Philodendron madronense Croat, sp. nov.
TYPE: Panama. Panamá: Valle de Madroño, ca. 10 road mi. N of La Margarita (near Chepo), just S of Continental Divide along main trail to Cangandí, 350--500 m, 9E19'N, 79E08'W, 21 Feb. 1986, Hammel & McPherson 14526 (holotype, MO--3490432; isotypes, CM, M, PMA). Figures 279--280.
Planta hemiepiphytica; internodia usque 2.5 cm diam., longiora quam lata; cataphylla decidua; petiolus subteres, usque 68 cm longus, 1.5 cm diam., aliquantum spongiosus; lamina trisectus, 39.5 cm longis, 15 cm latis; segmentis medianis ellipticis; segmentis lateralibus valde inequilateris, 32--32.8 cm longis, 12.7--13 cm latis; infructescentia 1. INFRUCTESCENTIA with pedunculus usque 22 cm longus, 1 cm diam., in sicco denigratus; spatha usque 20 cm longa, ca. 4 cm diam.; spadix pistillata 11.8 cm longa, ca. 3 cm diam.; spadix staminata ca. 7.5 cm longus, ca. 1 cm diam.; 1 semen in quoque loculo.
Hemiepiphytic vine; internodes to 2.5 cm diam., longer than broad, epidermis drying light brown and semiglossy but conspicuously and irregularly folded; roots several per node, drying dark brown; cataphylls deciduous; petioles to 68 cm long, 1.5 cm diam., subterete, somewhat spongy, drying blackened, surface closely and finely ridged; sheathing to 8.5 cm long; blades trisect, subcoriaceous, moderately bicolorous, drying weakly glossy, upper surface dark green, drying dark brown, semiglossy, lower surface drying yellow-green, matte; median segments elliptic, somewhat inequilateral, 39.5 cm long, 15 cm wide (ca. 2.5 times longer than wide), (1.5 times longer than lateral lobes), somewhat acuminate at apex, base attenuate and somewhat inequilateral with leafy tissue extending to base on one side, ending 2.5 cm above the base of the other side; lateral segments markedly inequilateral, 32--32.8 cm long, 12.7--13 cm wide, acuminate; the outermost lobes with the inner margins attenuate, tissue ending 1--2.5 cm from base of petioles; outer margins rounded, barely or not at all naked along the sinus; midrib weakly raised, concolorous above, more or less round-raised, drying blackened and irregularly ridged below; basal veins lacking; primary lateral veins ca. 25 per side, ca. 4--5 mm apart, departing midrib at a 65--70E angle towards apex, 85--100E angle towards base, gradually curved to the margins, weakly sunken, scarcely more conspicuous than interprimaries above, prominently raised below; interprimary veins numerous, 1--3 between each pair of primary lateral veins; minor veins in part undulate upon drying, close, moderately visible, arising from both the midrib and primary lateral veins.
INFLORESCENCES (post-anthesis) 1 per axil; peduncle to 22 cm long, 1 cm diam., drying blackened, somewhat spongy; spathe to 20 cm long, ca. 4 cm diam., semiglossy, green outside, red at base inside, drying blackened; pistillate spadix 11.8 cm long, ca. 3 cm diam.; staminate spadix 7.5 cm long, ca. 1 cm diam., moderately tapered to a bluntly acute apex; pistils more or less cylindrical, 3--4 mm long, 2.5 mm diam.; ovary 6--7-locular, with sub-basal placentation; locules 2.3 mm long, 0.5 mm diam.; ovules 1 per locule, contained within a transparent evelope; funicle ca. 0.4 mm long, (can be pulled free to base), style similar to style type D; style apex flat; style boss pronounced but narrow; seeds 1 per locule, 1.4 mm long.
Flowering in Philodendron madronense apparently occurs in the rainy season, since immature fruits have been collected in January.
Philodendron madronense is endemic to central Panama along the border of Panamá and San Blas at 350 to 450 m elevation in a Tropical wet forest life zone.
Philodendron madronense is a member of P. sect. Tritomophyllum. This species is recognized by its scandent habit, elongate internodes, subterete, more or less spongy petioles, and especially by its trisect leaf blades with the medial segments elliptic, inequilaterally attenuate at the base and with many close prominent primary lateral veins only 4--5 mm apart and departing the midrib at about a 90E angle.
Philodendron madronense is superficially most similar to P. cotobrusense which has deeply 3-lobed blades with more or less elliptic, closely veined divisions. The latter species differs in having the lobes united and confluent at the base and up to five inflorescences per axil. It is also similar to some broad-leaved forms of P. tripartitum (e.g., Whitefoord & Eddy 223) which occur in eastern Panama, but those differ in having no more than 12 pairs of primary lateral veins, which depart the midrib at a 50--60E angle.