Syzygium aporematum Craven & Damas, 2021

Craven, L. A., Damas, K. Q. & Cowley, K. J., 2021, Studies in Papuasian Syzygium (Myrtaceae): 2. The furfuraceous species of subg. Syzygium, Blumea 66 (1), pp. 57-81 : 61-62

1. Syzygium aporematum Craven & Damas , sp. nov. — Fig. 2 : 1.8; Map 1

From Syzygium furfuraceum Merr. & L.M.Perry it differs in having the leaf lamina elliptic or obovate with the acumen recurved and the base attenuate or obtuse (broadly oblong or sometimes obovate, the acumen flat and the base obtuse in S. furfuraceum ); inflorescences on branchlets below the leaves or on branches (cauline in S. furfuraceum ); and the hypanthium not furfuraceous (furfuraceous in S. furfuraceum ). — Type: Clemens 9428 (holo L!; iso A!), Papua New Guinea, Morobe Province, Samanzing vicinity, mountain bush, 1830‒2130 m, 1, 2 Dec. 1938.

Etymology. The specific epithet is derived from the Greek, aporema, doubt, question, perplexity, in reference to the issues we have had in arriving at its circumscription.

Tree to 25 m tall, to 75 cm dbh; bark light brown or rust red, papery flaky or flaking in small plates. Vegetative branchlet terete or compressed, rounded, 3‒4 mm diam; bark dull-glossy or glossy, smooth or slightly glandular-verrucose, persistent (to cracking and then caducous). Leaf lamina elliptic or obovate, 14‒16(‒19) by 7‒9 cm, 1.6‒2.3 times as long as wide; base at- tenuate or obtuse; apex roundly acuminate, truncate or obtuse; acumen recurved; margin flat (to weakly revolute); cartilaginous; primary and secondary venation generally similar with all or nearly all secondaries joining the intramarginal vein; primary veins c. 15‒20 on each side of the midrib, in median part of lamina at a divergence angle of c. 90° and 6‒10 mm apart; intramarginal vein present, weakly arched, 1.5‒2.5 mm from margin, secondary intramarginal vein present. Petiole 4‒5 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence leafless, on branchlets below the leaves or on branches, paniculate, up to 16‒29 by 12‒20 cm, major axis 3‒6 mm thick at the midpoint, bark furfuraceous; bracts caducous; bracteoles subtending each flower, caducous. Flowers white. Hypanthium dull-glossy, glandular-verrucose; stipitate; broadly clavate, stipitate-cup-shaped or goblet-shaped, 5.5‒6 by 4.5‒5 mm; stipe 0.5‒0.75 mm long. Calyx lobes 0 or 4, not or only weakly distinguishable on a rim of tissue c. 0.2 mm high, when distinguishable then lobes c. 0.3 mm long including the rim. Staminal disc flat ( Fig. 2 : 1.8 with a thinner lip). Style c. 5.5 mm long. Placentation axile-basal; placenta a small cushion. Ovules c. 15 per locule, ascending, arranged irregularly. Petals, stamens and mature fruit not seen.

Distribution — Papua New Guinea.

Habitat & Ecology — Mid-mountain rainforest, edge of rain- forest adjoining Eucalyptus grassland at top of hill, submontane rainforest. Altitude 520‒2130 m.

Note — The inflorescence has also been recorded as cauline but this condition, usually given by collectors as ‘inflorescence cauliflorous’, is commonly misinterpreted and may not be applicable to S. aporematum . Clemens 9428 is at the post anthesis-young fruit stage. The placentation is axile-basal in NGF 34451 but is unclear in Hartley 12455. Clemens 4831 (Ogeramnang, c. 1670 m, 28 December 1936) possibly does not belong to this species.

Figures

Map 1 Distribution of Syzygium aporematum Craven & Damas (●), S. araucariarum Craven & Damas (■), S. bowersiae Craven & Damas (▲).

Fig. 2 Staminal disc types in Syzygium species. Series 1: Flat; series 2: descending; series 3: ascending; series 4: raised.