Monotagma tuberosum Hagberg & R.Erikss., 2011

Hagberg, Mats & Eriksson, Roger, 2011, New names in Monotagma (Marantaceae), Phytotaxa 20 (1), pp. 1-25 : 23-24

18. Monotagma tuberosum Hagberg & R.Erikss. , sp. nov. ( Fig. 5B )

Synflorescentiae nodis omnibus foliis frondosis instructis Monotagmatis nutanti similis, sed ab eo differt radicibus tuberiferis, rhizomate ramis pluribus internodiis brevioribus, lamina majore (6–12 × 2.4–4.1 vs. 3–9 × 1.3–3.5 cm), praesentia (vs. absentia) petiolo, florescentiae bracteis longioribus (1.5–2.1 vs. 1.1–1.4 cm), et corollae tubo longiore (15–24 vs. 9–11 mm).

Type:— PERU. Loreto: Mishana on Río Nanay , 30 km SW of Iquitos, 19 February 1986, Hagberg & Medin 362 (holotype AMAZ, isotypes AAU, F, GB, INPA, L, MO, NY, S, US).

Small herb 0.1–0.4 m tall. Roots with distal tubers. Rhizomes subterraneous, branched to form clusters of 3–9 aerial shoots, each shoot bearing 0–9 basal leaves. Ultimate basal leaf with sheath 3.8–7.6 cm long, green or sometimes tinged with red, hirtellous to hirsute throughout, auriculate; petiole 0.5–7.3 cm long, laterally flattened, hirtellous or rarely puberulent; pulvinus 0.1–0.4 cm long, pale green, ± terete, hirtellous throughout or at least adaxially, without annulus; blade narrowly elliptic to narrowly ovate, somewhat scalloped, base cuneate to obtuse, apex acuminate to caudate, ± centric, 6–11 × 2.4–4.1 cm, adaxial surface ± papillose, matt green, hirtellous to puberulent throughout or at least along midrib and margins, and at apex, abaxial surface not papillose, greyish green, hirtellous to hirsute throughout or at least puberulent along midrib and at apex. Synflorescence 1–3-nodate with 1–4 florescences, sometimes also with auxiliary florescences at base of the aerial shoot, each node with a well-developed leaf, lowermost one with sheath (3–)3.5–6(–8) cm long, petiole (0.1–)0.3–2.6(–4.6) cm long, blade 6.4–12 × 1.9–3.4 cm, first internode 0.6–8.4 cm long, peduncle (0.7–)1.2– 7.3(–9.7) cm long, hirtellous. Main florescence (4–) 6–11 cm long with 6–22 ± distichous bracts, first internode 0.3–1(–1.2) cm long, peduncle 2–7 cm long, base of florescence peduncle becoming pulvinate at maturity, florescences bending towards ground; lowermost bract 1.5–2.1 × 0.4–0.5 cm, greenish to somewhat tinged with red, subpapyraceous, hirtellous (or rarely hirsute) throughout; first prophyll 7–11 mm long, hirtellous throughout or at least on back, rarely hirsute on back, ± distinctly bicarinate. Flowers 3–5 per bract, white; pedicel 0.5–1 mm long; ovary 0.5–1 mm long, hirtellous (or rarely puberulent) apically; sepals 1.5– 2.5(–3) × 0.5–1 mm, narrowly ovate with obtuse apex to ± quadrate with truncate apex; corolla tube 15–24 × 0.5–1 mm, outside glabrous, inside hirsute except for a glabrous basal portion, or at least hirsute in mouth, lobes 2–5 × 1–2 mm; outer staminode 4–7 × 1.5–3 mm; stamen 2–2.5 mm long, theca 0.5–1 mm long; callose staminode 2–3 × 1.5–2 mm, fleshy throughout, without a specialized callus; cucullate staminode 2–3.5 mm long, appendage 0.5–1 mm long; style 2.5–3.5 mm long (untripped), or 1–2.5 mm long (tripped). Capsule 10– 13 × 2–3 mm; seed 10–13 × 2–3 mm, brownish; aril 1.5–3.5 mm long, with 2 narrow and string-shaped, straight lobes.

Distribution and habitat:— Monotagma tuberosum is distributed in the western Amazon basin of Bolivia, Brazil, Colombia, and Peru. It grows in primary lowland forests on white sand. At the type locality it was found along a path, which became flooded after rainfall.

Discussion:— Monotagma tuberosum is most similar to M. nutans , from which it differs by having root tubers, rhizomes with shorter internodes and more branches, usually larger leaf blades (6–12 × 2.4–4.1 vs. 3– 9 × 1.3–3.5 cm), petioles present (vs. absent), longer bracts (1.5–2.1 vs. 1.1–1.4 cm), and longer corolla tubes (15–24 vs. 9–11 mm). The tubers are unique in the genus.

Paratypes:— COLOMBIA. Amazonas: Peña Roja at Río Caquetá, June 1991, Galeano et al. 2763 ( COL, GB, MO) ; Santa Rosa, La Chorrera, Río Igara-Paraná , July 1974, Sastre 3564 ( P) . PERU. Loreto: Mishana, Río Nanay , November 1977, Gentry & Revilla 20667 ( MO) ; November 1984, Maas et al. 6357 ( GB, L) ; November 1984, Maas et al. 6367 ( L) ; Río Nanay, halfway between Santa María and Iquitos , February 1981, Gentry et al. 31586 ( GB, MO) ; Angamo, Río Javarí , August 1973, Lleras P 17140 ( GB, INPA, MG) ; Río Ampiyacu, above Estirón , April 1977, Plowman et al. 7100 ( F, GH, INPA, K, L, MO, S, US) . BRAZIL. Acre: Cruzeiro do Sul , March 1976, Calderón & Soderstrom 2321 ( F) ; lower Rio Moa , May 1971, Maas et al. P 12856 ( F, GB, INPA, L, MG, MO, NY) ; Cruzeiro do Sul , near new airport, February 1976, Monteiro & Damião 363 ( INPA, MG) . Amazonas: Palmeiras army post, Rio Javari , July 1973, Lleras P 16975 ( GB, INPA, MG) ; Uanari, near São Gabriel , October 1947, Pires 809 ( IAN) ; margin of Lábrea airstrip, Rio Purus, Rio Ituxi , June 1971, Prance et al. 13901 ( INPA, L, NY) ; Rio Cunhuá at Canaça, Basin of Rio Purus , November 1971, Prance 16396 ( GB, INPA, L, MG, NY, US); Uaupés (= São Gabriel), Spruce 2922 ( G, P) ; Rio Negro, opposite São Gabriel , December 1987, Stevenson 1113 ( GB, INPA) . Rondônia: vicinty of Abunã , July 1968, Prance et al. 5886 ( A, F, GB, INPA, L, MO, NY, UBC, VEN) . BOLIVIA. Pando: 3 km above Abunã, Rio Madeira , November 1968, Prance et al. 8395 ( INPA, NY) .

Figures

FIGURE 5. Monotagma isotypes at GB. A, M. uliginosum; B, M. tuberosum.