Philodendron gigas Croat, sp. nov.

TYPE: Panama. San Blas: El Llano--Cartí road, 10.1 mi. N of Inter-American Highway, then 1.9 mi. N of Nusagandi, 310 m, 9E20'N, 79EW, 20 July 1994, Croat & Zhu 76988 (holotype, MO--4619563--69; isotypes, B, CAS, CM, COL, CR, F, K, MEXU, NY, PMA, QCNE, VEN, SCZ, US). Figures 192--196, 205.

Planta hemiepiphytica; internodia 1--2 cm longa, (3)6--10 cm diam.; cataphylla acute D-formata (ribs low), 30--50 cm longa, in sicco rubribrunnea persistentia ut grasso reticulo fibrarum et frustris epidermidis; petiolus semiteres, (59)98--137 cm longus; lamina ovata vel late ovata, cordata vel sagittata basi, (44)81--125 cm longa, (30)37--90 cm lata, in superficie superiore velutina; inflorescentia usque 7; pedunculus 13--16.5 cm longus; spatha 13--16.5 cm longa; lamina spatha alba extus, suffusa rubella atrirubriviolacea; tubo spathae extus purpurascentiviolaceo, intus atripurpascentiviolaceo; pistilla 4--5-locularia; loculi 20-ovulati; baccae viridalbae aut alba.

Hemiepiphytic, growing to 15--20 m; stem appressed-climbing (or scandent when preadult), sap reddish, viscous, leaf scars conspicuous, to 4 cm wide; internodes short, 1--2 cm long, (pre-adult length to 15 cm long), (3)6--10 cm diam., glaucous, olive-green to dark green, coarsely white striate near apex, the epidermis with reddish brown patches and reddish brown raised ridges, becoming brown and scurfy, ridged; roots scurfy, short and blunt, dark reddish brown, 5--11 mm diam., feeder root to 3 cm diam., grayish, sparsely and conspicuously warty; cataphylls 30--50 cm long, to 25--30 cm broad at base (when flattened out), more or less D-shaped, unribbed to sharply 2-ribbed (ribs low), greenish white to reddish, thick, juicy, drying reddish brown, persisting semi-intact, eventually as a reticulum of fibers and patches of epidermis; petioles (59)98--137 cm long, (1.5)2--3 cm diam., subterete, medium to dark green, semiglossy, weakly and obtusely flattened adaxially, especially near apex, surface densely and finely short-lineate to faintly striate; blades ovate to narrowly ovate, moderately coriaceous, bicolorous, acuminate at apex (the acumen weakly inrolled), cordate to sagittate at base, (44)81--125 cm long, (30)37--90 cm wide (1.4--1.7 times longer than wide), (0.9--1.2 times longer than petiole), subcoriaceous, margins hyaline, upper surface dark green, velvety, matte, lower surface slightly paler, semiglossy to matte, sometimes tinged pale reddish between veins; anterior lobe 33--102 cm long (3.5--6.1 times longer than posterior lobes); posterior lobes 13--26 cm long, 13--24 cm wide, incurved and overlapping with sinus closed on adult plants, obtuse; midrib flat to weakly convex, silvery-white to yellowish green, paler than surface above, narrowly rounded and slightly paler than surface below; basal veins (3)9--12 per side, first and second free to base, most of remainder coalesced to 4 cm, 2 coalesced to 14 cm; posterior rib naked 1.5--4 cm; primary lateral veins (4)7-10 per side, departing midrib at a 40--60E angle, arcuate to the margins, narrowly weakly sunken and slightly paler than surface and marginally discolored above, prominently round-raised, paler than surface below; minor veins weakly visible but not distinct below, arising from both the midrib and primary lateral veins. INFLORESCENCES (post-anthesis) to 7 per axil; peduncle 13--16.5 cm long, green, white-striate, especially at apex; prophylls to 22 cm long; spathe 13--16.5 cm long, 5 cm diam., moderately constricted above the tube, weakly glossy; spathe blade 5.8 cm long, white, tinged reddish outside, dark red-violet inside; spathe tube oblong-ellipsoid, 7.5 cm long, purplish violet, short white lineate outside, dark violet-purple, short white lineate inside; spadix sessile; to 12.5 cm long, ca. 1.5 cm diam., constricted above sterile portion; pistillate portion pale green, more or less ovoid, 4.2 cm long in front, 3.4 cm long in back, 2.2 cm diam.; staminate portion 11 cm long; fertile staminate portion to 2.5 cm diam. midway; sterile staminate portion 2.4 cm diam., slightly broader than pistillate portion; pistils 4--6 mm long, 1.4 mm diam.; ovary 4--5-locular, with more or less axile placentation; locules 2.8--5.2 mm long; ovules ca. 20 per locule, 0.1--0.25 mm long, funicle shorter than to equal in length to ovules, style similar to style type B; style crown domed, irregularly lobed; stigma hemispheroid, 1--1.2 mm diam., 0.4--0.7 mm high. INFRUCTESCENCE with berries greenish white; seeds 3--4 per locule, 1.6 mm long.

Flowering in Philodendron gigas occurs during the rainy season beginning in about July and probably lasting for more than one month, perhaps as much as two months. Immature fruits have been collected in March.

Philodendron gigas is endemic to the Canal Area where it is known only along the El Llano--Cartí road in both Panamá Province and in the Comarca de San Blas at 300 to 375 m in Premontane wet forest and Tropical wet forest.

Philodendron gigas is a member of P. sect. Philodendron subsect. Philodendron ser. Velutina. This species is distinguished by its appressed climbing habit, short, thick internodes (6--10 cm diam.), sharply D-shaped, semi-persistent cataphylls, subterete petioles, thick, scaly roots, and especially by its huge, ovate, velvety, dark green leaf blades. It is found growing high on trees, to about 20 meters.

Philodendron gigas is apparently most closely related to P. andreanum Devansaye from Colombia. That species shares with P. gigas dark green, velvety leaf blades, but differs in having more elongate ovate-triangular blades with the lobes much longer than broad (versus rounded and about as long as broad on P. gigas). Philodendron gigas has blades about 1.6--2.5 times longer than broad, versus 2.6--3 times for P. andreanum. In addition, P. andreanum is described as having the spathe tube green outside and becoming whitish within. In contrast, P. gigas has the post-anthesis spathe tube purplish both inside and outside.

Philodendron gigas is not easily confused with any of the other velvety-bladed species of Philodendron from Central America. Both P. verrucosum L. Mathieu ex Schott and P. squamipetiolatum Croat have velvety blades, but both have scaly petioles. In South America, two other species with velvety, ovate leaf blades, P. gloriosum André and P. mamei André, differ in being terrestrial with repent stems. Both are probably restricted to the eastern slopes of the Andes.

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Additional specimens examined.

PANAMA. Panamá: El Llano--Cartí Road, Mile 8.2, 300--350 m, Croat 33680 (B, F, L, MEXU, MO, PMA, QCA, US); Mile 5--6, 350--375 m, Croat 34778 (F, MO); Mile 10, Croat 33714 (F, MO). San Blas: El Llano-Cartí road, Mile 14, 300 m, 9E15'N, 79EW, Croat 69242 (CM, MO).