Begonia aptera Blume (1827: 97)

Espeja, Bryll L., Bucay, Mark Angelo C., Tandang, Danilo N., Rubite, Rosario R., Chen, Hong-Wun, Chung, Kuo-Fang & Bautista, Majella G., 2024, A new record of Begonia aptera in Southern Mindanao: the second species of Begonia sect. Platycentrum recorded from the Philippines, Phytotaxa 670 (3), pp. 181-186 : 182-185

Begonia aptera Blume (1827: 97)

§ Platycentrum ( Fig. 1 ).

≡Diploclinium apterum (Blume) Miquel (1856: 691).

Type:— INDONESIA. Sulawesi: Tondano, s.coll., s.n. (lectotype L [Herb. Ludg. Bat. 898194-39 ], designated by Hughes [2008]) .

= Begonia cristata Warb. ex Smith & Wasshausen (1983: 442) . Type:— INDONESIA. Sulawesi, North Sulawesi: Minahasa, Tomohon, iv 1984, K.F. & P.B. Sarasin 288 (lectotype K000761122, designated by Smith & Wasshausen [1983]).

= Begonia renifolia Imscher (1913: 379) . Type: — INDONESIA. Sulawesi, North Sulawesi: Minahasa, Bojong, N. Wallich 15188 (holotype B10023802).

= Begonia aptera subsp. hirtissima Girmansyah & Thomas (2009: 72) . Type: — INDONESIA. Sulawesi, Southeast Sulawesi: Kolaka Regency, Ranteangin District, Tinukari Village, Mt. Mekongga, 21 March 2006, D. Girmansyah Deden 654 (holotype BO, isotypes E00678417, L, K, US).

Monoecious, perennial, shrub, 30–35 cm tall. Stems brown to pale green, fleshy, glabrous, 1.2 cm width at base, internode 5–13 cm. Stipules deciduous, green or brown, triangular, 10 × 4 mm, herbaceous, glabrous, margins bi-toothed, serrate, apex acute. Leaves alternate; petioles terete, fleshy, pale green and/or brownish, 4.5–10.5 cm long, glabrous; lamina broadly elliptic, 12–14.5 cm from the point of attachment to apex, 16–18 cm from basal lobes to tip, 9–10.5 cm wide, basal lobes rounded, sometimes shallowly overlapping, attenuate at apex, margins glabrous, serrate to serrulate, adaxial surface pale green, glabrous, abaxial surface light green, glabrous, venation palmate, 5–7 veins, dichotomously branching, slightly depressed in adaxial surface, slightly raised in abaxial surface. Inflorescence axillary, bisexual, protandrous, 2–3 cm long, peduncle erect, pale green, glabrous 1–1.5 cm long. Bracts caducous, light brown, lowest pair 1–1.5 × 0.2–0.5 cm, glabrous, persistent, apex acuminate, margin entire. Staminate flowers: pedicel 1.6 cm long, white to light green, glabrous, tepals 4; 2 outer tepals, orbicular, white, 1 × 1.3 cm, glabrous, apex rounded, margins entire; 2 inner tepals ovate, white, 0.5 × 0.6 cm, glabrous, apex rounded, margin entire; androecium actinomorphic, 8 mm across; stamens yellow, 60–80, filament light yellow, 2.5 mm long, united at base; anthers obovate, 5–6 mm long, apex rounded, connective projecting 0.2 mm. Pistillate flowers: pedicel 1 cm long, glabrous; tepals 6; 3 outer tepals ovate to broadly ovate, white, 1 × 1.2 cm, apex obtuse, margins entire, glabrous; 3 inner tepals ovate, 0.5 × 0.6 cm, white, apex obtuse, margins entire, glabrous; ovary trigonal-ellipsoidal, ovate to oblong outline, green, 0.6–0.8 × 1–1.2 cm, 3-locular, placentae bilamellate, glabrous; wings 3, reduced, triangular, base rounded, apex obtuse, green, 0.5 × 0.3 cm. Fruit, 3-locular, fleshy, rhomboidal-spherical, 1 × 1.5 cm (wings included), nodding, pedicel, 0.8–1.0 cm long; wings, reduced, triangular, base obtuse, apex acute, pale green, 0.5 × 0.3 cm.

Distribution and Ecology:—The populations of B. aptera were recorded in Mt. Matutum and Mt. Melibengoy, two mountains in southern Mindanao ( Fig. 2 ). The populations were found thriving on mid-elevation (1000-1800 masl) forest understories associated with the dense forest cover in Mt. Matutum, and in a shaded moist environment near an abaca ( Musa textilis ) plantation in Mt. Melibengoy.

Phenology:—The plant is observed to bear flowers and fruit in the months of May to June.

Proposed Conservation Status:—It was observed that the patches of individuals were scattered along the trails of both Mountain Ranges and the populations appear to be well-established across the forests. However, because of the observed threats in the population such as trail clearing for tourist use and farm intrusions, we propose the newly recorded species to be declared locally as Vulnerable. This is based on the guidelines set by the Philippine Department of Environment and Natural Resources (DENR) under the National List of Threatened Plants and their Categories, whereas Vulnerable species are defined as species vulnerable to ‘adverse’ factors throughout its range (DENR 2017).

However, on a global scale, the provisional IUCN conservation assessment of Sulawesi populations of B. aptera as Least Concern (LC) will remain as the initial Extent of Occurrence (EOO) of 690,000 km 2 recorded in Sulawesi is expected to be even larger because of this new distribution record in Mindanao island (Ardi et al. 2017).

Notes:— The species was identified as B. aptera primarily by having the bi-toothed serrated leaf margins and broadly elliptic leaf shape which are distinct from the leaves of B. longifolia . It is also deemed distinct from B. halconensis , the only species in B. sect. Platycentrum in the Philippines by having a glabrous leaf margin (vs. soft, setae-like hairs in leaf margins of B. halconensis ). The overall leaf shape also differs with B. aptera having generally broadly elliptic leaves (vs oblong-ovate) and having reduced triangular wing with acute apices (vs turbinate with prominent abaxial wing and having truncated apices) (Merill 1911).

Given the abundance of B. aptera records in Sulawesi, and possible island dispersal routes along Sangihe and Talaud islands, the occurrence of B. aptera in southern Mindanao is possible. This same Wallacean biogeographic distribution is observed on another widespread species B. rieckei which ranges from Sulawesi to Maluku and extends to the Philippines ( Thomas 2012, Hughes 2015).

Specimens examined:— PHILIPPINES. Mindanao Island: South Cotabato, Mt. Matutum , 1390 m, 2 May 2024, Espeja BLE007 & BLE008 (PNH) ; South Cotabato, Mt. Melibengoy , 1649 m, 25 June 2024, Espeja BLE012 & BLE013 (PNH) .

Figures

FIGURE 1. Begonia aptera. A. Habit. B. Adaxial leaf surface. C. Abaxial leaf surface. D-H. Fruits. I. Stipules. J & L. Staminate and pistillate flowers. K. Staminate flower. Photos by BLE from collection no. BLE013.

FIGURE 2. Map showing the location of the observed B. aptera populations in the Philippines. Map by MACB.