Rhodamnia toratot N. Snow, 2012

Snow, Neil, 2012, Five new species of Rhodamnia (Myrtaceae, Myrteae) from New Guinea, PhytoKeys 19, pp. 31-49 : 37-39

Rhodamnia toratot N. Snow sp. nov. Figures 1 5

Superficially resembling species with stellate and typically ferrugineous trichomes but differing by its highly crispate trichomes.

Type.

Papua New Guinea. Milne Bay District, Nowata, c. 6 miles W. of Rabaraba, 09°59'S, 149°43'E, ca. 520 m, 5 Jul 1969, R. Pullen 7709 (holotype: K!; isotypes: A! [barcode 00307479], BISH!, BO n.v., BRI!, CANB n.v. [00217141.1 and 00217141.2], G!, L n.v., LAE n.v.).

Description.

Trees to ca. 5.5 m. Bark of main bole unknown. Indumentum (branchlets, leaves, flowers, fruit) mostly densely tomentose-lanate, the trichomes highly crisped, ferrugineous, and generally somewhat appressed (see also description of abaxial leaf surface below). Branchlets terete to slightly compressed, reddish-brown (dried); epidermis smooth but finely and evenly striate throughout becoming somewhat fissured with age; oil glands sparse to common (obscured by indumentum on younger branchlets). Leaves opposite, evenly distributed along branchlets, somewhat discolorous; venation perfect basal to slightly suprabasal perfect or imperfect acrodromous, secondary and higher order veins abaxially prominent, the secondaries varying greatly in prominence (and thus hard to estimate numerically) but mostly spaced (2-)3-7 mm along the midvein; intramarginal vein less pronounced than the secondary veins, paralleling leaf margin closely, mostly ca. 0.5-1.0 mm from margin at midpoint of blade. Colleters absent. Petioles 9.0-13.5 mm long, terete, densely lanate-tomentose. Leaf blades 6.5-12.0 cm long, 3.1-5.2 cm wide, elliptic to ovate, base cuneate to nearly rounded, apex acute to acuminate, tip acute to acuminate; adaxial surface matte, initially lanate but becoming glabrescent, midvein slightly impressed throughout; abaxial surface lanate along midvein and secondary veins when younger, increasingly glabrous with age, densely/minutely hoary between veins, midvein raised prominently throughout. Inflorescence lateral in current season’s growth, flowers solitary to mostly densely fascicled, sessile to subsessile with pedicels up to 5 mm long, the pedicels lax, sometimes bending. Bracteoles ca. 2.0-2.5 mm long, ca. 0.5 mm wide at base, linear, persisting in flower and frequently in fruit. Hypanthium cupulate. Calyx lobes 2.5-3.5 mm long, ovate, apex obtuse, densely hairy abaxially but adaxially less so (especially proximally) with age, persisent and erect in fruit. Petals (material scanty), ca. 4.0-4.5 mm long, up to 3.5 mm wide, broadly obovate, more or less glabrous adaxially, densely lanate abaxially. Staminal disk ca. 4.5 mm in diameter; staminal ring narrow, shortly villous-lanate (trichomes whitish-yellow). Stamens numerous (estimated 75-105); anthers sacs (material scanty) cylindrical, ca. 1.0 mm long, bearing a single apical gland; filament length unknown. Styles not seen, but persisting bases densely lanate in fruit. Ovary with 1 locule; placentas 2; placentation parietal; ovules numerous. Fruit subglobose, 7.5-8.5 mm long (probably immature) x 8.0-9.5 mm wide, greenish when young but becoming brownish on account of dense indumentum. Seeds somewhat compressed, ca. 1-2 mm thick.

Phenology.

Flowering unknown; fruiting in July.

Distribution.

Milne Bay Province in Papua New Guinea; in secondary (regrowth) forest with Dodonaea Adans. ( Sapindaceae ) and Castanopsis (D. Don) Spach ( Fagaceae ).

Conservation status.

Data Deficient; possibly Threatened for same reasons cited above for Rhodamnia asekiensis .

Etymology.

The specific epithet is derived from toratot as a noun in the nominative.

Vernancular name.

Locally known as toratot in the Nowata language.

Comments.

The tomentose to lanate indumentum on the branchlets and inflorescences ( Fig. 5 ) of Rhodamnia toratot suggests its inclusion in the “villous” group of species ( Snow 2007), but the minute trichomes between the tertiary and higher-order venation on the abaxial leaf surface suggest possible inclusion in the “hoary” group ( Snow 2007).

Scott (1979) had assigned the type gathering of Rhodamnia toratot to Rhodamnia blairiana var. propinqua.However, the two taxa are easily distinguished based on trichome density and appearance. The abaxial laminar indumentum of Rhodamnia toratot is characterized by the highly contorted form of the individual trichomes, which are more sparsely distributed than the densely stellate trichomes present on the type specimen of of Rhodamnia blairiana var. propinqua.

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 5. Rhodamnia toratot N. Snow. Drawing of isotype at BISH (R. Pullen 7709). Clockwise from top center: branchlet; detail of branchlet indumentum; bracteole; abaxial leaf surface; seed. Scale bars = 1 mm, except branchlet bar = 1 cm.