Land of giants: two new pachycaul Monstera (Araceae, Monsteroideae, Monstereae) from Panama

109 Land of giants: two new pachycaul Monstera (Araceae, Monsteroideae, Monstereae) from Panama Marco Cedeño-Fonseca1,2,3 , Orlando O. Ortiz1,4,5 , Alistair Hay6,7 , Alejandro Zuluaga8 1 Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Königin-Luise-Straße 6-8, D-14195 Berlin, Germany 2 Centro de Investigación Jardín Botánico Lankester, Universidad de Costa Rica, P.O. Box 302-7050, Cartago, Costa Rica 3 ResearchAssociate,HerbarioLuisFournierOriggi(USJ),CentrodeInvestigaciónenBiodiversidadyEcologíaTropical,UniversidaddeCostaRica,Apdo.11501−2060, San José, Costa Rica 4 Universidad de Panamá, Herbario PMA, Estafeta Universitaria, Apdo. 3366, Panama City, Panama 5 CoibaScientificStation(COIBAAIP),Clayton,CiudaddelSaber,PanamaCity,Panama 6 Royal Botanic Gardens Sydney, Mrs Macquarie’s Road, Sydney 2000, Australia 7 Jardín Botánico de la Paz y Flora, Bitaco, Valle del Cauca, Colombia 8 Departamento de Biología, Universidad del Valle, Calle 13 # 100-00, Cali, Colombia Corresponding author: Marco Cedeño-Fonseca ([email protected]) Copyright: © Marco Cedeño-Fonseca et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Review Article Abstract The genus Monstera is a diverse group of nomadic vines endemic to the Neotropics, with its greatest diversity concentrated in the montane forests of southern Central America. The Cordillera de Talamanca, spanning southern Costa Rica and western Panama, has emerged as a hotspot for pachycaul Monstera species which exhibit large leaf and inflorescence sizes. This study presents the discovery and description of two new giant Monstera species from Panama: M. corana and M. colossica. Both species occur relatively close to M. gigas in the cloud forests of the southern Talamanca range, an area characterised by high humidity, persistent cloud cover and heterogeneous volcanic soils. We provide detailed morphological descriptions, field observations, distribution maps and comparisons with morphologically related taxa. Key words: Central America, cloud forests, Talamanca Mountain, taxonomy Introduction Monstera [Araceae Juss., Monsteroideae Schott, tribe Monstereae Engler (aka Rhaphidophora clade] (Cusimano et al. 2011; Zuluaga et al. 2019; Haigh et al. 2022) is a genus endemic to the Neotropics, representing a diverse group of nomadic vines, with its greatest diversity concentrated in the montane forests of southern Central America, nonetheless largely in Costa Rica and Panama (Madison 1977; Zuluaga et al. 2019; Cedeño-Fonseca et al. 2022). Monstera exhibits particularly high species diversity in the Cordillera de Talamanca, especially in southern Costa Rica and western Panama (Madison 1977; Cedeño-Fonseca et al. 2022). Recent discoveries of exceptionally large pachycaul Monstera species have drawn increasing scientific attention to this region, such as M. alfaroi Croat & M.Cedeño, M. gigas Croat, Zuluaga, M.Cedeño & Academic editor: Duilio Iamonico Received: 2 September 2025 Accepted: 18 October 2025 Published: 4 December 2025 Citation: Cedeño-Fonseca M, Ortiz OO, Hay A, Zuluaga A (2025) Land of giants: two new pachycaul Monstera (Araceae, Monsteroideae, Monstereae) from Panama. PhytoKeys 267: 109–122. https://doi.org/10.3897/ phytokeys.267.170789 PhytoKeys 267: 109–122 (2025) DOI: 10.3897/phytokeys.267.170789 110 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama O.Ortiz and M. titanum Croat, M.Cedeño & O.Ortiz, the last two taxa currently holding the genus records for the largest leaves and inflorescences, respectively (Cedeño-Fonseca et al. 2021). Other notable examples of very large species within the genus include M. lechleriana Schott from South America and M. deliciosa Liebm. from Mesoamerica. Despite the recent discovery of several giant-leaved species, the full extent of species-level diversity within these montane forests remains underexplored, specifically amongst large-leaved, morphologically similar taxa, which often remain overlooked due to their challenging taxonomy and collection and remote habitats. The phenomenon of very large size in Monstera has yet to be formally studied. However, research on plant gigantism