Mecardonia reneeae Greppi & Sosa, 2017

Greppi, Julián A., Sosa, María De Las Mercedes & Dematteis, Massimiliano, 2017, A new polyploid species of Mecardonia (Gratioleae, Plantaginaceae) from South America, Phytotaxa 303 (3), pp. 264-270 : 265

Mecardonia reneeae Greppi & Sosa , sp. nov. ( Figs. 1–2 , Table 1)

Type:― ARGENTINA. Corrientes. Dep. Empedrado, Ruta Provincial 6 y arroyo Empedrado [27° 48’S, 58°30’W], 20 December 2005. Greppi & Hagiwara 560 (holotype BAB!, isotype SI!).

Diagnosis:― A Mecardonia procumbens var. flagellaris similis, sed habitu terophyto, caulibus erectis, radicibus gemmiferis, foliis serratis, petalis angustis, deltoideis et linearibus, fructus minore, chromosomatum numero tetraploideo 2n=44 (contra 2n=22).

Terophyte, 15–17(–20) cm high. Roots gemiferous. Stems erect, quadrangular, glabrous, 1 mm diam., internodes 5–20 mm long. Leaves opposite, sessile, narrowly elliptic, 6–16(–20) × 2–5(–6) mm, margin serrate, base attenuate. Bracteoles 3–7 × 0.5–1.5 mm, linear, margin entire to denticulate. Pedicels 10–35(–40) mm long, erect, flexuous. Flowers one or two per node, 10–16 mm long, yellow with chestnut streaks in the throat. Calyx 5–7 mm long; sepals narrowly deltoid to linear, acute, dorsal sepal 5–7(–10) × 1–1.2 mm; two ventral sepals 5.5–7(–8) × 0.8–1(–3) mm; two lateral sepals 4–6(–8) × 0.3–0.6 mm. Corolla 8–14 × 6–8 mm, posterior lip 6–8 × 6–7 mm, entire, briefly apiculate, internally pubescent at base; middle lobe of frontal lip 6–7 × 7–8.5 mm; broadly obovate, glabrous; lateral lobes of equal size, sometimes obovate. Stamens 4, anterior filaments 5 mm long, posterior 4 mm long, all inserted at the base and reaching half of the corolla tube length. Ovary ellipsoid, 3 mm long; style 3–4 mm long. Capsule ellipsoid, light brown, 3–5 × 1.5–1.8 mm. Seeds, 0.4–0.5 × 0.3–0.4 mm, rough, blackish.

Distribution, habitat and phenology:— Mecardonia reneeae grows in open and humid areas, low clayey loam soils near watercourses, or border of streams in eastern Formosa, Chaco, northwest of Corrientes and northeast of Santa Fe in Argentina, within the Chaco phytogeographic province ( Cabrera 1976). The species flowers from August to March.

Etymology:— The specific epithet is dedicated to Renée H. Fortunato, Argentinean botanist dedicated to the study of Leguminosae.

Additional specimens examined: ─ARGENTINA . Prov. Chaco: Dep. Bermejo, Las Palmas , 14 November 1983, Fortunato et al. 607 ( BAB) ; Dep. Primero de Mayo, Colonia Benítez , 10 June 1959, Schulz 10437 ( BAB). Prov. Corrientes: Dep. Capital, near to Ingenio Primer Correntino, 18 Km NE of Corrientes, 15 September 1982, Schinini & Martínez-Crovetto 2636 ( CTES) ; 5 Km E of Laguna Brava, 29 August 1970, Krapovickas & Cristóbal 15836 ( CTES) ; 10 Km E of Laguna Brava, route 5, 21 August 1970, Krapovickas & Cristóbal 16099 ( CTES) ; Parques de la Facultad de Ciencias Agrarias , 23 August 1974, Quarín 2403 ( CTES) ; Molina Punta , November 1978, Arbo 1562 ( CTES) ; Perichón , 8 September 1975, Schinini 11601 ( CTES) ; Dep. San Cosme, Paso de la Patria , 12 August 1967, Krapovickas & Cristóbal 1302 ( CTES) ; Desvío a Pto. González, 9 Km. near to Paso de la Patria , 10 September 1971, Tressens et al. 168 ( CTES) ; Dep. San Luis del Palmar, 10 Km SE of San Luis del Palmar , Route 6, 26 September 1973, Quarín & Tressens 1349 ( CTES). Prov. Formosa: Dep. Pilcomayo, Parque Nacional Pilcomayo, near to Puerto Soledad, 9 November 1991, Fortunato et al. 2097 ( BAB, SI). Prov. Santa Fe: Dep. Gral. Obligado, Villa Ana, 18 August 1973, Quarín 1193 ( CTES) .

Figures

FIGURE 1. Mecardonia reneeae. A: Habit. B: Stem. C: Detail of the leaf. D: Flower in lateral view. E: Calyx. F: Dissected corolla. G: Anterior anther. H: Posterior anther. I: Gynoecium. J: Fruit (A-C: from Greppi & Hagiwara 560, BAB; illustrated by M. Marino; B–J: from Schinini 11601, CTES; illustrated by Mirtha L. Gómez).

FIGURE 2. A, C: Mecardonia procumbens var. flagellaris. A. Habit, C. Metaphase image showing 22 chromosomes. B, D. M. reneeae. B. Habit. D. Metaphase image showing 44 chromosomes.