Barneby, Rupert C. 1990. Two New Species of Disiphania (Menispermaceae: Tinosporeae) from Subandean Ecuador and Peru. Brittonia. 42 (3): 178-181.
Menispermaceae
Species Description - Vines of unknown length, the herbaceous flowering stems terete but deeply canaliculate, remotely pilose with lustrous translucent unicellular hairs up to +/- 0.8-1.2 mm, the ample leaf-blades similarly but more shortly pilosulous along all veins of lower face, glabrous or microscopically granular along main veins above, the leaf-petioles and narrowly spicate-amentiform staminate inflorescence glabrous, the small cream-colored flowers nigrescent when dried. Petioles includ- ing twisted base 7-12 cm; blades basifixed, amply suborbicular from broadly obtusely cordate base, those subtending peduncles 12-20 x 10-16 cm, all shortly caudate-acuminate at apex, the margin above mid-blade, on one or on both sides, shortly broadly lobed and each lobe caudate-acuminate; venation of 9 primary veins radiating from insertion of petiole, one or both of the inner pair, like the midrib, excurrent into a lobe, the exterior ones brochidodrome within the plane margin, all giving rise to fine subhorizontal secondary venules and thence to a finer open reticulum, the whole venation sharply prominulous on lower face, less so on upper. Staminate flower-spikes shortly supra-axillary, commonly geminate, flexuously pendulous, +70-100-flowered, the axis including peduncle 10-17 cm; bracts linear-lanceolate, deflexed and incurved, 1-1.5 mm; flowers horizontal, sessile, in profile plumply campanulate, 3-3.2 x 2.6-3 mm; sepals camosulous, united through a little more than half their length into a hemispherical tube, the ovate lobes a little unequal, the 3 outer ones 1.2-1.4 x 1-1.2 mm, at full anthesis erect with divergent tip; petals 6, membranous, narrowly oblanceolate, deltately acute or truncate, 0.6-1 x 0.3-0.45 mm, the blade infolded; androecium tri- merous, the clavate filaments distally inclined over the center of the flower, the anther-locules vertically dehiscent. Pistillate inflorescence and fruit unknown.
Florum masculorum sepalis medium usque in perianthium campanulatum concretis petalisque membranaceis minimis (nec pseudodiscum carnosum efformantibus) sectioni Taubertiae (K. Schu- mann) Barneby pertinens, foliorum lamina ampla suborbiculari-acuminata basi cordata necnon in- florescentia multiflora anguste spicata D. juliforae Barneby proxima, sed ab ea petiolis glabris (nec retropilosis), foliorum lamina saepissime ultra mediam utraque margine breviter caudato-lobata, flosculisque glaberrimis abstans.
TYPE: ECUADOR. NAPO: en bosque muy humedo premontano, 1200 m, via Hollin-Loreto km 40, entre rio Guamani y rio Pucuno, 12 Dec 1987 (fl d), Walter Palacios 2269 (HOLOTYPE: MO 3580724; ISOTYPES: F, K, NY, US).
Ecology and dispersal: lianas of humid equatorial forest at 1200 m; known only from headwaters of rio Napo near 1º00'S, 77º45'W in prov. Napo, Ecuador.
In size and structure of the inflorescence and the individual staminate flower D. tricaudata closely resembles D. juliflora Bameby, a species known as yet only from Pacific lowland Ecuador, at about the same latitude but at 80º20'W in the province of Manabi. It differs, however, in glabrate petioles and upper face of leaf-blades, in perfectly glabrous (not setose) flowers, and most strikingly in outline of the leaves. In D. juliflora the leaf-blade is simply cordate-acuminate, and all nine primary nerves are incurved to anastomosis within the entire margin. By contrast, in all but a few small distal leaves of D. tricaudata at least one and commonly both of the innermost pair of primary nerves, those flanking the midrib, run out into depressed-deltate, caudately acuminate lobes, as illustrated in the accompanying figure. Leaves similarly lobed are known in this genus only in D. lobata Eichler, which differs fundamentally from D. tricaudata in structure of the much larger perianth and superficially in its indumentum of coarse retrorse setae up to 2.5-5.5 mm long.