Rhodamnia asekiensis N. Snow, 2012

Snow, Neil, 2012, Five new species of Rhodamnia (Myrtaceae, Myrteae) from New Guinea, PhytoKeys 19, pp. 31-49 : 32-34

Rhodamnia asekiensis N. Snow sp. nov. Figures 1 2

Resembling Rhodamnia latifolia but with distinctly larger leaves that have an acute to acuminate apex and differing by the larger fruits.

Type.

Papua New Guinea. Morobe Province, Aseki, Menyama Subdistrict, 7°21'S, 146°10'E, 20 May 1968, H. Streimann & A. Kairo NGF 39049(holotype: BISH [sheet no. 30914]!; isotypes: A!, CANB!, K!, L!, LAE n.v., NSW n.v., US!)

Description.

Trees of unknown height; crown dense. Bark of main bole light grey, vertically fissured. Indumentum (branchlets, flowers, fruit) short-sericeous, sparsely to moderately dense, color more or less saffron ( Beentje 2010). Branchlets terete, wingless, dark brown (dried); epidermis smooth, oil glands absent. Leaves opposite, evenly distributed along branchlets, strongly discolorous; venation perfect basal or slightly suprabasal acrodromous, secondary and tertiary veins visible above and below, the more prominent secondaries ca. 20-25 per side abaxially, the secondaries near base of blade splitting as they approach lateral primary vein and contrasting with those towards apex of blade that are mostly unbranched; intramarginal vein less pronounced than secondaries, parallel to leaf margins, 0.8-1.1 mm from margin at midpoint of blade. Colleters absent. Petioles 11-13 mm long, round to slightly sulcate above. Leaf blades 10.5-16.0 cm long, 3.5-4.5 cm wide, narrowly ovate (to elliptic), base cuneate, apex acuminate, tip acute; adaxial surface matte, glabrescent at base, midvein slightly and narrowly raised proximally but becoming flush distally; abaxial surface densely short and strongly-appressed sericeous between the secondary and tertiary veins, midvein projecting throughout, oil glands not visible. Inflorescence terminal or lateral, flowers solitary (=monads) or in 3-flowered cymes ( “botryoids” of some authors), pedicels of monads up to 10 mm long. Bracteoles not seen, apparently caducous in fruit. Flowers unknown. Hypanthium (based on fruit) evidently not ribbed, hairy. Calyx lobes (in mature fruit) 2.5-3.0 mm long, more or less glabrous adaxially, moderately sericeous abaxially, persisent and erect in fruit. Ovary (from mature fruit) and locule 1, placentas 2, linear; ovules disposed in regular rows. Berries subcylindrical, somewhat pyriform or tapering at the base, 8.5-14.0 mm long, 8-11 mm wide, sparsely sericeous, dull dark red (fresh) or blackish (dried). Seeds 4-10 per fruit, 4.5-5.2 mm long, 2.8-5.0 mm wide, rounded on outer portion adjacent to fruit wall but highly angular and irregularly elsewhere, light brown, seed coat highly sclerotized. Embryos not seen.

Phenology.

Flowering unknown; fruiting confirmed only for May.

Distribution.

Known only from Morobe Province, Papua New Guinea, on the side of a ridge in a secondary forest; ca. 1465 m.

Conservation status.

Data Deficient; but the subsequent lack of collections of this species over the past 45 years locally and regionally suggest that Threatened might more accurately reflect is true status.

Comments.

Rhodamnia asekiensis is included among the “pearly” group of species ( Snow 2007) by virtue of its nacreous abaxial laminar indumentum. The 10-16 cm long leaves with the acute to acuminate apices distinguish it from Rhodamnia latifolia , in which Scott (1979) earlier had placed the type specimen.

Figures

Figure 1. Island of New Guinea, showing localities of new species. Triangle (▲) = Rhodamnia asekiensis; Square (■) = Rhodamnia daymanensis; Diamond (◆) = Rhodamnia makumak (at bottom of line); Closed circle (⚫) = Rhodamnia toratot (at top of line); Inverted triangle (▼) = Rhodamnia waigeoensis (upper left, at bottom of line); Open circles (⚪) = Rhodamnia sharpeana (left end of line [upper] and bottom of line [lower, on truncated eastern half of Tagula Island]).

Figure 2. Rhodamnia asekiensis N. Snow. Photo of the holotype at BISH (H. Streimann and A. Kairo NGF 39049).