AMORPHOPHALLUS MIRABILIS

PROTOLOGUE: Amorphophallus mirabilis , published in Nordic J. Bot. 2023: e04238 (2023).

Amorphophallus mirabilis K.Z.Hein, Naive, Serebryanyi and Hett., sp. nov. Diagnosis: A species whose inflorescence is most similar to that of Amorphophallus dzui Hett., but differing by the much longer peduncle (up to 30 cm versus 3-9 cm in Amorphophallus dzui), the spathe outside being pale purplish brown, inside basal half pale being maroon and densely clothed with fleshy, irregularly shaped warts, the upper half yellowish green (versus the spathe outside greyish green or pale grey and inside almost entirely blackish maroon with a smooth or grooved base in Amorphophallus dzui), and entire or transversely bilabiate stigmas (versus distinctly lobed stigmas in Amorphophallus dzui). The leaf with crenate-undulate margin, adaxially velvety dark olive green with a more or less distinct grey green to silvery variegation along the midrib and abaxially greenish to purplish red which is similar to that of Amorphophallus pendulus Bogner and Mayo, but in the latter species the spadix has a whip-like, pendulous appendix (versus narrowly elongate-conical, erect in Amorphophallus mirabilis). Type: Myanmar, Kayin State, Hpa-an District, full locality data withheld owing to the risk of potential exploitation of wild populations for commercial purposes, 3 June 2023, S. C. S. Paing s.n. (holotype KKU).

DISTRIBUTION: Myanmar: Myanmar.

DISTRIBUTION NOTE: Myanmar: Kayin State, Hpa-an District. The species is known only from its type locality, and the authors withhold the precise locality because of the risk that wild plants would be collected for sale.².

SPECIES DESCRIPTION:

Seasonally dormant herb. Tuber napiform, up to 10 cm long and 3.0-4.5 cm in diameter. Leaf solitary; petiole terete, 35-46 cm long and 1.0-1.2 cm in diameter, smooth, uniformly pale olive green. Lamina strongly decompound, up to 65 cm across, divided into three main segments; rachises narrowly winged throughout. Leaflets elliptic to elliptic-obovate, 10-28 cm long and 4-6 cm wide, acuminate at the apex with a 2-3 cm long acumen, asymmetric and decurrent at the base, the margin weakly or more prominently crenate-undulate; the upper surface velvety dark olive green carrying a more or less distinct interrupted linear or slightly irregular gray green to silvery variegation along the midrib, the venation distinctly impressed; the lower surface greenish to purplish red; both surfaces glabrous.²

INFLORESCENCE:

Inflorescence solitary, long-pedunculate; peduncle up to 30 cm long and 0.9-1.2 cm in diameter, terete, smooth, brownish olive green. Spathe reaching only halfway up the staminate zone of the spadix or slightly beyond, broadly triangular-ovate, erect, 9-11 cm long and about 9 cm in diameter, the base and limb not separated, the margins involute, rounded at the apex, cucullate; pale purplish brown outside; inside the basal half pale maroon and densely clothed with fleshy, irregularly shaped warts, the upper half yellowish green. Spadix sessile, much longer than the spathe, 36-43 cm long. Pistillate zone cylindric, 1.9-2.1 cm long and 1.1-1.5 cm in diameter, the flowers slightly distant. Sterile zone between the pistillate and staminate zones 1.2-1.7 cm long and 1.8-2.0 cm in diameter, covered with three to five spirals of synandrodes. Staminate zone cylindric, 8.6-11.0 cm long and 1.5-2.1 cm in diameter, the lower flowers slightly distant but the upper ones congested. Appendix contiguous with the staminate zone, narrowly elongate-conical, tapering to the top, erect, 26-30 cm long and 1.6-2.7 cm in diameter at the base, terete or slightly laterally compressed, slightly truncate at the base, acute at the apex, the surface rugulose, yellowish brown to pale brown, producing a faint rotting-flesh odor at anthesis. Ovary depressed globose, angular or subangular in cross section, about 1.5 mm high and 2 mm in diameter, one-chambered, yellowish white at the base and dark purple over the rest; style cylindrical, about 0.8 mm long and 1 mm in diameter, dark purple; stigma depressed, entire or transversely bilabiate, about 0.6 mm high and about 1.3 mm in diameter, the surface verrucate, light orange. Staminate flowers of five or six stamens in the lower part of the staminate zone, the number indeterminable over the rest; stamens about 1.5 mm long and 1.7-2.0 mm in diameter; filaments about 0.5 mm long; anthers about 1 mm long and about 0.7 mm in diameter, ivory, the connective slightly sunken, the pores apical and slit-like. Synandrodes at pistillate anthesis hemispherical to depressed hemispherical with shallow grooves, about 2.5 mm high and 5-6 mm in diameter; at staminate anthesis a larger and irregular central depression develops with distinct grooves, the surface verrucose, cream or yellow. The infructescence and berries have never been seen.²

ECOLOGY:

Karst limestone forest, the plant growing in a crack of a moist sandstone rock under a closed to semi-open canopy of seasonal rain forest or dry evergreen forest, at an elevation of about 100 m. Observed flowering in the wild in May and June.²

ETYMOLOGY:

The epithet refers to the eye-catching foliage, which strongly resembles that of Amorphophallus pendulus - a species of subgenus Amorphophallus only distantly related to this one.²

NOTES:

1. The species was found by a local plant enthusiast, Saw Chit Soe Paing, flowering in May and June 2023 in Hpa-an District, Kayin State. He sent the material to the second author, and comparison against protologues and digitized type specimens from Myanmar and neighboring countries showed it to be undescribed.²

2. The authors place it in Amorphophallus subgenus Metandrium. The resemblance that gives the species its name is misleading on this point: the variegated foliage recalls Amorphophallus pendulus, which sits in subgenus Amorphophallus and is only distantly related.²

3. It is told from Amorphophallus dzui, the species its inflorescence most resembles, by a much longer peduncle - up to 30 cm against 3 to 9 cm - by a spathe that is pale purplish brown outside and pale maroon over the warty basal half inside with a yellowish green upper half, where Amorphophallus dzui is grayish green or pale gray outside and almost entirely blackish maroon inside over a smooth or grooved base, and by an entire or transversely bilabiate stigma against a distinctly lobed one.²

4. It is told from Amorphophallus pendulus by the appendix, which is narrowly elongate-conical and erect here and whip-like and pendulous in that species.²

5. The inflorescence draws numerous flies, and also beetles of the family Staphylinidae, subfamily Aleocharinae. The beetles were seen descending into the spathe and onto the pistillate zone, and on that observation the authors suggest Staphylinidae as the effective pollinators. This is a hypothesis from field observation, not a pollination study.²

6. Proposed as Data Deficient. The species is known from its type locality alone and nothing is recorded about threats to its habitat, so the authors state there is too little information to assess it.²

7. The same paper reports Amorphophallus napalensis as a new record for Myanmar, from Natma Taung (Mount Victoria) National Park in Chin State. With that record and this species, Myanmar holds seventeen Amorphophallus species.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus mirabilis

2. Nordic J. Bot. 2023: e04238 (2023) — protologue.