Philodendron antonioanum Croat, sp. nov.
TYPE: Panama. Veraguas: vic. of Santa Fe, along road between Alto Piedra and Calovébora, 0.5 mi. N of Alto Piedra, on slopes of Cerro Tute, Parque Nacional Cerro Tute, 1030 m, 15 July 1994, Croat & Zhu 76909 (holotype, MO--4619868--9, MO--4619871--2; isotypes, B, CAS, COL, CR, F, GH, K, MEXU, MO, NY, PMA, SCZ, US, VEN). Figures 61--64.
Planta hemiepiphytica; internodia brevia, 4--7 cm diam.; cataphylla rubra, acute 2-costata, persistentia ut fibrae tenues; petiolus 28--91 cm longus, obtuse complanatus adaxialiter; lamina ovata, 26--86 cm longa, 18--57 cm lata, nervis primariis lateralibus 5--6 utroque; inflorescentia 2; pedunculus 6--7 cm longus; spatha 15--16 cm longa; lamina spathae extus viridalba, intus alba suffusa rubella in dimidio inferiore; tubo spathae in superficibus ambabus marronino; pistilla 5-locularia; loculi 25--30-ovulati.
Hemiepiphytic; larger stems drying reddish brown, smooth, and coarsely striate at nodes, smaller stems drying light yellow-brown, glossy, and finely longitudinally ribbed, finally dark brown and transversely finely cracked; internodes short, 4--7 cm diam., broader than long; roots to 30 cm long, numerous per node, drying reddish brown, weakly glossy, and somewhat ridged; cataphylls 35--39 cm long, sharply 2-ribbed, red, broadly sulcate abaxially, persisting as pale brown fibers densely clothing the entire apex of the stem with tiny fragments of reddish brown epidermis persisting among the fibers; petioles 28--91 cm long, 1.5--2 cm diam., subteret, obtusely flattened adaxially, weakly 1-ribbed near apex, broadly and obtusely sulcate, to 3.5 cm diam. near base, dark green (reddish brown when young), drying reddish brown and matte, surface moderately glossy, prominently striate-lineate throughout; blades broadly ovate, moderately coriaceous, bicolorous, semiglossy, 26--86 cm long, 18--57 cm wide (1.2--1.5 times longer than wide), margins broadly and sparsely undulate, upper surface drying dark brown to gray-brown, lower surface drying reddish brown; sinus hippocrepiform to obovate, 4--18 cm deep; midrib flat and slightly paler than surface, drying convexand darker than surface above, convex, sometimes tinged reddish, drying obtusely angular, grayish brown, and sparsely short pale-lineate below; basal veins 7 per side, with the first and second free to base, the third through sixth veins coalesced to 7 cm, posterior rib barely naked near the base, weakly curved; primary lateral veins 5--6 per side, departing midrib at a 40--50E angle, drying reddish brown below, obtusely and deeply sunken, concolorous, drying raised and somewhat darker above, convex, more or less concolorous, drying concolorous, matte below; minor veins moderately distinct, drying prominulous above and below, arising from both the midrib and primary lateral veins, secretory canals appearing but not obvious below; "cross-veins" numerous, more or less transverse. INFLORESCENCES 2 per axil; peduncle 6--7 cm long, 1.5 cm diam., magenta, conspicuously white-striate toward the apex; spathe 15--16 cm long, weakly constricted midway, weakly glossy, moderately coriaceous, drying reddish brown both surfaces, acuminate at apex; spathe blade greenish white outside, white, tinged reddish in lower half inside; spathe tube inflated, dark maroon outside, to 7 cm long, 5.8 cm diam., dark maroon inside; spadix 15 cm long; pistillate portion 3.5--5 cm long in front, 3.3--3.7 cm long in back, 2--2.5 cm diam. at apex, 2.3--3 cm wide at base; staminate portion 9--11.7 cm long; fertile staminate portion gradually tapered toward apex; sterile staminate portion 2.5--2.6 cm diam.; pistils 3.2--3.5 mm long, creamy brown, ovary 5-locular, ca. 0.4 mm long, with parietal placentation; ovules 25--30 per locule, 2--3-seriate; funicle ca. 0.2 mm long, style 1 mm diam., similar to style type B; style apex flat, with small depressions; stigma 1.3--1.5 mm diam., 0.4 mm high, covering entire style apex; the androecium margins sharply 4--6-sided, 0.6--1.2 mm diam. at apex; sterile staminate flowers rounded to bluntly 4--6-sided, larger toward the base, 0.6--2.8 mm wide.
Flowering in Philodendron antonioanum probably takes place in the early rainy season. Two fertile collections have been seen, one with immature fruits in June and one post-anthesis in July.
Philodendron antonioanum is endemic to central Panama and known only from the type locality at Cerro Tute and at El Copé at 800 to 1200 m elevation in Tropical Lower Montane rain forest. Philodendron antonioanum is a member of P. sect. Philodendron subsect. Philodendron ser. Fibrosa. The species is distinguished by its red, sharply two-ribbed cataphylls which persist as fibers, its subterete petioles longer than the blades, broadly ovate reddish brown drying blades with 5--6 primary lateral veins and by the stout inflorescences with scarcely constricted spathes having the tube magenta on both surfaces.
Philodendron antonioanum is most easily confused with Philodendron tysonii, a species with which it may occur. Both species occur at higher elevations, have subterete petioles longer than blades, large, ovate, glossy blades and red or reddish cataphylls persisting as fibers. Philodendron tysonii differs in having mostly unribbed cataphylls and blades with usually 6--10 primary lateral veins and with the upper surfaces drying usually more or less blackened and smooth, in contrast to blades with 4--6 primary lateral veins and with upper surfaces drying gray-green with prominulous cross-veins as in P. antonioanum. In addition, P. tysonii has more prominently pedunculate inflorescences with green spathes which are merely tinged red on the tube outside and are proportionately more slender and more constricted above the tube rather than being dark magenta on the tube and barely constricted above the tube as in P. antonioanum. Finally, the species differ in the nature of ovules, with P. tysonii having ovaries (5)6--8(9)-locular with sub-basal placentation and (4)5--7 ovules per locule borne in an evelope, while P. antonioanum has ovaries 5-locular with parietal placentation and about 30 ovules per locule not borne within an envelope.
The species is named in honor of Thomas Antonio of the Chicago Botanic Garden who was resident botanist in Panama for the Missouri Botanical Garden and who first collected the species in June 1980.
Additional specimens examined.
PANAMA. Coclé: Alto Calvario above El Copé, ca. 6 km N of El Copé, 710--800 m, 89E39'N, 80E36'W, Croat 68766A (MO); 930 m, 49197 (CM, M, MO); along Continental Divide, 900--1000 m, 8E39'N, 80E36'W, 75051 (MO). Veraguas: vic. of Santa Fe, along road between Alto Piedra and Calovébora, 0.5 mi. N of Alto Piedra, on slopes of Cerro Tute, 1150 m, Antonio 4945 (MO, PMA).