Philodendron folsomii Croat, sp. nov.
TYPE: Panama. Coclé: Alto Calvario, 9 km N of El Copé, N of Continental Divide along path to W, ca. 800 m, 8E40'N, 80E37'W, 24 Jan. 1989, McPherson 13619 (holotype, MO 3693168; isotypes, B, K, PMA, US). Figures 172, 176.
Planta epiphytica; internodia brevia, 1--1.5 cm longa, 8--20 mm diam.; cataphylla 11--16 cm longa, acute 2-costata, decidua; petiolus subteres, obtuse sulcatus, 12--17 cm longus; lamina oblongo-lanceolata, 28--33 cm longa, 5--7 cm lata, rotundata aut truncata basi; inflorescentia 1--2; pedunculus 10--11.5 cm longus, 2--5 mm diam.; spatha 10--12 cm longa, extus alba; pistilla 6--7-locularia; loculi 1-ovulati.
Epiphytic; stem scandent; internodes short, 1--1.5 cm long, 8--20 mm diam., about as long as broad; cataphylls 11--16 cm long, sharply 2-ribbed, green, deciduous; roots not seen; petioles 12--17 cm long, 3--5 mm diam., subterete, obtusely sulcate; blades oblong-lanceolate, narrowly acuminate at apex, obtuse to almost rounded and decurrent, sometimes nearly truncate at base, 28--33 cm long, 5--7 cm wide (4.6--5.2 times longer than wide), (1.8--2.3 times longer than petiole), upper surface drying gray-green to brownish green; lower surface paler, drying yellowish green; midrib sunken above, convex, drying paler than surface below; basal veins 1--2, free to base; primary lateral veins 8--10 per side, departing midrib at a 35E angle, arcuate to the margins, distinct above; minor veins arising from the midrib only. INFLORESCENCES 1--2 per axil; peduncle 10--11.5 cm long, 2--5 mm diam.; spathe 10--12 cm long (about as long as the peduncle), white throughout outside; spathe tube 5.5 cm long, 2.5 mm diam.; spadix short stipitate; 7--8 cm long; pistillate portion 3--4.1 cm long, 6--7 mm diam.; staminate portion 3.8--4 cm long; sterile staminate portion whitish; pistils 0.8 mm long, 0.6 mm diam.; ovary 6--7-locular, locules 0.6 mm long, 0.3 mm diam., ovule sac 0.6 mm long, with sub-basal placentation; ovules 1 per locule, contained within gelatinous transparent matrix (no true envelope), 0.2--0.35 mm long, as long as funicle; funicle 0.2--0.3 mm long (can be pulled free to base), with glands at base, style similar to style type B; style apex flat; stigma subdiscoid, unlobed, more or less truncate, 0.9 mm diam., 0.3 mm high, covering almost entire style apex; the androecium truncate, prismatic, margins irregularly 5--6-sided, 0.6--0.8 mm long.
Flowering phenology in Philodendron folsomii is uncertain because few collections exist. Flowering collections are known from January and April, both within the dry season but in an area that is not markedly seasonal.
Philodendron folsomii is endemic to Panama, known only from the type locality in Coclé Department, at 700 to 800 m elevation in Premontane rain forest.
Philodendron folsomii is a member of P. sect. Calostigma subsect. Glossophyllum ser. Glossophyllum. This species is characterized by internodes about as long as broad, sharply two-ribbed, deciduous catphylls, oblong, narrowly acuminate, oblong-lanceolate, green-drying blades with obtuse-attenuate bases, and solitary, long, slender-pedunculate inflorescences with white spathes.
Philodendron folsomii is most easily confused with P. sphalerum Schott from the Guianas and eastern Venezuela, which has similar leaves. The latter species differs in having smaller, generally more numerous (up to four) inflorescences per axil with more slender peduncles (drying scarcely 2 mm diam. versus 4 mm or more in P. folsomii) and spathes less than 7 cm long (versus 10--13.5 cm long in P. folsomii).
Philodendron folsomii is also similar to P. correae, which has similarly shaped leaf blades which also sometimes dry green. The latter species differs in having generally longer internodes, petioles usually sheathed to near the apex, blades usually drying black and lacking conspicuous primary lateral veins, and spathes not so conspicuously constricted above the tube.
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Additional specimen examined.
PANAMA. Coclé: El Copé region, 700 m, Folsom & Robinson 2447 (MO).