taxonID	type	description	language	source
59BF0A8CBF695B1CBA0BF08EB09D8E93.taxon	description	Fig. 1	en	Calviño, Pablo A., Lehtonen, Samuli, Waldbillig, Marcos, Acuña, Tomás, Alonso, Felipe (2026): A new species of Echinodorus (Alismatales, Alismataceae) from the Chaco region with a waterlily soul. PhytoKeys 269: 59-78, DOI: 10.3897/phytokeys.269.170618
59BF0A8CBF695B1CBA0BF08EB09D8E93.taxon	diagnosis	Diagnosis. Echinodorus nenufar is readily distinguishable from all other members of the genus by its unique floral coloration — petals ranging from pale yellow to creamy white (versus consistently intense white in other species) — and the shape of its mature floating leaf blades, which are broadly cordate to ovate to suborbicular (versus typically ovoid, lanceolate, elliptic, or oval in congeners).	en	Calviño, Pablo A., Lehtonen, Samuli, Waldbillig, Marcos, Acuña, Tomás, Alonso, Felipe (2026): A new species of Echinodorus (Alismatales, Alismataceae) from the Chaco region with a waterlily soul. PhytoKeys 269: 59-78, DOI: 10.3897/phytokeys.269.170618
59BF0A8CBF695B1CBA0BF08EB09D8E93.taxon	description	Description. Herbs perennial or annual, rooted hydrophytes, either emergent or submerged. Rhizomes short, fusiform, erect, firm, 10 – 30 mm long, 15 – 25 mm in diameter, with fasciculate, fibrous roots, some of which are finely septate and spongy. Leaves submerged, with floating blades or emergent; venation campylodromous. In mature plants, emergent aerial blades ovate to oval, 9 – 16 (– 19) cm long × 8 – 12 (– 16) cm wide, with 10 – 13 veins, green to light green, lacking pellucid lines, apex obtuse to rounded, base cordate, often with basal lobes contiguous or overlapping to form an oval; petioles sheathing at base; epidermis with faint longitudinal striations. Juvenile emergent leaves. Blades ovate, 3 – 5 × 2 – 3 cm, with 5 – 7 veins and a cordate base. Floating leaves. Blades ovate to broadly ovate or suborbicular, with a cordate base whose basal lobes often overlap; (2.5 –) 7 – 15 (– 26) cm long × (1.5 –) 4 – 12 (– 18.5) cm wide; lacking translucent markings. Petioles from 10 up to 50 cm long and 2 – 8 mm in diameter, with 7 – 11 veins and indumentum composed of glandular, papillate trichomes bearing 1 – 3 dendritic or stellate hairs. Submerged leaves. Blades initially linear-lanceolate, later lanceolate, with attenuate bases, obtuse apices, and 3 – 5 veins. Petioles triangular in cross-section, winged at the base; early petioles subpetiolate, later ones up to 20 cm long and 5 – 10 mm in diameter. Juvenile emergent leaves ovate, 3 – 5 cm × 2 – 3 cm, with 5 – 7 veins and cordate base. Floating blades ovate to broadly ovate or suborbicular, base cordate with often overlapping basal lobes, (2.5 –) 7 – 15 (– 26) cm long × (1.5 –) 4 – 12 (– 18.5) cm wide, lacking translucent markings, petioles up to 50 cm long and 2 – 8 mm in diameter, with 7 – 11 veins and indumentum composed of glandular, papillate trichomes, bearing 1 – 3 dendritic or stellate hairs. Submerged blades initially linear-lanceolate, then lanceolate, with attenuate bases and obtuse apices, 3 – 5 veins, petioles triangular in cross-section, winged at base, early leaves subpteriolate (with a very short or partially differentiated petiole, intermediate between sessile and fully petiolate); later ones up to 20 cm long, 5 – 10 mm in diameter. Inflorescences racemose or paniculate, bearing 4 – 7 whorls of flowers, each whorl with 3 – 14 flowers, upright or decumbent, often proliferous, up to 45 cm tall and 10 cm wide. Rachis triangular in cross-section, longitudinally striated, puberulent, with some glandular and dendritic trichomes. Peduncles terete, up to 50 cm long and 7.5 mm in diameter, sparsely pilous. Bracts lanceolate, robust, 1.5 – 4.5 cm long, sometimes shorter, equal to or longer than subtended pedicels, with 10 – 17 veins, apex