Begonia flacca Irmscher (1953: 486)

Ardi, Wisnu H., Chikmawati, Tatik, Witono, Joko R. & Thomas, Daniel C., 2018, A synopsis of Begonia (Begoniaceae) of Southeastern Sulawesi including four new species, Phytotaxa 381 (1), pp. 27-50 : 34

3. Begonia flacca Irmscher (1953: 486) ( Figures 1 & 4 )

Sect. Petermannia

Type:— INDONESIA. Sulawesi, Southeast Sulawesi: Kendari, Peninsula SE of Kendari, 1874, O. Beccari CB4501A (lectotype FI [scan!], designated here).

Distribution:— Indonesia; endemic to Sulawesi, Southeast Sulawesi (Danau Biru, Kendari, Tamborasi, Tanjung Peropa, Uluiwoi and Wawonii Island).

Habitat:— Vertical limestone cliffs, limestone boulders, cave mouths in coastal areas and steep slopes in lowland forests, at 0–60 m elevation.

Notes:— Begonia flacca was previously only known from a few specimens. The recently collected material from Kolaka, Tanjung Peropa and Wawonii Island indicates that it is relatively widespread in lowland forests on limestone in Southeast Sulawesi.

Begonia flacca is a morphologically highly variable species. At least three populations were observed and differentiated during field work in Southeast Sulawesi. These populations show considerable variation in leaf morphology and indumentum characters. The first population was observed in Tanjung Peropa. The individuals in this population tend to have hairier stems and petioles compared to the other two populations from Kolaka and Wawonii. Other differences are related to leaf shape. The Tanjung Peropa population has elliptic leaves that have dentate to bisserate margins and are adaxially sparsely bristly between the veins. The Kolaka population is morphologically more variable than the populations in Tanjung Peropa and Wawonii. Generally the individuals in the Kolaka population are glabrous, the leaves are ovate to elliptic with entire to biserrate to slightly lobed (up to 25% of the lamina width) margins. Individuals within this population show different colour forms; some plants show reddish-brownish stems and leaves indicating a high anthocyan content. Moreover the shape of the ovary and wings are also variable, with considerable variation observed within the populations. The ovary can be obovoid, ellipsoid or cylindrical, and the wings rounded to cuneate at the base and truncate to slightly convex at the apex. Only a single individual was collected on Wawonii Island. It has ovate leaves with shallowly lobed margins. However, although some morphological differences were noticed, none seem complex enough to warrant formal taxonomic separation. All collections have the same characteristic inflorescence structure: single female flowers, frequently paired with a single male flower, and basal to the main male inflorescences, which are composed of one to three monochasial partial inflorescences.

Provisional IUCN conservation assessment:— Vunerable (VuD2). This species’ distribution includes lowland forest habitats in the karst area of North Kolaka (Tamborasi, Danau Biru and Gua Marmer), Tanjung Peropa Forest Reserve and Wawonii Island. Healthy populations of Begonia flacca were observed in the legally protected area of Tanjung Peropa Forest Reserve. Collections from Kolaka were from shaded road embankments where the species was locally common, but it will likely also occur deeper in the karst area as a collection has been made from Mount Watuwila (Deden 717 [BO]). Given the patchy and relatively small distribution (EOO: 5489 km 2; AOO: 28 km 2), and the poor state and pressures of lowland rain forest habitats on Sulawesi ( Cannon et al. 2007), a Vunerable (VuD2) status seems warranted.

Additional specimens examined:— INDONESIA. Sulawesi, Southeast Sulawesi: Kendari, Peninsula SE of Kendari, 1874, O, Beccari CB 4501 ( FI) ; Kendari , 12 Apr. 1929, G.K. Kjellberg 1289 (S) ; Uluiwoi District, Cave Marmer , 28 Mar. 2006, Deden 717 ( BO) ; South Konawe, Tanjung Peropa Forest Reserve, Moramo Waterfall , 1 Feb. 2017, W.H. Ardi WI 118 ( BO, KRB, SING) ; South Konawe, Tanjung Peropa Forest Reserve, Moramo Waterfall , 1 Feb. 2017, W.H. Ardi WI 120 ( BO, KRB, SING) ; South Konawe, Tanjung Peropa Forest Reserve, Moramo Waterfall , 1 Feb. 2017, W.H. Ardi WI 121 ( BO, KRB, SING) ; North Kolaka, Tamborasi , 4 Feb. 2017, W.H. Ardi WI 137 ( BO, KRB, SING) ; North Kolaka, Tamborasi , 4 Feb. 2017, W.H.Ardi WI 138 ( BO, KRB, SING) ; North Kolaka, Tamborasi , 4 Feb. 2017, W.H. Ardi WI 139 ( BO, KRB, SING) ; North Kolaka, Tamborasi , 4 Feb. 2017, W.H. Ardi WI 140 ( BO, KRB, SING) ; North Kolaka, Danau Biru , 4 Feb. 2017, W.H. Ardi WI 141 ( BO, KRB, SING) ; North Kolaka, Danau Biru , 4 Feb. 2017, W.H. Ardi WI 142 ( BO, KRB, SING) ; North Kolaka, Danau Biru , 4 Feb. 2017, W.H. Ardi WI 143 ( BO, KRB, SING) ; Wawonii Island, Tekonea village , 24 Feb. 2017, W.H. Ardi WI 182 ( BO, KRB, SING) .

Figures

FIGURE 1. Distribution map.A. Overview of Sulawesi. B. Distributions of B. aptera, B. johntania, B. mekonggensis, and B. ozotothrix.C. Distributions of B. balgooyi, B.flacca, B. matarombeoensis, and B. watuwilensis. D. Distributions of B.incudiformicarpa, B. iskandariana, and B. tumburanoensis. Specimen location information was georeferenced using the GeoNames geographical database at http://www. geonames.org/.

FIGURE 4. Begonia flacca. A. Plant in situ, Kolaka population; scale bar: 15 cm. B. Plant in situ, Tanjung Peropa population; scale bar: 10 cm. C. Plant in situ, Wawonii island population; scale bar: 20 cm. D. Leaf shape variation, (a-c) Kolaka population, (d) Tanjung peropa population, (e) Wawonii island population; scale bar: 5 mm. E. Inflorescence, Kolaka population; scale bar: 10 mm. F. Inflorescence, Tanjung Peropa population; scale bar: 5 mm. G. Inflorescence, Wawonii island population; scale bar: 5 mm.A, D (a-c), E from Ardi, W.H. 138; B, D (d), F from Ardi, W.H. 120; C, D (e), G from Ardi, W.H. 182 (Photos: W.H. Ardi).