more broadly suggests that extreme organ size, particularly in leaves and stems, is often shaped by ecological, physiological and evolutionary pressures (Givnish 1988; Zotz et al. 2002; Blackman et al. 2005; Poberezhnaya and Kopanina 2009; Bernal et al. 2017; Cox and Burns 2017). In Panama, which harbours the majority of large Monstera species, these taxa are typically found in montane cloud forests (except M. corana, described here), particularly in regions with volcanic soils. M. titanum, for example, is confined to the outskirts of the inactive volcano El Valle de Antón in central Panama. Notably, in a single locality (Fortuna in western Panama), two very large species (M. gigas and the here-described M. colossica) have been documented growing in proximity. Recent studies have identified this region as one of the cloudiest areas in Central America and as a zone of high soil heterogeneity, both of which significantly influence the composition and distribution of plant communities (Dalling et al. 2021). The specific soil type found in these sites, classified as Mafic-Volcanic, is characterised by its relatively high bulk density and clay content as well intermediate fertility (Turner and Dalling 2021). Soil traits, combined with consistently high humidity and/or cloud cover, may represent key environmental factors contributing to the evolution of very large species in Monstera. However, the evolutionary and functional significance of these traits remains poorly understood, highlighting the need for integrative studies that explore the morphological, ecological and genetic underpinnings of the very large size in this genus. Through an approach combining extensive fieldwork and detailed herbarium-based morphological analysis, we identified two previously undescribed pachycaul species of Monstera from Panama. These discoveries contribute to the growing recognition of the Talamanca Mountain Range as a centre of diversity and endemism for Araceae, particularly within the subfamily Monsteroideae. Material and methods Morphological comparisons were based on a careful examination of both herbarium specimens and living plants in the field. Further, all relevant taxonomic literature from Central and South America, type specimens from JSTOR Global Plants (2022) and protologues were examined. To compare morphological variation and to delimit the new species from closely-similar species, the following Herbaria were consulted (acronyms follow Thiers (2025) [continuously updated]): AGUAT, B, BM, BIGU, CHIP, COAH, COL, CR, CSAT, CUVC, DUKE, ENCB, F, HEM, HLDG, HNMN, HUAZ, ITIC, JAUM, JBB, JVR, K, LAGU, LSCR, MA, MEXU, MHES, MO, NY, PMA, SEL, SCZ, TEFH, UDBC, UCH, UJUAT, USCG, USJ, XAL, WU, as well as images of specimens accessible on-line at C, COL, EAP, ENCB, MEXU and TEFH. 111 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama Live plants were studied and photographed in situ with a digital camera Nikon COOLPIX P530 Sony A6000, as well as mobile phones with integrated high-resolution cameras, such as Huawei p20, iPhone 11 Pro and Samsung Galaxy S22 Ultra. Measurements in the description consist of a mix between living plants and herbarium specimens. All images and plates were processed in Adobe Photoshop v. 24.0.1 (Adobe Inc., San Jose, USA). The specimens from different localities were pressed and deposited at PMA. Due to the high demand for aroid species such as ornamental plants and a rapidly growing black market that endangers native populations (even in protected areas), geographic coordinates are here omitted from all specimen citations and no distribution maps are provided. Taxonomic treatment Monstera corana M.Cedeño & O.Ortiz, sp. nov. urn:lsid:ipni.org:names:77372764-1 Figs 1–3 Type. Panama • Provincia Bocas del Toro: distrito Chiriquí Grande, corregimiento Chiriquí Grande, áreas abiertas alrededor de la carretera principal, 17 November 2022, 85 m elev., M. Cedeño, O. Ortiz, N. Köster, A. Hay & R. da pena 2730 (holotype PMA!; isotype B!). Diagnosis. Monstera corana differs from M. buseyi Croat & Grayum by having white, connected and consistently branched primary lateral veins (vs. weakly connected to each other at the base and sometimes weakly branching), 