Phyllanthus ridsdalei R.W.Bouman & Verwijs, 2019

Verwijs, J. I. M., Bouman, R. W. & Welzen, P. C. van, 2019, A taxonomic revision of Phyllanthus subgenus Macraea (Phyllanthaceae), Blumea 64 (3), pp. 231-252 : 245

16. Phyllanthus ridsdalei R.W.Bouman & Verwijs , sp. nov. — Fig. 1 ; Map 11

Resembling P. tenuipes by the presence of a gynophore, but differing in its larger leaves,larger staminate and pistillate sepals,pistillate annular disc (vs free disc glands in the pistillate flowers of P. tenuipes ) and a longer gynophore and style.The stigmas in P. ridsdalei are also only bifid at the tip, while those in P. tenuipes are bifid for their entire length. — Type: CE Ridsdale 1479 (holo L (L.3958300); iso A, IBC, K), Philippines, Luzon, Zambales, Santa Cruz, Acoje mine concession area, c. N15°46.0' E120°00.0'.

Shrubs, c. 1 m high, monoecious; branches terete, glabrous, slightly winged, wing c. 0.1 mm wide; internodes 6‒7 mm long. Stipules ovate to elliptic to triangular, c. 1 by 0.3 mm, caducous, flat, membranous, base bilaterally auricled, margin brittle, thin, apex caudate. Leaves: petiole 0.8‒1.2 mm long, glabrous; blade elliptic, 11‒22 by 6‒10 mm, 1.5‒3.1 times longer than wide, membranous, glabrous, base oblique, subcordate, attenuate to obtuse, margin slightly revolute, apex slightly retuse to acute, upper side darker than lower side; midrib slightly elevated on lower side, lateral veins 5‒9 per side, barely visible on upper side. Staminate flowers 1‒3 together, axillary, 1‒1.3 mm diam; pedicel 10‒15 mm long, glabrous; sepals 6, elliptic to oblong, 1.5‒2 by 0.8‒1 mm, midrib slightly raised on inside of flower, apex curved inward, rounded to obtuse, green turning red; disc glands 6, ovate, 0.5‒0.6 by 0.1‒0.2 mm, c. 0.3 mm high, massive; stamens 3, c. 1.1 mm long, filaments variably connate from base to more than half of filament length, deflexed, 0.6‒0.7 mm long, thecae 0.3‒0.4 mm long. Pistillate flowers 1 or 2 together, 2.5‒3 mm diam; pedicel 9‒13 mm long, glabrous, slender; sepals 6, ovate, c. 3 by 1.5 mm, midrib slightly elevated on inside, apex acute; disc annular, fused with base of gynophore and forming a rim around the base just in front of sepals, rim lobed with lobes alternating with sepals, folded; gynophore 0.6‒0.8 mm high, ovary subglobose, 0.4‒5 by c. 0.6

mm, each locule with a groove, glabrous, smooth, blueish when dry; style 1.5‒1.6 mm long, stigmas 3, 1‒2 mm long, with tips bifid, 0.1‒0.2 mm long. Fruits and seeds not seen.

Distribution — Philippines (Luzon).

Habitat & Ecology — Secondary forests on ultrabasic soils. Flowering in May.

Note — Pollen studied by Wu et al. (2016) showed that this species is part of subg. Macraea , and it was previously filed under ‘ aff. samarensis ’. However, it differs markedly from P. samarensis by its larger pistillate flowers, the long gynophore and a long style below three elongated stigmas.

Figures

Map 11 Distribution of Phyllanthus ridsdalei R.W.Bouman & Verwijs (●) and P. tenuipes C.B.Rob. (▲) in the N Philippines.

Fig. 1 Phyllanthus ridsdalei R.W.Bouman & Verwijs. a. Flowering branch drawn from herbarium specimen with hanging flowers; b. detail of staminate inflo- rescence; c. closed staminate flower; d. staminate flower (3 sepals removed); e. pistillate flower as seen when open, note the excerted style; f. pistillate flower (2 sepals removed), note the disc rim fused with the base of the gynophore (all: CE Ridsdale 1479, L). — Drawing by Esmee Winkel 2018.