Syngonium harlingianum Croat, Ann. Missouri Bot. Gard. 68(4): 615. (1982).
Terrestrial. Adult plants with stems ca. 1 cm diam.; internodes 1–2 cm long near the apex; petioles 12–14 cm long, sheathed ca. 2/3 their length, the free portion subterete, ca. 2 mm diam., the sheath merging almost imperceptibly with the petiole at its apex; blades 3-lobed, drying yellowish green, the median lobe oblong-elliptic, acuminate to obtuse at the apex, narrowed at the base and confluent with the lateral lobes, 7.5–10.5 cm long, 2.7–6 cm wide, the lateral lobes markedly inequilateral (the inner part 1/2 or less as wide as the outer part), more or less elliptic, obtuse to acute at the apex, 5.5–8 cm long, 2–4 cm wide, rounded or more commonly auriculate on the outer edge at base, the midrib naked for 510 mm, the auricles to 2.5 cm long, rounded or oblong, not at all constricted at the base, the surfaces drying matte, yellowish green, slightly paler beneath; midrib drying flat on upper surface, weakly raised beneath with obscure scabrid lines; primary lateral veins 2–4 pairs; tertiary and quaternary veins distinctly visible; primary collective vein arising from the first or second primary lateral vein, 2 mm from the margin. Inflorescences solitary; peduncle 9.5 cm long, ca. 3 mm diam. (dried); spathe 11.5 cm long; spathe tube green, narrowly ellipsoid, 4.5 cm long, ca. 2 cm diam.; spathe blade narrowly elliptic, membranous, yellowish, acuminate at the apex; spadix 8.5 cm long; pistillate portion of the spadix ca. 2 cm long, ca. 5 mm diam., the flowers contiguous, ca. 1 mm diam.; sterile staminate flowers irregularly elongated in the direction of the axis, 3–3.5 mm long in direction of the axis, 1–1.6 mm wide perpendicular to axis; staminate portion of the spadix cylindroid, narrowly tapered toward the apex, drying ca. 1 cm diam., the flowers mostly rhombic, the apex truncate, matte, the margin crenate, not at all incised between the anthers. Infructescences not seen.
Type: Ecuador, Pastaza, Mera, Pantanos, 1100 m, Harling 11064 (GB, holotype).
Pastaza: Mera: Pantanos; 1100 m, Harling 11064 (GB, holotype).