Syzygium snowianum W.N.Takeuchi, 2015

Syzygium snowianum W.N.Takeuchi View in CoL , sp. nov.

Type: — PAPUA NEW GUINEA. Western Province: Strickland drainage, Juha South , survey track 1 to sinkhole area, mossy premontane forest, 5°54.184’S, 142°26.260’E, 700 m, 1 April 2008, Takeuchi, Gambia & Jisaka 23684 (holotype A! GoogleMaps ; isotypes CANB! GoogleMaps , L! GoogleMaps , LAE! GoogleMaps ). ( Figures 1–2 View FIGURE 1 View FIGURE 2 ).

Among the Papuasian species of Syzygium , S. snowianum is most similar to S. ubogoense but differs in its taller stature (to at least 25 m in height), yellow perianth, and yellow filaments.

Canopy trees, glabrous; outer bark crustaceous, brunnescent to sooty, not fissured, periderm 3–5 mm thick on flowering branches, furrowed on inner surfaces. Branchlets terete, 1–2 mm diam. at the first node, opposed (or whorled), angular on new growth but never alate, dull brown, straight, fragile, without lenticels, abscission scars obscure; internodes 2.5–6 cm long. Leaves paired, lax, obliquely spreading; petioles 5–9 × 1–2 mm, black, planoconvex or channelled on upper side, not articulated; leaf-blades narrowly elliptic (or oblanceolate), 7.5–14.5 × 2.1–3.8 cm, thin, crispate, brittle, bifacially dull black to fuliginous, abaxial surfaces copiously furnished with raised glandular spots, pellucid punctate on transmitted light; lamina base attenuate-decurrent, equal, poorly delimited from the petiole, margin entire, apex caudate (longest cauda 15 × 3 mm); venation brochidodromous, midrib impressed above, prominent beneath; secondaries 8–17 per side, at the lamina center with divergence angles of 60–80°, 4–9 mm apart, straight (or slightly curved), uniting with a commissural vein 1–5 mm from margins, weak intersecondary nerves often medially interposed between the main laterals; reticulum filiform, irregular, coarsely areolate, raised only on abaxial surfaces. Inflorescence emerging from woody callosities 0.5–2.5 cm wide, black; peduncles cylindrical (or distally flared), 4–10 × 0.2–0.5 mm; bracts ovate-deltate, ca. 0.5 mm long, scalelike, paired, persisting, diverging, inserted at the peduncle base, apex, and occasionally near the middle. Flowers solitary or 2–5 together in loose fascicles; calyx tube (hypanthium) funnelform, 7–10 × 4.5–6 mm, rugulose, not pustulate, lobes 4 in 2 clearly unequal pairs, larger lobes retuse, 2–3.5 × 5.5–7 mm, smaller lobes obtusely ovate-triangular, 1.5–2 × 2.5–3.5 mm; corolla free, membranous, caducous, petals 4, obovate, 4–6 × 3.5–5.5 mm, not clawed, margins hyaline, undulate; androecium biseriate, filaments 5–14 × 0.1–0.3 mm, apically narrowed, anthers ovoid-oblongoid, ca. 1 mm long, medifixed; style subulate, 8–22 × 0.2–0.5 mm, stigma punctiform. Fruits not seen.

Etymology: —The new Syzygium is named after colleague Neil Snow, an authority in paleotropical Myrtaceae .

Field characters: —Canopy trees 25 m tall, without buttress or basal swell, outer bark orange brown, smooth, wood straw, dense; leaf-blades chartaceous, adaxially dark green, abaxially light green; flowers cauline and from older branches, fragrant (attracting swarms of bees in early afternoon); perianth/filaments yellow; anthers white.

Distribution: —Known only from the Strickland drainage of Western Province, from remote and uninhabited uplands ( Figure 3 View FIGURE 3 : A).

Habitat and ecology: —Perhumid premontane forest at 700 m elev.

Phenology: —Flowering in April.

Herbarium specimens of Syzygium snowianum and S. ubogoense can initially appear conspecific when placed side by side. Their principal distinctions are easily discerned in living plants but are not as apparent from dried collections except by reference to carefully prepared labels.

With statures to at least 25 m, Syzygium snowianum is one of the few canopy species discovered in postindependence Papua New Guinea. By comparison, S. ubogoense is a depauperate understory shrub <5 m tall (or at most an 8–10 m pole). Flower color provides the most defining separation—bright yellow in the new species; red calyces with white petals and filaments in the congener ( Figure 4 View FIGURE 4 ). These character states are invariably altered during specimen preparation, the inflorescences of both species turning black and superficially similar after drying. Table 1 View TABLE 1 presents a concise summary of selected distinctions between Syzygium snowianum and its closest ally.

When first discovered in 1991, S. ubogoense was only known from the limestone district near Lake Kutubu. Biodiversity surveys along the PNG LNG Pipeline subsequently recorded the species in a variety of non-calcareous environments ca. 110 km to the northwest, including Juha South. With the latest sightings of S. ubogoense on the Fly River (pers. obs.), its range has been extended at least to the Trans-Fly border with Indonesian Papua. The only known occurrences of S. snowianum are embedded within this expanded distribution of S. ubogoense . The new species is probably sister to the wider-ranging and more ecologically versatile ally.