MONSTERA KESSLERI

PROTOLOGUE: Monstera kessleri Croat, published in Novon 15: 91 (2005).

Monstera kessleri Croat, sp. nov. Planta hemiepiphytica; petiolus 15–36 cm longus, vaginatus ad geniculum; lamina anguste ovata, ovato-elliptica, 25–41(46.5) cm longa, 13–25 cm lata; pedunculus 22 cm longus, ca. 5 mm diam. in sicco; spadix 11.5 cm longus, 2.5 cm diam. Type: Bolivia. Cochabamba: Chapare, Parque Machia, 1 km E of Villa Tunari, 16°48′S, 65°24′W, 350 m, 14 Sep. 1996, T. Kessler 8479 (holotype, MO-05042748; isotype, LPB).

DISTRIBUTION: Bolivia: Bolivia.

DISTRIBUTION NOTE: Bolivia: Cochabamba.

SPECIES DESCRIPTION:

Hemiepiphyte; stems with pre-adult internodes 1–2 cm long, drying smooth, dark yellow-brown, densely and minutely granular on magnification; adult internodes unknown. Petioles 15–36 cm long, sheathed throughout to geniculum, drying matte, medium-dark yellow-brown, weakly and closely ridged; sheath margin narrow, sometimes flaking free. Leaf blades narrowly ovate to ovate-elliptic, 25–41(46.5) × 13–25 cm, (1.2)1.6–1.9(2.7) times longer than wide, 1.1–1.7 times longer than petioles, rounded to acute at apex, acute to weakly attenuated or rounded at base, drying dark brown and matte above, dark yellow-brown and semiglossy below; margins entire and with a single elongated perforation or with only 1 to 2 deep, narrow sinuses open to the margin (only 1 deep sinus on pre-adult blades); midrib drying weakly raised and concolorous above, convex and slightly paler below; primary lateral veins 9 to 11 pairs, arising at an acute angle then spreading at 30°–50° angle, flat and weakly visible above, convex and slightly darker than surface below; minor veins weak, fine, parallel.²

INFLORESCENCE:

Inflorescences with peduncle 22 cm long, ca. 5 mm wide on drying, drying dark yellow-brown; spadix 11.5 cm long, 2.5 cm diam. Styles 3–4.5 mm diam. on drying, irregularly angular, matte, concave; stigma raised, oblong, 1.8–2.2 mm long, 0.3–0.4 mm wide, the margins light brown, with a deep medial furrow.²

ECOLOGY:

Monstera kessleri is known only from the type, collected near Villa Tunari in Cochabamba, Bolivia, but juvenile material collected near Rurrenabaque and an aberrant specimen from Peru almost certainly belong to this species, too.²

ETYMOLOGY:

Named in honor of Michael Kessler, a German plant ecologist from the University of Göttingen who has devoted much of his professional career to the plants of Bolivia.²

NOTES:

1. The new species is characterized by its narrowly ovate, dark brown-drying leaf blades with only 1 to 2 deep sinuses per side. They are similar in size, shape, and color to those of Monstera spruceana (Schott) Engler, which also has similar pre-adult blades, but differs in having the peduncle shorter than the spadix (vs. about twice as long in Monstera kessleri). A collection from the department of La Paz, Province Franz Tamayo (Helme 252), collected 42 km west and 1 km north of Rurrenabaque at 14°25′S, 67°55′W, 330 m, is very likely a juvenile plant of Monstera kessleri, and it has exserted leaves rather than the shingle-leaves characteristic of Monstera spruceana.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Monstera kessleri Croat

2. Novon 15: 91 (2005) — protologue.

3. iNaturalist: Monstera kessleri

Additional photos from iNaturalist by jose_balderrama, lsw, Nicholas Pollock, Donovan Osorio and Andy Jordan