印尼秋海棠科一新種：納圖那秋海棠

Begonia natunaensis (sect. Reichenheimia, Begoniaceae), a new species from Natuna Island, Indonesia

本文報導印尼納圖那島東部之拉奈山低海拔瀑布區岩壁著生，通體近於光滑無毛的秋海棠科一新種：納圖那秋海棠（Begonia natunaensis C.W. Lin and C.-I Peng）。本種略似兩種產於蘇門答臘且直線距離超過1,000公里，原產地不詳但現已廣泛栽培的秋海棠：一為火焰秋海棠（B. goegoensis N.E. Brown），然新種葉柄截面近圓形，托葉窄三角形，雌花及雄花之花被片皆為兩枚；另一近似種為毛盾葉秋海棠（B. sudjanae Jans.），但後者全株密被糙硬毛，花被片數目不同，易於區分。

Begonia natunaensis, a new species of sect. Reichenheimia from Natuna Island, Indonesia, is here described and illustrated. Begonia natunaensis resembles B. goegoensis N.E. Brown in having suborbicular, peltate leaves with an abruptly tapering tip, differing in the number of tepals in staminate flowers (2 vs. 4) and in pistillate flower (2 vs. 3) and the petiole (terete vs. 4-angular). The new species is also similar to another peltate-leaved Begonia, B. sudjanae Jans., but is distinguishable by being glabrous (vs. hispid throughout), the staminate tepals 2 [vs. (2–)4], and pistillate tepals 2 [vs. (2–)3]. Geographically, B. natunaensis is endemic to Natuna Island in the South China Sea, whereas B. goegoensis and B. sudjanae are distributed in western Sumatra, ca. 1,000 km away from Natuna.