20-35 lateral veins per side (vs. 35–65 per side), blades decurrent at the geniculum (vs. broadly cuneate to truncate at base) and a thin, distally undulate petiole sheath (vs. petiole sheath never undulate). Description. Robust appressed-climbing nomadic vine. SEEDLINGS: unknown. JUVENILE PLANTS: unknown. ADULT PLANTS: root climbers; stem cylindrical, minutely white-green warty, looking like a pulverulent indument ; internodes 0.5–7 cm long, 4–7 cm diam.; anchor roots blackish; feeder roots blackish; petiole 50–75 cm long, green, minutely white punctulate especially towards the base, minutely white-green warty the rest of its length (like the stem), sheathed along its entire length; petiole sheath thin, persistent and undulate from the middle of the petiole to the geniculum, deciduous from middle to the base; geniculum minutely white-green warty throughout, flattened adaxially and transversally convex abaxially, 5.0–7.5 cm long; blades 50–80 × 40–55 cm, narrowly ovate, rounded or asymmetric at base, shortly acuminate at the apex, membranaceous, decurrent on the geniculum and almost connecting with petiole sheath; mid-rib white, concave adaxially, square abaxially; primary lateral veins 20–35 per side, impressed adaxially, prominent abaxially the base of each vein abruptly prominent, connected to each other at the union with the main vein, thick and white up to half their length, diverging at 80–90° and often with one or two subsidiary (branching) veins starting from the base or close to the base, on either side of the primary lateral vein, running near the primary vein and then separate until they reach the margin; secondary veins parallel to the primary lateral veins; collective vein poorly visible; fenestrations scarce, near the mid-rib, when present in two rows along the mid-rib, comprising small oblong holes 0.5–4 cm long, often scattered towards 112 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama the margin; margins entire. INFLORESCENCES solitary, produced on ascending stems; peduncle 25 cm long, minutely white-green verrucose; spathe unknown; spadix 22 cm long, 5 cm diam.; basal sterile flowers 3–4 mm long; fertile flowers 5–7 mm long; stamens unknown; anthers unknown; ovary quadrangular in longitudinal section, 2–3 mm long, style truncate; stigma linear; berries with the stylar cap after anthesis white, white-cream when ripe; pulp white; seeds unknown. Etymology. The epithet “corana” refers to Cora Jane, the daughter of Dr. Sarah Spaulding, who has been a supporter of several projects about Aroid conservation in Costa Rica. Figure 1. Monstera corana M. Cedeño & O. Ortiz. A. Adult plant growing in the forest around Chiriquí Grande; B. The first and second authors with the adult plant in the type locality – Photo by A. Hay; C. Petiole sheath thin and undulate (white arrow) and the geniculum flattened adaxially and transversally convex abaxially (black arrow); D. Infructescence in development; E. Spadix with the white stylar caps after anthesis and the styles truncate (black arrow). Photos by M. Cedeño. 113 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama Distribution and ecology. Monstera corana is endemic to Panama, known only from the type locality (Chiriquí Grande, Bocas del Toro Provinces) at 85 m elevation in a Tropical rain forest life zone. Figure 2. Patterns of primary lateral veins of Monstera corana M. Cedeño & O. Ortiz and similar species. A. M. corana with primary lateral connected to each other at the base (white arrow), thick and white up to half its length, with one or two branching veins that start from the base (black arrow); B. M. buseyi with primary lateral veins green and weakly branching; C. M. alfaroi with primary lateral veins white and not branched; D. M. costaricensis with primary lateral veins white and not branched. Photos by M. Cedeño. 