Monstera juliusii M.Cedeño & Croat, Phytotaxa

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 103

27. Monstera juliusii M.Cedeño & Croat, Phytotaxa 461(3): 186. 2020. ( Fig. 48 )

Type: — COSTA RICA. Puntarenas: Buenos Aires, Biolley, Parque Internacional de La Amistad , Cerro Frantzius , 2000 m, 5 February 2018, M. Cedeño, I. Chinchilla, J. Jiménez & J. Porras 1220 (holotype USJ!, isotype MO!) .

Robust nomadic vine, appressed-climbing. SEEDLINGS: bearing foliage leaves. JUVENILE PLANTS: root climbers; stem smooth, dark green with white spots; internodes 4–7 cm long, 4–6 mm diam.; petioles conspicuous, dark green with white spots, smooth, 7–12 cm long, sheathed throughout, sheath margins convolute, persisting; blades ovate; without fenestrations, acuminate at apex, subcordate to truncate at base, coriaceous, 9–15 × 7–10 cm, not flattened against the phorophyte. ADULT PLANTS: root climbers; stem dark, opaque beige, smooth, terete; internodes 1–3 cm long, 1.5–2.5 cm diam., 0.6–1.2 times as long as wide; support roots light brown, 2–4 cm long, feeder roots dark brown; petioles whitish green or with minute white spots, smooth, 25–60 cm long, sheathed to within 2 cm before or up to base of the geniculum; petiole sheath thick and persistent; geniculum smooth, 5–10 mm long; blade lanceolate to ovate in outline, entire or partially pinnatilobed, narrowly rounded, shortly acuminate at apex, subcordate to obtuse at base, decurrent onto the geniculum, the decurrent portion 1–2 mm wide, coriaceous, 25–60 × 15–30 cm; midrib grooved adaxially, transversally convex abaxially; primary lateral veins 13–17 per side, moderately sunken above, prominently raised below; collective veins not visible; fenestrations rounded near the midrib, oval toward the margin; margin sometimes breaking. INFLORESCENCES on ascending stems; peduncle smooth, 15–23 cm long; spathe acuminate, light green in developing inflorescences, greenish-yellow externally and white internally at anthesis, thick, completely open at the apex, the margins slightly overlapping at base, deciduous after anthesis, 15–30 × 7–11 cm, up to 15 cm longer than the spadix; spadix white in developing inflorescences, yellowish cream at anthesis, 8–14 cm long, 1.5–3.0 cm diameter; basal sterile flowers 4–5 mm long with a transparent secretion; fertile flowers 5–7 mm long; stamens 2–6 mm long, with filament laminar; anther 2–3 mm long; ovary rectangular in longitudinal section, ridged, 4–5 × 2–3 mm; style hexagonal, 2–3 × 3–4 mm; stigmatophore cupular, 0.5–1.0 mm long, stigma linear, with yellowish discharge; berries with the stylar layer white-cream at maturity; pulp white; seeds smooth, green or light brown, sub-elliptical, 5–7 mm long.

Distribution and ecology: — Monstera juliusii ranges from eastern Costa Rica to western Panama in the Cordillera de Talamanca in Puntarenas Province, and in western Panama in Chiriquí Province, at 1650–2010 m. In Costa Rica is it known from a Premontane rain forest life zone while in Panama it occurs in Lower montane rain forest life zones.

Phenology: —Flowering January to March, August-September. Fruits in January, February and September.

Discussion: —The species is a member of sect. Monstera . It differs from other species by the combination of leathery leaves with whitish or mottled petioles, thick and persistent petiole sheath margins, and by spathes yellowish green externally and white internally.

Herbarium material of Monstera juliusii has been confused with M. standleyana , but the latter species has deep green petioles with white dots, usually non-perforate (rarely with few fenestrations), usually entire (rarely with few lobes), lanceolate to ovate leaf blades, creamy yellow spathes with brown spots on the outside, cream on the inside, and laterally flattened stigmatophores.

Additional specimens examined: — COSTA RICA. Puntarenas: Coto Brus, P.I. La Amistad, Cordillera de Talamanca, Estación Pittier, Sendero Altamira , 1700 m, 28 January 1995 (fl.), A. Mora 12 ( CR-INB, MO) ; Buenos Aires, Biolley, Cordillera de Talamanca , Cerro Frantzius to Valle de Silencio , Oak-Podocarpus-laurel forest with Chusquea longifolia understory, 2250 m, 7 September 1984, (fl.), G. Davidse et al. 28563 ( MO!) ; Buenos Aires, Biolley, Camino a Casa Coca , 1600 m, 5 February 2018, (fr.), M. Cedeño et al. 1219 ( USJ!) ; Coto Brus, Pittier, P.I. La Amistad, Cordillera de Talamanca , Estación Pittier , Sendero Fila Pittier , 1900 m, 27 January 1995 (fl., fr.), A. Mora 1 ( CR!, MO!) ; Cantón Buenos Aires, distrito Changuena, Boques en Fila Anguciana , Finca Bonillas , 1480 m, 25 abril 2020, M. Cedeño et al. 1716 ( USJ!) . PANAMA. Chiriqui: distrito Renacimiento, corregimiento Río Sereno, Mount Totumas Cloud Forest , O. Ortiz et al. 2803 ( PMA!) .

Figures

FIGURE 48. Monstera juliusii from Puntarenas, Costa Rica. (A) Developing inflorescence. (B) Open inflorescence, front and back views. (C) Mature infructescence, stylar plates detached toward the apical part. (D) Fertile flower; in lateral view (left), and longitudinal section (right). (E) Stylar plate with stigma (left) and one stamen (right). (F) Sterile flower; in lateral view (left), and longitudinal section (right). (G) Seeds. (H) Portion of juvenile plant. (I) Adult plant. M. Cedeño et al. 1220 (USJ). Image from Cedeño-Fonseca et al. (2020b).