Syzygium rhysgardneri Craven, 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 : 76-77

33. Syzygium rhysgardneri Craven , sp. nov. — Fig. 2 : 1.5; Map 8

From Syzygium royenii Craven & Damas it differs in having larger and apically acuminate leaves (5‒6 by 2.5‒3.5 cm, broadly obovate to narrowly elliptic, apex truncately acuminate to acuminate as opposed to 2.5‒5.3 by 1.4‒1.7 cm,narrowly elliptic or sometimes obovate,apex acute in S. royenii ), a larger hypanthium (5‒6 mm long as opposed to 3‒4.5 mm in S. royenii ), and a calyx that is an irregularly ragged rim of tissue (in S. royenii the calyx is a rim of tissue on which 4 points are discernible or consists of 4 relatively distinct lobes). — Type: Gardner 9730 (holo CANB!; iso AK, K, L, all n.v.), Papua New Guinea, Madang Province, Schrader Range, Kaironk Valley , large tree of primary forest on steep talus slope,alt. c. 2200 m, 13 Nov. 1999 .

Etymology. The specific epithet honours Rhys Owen Gardner (1949‒), an expert on the flora of New Zealand and several of the South West Pacific islands.

Large tree, 150 cm dbh; bark pinkish brown with a thin flaky layer over a fibrous layer of at least 10 mm thick. Vegetative branchlet generally terete (distally compressed or quadrangu- lar), rounded, c. 1.5 mm diam; bark dull, smooth and slightly glandular-verrucose or not, persistent on young growth units but at length peeling to reveal a soft, mealy, furfuraceous-like tissue. Leaf lamina broadly obovate to narrowly elliptic, 5‒6 by 2.5‒3.5 cm, 1.6‒2.4 times as long as wide; base attenuate to cuneate; apex truncately acuminate or acuminate, acumen flat; margin flat; lamina cartilaginous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein; primary veins 19‒22 on each side of the midrib, in median part of lamina at a divergence angle of 70‒80° and 1.5‒2 mm apart; intramarginal vein present, weakly arched, 1‒1.5 mm from leaf margin, secondary intramarginal vein present. Petiole 6‒11 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence leafless, on branchlets below the leaves, many-flowered, paniculate, up to 20 by 26 cm, major axis c. 4 mm thick at the midpoint, bark furfuraceous; bracts caducous; bracteoles subtending each flower, caducous. Flower buds with the apex rounded to obtuse. Flowers cream. Hypanthium dull, smooth to obscurely glandular-verrucose, visibly gland-dotted, angled laterally (i.e., 2-costate); stipitate; stipitate-napiform to stipitate-cup-shaped, 5‒6 by 5‒5.5 mm, stipe 1‒1.5 mm long. Calyx a persistent, irregularly ragged rim of tissue, up to 0.5 mm long. Petals calyptrate (coherent and falling as a cap). Staminal disc flat ( Fig. 2 : 1.5). Stamens c. 65, 4‒6 mm long. Style c. 6 mm long. Placentation axile-basal; placenta peltate and flattened. Ovules 15 or 16 per locule, ascending, arranged irregularly. Fruit not seen.

Distribution — Papua New Guinea.

Habitat & Ecology — Primary forest on steep talus slope. Altitude c. 2200 m.

Notes — 1. Once the smooth epidermis of the branchlets has cracked, a mealy tissue is exposed. This tissue superficially resembles the furfuraceous epidermis that occurs in other species but it is quite different. The calyx is another interesting feature of S. rhysgardneri as it is a ragged rim of tissue around the apex of the hypanthium and discrete lobes per se are not present.

2. The species is known from the type collection only.

Figures

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