Monotagma humile Hagberg & R.Erikss., 2011

Hagberg, Mats & Eriksson, Roger, 2011, New names in Monotagma (Marantaceae), Phytotaxa 20 (1), pp. 1-25 : 16-17

11. Monotagma humile Hagberg & R.Erikss. , sp. nov. ( Fig. 3C )

Staminodio exteriore elliptico Monotagmatis smaragdini et M. flavicomi similis , sed ab eis differt statura minore (scapus 2.5–5.2 vs. 11–64 cm longus, lamina 12–17 × 4.7–6.5 vs. 23–28 × 8.5–12 cm).

Type:— BRAZIL. Amazonas : ca 3 km from Benjamin Constant on trail towards Cruzeiro do Sul, 24 March 1986, Andersson & Hagberg 1824 (holotype INPA, isotypes AMAZ, F, GB, S) .

Herb 0.35–0.5 m tall. Rhizomes partly above ground and supported by “stilt” roots, branched to form clusters of 2–8 shoots, each shoot bearing 1–3, irregularly arranged basal leaves. Ultimate basal leaf with sheath 9–14 cm long, papyraceous, glabrous throughout, not auriculate; petiole 3.5–15 cm long, laterally flattened, glabrous; pulvinus 0.4–0.5 cm long, laterally flattened, hirtellous adaxially, without annulus; blade narrowly ovate, subcoriaceous, markedly scalloped, base obtuse to truncate, apex caudate, centric, 12–17 × 4.7–6.5 cm, length from base to broadest part 3.4–5 cm, adaxial surface not papillose, dark green, hirtellous to hirsute throughout, abaxial surface not papillose, greyish green, glabrous. Synflorescence 1-nodate with 2–3 florescences, node with a well-developed leaf, sheath 4.8–8.3 cm long, petiole 1.5–5.2 cm long, blade 7–13 × 4.4–4.8 cm, peduncle 2.5–5.2(–8.5) cm long, glabrous. Main florescence 4.3–11 cm long with 3–15 distichous to somewhat unilaterally arranged bracts, first internode 1–1.4 cm long, peduncle 2.8–4.2 cm long; lowermost bract 2.3–2.5 × ca 0.6 cm, pale green, chartaceous, glabrous; first prophyll 13–14 mm long, glabrous. Flowers 4–7 per bract, pale yellowish green to ± hyaline, except for the white outer staminode; pedicel 0.5–1 mm long; ovary 2–2.5 mm long, glabrous; sepals 5.5–6 × ca 1 mm; corolla tube 19–21 × ca 1 mm, outside glabrous, inside sparsely hirtellous in mouth, lobes 3–4 × 2–2.5 mm; outer staminode ca 5 × 4–5 mm, spathulate, emarginate; stamen 2.5–3 mm long, theca ca 1 mm long; callose staminode 2–2.5 × 1.5–2 mm, fleshy throughout, emarginate, with a shelf-shaped callus at ca 1 mm from apex; cucullate staminode 2.5–3 mm long, lateral appendage ca 0.5 mm long; style ca 3 mm long (untripped), or 2–2.5 mm long (tripped). Capsule ca 14 × ca 2.5 mm; seed 12–13.5 × 2–2.5 mm, brownish, narrowly pyramidal; aril ca 2.5 mm long, whitish, tubular without lobes.

Distribution and habitat:—Known only from the type locality, where the vegetation was destroyed in late 1986 due to cattle-breeding. It was a primary, lowland terra firme rain forest on latosol.

Discussion:— Monotagma humile is similar to M. smaragdinum and M. flavicomum with which it shares spathulate outer staminodes, but differs by a lower stature, a shorter synflorescence peduncle (2.5–5.2 vs. 11– 64 cm), and smaller leaf blades (12–17 × 4.7–6.5 vs. 23–38 × 8.5–12 cm).

Paratypes:— BRAZIL. Amazonas : 3 km SE of Benjamin Constant, March 1986, Andersson & Hagberg 1838 ( GB, S) .

Figures

FIGURE 3. Monotagma isotypes at GB. A, M. papillosum; B, M. remotum; C, M. humile; D, M. flavicomum.