Monstera donosoensis Croat, M.Cedeño & O.Ortíz, 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 : 66

14. Monstera donosoensis Croat, M.Cedeño & O.Ortíz, Webbia 76(2): 269–272. 2021. ( Figs. 26 , 27 )

Type: — Panama. Colón: Donoso District . Minera Panamá copper-mining concession, slopes and ridges in drainage of Quebrada Brazo , 243 m, 30 Aug 2014, M.Grayum, G.McPherson, C.Ramos, I.Vergara-Pérez & L.Rojas 13242 (holotype PMA!, isotype MO-6636330 !) .

Robust nomadic vine, appressed-climbing habit. SEEDLINGS: bearing foliose leaves. JUVENILE PLANTS: root climbers; stems light green or beige, sometimes white-dotted, smooth, cylindrical; internodes 2–5 cm long, 0.5–1.0 cm diam.; petiole distinct, light green, smooth, 8–15 cm long, sheathed to base of the geniculum; petiole sheath deciduous or slightly persistent; leaf-blades ovate to lanceolate, attenuate or cuneate at base, acuminate, subcoriaceous to coriaceous, 10–25 × 9–15 cm, not appressed to the phorophyte; fenestrations absent or present, only on one side of the lamina.ADULT PLANTS: root climbers; stems beige to light brown, smooth, cylindrical; internodes 1–4 cm long, 1–5 cm diam., 0.8–1.0 as long as wide; anchor roots light brown or beige; feeder roots corky, dark brown; petiole dark green, scarcely white-dotted, smooth, 22.0– 41.5 cm long, fully sheathed, or for up to 15 cm; petiole sheath deciduous or slightly persistent, horizontally open; geniculum smooth, sunken adaxially, convex abaxially, 0.5–3.0 cm long; blades ovate to elliptic, rounded or truncate at base, subcoriaceous to coriaceous, obtuse to short-acuminate at apex, drying glossy, beige or brownish, 26.5–47.0 × 16.3–25.0 cm, 1.62–1.88 times longer than wide, decurrent on the geniculum, decurrent portion 1–2 mm wide; midrib ribbed adaxially, convex abaxially, drying light or reddish brown on both surfaces, primary lateral veins 6–20 per side, strongly sunken adaxially, prominent abaxially, departing the midrib at 50–60°, drying brownish or reddish, secondary veins prominent and parallel, reticulate toward the margin; collective veins slightly visible toward lobes; fenestrations absent or present; margins entire, pinnatilobed or scarcely pinnatifid, with 2–8 lobes per side. INFLORESCENCES on ascending stems; peduncle smooth, 11.5–19.0 cm long; spathe obtuse to short-acuminate, light green during development, yellowish or cream externally and white or creamy internally at anthesis, completely open, marcescent after anthesis, 10–20 × 6–10 cm, up to 2 cm longer than the spadix; spadix white or cream (both during development and at anthesis), 9.0– 10.5 cm long, 1.8–2.5 cm diam., 4.1–4.2× longer than wide; basal sterile flowers 4–6 mm long, with an orange stigmatic secretion; fertile flowers 5–9 mm long; stamens 2.0– 6.5 mm long, with laminar filaments; anthers 1.3–2.0 mm long; ovary rectangular in longitudinal section, ribbed, 3–4 × 1.5–2.5 mm; style hexagonal and strongly conical, distally cylindrical, 2–5 × 2–3 mm; stigma circular, with an orange stigmatic secretion; berries with a light or dark green stylar cap during development, mature stylar cap cream-yellowish; pulp unknown; seeds unknown.

Distribution and ecology: — Monstera donosoensis is endemic to Panama, knowm from Coclé, Colón, Veraguas, Guna Yale, Panamá Oeste and Panamá, at elevations of 100–1600 m, in Premontane rainforest life zones.

Phenology: —Flowering in September to November. Fruiting occurs mostly February, September to November.

Discussion: —The species is a member of sect. Monstera and is characterized by its thick stems with moderately short internodes, long, nearly fully sheathed petioles, with the sheath deciduous or slightly persistent, and moderately coriaceous, dark brown-drying, usually sparsely perforate, ovate-elliptic, and weakly acuminate leaf blades, inequilaterally subrounded to acute at base, with the primary lateral veins heavily aggregated near base and the perforations (when present) large and few, mostly beginning near the midrib, as well as by its long-pedunculate inflorescences with the spathe greenish, cream-colored within, and the spadix about 2/3 as long as the spathe, and especially by its flowers with a protruding, hexagonal, strongly conical and distally cylindrical style.

Monstera donosoensis is similar to M. dissecta (Schott) Croat & Grayum (1987) , but differs in having petioles speckled with white dots, with the sheath deciduous or slightly persistent, coriaceous leaf blades, and flowers with a hexagonal, strongly conical, and distally cylindrical style. Monstera donosoensis has similar characteristics to the South American M. adansonii Schott subsp. klotzschiana (Schott) Mayo & Andrade (2013) , but the latter differs in having dark green, less frequently mottled petioles with the sheath persistent and slightly coriaceous leaf-blades.

