Syzygium rubroalabastrum 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 : 78

35. Syzygium rubroalabastrum Craven & Damas , sp. nov. — Map 10

From Syzygium pyrocarpum (Greves) Merr. & L.M.Perry it differs in having smaller leaves (the lamina 13–20 by 5‒8.5 cm as against 20‒31 by 6.5‒16.5 cm in S. pyrocarpum ); the hypanthium striate-glandular and obscurely gland-dotted (distinctly minutely wrinkled or ribbed and not visibly gland-dotted in S. pyrocarpum ); and 55‒60 stamens (130‒140 in S. pyrocarpum ). — Type: Carr 13068 (holo CANB!; iso L n.v.), Papua New Guinea, Central Province, Boridi, in forest, alt. c. 1460 m, 10 Sept. 1935.

Etymology. The specific epithet is a compound word to be treated as a noun in apposition and is derived from the Latin ruber, red, and alabastrum, flower bud, in reference to the red flower buds.

Tree to 12 m tall; both outer and inner bark brown. Vegetative branchlet terete, rounded, 2‒5 mm diam; bark dull, smooth, not glandular-verrucose, persistent. Leaf lamina elliptic, slightly obovate or slightly ovate, 13–20 by 5‒8.5 cm, 2.2‒3.2 times as long as wide; base cuneate to sometimes obtuse; apex acuminate; acumen flat; margin flat; lamina coriaceous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 30‒38 on each side of the midrib, in median part of lamina at a divergence angle of 70‒80° and 3‒5 mm apart; intramarginal vein present, weakly arched, 2‒4 mm from margin, secondary intramarginal vein present. Petiole 5‒14 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence leafless, cauline, shortly and congestedly paniculate, up to 4‒6 by 4‒6 cm, major axis 3‒3.5 mm thick at the midpoint, bark furfuraceous; bracts mostly persistent; bracteoles subtending each flower, persistent. Flower buds with the apex rounded to obtuse. Flowers red or with calyx red and corolla green. Hypanthium dull, furfuraceous, striate-glandular, obscurely gland-dotted; stipitate; turgid-goblet-shaped (when reconstituted, goblet-shaped with a very short stipe or obconic and then tending to be narrowly so), 6.5‒8.5 by 6‒6.5 mm, stipe 0.5‒1 mm long. Calyx lobes 5, very depressedly obtusely triangular or transversely semi-elliptic, c. 1‒1.5 mm long. Petals 5, calyptrate (coherent and falling as a cap). Staminal disc immature. Stamens 55‒60. Placentation axile-basal; placenta a small cushion. Ovules c. 12 per locule, ascending, arranged irregularly. Open flowers and fruit not seen.

Distribution — Papua New Guinea.

Habitat & Ecology — Rainforest. Altitude 1130‒1560 m.

Note — Mature, i.e., open, flowers have not been seen and floral characters have been recorded from the late bud stage. The staminal disc is modified but it is too immature to assign to any particular form. Pullen 5776 pro parte possibly may not belong to this species although its leaves are generally consistent with those of Pullen 5447 which does. The separate infructescence forming a part of the specimens of Pullen 5776 in CANB is of S. furfuraceum .

Figures

Map 10 Distribution of Syzygium rubroalabastrum Craven & Damas (■), S. thornei T.G.Hartley & L.M.Perry (✚).