MONSTERA FILAMENTOSA
PROTOLOGUE: Monstera filamentosa Croat & Grayum, published in Phytologia 82: 43 (1997).
Monstera filamentosa Croat & Grayum, spec. nov. Type: COSTA RICA. Heredia: S base of Cerros Sardinal, Chilamate de Sarapiqui (N side of Rio Sarapiqui), 10° 27.5’ N, 84° 04’ W, 80–110, 4 Jul 1985, M. Grayum & B. Hammel 5539 (HOLOTYPE: MO-3446661–4!; Isotype: CR!).
DISTRIBUTION: Costa Rica to NW. Colombia: Colombia, Costa Rica, Panama.
DISTRIBUTION NOTE: Costa Rica: Heredia iNaturalist: Limón.
SPECIES DESCRIPTION:
Nomadic vine, appressed-climbing and pendent. Seedlings: filiform. Juvenile plants: root climbers; stems dark green, dorsoventrally compressed; internodes 3–5 cm long, 2–4 mm diam.; blades appressed to the phorophyte. Adult plants: root climbers; stems brown to light brown, dorsoventrally compressed and markedly sulcate on one side; internodes 3–4(10) cm long, (0.6)1–2 cm diam., 2–3 times longer than wide; cataphylls pink, marcescent and fibrous; anchor roots black; feeder roots dark brown; petiole brown, grooved at base and smooth towards the geniculum, slightly terete at apex, 25–55 cm long, sheathed to base of the geniculum or 2 cm below it; petiole sheath deciduous with fibrous residues; geniculum smooth or striated, grooved adaxially, convex abaxially, 3–5 cm long; blades narrowly elliptic to lanceolate-oblong, broadly cuneate to rounded or cordate to subcordate at base, acuminate at apex, membranous, drying light green, yellowish or dull beige, 35–105 × 25–40 cm, not decurrent on geniculum; midrib flattened adaxially, convex abaxially, drying light or yellowish brown on both surfaces; primary lateral veins 12–30 per side, departing midrib at 80–90°, sunken adaxially, prominent abaxially, drying yellowish or light brown; secondary veins prominent and reticulated; collective veins present along the margins of the lobes; fenestrations present, arranged along midrib with filamentous strands connecting between the lobes; margins deeply pinnatifid, 6–15 lobes per side, each 2–3 cm wide, each lobe with 1 or 2 veins and a collective vein along the margin.⁴
INFLORESCENCE:
Inflorescences on ascending stems, 1 or 2 simultaneously at flowering time, arranged into cataphylls; peduncle smooth, 4–10 cm long; spathe dark green during development, pink externally and pale pink internally at anthesis, deciduous at the end of anthesis; spadix white during development, cream at anthesis, 6–11 cm long, 1.5–2.5 cm diam., 4.1–4.5 times longer than wide; basal sterile flowers 4–5 mm, with a transparent stigmatic secretion; fertile flowers 5–8 mm long; stamens 2–6 mm long, with laminar filaments; anthers 2–3 mm long; ovary quadrangular in longitudinal section, ribbed, 3–4 × 2–3 mm; style compressed and hexagonal, 1–2 × 3–4 mm; stigma linear, sunken over style; berries with a green stylar cap during development, mature stylar cap dark green; pulp white; seeds yellowish and light brown with white dots, 4–6 mm long.⁴
ECOLOGY:
Monstera filamentosa ranges from Costa Rica to extreme NW Colombia at 0–700 m, in Tropical wet forest and Premontane rain forest life zones. Flowering in January, April, July-September. Fruits in August-September, and January.⁴
ETYMOLOGY:
From Latin filamentosus, "thread-like," referring to the leaf blades perforated medially by filamentous laminar strands.²
NOTES:
1. The species is a member of sect. Marcgraviopsis. It differs from the other species of the genus in Costa Rica by its brown petiole, grooved at base and smooth toward the geniculum, adaxially flat and abaxially convex, the petiolar sheath deciduous with fibrous residues, the leaf blade pinnatifid (with the lobes themselves weakly pinnately lobed) and fenestrate on each side next to the midrib with very slender filaments connecting the lobes, each lobe with a distinct submarginal collective vein and the spathe dark green during development, pink externally and pale pink internally at anthesis (Cedeño-Fonseca et al. 2022). Monstera filamentosa is a seldom-collected species in Costa Rica; the majority of the collections are sterile or include only the spadix. The spathe color notes derive from the first and second author’s field observations. Madison (1977) treated material of this species as Monstera punctulata, from which it is amply distinct (Cedeño-Fonseca et al. 2022).⁴
2. Conservation status: Monstera filamentosa is protected in the Reserva Forestal Golfo Dulce, Refugio de Vida Silvestre Barra del Colorado, Reserva Forestal Río Pacuare, Parque Nacional Braulio Carrillo, Parque Nacional Tortuguero, and Parque Nacional Piedras Blancas.⁵
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Monstera filamentosa Croat & Grayum
2. Phytologia 82: 43 (1997) — protologue.
3. iNaturalist: Monstera filamentosa
Additional photos from iNaturalist by njweess and mdoliveira