114 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama Phenology. Flowering unknown; mature fruits in November. Discussion. This species is a member of Monstera sect. Monstera and is characterised by its stem with densely and finely white-green warts, the green petiole white punctulate towards the base and densely and finely white-green warty towards the apex, the petiole sheath undulate from the middle of the petiole extending to the base of the geniculum, the blades narrowly ovate, Figure 3. Petioles ornamentation of Monstera corana M. Cedeño & O. Ortiz and similar species. A. Adult plant of Monstera corana with petiole sheath deciduous in the lower half of the petiole and undulate in the upper half to near the base of the geniculum; (I) petiole green punctulate at the base with green and white punctae; B. Adult plant of M. buseyi with petiole sheath deciduous; (II) petiole green black verrucose; C. Adult plant of M. alfaroi with petiole sheath deciduous; (III) petiole brown with brown and black verrucose; D. Adult plant of M. costaricensis with petiole sheath undulate throughout its length; (IV) petiole with green and white verrucose. Photos by M. Cedeño. 115 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama rounded or asymmetric at base and weakly perforated near the mid-rib, primary lateral veins thick and white, connected to each other and the union with the main vein and abruptly prominent at the base, with subsidiary veins arising from the base or close to the base of the primary vein (Table 1). Monstera corana is most similar to M. buseyi which differs in having green petiole white punctulate toward the base and densely and finely white-green warts towards the apex (vs. petiole green with black warts), the petiole sheath distally undulate (vs. petiole sheath never undulate), leaf blade 50–80 × 40–55 cm, narrowly ovate, rounded or asymmetric at base (vs. leaf blade 27–75 × 11–33 cm, ovate to lanceolate-ovate or elliptic, broadly cuneate to truncate at base), and primary lateral veins 20–35 per side, white and strongly connected to each other at the base and always strongly branching (vs. primary lateral veins 35–65 per side, pale green and weakly connected to each other at the base and sometimes weakly branching) (Table 1). Monstera corana is also similar to M. alfaroi and M. costaricensis (Engl. & K. Krause) Croat & Grayum. However, it differs from M. alfaroi in having the green petiole minutely white punctulate toward the base (vs. petiole brown at base, brown-black and white warty), the petiole sheath thin and distally undulate, persistent from half way to the geniculum or deciduous from half way towards the base (vs. petiole sheath undulate in the new leaf and later deciduous), primary lateral veins abruptly prominent at the base connected to each other, diverging at 80–90° and with two branching veins that start from the base or close to the base (vs. primary lateral veins never connected to each other at the base, diverging at 50–70° and never branching), leaf blade membranaceous, decurrent on the geniculum and almost connecting with petiole sheath, (vs. leaf blade coriaceous or subcoriaceous, not decurrent on the geniculum) and Monstera corana occurs at 85 m elevation in Tropical rain forest whereas M. alfaroi occurs at 1100–1250 m elevation in Lower montane rain forest life zone (Table 1). Table 1. Overview of morphological characters of pachycaul Monstera species. Note: Leaf length = petiole length + leaf blade length; inflorescence length = peduncle length + spathe length. Species Leaf length (cm) Leaf blade size (cm) Inflorescence length (cm) Diagnostic features Distribution M. alfaroi 100–160 cm 60–90 × 30–45 30–55 Unbranched primary lateral veins, fenestrations present, ovary quadrangular, style hexagonal, stigma linear. Costa Rica M. colossica 97–65 cm 47–70 × 28–40 35–54 Branched primary lateral veins, fenestrations absent or present, ovary rectangular, style hexagonal with a slightly conical stigmatophore, stigma linear. Panama M. corana 100–155 50–80 × 40–55 47 Branched primary lateral veins, fenestrations present, ovary quadrangular, style truncate, stigma linear. Panama M. deliciosa 40–222 cm 40–112 × 40–88 22–48 Unbranched primary lateral veins, fenestrations present, ovary quadrangular, style compressed and hexagonal with a cupuliform stigmatophore, stigma circular. Southern Mexico, Guatemala M. gigas 138–300 72–140 × 34–61 64–76 Unbranched primary lateral veins, blades entire, ovary rectangular, style hexagonal, stigma circular. Panama M. lechleriana 63–105 cm 47–75 × 31–49 