 5. 2020. ( Figs. 83 , 84 )

Type: — COSTA RICA. San José: Cantón Tarrazú, distrito San Lorenzo, Camino de Tarrazú hacia Quepos , 1386 m, 9 July 2019, (fr.), M. Cedeño 1686 (holotype USJ!) .

Nomadic vine, appressed-climbing and pendent habit. SEEDLINGS: bearing foliage leaves. JUVENILE PLANTS: root climbers; stems light-green with white dots, smooth; internodes 3–7 cm long, 3–5 mm diam.; petiole distinct, dark or light-green, smooth, 4–10 cm long, sheathed to base of the geniculum or blade; petiole sheath persistent; blades lanceolate, cordate at base, acuminate at apex, coriaceous, 7–14 × 5–9 cm, not appressed to the phorophyte; fenestrations absent. ADULT PLANTS: root climbers; stems dark green with white dots, smooth, cylindrical; internodes 4–11 cm long, 1.2–1.7 cm diam., 3.3–6.5 times longer than wide; anchor roots and feeder roots light-brown; petiole light-green with white dots, smooth, 11–14 cm long, sheathed along its entire length; petiole sheath persistent or rarely deciduous; geniculum obscure, 0.5–1.0 cm long; blades ovate to ovate-elliptic, rounded or asymmetrical at base, short-acuminate at apex, coriaceous, 13–26 × 7.5–13.8 cm, 1.5–2.0 times longer than wide, not decurrent on the geniculum, drying grayish or brown, faintly glossy; midrib ribbed adaxially, convex abaxially, drying dark brown; primary lateral veins 5–9 per side, departing midrib at 45–60°, slightly sunken adaxially, prominent abaxially, drying dark brown and wavy; secondary veins completely parallel to the primary lateral veins and finely wavy; collective veins scarcely visible; fenestrations absent; margins entire. INFLORESCENCES on pendent stems, arranged in the axils of the leaves; peduncle smooth, 13–15 cm long; spathe long-acuminate, open at apex and overlapping margins at the medial part, light green during development, white internally and greenish-white or creamy white externally at anthesis, 10–15 × 5–7 cm, up to 5 cm longer than the spadix, falling intact after anthesis; spadix oval, white during development, white at anthesis, 5–6 cm long, 2–3 cm diam.; basal sterile flowers 2.5–4.0 mm long, with a transparent stigmatic secretion; fertile flowers 3–4 mm long; stamens 2–4 mm long, with laminar filaments; anthers 1.5–2.0 mm long; ovary rectangular in longitudinal section, 2–3 × 1.5–2.0 mm; style hexagonal, 1.5–2.0 × 2–3 mm; stigmatophore absent; stigma linear, with a transparent stigmatic secretion; berries with a white stylar cap during development, mature stylar cap white-cream; pulp white; seeds unknown.

Distribution and ecology: —Endemic to Costa Rica in the central Pacific region, on Cerro Hormiguero, at 1100 to 1200 m elevation, occurring in Tropical wet forest and Premontane rain forest life zones.

Phenology: —Flowering and fruiting have been recorded in July and September.

Discussion: —The species is a member of sect. Monstera and is characterized by its long slender internodes, small narrowly ovate, entire blades which lack perforations and the inflorescences with a stubby spadix which is much shorter than the coriaceous caviform spathe that is yellowish on outside and creamy white inside as well as by the subterete, somewhat caviform styles and subcircular, barely raised stigma.

Mostera tarrazuensis can be confused with M. luteynii , which also has hanging stems and leaf blade without perforations. But it differs because M. lutein has stems completely covered with pustules, leaf blade with tertiary venation strongly prominent on both surfaces and the terete geniculum.

Additional specimens examined: — COSTA RICA. San José: Tarrazu Cantón, San Marcos de Tarrazu between Cerro Toro and Cerro Hormiguruero along the road between Basuera de Tarrazu and Esquipula, vicinity of Cerro Hormiquero , 1100–1200 m, 5 Septiembre 1996, T.B. Croat 78912 ( CR!, MO!); Tarrazu, San Marcos de Tarrazu between Cerro Toro and Cerro Hormiguero along the road between Basuero de Tarrazu and Esquipulas, 1100–1200 m, 5 septiembre 1996, (fr.), T.B. Croat 78934 ( INB, MO) .

Figures

FIGURE 83. Monstera tarrazuensis from Tarrazú, Costa Rica. (A) Seedling. (B) Adult plant. (C) Sterile flower; in lateral view (left), and longitudinal section (right). (D) Fertile flower; in lateral view (left), and longitudinal section (right). (E) Immature infructescence. (F) Stylar plate with stigma (left) and one stamen (right). (G) Developing inflorescence. M. Cedeño 1686 (USJ). Image from Cedeño-Fonseca et al. (2020a).

FIGURE 84. Monstera tarrazuensis from Tarrazú, Costa Rica. (A, B) adult plants in their natural habitat, with hanging stems at the edge of the forest. (C) hanging stem with erect inflorescence (arrow). (D) hanging stem with erect infructescence (arrow). M. Cedeño 1686 (USJ). Image from Cedeño-Fonseca et al. (2020a).