Monstera croatii M.Cedeño & A.Hay, 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 : 53-56

11. Monstera croatii M.Cedeño & A.Hay, Webbia 75(1): 124. 2020. ( Figs. 20 , 21 )

Type: — COSTA RICA. Puntarenas Province, Golfito Cantón, Golfito , camino hacia las antenas, 389 m, 4 February 2019 (fr.), M. Cedeño & A. Hay 1624 (holotype USJ! [2 sheets]) .

Nomadic vine, appressed-climbing habit. SEEDLINGS: bearing foliage leaves. JUVENILE PLANTS: root climbers; terrestrial or with ascending stem; stems dark or light green, smooth, cylindrical; internodes 1.0– 2.4 mm long, 0.5– 10.0 mm diam.; cataphylls light green-pruinose, mucronate, persistent; petiole distinct, dark or light green, smooth, 8–10 cm long, sheathed 3–6 cm long; petiole sheath persistent; unsheathed portion slightly terete or slightly ribbed; blades lanceolate, attenuate at base, acuminate, thinly coriaceous, 10–20 × 4–10 cm, not appressed to the phorophyte; fenestrations present or absent, generally one fenestrated side which breaks at the margin (when present). ADULT PLANTS: root climbers; stems dark green or bright beige, cylindrical, internodes 1.0– 1.5 cm long, 1.5–2.0 cm diam., 0.7–1.0 times as long as wide; anchor and feeder roots light brown; petioles light green, smooth and glaucous throughout, 35–45 cm long, sheathed for 20–28 cm; petiole sheath persistent and involute; unsheathed portion terete and slightly ribbed near geniculum; geniculum nearly terete, sulcate adaxially, 2.0– 2.5 cm long; blades oblong-ovate, rounded or asymmetrical at base, short acuminate at apex, subcoriaceous, 30–45 × 25–33 cm, not decurrent on the geniculum; midrib ribbed adaxially, convex abaxially; primary lateral veins 8–13 per side, departing midrib at 75–90°, sunken adaxially, prominent abaxially; secondary veins parallel; collective veins scarcely visible on the margins of each lobe; fenestrations absent; margins deeply pinnatifid, 6–12 lobes per side with 1–2 veins per lobe, 0.5–2.5 cm wide. INFLORESCENCES on ascending stems, 1 or 2 simultaneously at flowering time into cataphylls that cover the middle of the peduncle; peduncle smooth, 20–25 cm long; spathe long acuminate, 2-ribbed, light green during development, cream externally and white internally at anthesis, 9–14 × 3–5 cm, up to 5 cm longer than the spadix; spadix white in pre-anthesis and anthesis, 6–8 × 2.5–3.0 cm in early fruit, the basal zone of basal sterile flowers slender, very conspicuous; basal sterile flowers 3–5 mm long, globose and with a very prominent stigmatophore; fertile flowers 5–6 mm long; stamens 2–5 mm long, with laminar filaments; anthers 1–2 mm long; ovary quadrangular in longitudinal section, 1.5–3.0 × 1.5–2.0 mm; style quadrangular from above, cylindrical, or hexagonal, 0.5–1.0 × 2–3 mm; stigma linear; berries with green stylar cap during development, ripe berries unknown; seeds unknown.

Distribution and ecology: — Monstera croatii is endemic to Costa Rica, where it is known only from the south on the Pacific side in the region of Golfito and the Parque Nacional Corcovado (both in the Cantón of Golfito) at ca. 300– 600 m. It lives in Tropical wet forest and Premontane wet forest transition life zone; in primary and secondary forest, and in open areas.

Phenology: —The flowering has been recorded in February, and fruiting in October and November.

Discussion: —The species is a member of sect. Monstera and is characterized by its long-petiolate, nearly fully sheathed petioles, deeply pinnately lobed, yellowish green-drying blades and narrow pinnae with short pale lineations on both surfaces.

Monstera croatii is differentiated from all other Costa Rican species of Monstera by having pruinose/glaucous stems and petioles, the petioles sheathing for about half their length, with the sheath wings involute and persistent and the free (distal) part terete or only weakly channeled. It is further differentiated by the deeply pinnatifid and bluish green leaf blades, sometimes with bifid lobes, and the pruinose peduncles with a persistent sheathing mucronate cataphyll. A unique characteristic of this species is its terrestrial habit, reaching the adult plants vegetative stage in this state and climbing only to very limited height before flowering. Fertile terrestrial individuals were not found, but one plant was observed fertile after climbing only 50 cm above ground level with the same stem and leaf morphology as terrestrial examples.

Monstera croatii has basal sterile flowers with the ovary spherical, as is also the case in M. glaucescens , which too has glaucous stems and briefly sheathed petioles, but that species (known only from the Caribbean side of Costa Rica) has the leaves pinnately lobed (never deeply pinnatifid), the petiolar sheath persistent but not with involute margins, and the non-sheathing part of the petiole channeled (never terete). Monstera croatii can also be confused with Monstera pinnatipartita Schott (1857: 197) , but that species has the petioles green or speckled (never glaucous), never develops to the adult plants vegetative form on the ground, is fertile only after significantly ascending its phorophyte, and has acuminate and marcescent (not mucronate and persistent) cataphylls.

Additional specimens examined: — COSTA RICA. Puntarenas, Golfito, Golfito , camino hacia las antenas, 8°38’55.1’’N, 83°9’30.8’’W, 389 m, 4 February 2019 (fr.), M. Cedeño & A. Hay 1625 ( USJ!) . Puntarenas, Golfito, Golfito , camino a las torres del I.C.E., aprox. 2 km antes de llegar, 8°39’25’’N, 83°9’25’’W, 389 m, 29 January 1992 (fr.), Á. Fernández 205 ( CR!, MO!) . Puntarenas, Golfito, Parque Nacional Corcovado, Estación Agujas , Cerro Rincón , 8°31’34.467’’N, 83°28’3.9’’W, 600 m, 11 November 1999 (fl.), E. Mora 725 ( CR!) .

Figures

FIGURE 20. Monstera croatii from Golfito Costa Rica. (A) Developing inflorescence. (B) Front and back views of open inflorescence. (C) Fertile flower; in lateral view (left) and in longitudinal section (right). (D) Stylar plate with stigma (left) and one stamen (right). (E) Sterile flower; in lateral view (left) and in longitudinal section (right). (F) Infructescence. (G) Juvenile plant. H.Adult plant. M. Cedeño et al. 1624 (USJ). Image from Cedeño-Fonseca et al. (2020d).

FIGURE 21. Monstera croatii from Golfito, Costa Rica.(A) Hemi-epiphytic habit, ascending to only 1.5 m above the ground, showing the glaucous leaf color especially on the youngest leaves. (B) Terrestrial habit, with the same morphology as that of reproductive individuals. (C) Young infructescence with the green stylar layer, conspicuous basal sterile zone, and persistent subtending cataphylls. (D) Base of the glaucous/pruinose petiole and persistent involute petiole sheath (arrow). (E) Part of the petiole completely terete beyond the sheath. (F) Leaf with two primary veins per lobe, sometimes bifid into lobules that divide up to 4 cm away from the costa (arrow). M. Cedeño et al. 1624 (USJ). Image from Cedeño-Fonseca et al. (2020d).