Aponogeton kannangarae De Silva, Deshaprema & Manamperi, 2016

Silva, Madura Anusha De, Deshaprema, K. M. S. & Manamperi, J. P. J., 2016, Aponogeton kannangarae, a new species of Aponogeton (Aponogetonaceae) from Rakwana hills, Sri Lanka, Phytotaxa 272 (2), pp. 220-224 : 220-223

Aponogeton kannangarae De Silva, Deshaprema & Manamperi sp. nov. ( Fig. 1 )

Similar to A. rigidifolius , but can be distinguished by the following characteristics: plumule is attached just below the middle of the embryo; flowers are arranged in whorls around the inflorescence and cylindrical rhizome is not branched.

Type: — SRI LANKA. Ratnapura District, Illumbakanda dola, Morning Side, Sinharaja World Heritage Site. 6 o 24’27.6”N, 80 o 36’37.5”E, 1059 m, 24 April 2015, Wildlife Conservation Society-Galle 1202276. (holotype PDA! isotypes PDA!)

A perennial aquatic plant. Rhizome cylindrical, not branched, 1 cm in diameter and up to 8 cm in length; fibrous roots abundant. Leaves submerged, blades linear to lanceolate, slightly glabrous, 12.5–38 cm × 2.8–5.3 cm. Immature leaves are purple to maroon, turns to dark green with maturity; margins slightly to highly undulate; base acute to cuneate; apex highly to less acute; veins 8, parallel; petiole 8–13 cm in length. Floating leaves absent. Inflorescence is a spike, densely flowered, up to 10 cm in length, highly curved, at maturity flowers are arranged in whorls around inflorescence. Flowers bisexual, turned in all directions, scentless. Tepals 2, rounded square, 2–2.5 mm in width, vein 1, slightly notched at middle, at maturity pink in color. Stamens 6, filaments widened toward base, 2–2.5 mm in length, anthers green in color, pollen yellow in color. Peduncle 28–32 cm in length, not thickening towards inflorescence. Spathe caducous, 1.5–2 cm in length. Ovaries 3, 1.5 mm × 1 mm, 2 ovules per each. Fruits 12 mm × 8 mm, slightly curved with short terminal beak, surface is slightly furrowed. Seeds 8–13 mm × 3–5 mm, simple testa. Embryo 12 mm × 4 mm, plumule with two leaflets, attached the embryo just below the middle.

Phenology:— Flowering occurs throughout the year. But flowering intensity increases just after the rainy season.

Distribution and ecology:— Aponogeton kannangarae is restricted to less shaded, slow flowing shallow streams in Rakwana hills in Ratnapura District of Sri Lanka (Figures 2,3).

Eponymy:—This species is named for Dr. C. W. W. Kannangara (1884–1969), “The father of free education in Sri Lanka ”, for his immense service on initiating the free education system of Sri Lanka.

Notes: —The species closely resembles with A. rigidifolius , but differs with the combination of these morphological characters ( Figures 4 , A–H). The plumule of A. kannangarae is attached to just below the middle of embryo while A. rigidifolius has a plumule attached to the bottom of the embryo. After maturity, the inflorescence of A. kannangarae shows a whorled flower arrangement around the inflorescence while A. rigidifolius shows a spiral flower arrangement. Fruits of A. kannangarae have slightly furrowed surface with a short curved terminal beak. Aponogeton kannangarae has a non-branching cylindrical rhizome while A. rigidifolius has a branching cylindrical rhizome. Immature leaves of A. kannangarae are purple to maroon color while light green in A. rigidifolius .

Additional specimens examined:— SRI LANKA. Ratnapura District , Sooriyakanda , Sinharaja Aranyaya,. 6 o 26’27.2”N, 80 o 73’28.3”E, 997 m, 23 August 2014, Wildlife Conservation Society-Galle 1202275 ( PDA!) ; Ratnapura District , Sinharaja , Tangamale, Plains of Morning Side. 6 o 24’N, 80 o 36’E, A. H. M. Jayasooriya, B. W. M. Wijesinghe 7041 ( PDA!) ; Ratnapura District , Morning Side , Sinharaja World Heritage Site. 6 o 24’36.6”N, 80 o 36’39.7”E, 1052 m, 27 February 2012, Madhura De Silva 1202273 ( PDA!) ; Ratnapura District , Morning Side , Sinharaja World Heritage Site. 6 o 24’11.2”N, 80 o 36’47.8”E, 1055 m, 27 February 2012, Madhura De Silva 1202274 ( PDA!) .

Figures

FIGURE 4. Aponogeton kannangarae (A) Growth habit, (D) Matured inflorescence, (E) Embryo (G) Fruit. A. rigidifolius (B) Growth habit, (C) Matured inflorescence, (F) Embryo, (H) Fruit.

FIGURE. 1. Aponogeton kannangarae (from the holotype).A, habit, scale bar 15 mm; B, fruit, scale bar 1 mm; C, Embryo with plumule, scale bar 1 mm; D, flower, scale bar 1 mm; E, stamen, scale bar 1 mm; F, petal, scale bar 1 mm.