Monstera alfaroi Croat & M.Cedeño, Nordic

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 36

5. Monstera alfaroi Croat & M.Cedeño, Nordic Journal of Botany 38(12): 1–13. 2020. ( Figs. 10 , 11 )

Type: — COSTA RICA. San José: Cantón Tarrazú, distrito San Lorenzo, Camino de Tarrazú hacia Quepos , 1386 m, 22 October 2019, (fl.), M. Cedeño 1702 (holotype USJ!, isotypes MO!, PMA!) .

Robust nomadic vine with appressed-climbing habit. SEEDLINGS: bearing foliage leaves. JUVENILE PLANTS: root climbers; appressed-climbing; stem dark green, cylindrical or dorsally flattened, with whitish-green pustules making a rough-warty surface; internodes 1–15 cm long, 5–10 mm diam.; petioles partly concealed by the leaf blades or not at all, light green, warty, 3–16 cm long, sheathed to base of the geniculum; petiole sheath deciduous; blades not appressed to the phorophyte, ovate-lanceolate, acuminate at the apex, coriaceous, 9–20 × 8–13 cm, fenestrations absent. ADULT PLANTS: root climbers; stem with black and dark green pustules, cylindrical; internodes 1–2 cm long, 2–3 cm diam., 0.5–0.6 times as long as wide; anchor roots blackish; feeder roots blackish; petiole brown or rarely light green at base, with brown black and white pustules, 40–70 cm long, sheathed along their entire length; petiole sheath undulate, persistent or deciduous; geniculum warty throughout, flattened adaxially and transversally convex abaxially, 2.0– 2.5 cm long; blades narrowly ovate, rounded or asymmetric at base, shortly acuminate at the apex, subcoriaceous, with entire margins and few fenestrations, 60–90 × 30–45 cm, drying dark brown and weakly lustrous, not decurrent on the geniculum; midrib concave adaxially, convex abaxially, drying black or yellowish; primary lateral veins 8–13 per side, diverging at 50–70°, impressed adaxially, prominent abaxially; secondary veins parallel to the primary lateral veins; collecting veins poorly visible; fenestrations present (weakly perforated near the midrib); margins entire. INFLORESCENCES produced on ascending stems; peduncle with green or brown pustules, 20–35 cm long; spathe obtuse or acuminate, light green in developing inflorescences, internally white and externally light green at anthesis, 13–20 × 8–14 cm; spadix white during development, white or yellowish white at anthesis, 10–15 cm long, 1.2–2.5 cm diam.; basal sterile flowers 4–5 mm long; fertile flowers 5–7 mm long; stamens 2–7 mm long, with laminar filaments; anthers 2.0– 2.5 mm long; ovary quadrangular in longitudinal section, ribbed; style hexagonal, 1.2–2.5 mm long, truncate; stigma linear; berries with the stylar cap after anthesis white, white-cream when ripe; pulp white; seeds black, 3–6 mm long.

Distribution and ecology: — Monstera alfaroi is endemic to Costa Rica. It is distributed in the Pacífic Central, Tarrazú, and south in the Fila Chonta and Fila Costeña, at 1100–1250 m. It occurs in Lower montane rain forest life zone.

Phenology: —Flowering has been recorded in February, October and November, and fruiting in January.

Discussion: —This species is a member of sect. Monstera . It differs from other Costa Rican species in having light brown petioles with black or white warts throughout their length, and the sheath wavy and warty, then promptly deciduous, as well as leaf blades that are coriaceous and scarcely fenestrated, and inflorescences with the peduncle warty and the spathe light green externally. It is most closely related to Monstera buseyi , with which it shares tuberculate petioles. Most collections of Monstera buseyi differ from M. alfaroi in having narrowly ovate-elliptic leaf blades 2.0–2.5 times longer than wide which dry medium grayish yellow-brown above and much paler (yellowish green) and often matte below, although some collections have blades only 1.7 times longer than wide which dry dark brown. Also, Monstera buseyi has flowering spadices only 6–9 cm long and ca. 1 cm diam., versus more than 18 cm long and 2 cm diam. in M. alfaroi . Finally, Monstera buseyi has peduncles drying matte and smooth or only weakly puberulentscurfy, whereas those of M. alfaroi dry grossly ridged and pitted and covered by conspicuous tubercles.

Monstera alfaroi can also be confused with M. costaricensis , but the latter has petioles with white pustules and markedly wavy and persistent wings, and flowers with markedly conical styles. Monstera alfaroi is restricted to the Pacific slope of the Cordillera de Talamanca, while M. costaricensis occurs only in the Caribbean lowlands (below 600 m elevation) of Costa Rica.

Additional specimens examined: — COSTA RICA. Puntarenas: Buenos Aires, Changuena, Boques en Fila Anguciana. Finca Bonillas , 1480 m, 25 abril 2020, M. Cedeño et al. 1719 ( USJ!) ; Buenos Aires, Potrero Grande, La Lucha, Punto , 1400–1500 m, 20 February 2018, (Fl.), D. Santamaría et al. 7036 ( MO!) ; Parrita, Parrita, Fila Chonta , 1295 m, 27 November 2003, (Fl.), A. Quesada 1264 ( CR!) ; Parrita; Fila Chonta, camino de San Marcos de Tarrazú a Cerro Cura, La Virgen y Fila Chonta, 1400 m, 31 January 1996, (Fr.), B.E. Hammel & J. Morales 21189 ( INB, MO) ; San José: Tarrazú, San Lorenzo, Nápoles , Estribaciones al Oeste de Cerro Toro , 1200 m, 30 November 1995, (Fl.), G. Herrera et al. 8785 ( CR!) ; San José, Pérez Zeledón, Fila Costeña , 1100 m, 15 February 1996, (Infer.), B.E. Hammel et al. 20161 ( INB, MO) ; Cantón de Pérez Zeledón, Cordillera de Talamanca, Las Nubes , Estación Santa Elena , 1240 m, 15 de febrero de 1996, E. Alfaro 508 ( MO!) .

Figures

FIGURE 10. Monstera alfaroi from Tarrazú, Costa Rica. (A) Developing inflorescence. (B) Portion of juvenile plant. (C) Longitudinal cut of the spathe at female anthesis. (D) Stylar plate with stigma (left) and one stamen (right). (E) Fertile flower; in lateral view (left), and longitudinal section (right). (F) Portion of adult plant. (G) Sterile flower; in lateral view (left), and longitudinal section (right). M. Cedeño 1702 (USJ). Image from Cedeño-Fonseca et al. (2020a).

FIGURE 11. Monstera alfaroi. Adult plant growing in the locality type in Tarrazú, Costa Rica. M. Cedeño 1702 (USJ). Photo by M. Cedeño-Fonseca.