Monstera acacoyaguensis Matuda, Madroño, 1949

Croat, Thomas B., Cedeño-Fonseca, Marco & Ortiz, Orlando O., 2024, Revision of Monstera (Araceae: Monsteroideae) of Central America, Phytotaxa 656 (1), pp. 1-197 : 14

1. Monstera acacoyaguensis Matuda, Madroño 10: 48. 1949. ( Figs. 1 , 2 )

Type: — MEXICO. Chiapas: in shaded woods or forest, along the Rio Grande, Acacoyagua, near Escuintla , at about 100 m. altitude, 25 May 1948, Matuda 17853 (holotype MEXU!, isotypes EAP!, F, MEXU!) .

Monstera magnispatha Matuda, Rev. Soc. Mex. Hist. Nat. 11: 97 (1950). TYPE:— MEXICO, Chiapas, en orilla de arroyo, bosque alto, Esperanza, Escuintla , 160 m., 28 Sept. 1947, E. Matuda 17015 (lectotype HEM [Matuda Herbarium], designated by Madison (1977), isolectotypes F (1273057, 1273060)!, MEXU!, NY [photo]!).

Nomadic vine, appressed-climbing. SEEDLINGS bearing foliose leaves. JUVENILE PLANTS root climbers; stems cylindrical, smooth, light green, internodes 3–7 cm long, 3–6 mm diam.; petiole distinct, light-green, smooth, 5–10 cm long, sheathed to the geniculum; petiole sheath semi-persistent; blades elliptical, subcordate at base, acuminate at apex, thinly coriaceous, 10–15 × 5–10 cm, not appressed to the phorophyte; fenestrations present or absent. ADULT PLANTS: root climbers; stems cylindrical, smooth, light green or grayish, internodes 1–3 cm long, 1–3 cm diam., as long as wide; anchor roots black, feeder roots light brown; petioles 35–55 cm long, light or dark green, smooth, sheathed to the geniculum; petiole sheath semi-persistent; geniculum 2–5 cm long, smooth, flattened or slightly corrugated adaxially and convex abaxially; blades 45–85 × 35–45 cm, 1.7–2.5 times longer than wide, slightly decurrent on the geniculum (decurrent part 1.5–2.0 mm wide), lanceolate, elliptical, subcordate to obtuse, acuminate at apex, thinly coriaceous, drying blackish or greenish brown; midrib sulcate adaxially, convex abaxially; primary lateral veins 15– 25 per side, parallel, sunken adaxially, raised abaxially, departing midrib at 75–85°; secondary veins inconspicuous and reticulate towards the margin; collective veins present; fenestrations elongated and ellipsoid, arranged in 1 or 2 series on each side of the midrib; margins entire or pinnatilobed (3–5 lobes per side). INFLORESCENCES on ascending stems, arranged in the axils and into deciduous cataphylls, 1–3 simultaneously during the flowering season; peduncle smooth, 15–35 cm long, 1.5–2.0 cm diam.; spathe acuminate, light-green and pruinose during development, yellowish green externally and white internally at anthesis, coriaceous, deciduous after anthesis, 10–20 × 7–10 cm, up to 10 cm longer than the spadix; spadix acute at apex, white during development, yellowish at anthesis, 15–17 cm long, 2–3 cm diam., (6.3)9.0–10.0(11.0) times longer than wide; basal sterile flowers 5–6 mm long, with yellowish stigmatic secretion; fertile flowers 5–7 mm long; stamens 2–6 mm long, with laminar filaments; anthers 1–3 mm long; ovary quadrangular in longitudinal section, ribbed, 3–4 × 2–3 mm; style hexagonal, 0.5–1.5 × 3.5–4.0 mm; stigmatophore columnar, 0.5–1.5 mm long; stigma linear, with a transparent stigmatic secretion; berries with a stylar cap white, cream white or cream during development, pulp white; seeds spherical, 4–7 mm diam., black.

Distribution and ecology: — Monstera acacoyaguensis ranges from Mexico (western Chiapas) to Belize and Guatemala; elevations range from 0–200 m, in Tropical moist forest, Premontane wet forest.

Phenology: —Flowering in January and March. Fruiting in March.

Discussion: —The species, a member of sect. Monstera , is characterized by its large, non-pinnate, heavily perforated blades with attenuated leaf bases, with elongated and ellipsoid fenestrations arranged in 1 or 2 series on each side of the midrib, petiole sheath semi-persistent, and by the long inflorescence which is one of the longest and narrowest inflorescences of species in Central America. The epidermis of this species is characteristic in drying with a series of raised minute ridges with frequent diagonal cross-veins.