acute. Pedicels cylindrical, terete, ascending, accrescent to 0.5 – 3.5 cm long, 1.0 – 1.5 mm in diameter. Flowers bisexual, 1.5 – 2.5 cm in diameter, ephemeral, each lasting a single day. Sepals three, green, erect, ovate, obtuse, concave, 10 – 14 - nerved, ca. 5 × 3 mm, abaxially bearing whitish to hyaline trichomes, filiform, branched, or dendritic. Petals three, obovate to orbicular, delicate, non-overlapping to slightly imbricate, pale yellow to creamy white, often with a deeper yellow basal blotch extending up to one-third of the petal length, ca. 12 × 13 mm. Stamens 19 – 26; filaments slender, ca. 3.5 mm long; anthers oblong, subbasifixed, versatile, ca. 3 mm long. Gynoecium apocarpous; style simple; carpels numerous. Fruits achenes, oblanceolate, ca. 1.5 × 0.5 mm, with 4 – 6 lateral ribs and 2 – 4 dorsal keels extending toward the persistent style beak, usually bearing 1 – 3 small irregular glands; style beak 0.2 – 0.4 mm long, erect, or lateral. Floral morphology and pigmentation are markedly variable. Most individuals display the typical cup-shaped corolla with erect petals, pale yellow to creamy white, each marked by a conspicuous yellow basal spot that fades gradually toward the center. A smaller proportion shows distinct morphotypes. In one variant, petals are shorter and uniformly deep yellow yet retain the cup-shaped configuration. Another, less frequent form, has fully expanded, non-overlapping, creamy-white petals with a pale yellow to lime-green basal blotch; rare individuals present slightly overlapping petals of similar hue and pattern.	en	Calviño, Pablo A., Lehtonen, Samuli, Waldbillig, Marcos, Acuña, Tomás, Alonso, Felipe (2026): A new species of Echinodorus (Alismatales, Alismataceae) from the Chaco region with a waterlily soul. PhytoKeys 269: 59-78, DOI: 10.3897/phytokeys.269.170618
59BF0A8CBF695B1CBA0BF08EB09D8E93.taxon	distribution	Distribution and ecology. Echinodorus nenufar is currently known from temporary aquatic habitats in the western Chaco region of northern Argentina (Salta Province) and western Paraguay (Boquerón Department), at elevations of 250 – 270 m a. s. l. (Fig. 3). Between late November and early May, individuals were observed at a range of developmental stages across various habitats. These stages include submerged, floating, and emergent blades, as well as mature and juvenile terrestrial forms. Among these, floating and juvenile terrestrial forms were most frequently observed, whereas fully mature emergent individuals were relatively uncommon. The species appears to exhibit a life-history strategy analogous to that of seasonal killifishes (Cyprinodontiformes, Rivulidae) inhabiting the same ephemeral environments (Calviño et al. 2016; Alonso et al. 2018). Like these fishes, E. nenufar seems to rely on the simultaneous presence of multiple life stages and overlapping generations as an adaptation to the unpredictability of flooding and drought events beyond typical seasonal cycles.	en	Calviño, Pablo A., Lehtonen, Samuli, Waldbillig, Marcos, Acuña, Tomás, Alonso, Felipe (2026): A new species of Echinodorus (Alismatales, Alismataceae) from the Chaco region with a waterlily soul. PhytoKeys 269: 59-78, DOI: 10.3897/phytokeys.269.170618
59BF0A8CBF695B1CBA0BF08EB09D8E93.taxon	etymology	Etymology. The specific epithet nenufar refers to the Spanish common name “ nenúfar, ” used to designate water lilies (Nymphaeaceae). The name highlights the striking resemblance between the broad floating leaves of Echinodorus nenufar and those of true water lilies, particularly in habit and overall architecture.	en	Calviño, Pablo A., Lehtonen, Samuli, Waldbillig, Marcos, Acuña, Tomás, Alonso, Felipe (2026): A new species of Echinodorus (Alismatales, Alismataceae) from the Chaco region with a waterlily soul. PhytoKeys 269: 59-78, DOI: 10.3897/phytokeys.269.170618
