Syzygium kokomo Craven, 2019

Craven, L. A., 2019, Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised, Blumea 64 (2), pp. 115-122 : 119

5. Syzygium kokomo Craven , sp. nov. — Fig. 1 ; Map 3

From Syzygium claviflorum (Roxb.) Steud. it differs in the quadrangular vegetative branchlets; the flat leaf lamina acumen; and the stipitately very narrowly obconic hypanthium with a stipe 6–7.5 mm long. (In S. claviflorum the vegetative branchlets are terete or compressed, the leaf lamina acumen is recurved,and the hypanthium is funnel-shaped or elongated goblet-shaped with a stipe 6.5–17 mm long.) — Type: Henty & Foreman NGF 42673 (holo L!; iso A!, BISH, BO, BRI, CANB, K, LAE, NSW,SING, all n.v.), Papua New Guinea, West Sepik (Sandaun) Province, Telefomin Subprovince, Kokomo Creek (a tributary of Frieda River), ridge forest, alt. c. 670 m, 28 June 1969.

Etymology. The specific epithet is a noun in apposition derived from the locality Kokomo Creek.

Tree to 27 m tall, to 25 cm dbh; bark dark brown outside, red brown inside. Vegetative branchlet quadrangular initially but at length terete, winged or angled, 0.8–1.4 mm diam; bark dull, smooth or cracked (cracking is fine and longitudinal), not glandular-verrucose, persistent or peeling in relatively thin strips. Leaf lamina 3.5–5 by 1.3–1.8 cm, 2.5–3.9 times as long as wide, narrowly ovate or ovate; base cuneate or narrowly cuneate; apex long acuminate, acumen flat and up to 1.5 cm long; margin flat; thickly coriaceous, approaching cartilaginous; primary and secondary venation distinctly different with secondaries relatively little developed and not or rarely joining the intramarginal vein (in some cases not even the primary veins reach the intramarginal vein); primary veins 3–6 on each side of the mid-rib, in median part of the lamina at a divergence angle of 40–60° and 3–6 mm apart; intramarginal vein present, weakly arched, 0.8–1 mm from leaf margin, secondary intramarginal vein present or absent. Petiole 3.5–5 mm long. Reproductive seasonal growth unit with a reproductive zone only. Inflorescence terminal, or distal or median axillary, few- to many-flowered, paniculate up to 1–3.5 by 1–2.5 cm, major axis 0.5–0.7 mm thick at the midpoint, bark glandular-verrucose; bracts deciduous; bracteoles apparently subtending each flow- er, deciduous (rarely a few persisting). Flowers (immature) with free calyx lobes . Hypanthium dull, smooth; stipitate; stipitately very narrowly obconic; 6–7.5 by 2 mm. Calyx lobes 5. Petals probably 5. Staminal disc, stamens and fruit not seen (see note).

Distribution — Papua New Guinea.

Habitat & Ecology — Ridge forest . Altitude 670 m.

Notes — This species is known from a single collection only, this being in the bud stage.

The inflorescence is a simple paniculate structure, often with 2 pairs of lateral branches and then a terminal cluster of flowers at the apex of the final internode of the main axis. Flowers may terminate axes in groups of 3 or 7 (the latter presumably being 2 triads and 1 monad). Occasionally, perhaps through abortion, monads or dyads occur. There can be up to 7 inflorescences at the apex of a vegetative seasonal growth unit.

The figure of 6–7.5 mm given above for the hypanthium length is the total length of the buds at what is possibly the mid-bud stage.

Figures

Map 3 Distribution of Syzygium kokomo Craven (●) and S. leptopodium Merr. & L.M.Perry (■).

Fig. 1 Diagrams of staminal disc types occurring in Syzygium subg. Perikion species, showing staminal discs that are flat (1.1–1.10), descending (2.5), ascending (3.2) and raised (4.2). Within the flat staminal disc type, structure may differ in the degree of ‘lip’ projection at the inner edge of hypanthium apex (1.4, 1.5, 1.6 and 1.9) and the presence of a grooved petal insertion point (1.10).