Amorphophallus wasa Naive, K.Z.Hein & Hett., 2022

Naive, M. A. K., Hein, K. Z. & Hetterscheid, W., 2022, Taxonomic studies of Araceae in Myanmar IV: A new species, a new record and a new synonym for the genus Amorphophallus, Blumea 67 (2), pp. 123-128 : 124-127

Amorphophallus wasa Naive, K.Z.Hein & Hett. , sp. nov. — Fig. 1 , 2 ; Map 1

Amorphophallus wasa is similar to Amorphophallus saraburiensis Gagnep. from Thailand, but differs by lacking staminodes between pistillate and staminate zones, having a shorter, 0.7 mm long, brownish green style (vs style 1–2 mm long, purple), a unilocular ovary (vs bilocular ovary), an acute and rugulose appendix (vs obtuse and corrugate appendix), and spathe base inside with shallow warts (vs thick shortly elongate, fleshy warts). — Type: K. Z. Hein 043 (holo KKU; iso KKU, TTM), Myanmar, Sagaing Region, Yinmabin District, Yinmabin Township , near Shwe Taung Oo Pagoda , elev. 40 m, N22°12'00" E95°04'10", 11 June 2021 .

Etymology. The specific epithet ‘ wasa ’ is coined from the species local name and used as a noun in apposition.

Seasonally dormant herb. Tuber napiform, 8.5–11 cm long by 4–10 cm diam, brown outside, white inside. Leaf solitary; petiole 63–77 cm long by 2.1–3.3 cm diam at the base, 1.3–1.9 cm diam at the apex, smooth, terete, green to brownish purplish green with dark brown-olive spots; lamina decompound, 68– 70 cm across, divided into 3 main segments, rachises narrowly winged throughout; leaflets elliptic to obovate, 4.3–11.5 cm long by 3–5.2 cm wide, apex acuminate, with an 0.2–1.2 cm long acumen, base asymmetric and decurrent, adaxially pale green, abaxially green, both surfaces glabrous. Inflorescence solitary, cataphyll 10–35 cm long; peduncle 58–84 cm long by c. 1.2 cm diam at the base, smooth, terete, green to brownish purplish green with dark brown-olive spots. Spathe (narrowly) triangular-ovate, 15–30 cm long by 4.5–6 cm diam; base shortly convolute, nearly entirely open, inside light green, with shallow warts, green with olive spots, margin entire, dark purple; limb usually erect, recurved when old, inside dark purple with green streaks at the centre, outside paler dark purple with brownish green streaks and olive-green spots, apex acute. Spadix longer than spathe, 21–40 cm long, stipitate; stipe c. 0.6 cm long, c. 0.8 cm diam, smooth, green; pistillate zone cylindric, 2–2.5 cm long, 1.2–1.5 cm diam, flowers slightly dis-

Map 1 Map of northern Myanmar (inset) showing the distribution of Amorphophallus wasa sp. nov. (z) with the locality of the type indicated by Ì .

tant; staminate zone contiguous with pistillate zone, cylindric, 5–8.5 cm long, 1.1–1.5 cm diam, flowers congested; appendix contiguous with staminate zone, subulate, 14–32 cm long, 0.6–1.1 cm diam at the base, tapering, rugulose, coppery or claret, apex acute. Ovary globose to subglobose, c. 2 by 2 mm, unilocular, green; style cylindrical, c. 0.7 mm long, c. 0.8 mm diam, brownish green; stigma hemispheric, c. 1.3 mm high, c. 1.7 mm diam, bi- or trilobed, surface echinulate, yellow. Staminate flowers consisting of 2–4 stamens, slightly enlarged in the lowermost part of staminate zone; stamen c. 1.3 mm long, 1.5–2 mm diam; filaments c. 0.5 mm long; anther c. 0.7 mm long, c. 0.5 mm diam, yellow, connective yellow or purplish yellow, pore apical. Infructescence elongate; berries subglobose, c. 0.6 cm diam, green when young, red when ripe.

Distribution — This species is currently known from the Monywa District and Yinmabin District of the Sagaing Region, Myanmar.

Habitat & Ecology — The species grows in tropical dry forest, in a shaded and brightly lit environment at an elevation of 40–50 m a.s.l. Observed flowering in the wild from May to June and fruiting from July to August.

Conservation status — The extent of occurrence of A. wasa is 970.861 km 2 with an area of occupancy estimated to be 16 km 2 (calculated in GeoCAT with 2 km defined cell-width; Bachman et al. 2011), which complies with subcriterion ‘a’ of the Endangered category B2. With the distribution currently limited to areas within the Yinmabin and Monywa Districts, we herein propose this species to be treated as ‘Endangered’ (EN B2ab(iii)) following the Red List criteria of the IUCN Standards and Petitions Subcommittee (2019).

Vernacular name — Locally known by the Burmese people as wasa (၀0ာ).

Uses — The young inflorescences are cooked and eaten as a vegetable by local people.

Notes — Amorphophallus wasa is considered to belong to a small clade of 3 species ( A. saraburiensis , A. scutatus Hett. & T.C.Chapm. and A. tenuistylis Hett. ). This strongly supported clade was recovered in an extensive molecular phylogenetic analysis by Claudel et al. (2017) and belongs to A. subg. Scutandrium Hett. & Claudel. More detailed comparisons between the morphologically similar species are presented in Table 1, and an identification key to the Amorphophallus species of Myanmar is provided below.

Figures

Fig. 1 Amorphophallus wasa Naive, K.Z.Hein & Hett. a. Habit; b. leaf; c. inflorescence; d. infructescence. — Scale bars: c = 5 cm; d = 2 cm. — Photos: a, b, d: K.Z. Hein; c: Thuta Oo.

Fig. 2 Amorphophallus wasa Naive, K.Z.Hein & Hett.a. Inflorescence;b. spadix (inset:b1: pistillate flowers, b2: staminatee flowers);c. spathe. — Scale bars: a, c = 10 cm; b = 5 cm. — Photos: K.Z. Hein.