Monstera colossica M. Cedeño & O. Ortiz, 2025

Cedeño-Fonseca, Marco, Ortiz, Orlando O., Hay, Alistair & Zuluaga, Alejandro, 2025, Land of giants: two new pachycaul Monstera (Araceae, Monsteroideae, Monstereae) from Panama, PhytoKeys 267, pp. 109-122 : 109-122

publication ID	https://doi.org/10.3897/phytokeys.267.170789
DOI	https://doi.org/10.5281/zenodo.17821989
persistent identifier	https://treatment.plazi.org/id/D7003B35-1862-5711-A638-9899F17259DC
treatment provided by	PhytoKeys by Pensoft
scientific name	Monstera colossica M. Cedeño & O. Ortiz
status	sp. nov.

Treatment

Monstera colossica M. Cedeño & O. Ortiz sp. nov.

Figs 4 View Figure 4 , 5 View Figure 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 reticulate towards the margin; collective vein visible; fenestrations absent or present; when present, in two or three rows along the mid-rib, usually comprising small sub-circular holes 1.0–5.0 cm diameter, near the mid-rib; margins entire, but sometimes the larger perforations tearing through to the margins. INFLORESCENCE solitary; peduncle 20–22 cm long; spathe 15–32 cm long, 25 cm wide when flattened, coriaceous, whitish; spadix 18–22 cm long, 3–4 cm diam., greenish; basal sterile flowers 4.0–5.0 mm long; fertile flowers 7.0–9.0 mm long; stamens 3–8 mm long, with laminar filaments; ovary rectangular in longitudinal section, 4.0–6.0 × 2.0–3.0 mm; style hexagonal and with stigmatophore slightly conical; stigma linear; berries with a creamy stylar cap during development, ripe berry colour unknown; seeds unknown.

Etymology.

The specific epithet “ colossica ” is derived from the Latin colossus, itself from the Greek kolossos (κολοσσός), meaning “ giant statue ” or “ colossus ”, highlighting the plant’s overall massive and striking appearance.

Distribution and ecology.

Monstera colossica is endemic to Panama, known only from the type locality on the border of Chiriquí and Bocas del Toro Provinces and in Cerro Colorado at 1450–1480 m elevation in a Premontane rainforest life zone.

Phenology.

Flowering time in November; mature fruits in June.

Discussion.

The species is a member of Monstera sect. Monstera and is characterised by its adult plants with an appressed-climbing habit, short internodes, minutely white punctulate and fully sheathed petioles with a sharply sulcate geniculum, large narrowly ovate-elliptic subcordate blades with two rows of small elliptic perforations on both sides and the primary lateral veins diverging at 50–70 ° and branching with 2–3 branches within 1.0–3.0 cm from the mid-rib.

Monstera colossica specimens were included as part of M. titanum in Cedeño-Fonseca et al. (2021) as paratypes, but this species differs from M. titanum in having primary lateral veins branching with 2–3 branches and pale green below (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) (Table 1 View Table 1 ).

Monstera colossica could be confused with M. oreophila Madison , but it differs in having more robust stems, 5–7 cm in diameter, (vs. slender stems, 2–4 cm diam.), the petiole smooth and minutely white punctulate at the base (vs. petiole never punctulate, but warty or sometimes smooth), up to 25 primary lateral veins branching with 2 or 3 branches (vs. up to 45 primary lateral veins never branching), peduncle up to 22 cm long (vs. peduncle up to 40 cm long), spadix 18–22 × 3–4 cm diam. (vs. 7–15 × 1.3–3.0 cm) and the spathe whitish (vs. spathe pinkish externally and light orange-yellow internally) (Table 1 View Table 1 ).

Monstera colossica also could be confused with M. gigas , but differs in having short petioles 50–65 cm long (vs. 66–140 cm long), petiole sheaths extending to the geniculum (vs. petiole sheathed up to ca. 10–15 cm before geniculum, the free portion terete), smaller leaf blades 47–70 cm long (vs. leaf blades 72–140 cm long), up to 25 primary lateral veins branching with two – three branches from the mid-rib (vs. up to 65 primary lateral veins never branched) and the geniculum sulcate adaxially and convex abaxially (vs. geniculum completely terete) (Table 1 View Table 1 ). M. colossica and M. gigas grow sympatrically in the cloud forest in the Fortuna area.

Additional specimens examined.

Panama • Comarca Ngäbe-Buglé: Cerro Colorado, along mining road 31.6 km beyond bridge over Río San Felix ( 10.6 km beyond turnoff to Escopeta ), 1690 m elev., 15 July, 1976, T. B. Croat 37178 sub Monstera titanum ( MO!) ; • 7 mi W of Chamé, along trail through Guaymí Village , 1500 m elev., 8 July 1988, T. B. Croat 69190 sub Monstera titanum ( MO!) ; • 9.2 mi W of Chamé, along trail E of road which leads down to stream , 1450–1480 m elev., 6 July 1988, T. B. Croat 69033 sub Monstera titanum ( MO!) ; • Cerro Colorado, 9.2 mi W of Chamé, along trail E of road which leads down to a stream , 1450–1480 m elev., 6 July, 1988, T. B. Croat 69012 sub Monstera titanum ( MO! PMA!) ; • Chiriquí: Distrito Gualaca, Reserva Forestal Fortuna, Divisora Continental , 1154 m elev., 9 November 2013, O. Ortiz, J. Batista & F. Miranda 1809 sub Monstera titanum ( PMA) ; • Chiriquí: Gualaca, Hornito, Fortuna, camino a Chiriquí Grande , 1230 m elev., M. Cedeño et al. 2329 sub Monstera titanum ( PAM!, USJ!) ; • Chiriquí: Gualaca, Hornito, Fortuna, camino a Chiriquí Grande , 780 m elev., 17 November 2022, M. Cedeño et al. 2733 ( PMA!, B!) .