AMORPHOPHALLUS SAMARENSIS

PROTOLOGUE: Amorphophallus samarensis , published in Webbia 79(2): 296 (2024).

Amorphophallus samarensis Fontarum-Bulawin, Medecilo-Guiang & Alejandro, sp. nov. Diagnosis: Amorphophallus samarensis has widely triangular, undulating, pale green, cream to maroon spathe, with maroon spots, an undulate to entire spathe margin; cylindric female zone; spadix longer than spathe; slightly distant depressed globose ovaries; pale to dark maroon slightly depressed globose capitate stigma; elongate cylindrical male zone; truncate anther; absent of staminode; and smooth narrowly elongate cylindric appendix. Amorphophallus samarensis is like Amorphophallus calcicola, Amorphophallus longispathaceus, and Amorphophallus rostratus for having solitary leaf, spadix longer than spathe, long peduncled solitary flower, congested male flowers, and slightly distant female flowers. However, it differed from Amorphophallus calcicola by its subglobose tuber, smooth petiole, distal part of winged rachis not branched, narrowly elliptic leaflets, undulate to entire leaf margin, undulated in the upper part and entire in the lower part spathe margin, pale to dark maroon slightly depressed globose capitate stigma, and elongate to widely triangular-ovate spathe. Also different from Amorphophallus longispathaceus by its tuber, rachis, leaflets shape, spathe margin, shape of stigma, and spathe shape. Different from Amorphophallus rostratus in leaflets, rachis, absence of staminode, ovary shape, and shape of stigma. Type: Philippines, Eastern Visayas, Samar Island, Municipality of Paranas, Samar Island Natural Park (SINP), 137-329 masl elevation, on the shady areas, karst forest, 23 June 2022, Norilyn Fontarum-Bulawin 031 (holotype PNH! [258714]; isotypes PNH! [258715] & USTH! [016887]).

DISTRIBUTION: Philippines: Philippines, Samar.

DISTRIBUTION NOTE: Philippines: Samar Province, Municipality of Paranas, inside the Samar Island Natural Park. The species is endemic to Samar Island and is known only from this area, across about 556 square kilometers of land.².

SPECIES DESCRIPTION:

Tuber subglobose, 6-7 cm in diameter and 3.5-4.5 cm high, pale to dark brown. Leaf solitary; petiole 55-58 cm long and 3.3-3.5 cm in diameter, the surface smooth, narrowing toward the upper part, pale to dark brown or pale to dark green with irregular to narrowly elliptic greenish white, purple or dark brown spots from the base to the upper part. Lamina 36-40 cm in diameter; rachis winged at the distal part and not branched, divided into three leaflets, green or light brown, smooth with white and green spots, 12.7-15 cm long and 1.5-2 cm in diameter. Leaflets narrowly elliptic, 13.5-16 cm long and 2-3.5 cm wide, with an acumen 1-1.5 cm long, the tip acuminate and the base cuneate to narrowly cuneate; the upper surface green to dark green, the lower surface pale green to green, the midrib depressed and the lateral veins impressed in seven to eleven nerve pairs, the brochidodromous secondary veins forming prominent upward loops near the margin; the lamina margin undulate to entire, the leaf attachment decurrent.²

INFLORESCENCE:

Inflorescence solitary, erect; peduncle 34-36 cm long and 3.2-3.5 cm in diameter, pale green to cream or white, smooth, with green and maroon spots toward the top and white and maroon spots toward the base. Spathe elongate, widely triangular-ovate when spread, 15-16 cm long and 13-14 cm wide, erect, without constriction; at the base outside distinctly convolute, pale green to cream or white with vertical veins and irregular purple or maroon spots, inside pale green to cream or white turning reddish to maroon downward, slightly grooved and set with verrucae; the limb outside widely triangular and undulating, pale green, reddish to maroon with purple or maroon spots, inside pale green to reddish to maroon with purple or maroon spots, the margin undulate above and entire below. Spadix sessile, much longer than the spathe, 17-19 cm long and 0.53-3 cm in diameter. Female zone cylindric, 4-5 cm long and 3-4 cm in diameter; female flowers slightly distant, pale to dark maroon; ovaries depressed globose, 1.7-3.4 mm in diameter and 1.33-2.85 mm high, pale to dark maroon, one-chambered; style straight and upward, 5-6.4 mm long and 0.58-0.62 mm in diameter, pale to dark maroon; stigma slightly depressed globose capitate, pale to dark maroon, 0.63-2.1 mm in diameter and 0.89-1.29 mm high. Male zone elongate, 4-5 cm long and 3-4 cm in diameter; male flowers with one stamen, irregularly nearly ovate, congested but slightly distant at the base, cream to pale yellow; stamens 1.79-2.3 mm long, cream to pale yellow; anthers 0.5-1 mm long, truncate, with subfusiform apical pores 0.3-0.5 mm long; filaments 1.5-2 mm long, slightly clavate. Staminodes absent. Appendix smooth, narrowly elongate cylindric, 7-11.5 cm long and 5.88-9.29 mm in diameter above the base; the base dilated cylindrically and slightly smooth, maroon to dark maroon, the apex narrowly long cylindric and tapered, maroon to dark maroon. The fruits have never been observed.²

ECOLOGY:

Shady areas in karst forest, at 137-329 m elevation. Flowering from June to July; fruiting has never been observed.²

DISTRIBUTION MAPS:

ETYMOLOGY:

The epithet is taken from the type locality, Samar Island.²

NOTES:

1. The first author found the species during fieldwork in 2019, and returned to the Samar Island Natural Park in 2022 to confirm it and collect the material the description rests on.²

2. It is compared against three Philippine species. It resembles Amorphophallus calcicolus in the solitary leaf, the long-pedunculate solitary inflorescence, the cylindric female zone, the depressed disk-shaped and slightly distant ovaries and the absence of staminodes, but differs in the subglobose tuber, the smooth petiole, the winged rachis unbranched at the distal part, the narrowly elliptic leaflets, the undulate to entire leaf margin, the spathe margin undulate above and entire below, the slightly depressed globose capitate stigma and the elongate to widely triangular-ovate spathe.²

3. It resembles Amorphophallus longispathaceus in the smooth petiole, solitary leaf, long-pedunculate solitary inflorescence, cylindric female zone, ovary shape and truncate anther, and differs in tuber, rachis, leaflet shape, spathe margin, stigma shape and spathe shape. It resembles Amorphophallus rostratus in the spadix being longer than the spathe, the slightly distant female flowers, the congested male flowers, the solitary leaf and the long-pedunculate solitary inflorescence, and differs in leaflets, rachis, the absence of staminodes, ovary shape and stigma.²

4. ⚠ The source spells the species it compares against most closely as calcicola, in its abstract, its keywords and its comparison table. The published name is Amorphophallus calcicolus, as given in the title of its own protologue (Tamayo and others, Phytotaxa 489(2): 229-235, 2021). The correct spelling is used above.²

5. Assessed as Critically Endangered. The extent of occurrence is under 100 square kilometers and fewer than 250 mature plants are thought to remain; thirty individuals and three inflorescences were found at the locality, under continuing pressure from human activity.²

REFERENCES:

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

2. Webbia 79(2): 296 (2024) — protologue.