Monstera harrisoniorum Croat, M.Cedeño & O.Ortíz, 2024

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 99-100

25. Monstera harrisoniorum Croat, M.Cedeño & O.Ortíz , sp. nov.

The species is characterized by its hemiepiphytic habit, petiolar sheath deciduous, leaf blades broadly ovate, obtuse to rounded at base, and flowers with truncated style and linear stigma.

Type: — PANAMA. Panamá: Santa Rita Ridge Road , 23 Mar. 1972, J. D. Dwyer & A. Gentry 9546A (holotype, MO!-2092911) .

Nomadic vine, appressed-climbing habit. SEEDLINGS: unknown. JUVENILE PLANTS: root climbers; stems smooth, dark green; internodes 2–5 cm long, 4–7 mm diam.; petiole distinct, dark green, smooth, 6–15 cm long, fully sheathed; petiole sheath deciduous; blades ovate, rounded at base, short-acuminate at apex, coriaceous, 10–20 × 9–12 cm, not appressed to the phorophyte; fenestrations absent or present. ADULT PLANTS: root climbers; stem dark or slightly light green, smooth, cylindrical; internodes 2–4(10) cm long, 1.0– 2.5 cm diam., 1.6–2.0 times longer than wide; anchor roots dark brown; feeder roots black and with radical trichomes; petiole dark green, smooth, 12–30 cm long, sheathed to base of the geniculum, petiole sheath deciduous; geniculum smooth, slightly ribbed, sulcate adaxially, convex abaxially, 1.5–2.5 cm long; blades broadly ovate to ovate, unequal and obtuse to rounded at base, short-acuminate at apex, coriaceous, drying dark brown and faintly glossy above, slightly paler below, 15.5–25.5 × 8.3–16.5 cm, 1.5–1.8 times longer than wide; midrib slightly ribbed adaxially, convex abaxially, drying blackish or yellowish on both surfaces; primary lateral veins 5–8 per side, slightly sunken adaxially, prominent abaxially, departing midrib at 35–45°, drying blackish or yellowish; collective veins not visible; fenestrations absent or present, perforations arranged near the midrib with one side of blade usually more prominently fenestrated; margins entire. INFLORESCENCES on ascending stems; peduncle smooth, 14 cm long, 4 mm diam.; spathe unknown; spadix unknown during development, green to brown at anthesis, matte, 8.3 cm long, 1.6 cm diam., 5.3 times longer than wide; basal sterile flowers 3–5 mm long; fertile lowers 5–7 mm long; stigma linear; berries unknown; seeds unknown.

Etymology: —The species is named in honor of American biologists and Cerro Jefe flora and fauna specialists Jerry and Linda Harrison.

Distribution and ecology: — Monstera harrisoneorum is endemic to Panama, known only from the type locality at 980 m, in a Premontane rain forest life zone.

Phenology: —Fruiting was recorded in March.

Discussion: —The species, a member of section Monstera , is characterized by its hemiepiphytic habit at 2.5–3.0 m above the ground, the pale brown-drying stem with the dried epidermis greatly fissured-ridged and flaking, petioles sheathed to the geniculum and promptly deciduous, sharply sulcate geniculum, coriaceous, glossy, weakly bicolorous blades with the midrib sunken above, narrowly rounded and paler below, primary lateral veins quilted-sunken and concolorous above, narrowly rounded and slightly paler below.

Monstera harrisoneorum could be confused with pre-adult individuals of Monstera donosoensis , but differs in having leaf-blades broadly ovate, obtuse to rounded at base (vs. ovate to elliptic, rounded or truncate at base), and in having flowers with the truncated style (vs. flowers with style hexagonal and strongly conical, and distally cylindrical). It could also be confused with Monstera dissecta , but differs by having leaf-blades broadly ovate, and obtuse to rounded at base (vs. ovate to elliptical or oblong, cuneate to rounded or truncate at base), petiolar sheath deciduous (vs. petiolar sheath persistent), and flowers with the truncated style (vs. flowers with style hexagonal with a stigmatophore cupuliform).

Additional specimens examined (paratypes): — PANAMA. Colón: Santa Rita Ridge , 23 Mar 1972, J.D. Dwyer & A. Gentry 9546A ( MO!) ; Panamá: Altos de Cerro Azul, cerca de la entrada del camino que va hacia los miradores Vistamares y Atakaya , 09°14’46”N 079°24’24”W, 903 m, 17 March 2018, O. Ortiz et al. 2952 ( MO!, PMA!) ; Chagres National Park: vic. Cerro Jefe, between Altos de Cerro Azul and Cerro Jefe, SW slopes of Cerro Jefe , 09°13’39”N 079°23’20”W, 980–990 m, 02 March 2015, T.B. Croat et al. 106207 ( MO!) ; Panamá. Cerro Jefe, at summit, 15.4 miles from Panamerican Highway , 09°14’02”N 079°22’30”W, 1000 m, 05 December 1979, T.B. Croat 49093 ( MO!) .