Additional specimens examined: — PANAMA. Coclé: Road to Coclesito. Logging camp 12 miles from Llano Grande , 200 m, W. Churchill et al. 3984 ( MO!) ; Along road past Furlong’s Finca , due N of Cerro Pilón, 880 m, T.B. Croat 37573 ( MO!) ; On Atlantic slope near the Continental Divide along lumbering road N of El Cope , 9.4 km above El Cope (2.2 km N of lumber sawmill), 750–900 m, T.B. Croat 44750 ( MO!) ; Near continental divide along lumber road 5.2 mi N of El Cope, 1.5 mi N of lumber camp. Cloud forest on steep slopes, 900 m, T.B. Croat 44574 ( MO!) ; North of El Copé , 500 m, G. D’Arcy 11294 ( MO!) ; Foot of Cerro Pilón, above El Valle de Antón, Rain forest , 2000 ft, D.M. Porter et al. 4431 ( MO!) ; Trail between the Río Blanco and the Continental Divide north of El Cope and El Petroso sawmill, 400–1700 ft, K.J. Sytsma et al. 2605 ( MO!) ; North rim of El Valle de Antón, near Cerro Turega , 650–700 m, R.E. Woodson & R.W. Schery 185 ( MO!) ; Colón: Santa Rita Ridge Road, 4–6 km from Transisthmian Highway. Disturbed primary forest, 150–200 m, T. Croat 34281 ( MO!) ; Santa Rita Arriba, Bosque secundario, orillas de la carretera, 380 m, O. Ortiz et al. 3452 ( MO!, PMA!) ; Darien: Cerro Tacarcuna massif west ridge, vicinity of summit camp, lower montane wet forest, 1500–1600 m, A. Gentry & S. Mori 14161 ( MO!) ; Panamá: Chepo, El Llano – Cartí Road, 7–12 km from Interamerican Highway , 360–400 m, T. Croat 25155 ( MO!) ; Capira, Cerro Campana, along trail to Summit , 780–875 m, Croat 25194A ( MO!) ; Capira, Cerro Campana , along trail to summit, 780–875 m, T. Croat 25244 ( MO!) ; Cerro Jefe, 21 km above Pan-Am Highway , 600 m, T. Croat 35890 ( MO!) ; Capira, Middle slopes of Cerro Campana , ca. 1 mile from Interamerican Highway , 150 m, T. Croat 35990 ( MO!) ; Chepo, Road from El Llano to Cartí , 8.7 km N of the Panamerican Highway , 200–300 m, J. Folsom & G. Small 6162 ( MO!) ; Near top of Cerro Jefe to 1 mile beyond, 900–1000 m, A. Gentry 3499 ( MO!) ; Cerro Jefe , in forest alongside road north off of road to tower, 820 m, B.E. Hammel & G. McPherson 14534 ( MO!) ; Chepo, Along newly cut road from El Llano to Carti-Tupile ; 12 miles above Pan-Am Highway , Primary forest , 200–500 m, R. Liesner 693 ( MO!) ; Capira, Summit of Cerro Campana, Rain forest , 3220 ft, D. Porter 4951 ( MO!) ; El Llano-Cartí Road, tropical moist forest, 12 km from Pan American Hwy , 1000 ft, K.J. Sytsma 1745 ( MO!) ; Chepo, 16–18 km from Interamerican Highway on the El Llano-Cartí Road, 400 m, E.L. Tyson & M.H. Nee 7356 ( MO!) ; San Blas: El Llano-Cartí Road , 350 m, de G. Nevers & G. Herrera 4356 ( MO!) ; Veraguas: Santa Fe, 5 miles W of Santa Fé on road past Escuela Agricola Alto Piedra on Pacific side of divide, 800–1200 m, T.B. Croat 23053 ( MO!) ; 2/ 10 mile beyond fork in road at Escuela Agricola Alto Piedra on road to Rio Calovebora , 750 m, T.B. Croat & J. Folsom 33969 ( MO!) ; ”Cerro Tute” ridge up from former Escuela Agrícola, Santa Fé , moist forest, 800–1000 m, W. Hamilton & R. Dressler 3042 ( MO!) ; Santa Fe, Along steep trail to summit of Cerro Tute , ca. 3 km above Escuela Agricultura Alto Piedra near Santa Fé , 3000–3100 ft, K.J. Sytsma & T. Antonio 3058 ( MO!) . Coclé: Near sawmill 16.7 km N of turnoff to Coclesito from Llano Grande , 700 ft, B.E. Hammel 1836 ( MO!) .

Figures

FIGURE 26. Monstera donosoensis from Colón, Panama. (A) Developing inflorescence. (B) Front and back views of open inflorescence. (C) Sterile flower; in lateral view (left) and longitudinal section (right). (D) Stylar plate with stigma (left), and individual stamen (right). (E) Fertile flower; in lateral view (left) and longitudinal section (right). (F) Immature infructescence. (G) Adult plant. Image from Cedeño- Fonseca et al. (2020b).

FIGURE 27. Monstera donosoensis. Adult plant growing 2 m above the ground in a tree in Santa Fe, Panama. Photo by M. Cedeño- Fonseca. (Not collected).