Aponogeton dassanayakei Manawaduge & Yakandawala, 2016

Manawaduge, Chapa G., Yakandawala, Deepthi & Les, Donald H., 2016, Morphometric analysis reveals a new species of Aponogeton (Aponogetonaceae) in Sri Lanka, Phytotaxa 275 (3), pp. 243-262 : 251-252

Aponogeton dassanayakei Manawaduge & Yakandawala , sp. nov. ( Fig. 6 )

Aponogeton dassanayakei is distinct from the other two proliferous species known in the genus by having the combination of characters; highly undulated long strictly submersed leaves with no alternately transparent or opaque patterns, broad white coloured persistent tepals and caducous spathe.

Type:— SRI LANKA. Western Province: Kalutara, Ittapana Thotupola-South End, (Ittapane–Horawala Thotupola Road), elev. 3 m, 08° 23.910 ′ N / 80° 4.067 ′ E, 15 February 2015, Manawaduge & Yakandawala 215. (Holotype: PDN!).

Tuber cylindrical and elongate; 9–20 mm Ø. Submerged leaves lamina; 17–56 × 1.4–5.2 cm; linear and slightly curved, apex acute and base cuneate, margin finely undulate, midrib with 6–8 parallel nerves; Petioles up to 56 cm long, brittle, bluntly triangular. Floating leaves absent. Peduncle up to 178 cm, widening towards the inflorescence. Spathe up to 35 mm, caduceus. Inflorescence with 1 spike; spike up to 15 cm, densely flowered; flowers turned towards all directions. Tepals 2, 1.2–2.3 × 1.3–2.5 mm, persistent, 1 nerved, white, broad. Stamens 6, 1–2 mm; filaments slightly widening towards the base, white, anthers grayish green. Carpels 3, white, 1.0–1.5 × 0.4–1 mm; ovules 2. Infructescence up to 31 cm. Folicals up to 10 × 6 mm, elongated, triangular, with rough coat and a short, terminal, curved beak. Seeds with a simple testa; embryo up to 8–9 × 3–6 mm, plumule attached near the base of the embryo and in a very wide groove. Proliferous peduncles ascending up to 45 cm, slightly thickened towards the tip.

Phenology:— Throughout the year.

Distribution:— Aponogeton dassanayakei occurs in the low land wet zone, in slow flowing rivulets and rivers in much deeper water (below 1–2 m in some cases) and also in saline water towards the lagoons.

Eponymy:— The new species has been named after Professor M. D. Dassanayake, an eminent Plant Taxonomist in Sri Lanka and the General Editor of “A Revised Handbook to the Flora of Ceylon ” (Vols. I–XV).

Additional specimens examined (Paratypes):— SRI LANKA. Western Province: Colombo, Hanwella , 06°54.109 ′ N, 80°05.613 ′ E, 13 m, 28 July 2014, Manawaduge & Yakandawala 105 (PDN!) ; Kalutara, Meegama, near Meegama Thotupola bridge, 06°24.825 ′ N, 80°04.005 ′ E, 4 m, 11 August 2014, Manawaduge & Yakandawala 408, 409 (PDN!) ; Lunuganga, Bawa Gardens , 06°24. 254 ′ N, 80°01.121 ′ E, 18 m, 11 August 2014, Manawaduge & Yakandawala 109 (PDN!) ; same locality, 06°24.30 ′ N, 80° 1.211 ′ E, 18 m, 15 February 2015, Manawaduge & Yakandawala 117 (PDN!) ; Bandaragama, Waskaduwa —Bandaragama road, 06°41.155 ′ N 79° 58. 857 ′ E, 2 m, 11August 2014, Manawaduge & Yakandawala 110 (PDN!) ; Gampaha, Kirindiwita, Kirindiwita –Ganemulla road, 07° 5.370 ′ N 79°58.156 ′ E, 10 m, 24 September 2015, Manawaduge & Yakandawala 126 (PDN!) ; Yagoda , 07°4.390 ′ N, 79°58.188 ′ E, 10 m, 24 September 2015, Manawaduge & Yakandawala 127 (PDN!) ; Sabaragamuwa Province: Ratnapura, Kuruwuta, Colombo –Batticaloa highway, 06°46.982 ′ N, 80°21.579 ′ E, 27 m, 17 December 2015, Manawaduge & Yakandawala 128 (PDN!) .

Figures

FIGURE 6. Aponogeton dassanayakei Manawaduge & Yakandawala (a) habit, (b) inflorescence, (c) floret, (d) tepal, (e) stamen, (f) gynoecium and (g) infructescence.