22–52 Unbranched primary lateral veins, fenestrations present, ovary rectangular, style hexagonal, stigma circular. South America M. titanum 87–195 47–100 × 28–35 43–95 Unbranched primary lateral veins, fenestrations present, ovary rectangular, style pyramidal, stigma linear. Panama 116 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama Monstera corana differs from M. costaricensis in having the petiole sheath thin and distally undulate (vs. petiole sheath thick and undulate throughout its length), the leaf blade 40–55 cm wide, membranaceous and decurrent on the geniculum and almost connecting with petiole sheath (vs. leaf blade 15–35 cm wide, coriaceous or thinly coriaceous, slightly decurrent-undulate up to medial part of the geniculum), lateral veins abruptly prominent at the base connected to each other, diverging at 80–90° and with two branching veins that start from the base (vs. primary lateral veins never branching, departing at 45–65°) and the flower in the spadix with truncate style (vs. flower in the spadix with conic style) (Table 1). Monstera corana and M. costaricensis occur sympatrically in the tropical rain forest in Chiriquí Grande area. Monstera colossica M.Cedeño & O.Ortiz, sp. nov. urn:lsid:ipni.org:names:77372987-1 Figs 4, 5 Type. Panama • Provincia Chiriquí: distrito Gualaca, camino a Bosque Protector de Palo Seco, 1 September 2018, 1100 m elev., O. Ortiz, H. Hentrich, M. Cedeño, P. Diaz-Jiménez, and R.M. Baldini 2730 (holotype PMA!). Diagnosis. Monstera colossica differs from M. titanum in having primary lateral veins pale green abaxially and with 2–3 branches close to the mid vein (vs. primary lateral veins never branched and white), short peduncle 22 cm long (vs. 25–48 cm long), short spathe up to 32 cm long (vs. spathe up to 47 cm long), style hexagonal with stigmatophore slightly conical (vs. style pyramidal and distally cylindrical) and always appressed-climbing (vs. appressed terrestrial on rocks or appressed-climbing). Description. Robust appressed-climbing nomadic vine. SEEDLINGS: unknown. JUVENILE PLANTS: root climbers; internodes 2.0–4.0 cm long, 5.0–7.0 mm diam.; petioles 22–30 cm long; sheathed up to ca. 5 cm before geniculum; leaves appressed to the phorophyte with visible petiole, blades 18– 28 cm long, 12–18 cm wide, 1.3–1.5 times longer than broad, abruptly acuminate at apex; collective veins 3.0–5.0 mm from margin; margin entire or rarely pinnatilobed. ADULT PLANTS: root climbers; stems light or dark green, white punctulate, smooth, cylindrical; internodes 1.5–4.0 cm long, 4.0–7.0 cm diam., medium green, semi-glossy; petioles 50–65 cm long, densely and conspicuously white punctulate, especially towards base, equally as long as or 1.1 times longer than blades, sheathing to the base of the geniculum to ca. 10 cm below it, free portion sulcate; petiole sheath deciduous; geniculum sulcate adaxially and convex abaxially, 4.0–7.0 cm long; blades 47–70 × 28–40 cm, narrowly ovate-elliptic, mostly entire, more or less equilateral, subcoriaceous and slightly bicolorous, dark green and semi-glossy above, moderately paler and matte below, drying dark brown and weakly glossy above, greenish-yellow-brown and semi-glossy below, short-acuminate at apex, subcordate at base; mid-rib broadly sunken and concolorous above, narrowly rounded and paler below; primary lateral veins 20–25 per side, narrowly sunken above, convex and slightly paler green below, diverging at 50–70°, sometimes branching with two to three branches within 1.0–3.0 cm from the mid-rib; secondary veins parallel and 117 PhytoKeys 267: 109–122 (2025), DOI: 10.3897/phytokeys.267.170789 Marco Cedeño-Fonseca et al.: Two new giant Monstera from Panama Figure 4. Monstera colossica M. Cedeño & O. Ortiz. A. Adult plant growing in the forest around Fortuna; B. Infructescence in development with remnants of the spathe; C. Free portion of the petiole sulcate adaxially (black arrow) and convex abaxially (white arrow); D. Petioles smooth and conspicuously light green punctulate; E. Lower surface of the adult leaf blade with many primary lateral veins (arrow) and two rows of sub-circular holes along the mid-rib; F. Adult leaf blade subcordate at base. Photos by M. Cedeño.