Monstera acacoyaguensis could be confused with M. adansonii but differs in having petiole sheath semi-persistent (vs. petiole sheath deciduous, sometimes with fibrous residues), blades 45–85 × 35–45 cm (vs. blades 23–65 × 17–30 cm), peduncle 15–35 cm long (vs. peduncle 12–20 cm long), spathe up to 10 cm longer than the spadix (vs. spathe up to 5 cm longer than the spadix), spadix 15–17 cm long (vs. 10–15 cm long), and spadix 9–10 times longer than wide (vs. spadix 7.0–9.2 times longer than wide).

The type specimen is from western Mexico, but most of the material observed is from the Caribbean slope in Yucatan, Belize, and eastern Guatemala.

Additional specimens examined: — MEXICO. Chiapas: Municipio Acacoyagua, ca. de 500 m antes de la desviación a Los Cacaos , 15°21’14”N 092°40’12”W, 114 m, 08 March 2020, P.D. Jiménez et al. 1463 ( HEM!) ; 150 m, 05 December 1949, E. Matuda 18716 ( EAP) ; 2 km from Highway 200 on road to El Triunfo , open site along stream, 100 m, 24 Aug 1972, M.T. Madison 638 ( SEL!) ; Guerrero: San Luis Acatlán. Yoloxóchitl . Parje ichi yata kurra Mateo Herrera , a 2.39 km al W en linea recta del centro de Yoloxóchitl, 50 m del camino viejo a San Luis, en la parcela del Sr. Timoteo Morales Isabel, 16°48’35”N 098°42’26”W, 470 m, 19 April 2017, K. Velasco 40327 ( MO!) ; Oaxaca: Concepción Progreso, 15 km al E de Putla. Veg. Bosque mesófilo con Pinus, 9 Jun 1985, R. Torres C. & A.J. García-Mendoza 6717 ( MO!) ; Veracruz: Along road between Catemaco and Montepio , 4.7 km S of Los Tuxtlas Field Station, 7.4 km beyond end of asphalt highway, 17.5 km N of Catemaco, 18°36’36”N 095°03’36”W, 50 m, 25 Aug 1996, T.B. Croat 78689 ( MO!) ; San Andrés Tuxtla. Ejido 1º de Mayo, faldas del Volcán San Martín . Selva alta perennifolia, 18°33’N 095°13’W, 920 m, 2 May 2005, T. Krömer & A. Acebey 2059 ( MEXU!, MO!) ; Yucatán: Sotuta. Sotuta, Cenote Xmucuy , el cenote y sus cercanías constituyendo un enclave, 20°33’32”N 088°59’47”W, 20 m, 09 dic 2000, G. Carnevali & J.L. Muñoz 6288 ( CICY!, MO!, SEL!) . BELIZE. Belize: Gracie Rock . Sibun River, 17°32’22”N 088°36’24”W, 5–130 m, 22 May 1935, Percy H. Gentle 1649 ( MO!) ; Cayo: 30 Miles section, Hummingbird Highway . High ridge, 17°05’N 088°37’W, 3 Mar 1958, P.H. Gentle 9670 ( LL!) . GUATEMALA. Izabal: Vicinity of Quiriguá , 15°16’13”N 089°02’24”W, 75–225 m, 15 May 1922 – 31 May 1922, P.C. Standley 24136A ( GH!, US!) ; Modesto Méndez. Swampy ground near Río Sarstun , 15°53’31”N 089°13’31”W, 10 m, 12 Jun 1970, W.E. Harmon 2562 ( MO!) .

Figures

FIGURE 1. Monstera acacoyaguensis from Acacoyagua, Mexico.(A) Open inflorescence, frontal view. (B) Immature infructescence.(C) Open inflorescence, back view. (D) Fertile flower; in lateral view (left), and longitudinal section (right). (E) Portion of juvenile plant. (F) Sterile flower; in lateral view (left), and longitudinal section (right). (G) Portion of adult plant. (H) Stylar plate with stigma (left) and one stamen (right). (I) Developing inflorescence. P. Diaz-Jiménez et al. 1463 (HEM). Photo bv M. Cedeño-Fonseca.

FIGURE 2. Monstera acacoyaguensis. Adult plant growing in the locality type in Acacoyagua, Mexico. P. Diaz-Jiménez et al. 1463 (HEM). Photo by M. Cedeño-Fonseca.