Begonia masilig, J.Collantes, C.J.P.Dela Cruz & Y.P.Ang, 2023

Collantes, Yu Pin Ang John Paul R., Mansibang, Jayson, Dela Cruz, Cyrus Job P., M. Aumentado, Jamieann, Bimeda, Shane B., Callado, John Rey, Fritsch, Peter W. & Bustamante, Rene Alfred Anton, 2023, Two new species of Begonia (Begoniaceae) from Aurora Memorial National Park, Luzon Island, Philippines, Phytotaxa 609 (4), pp. 253-264 : 254-258

Begonia masilig, J.Collantes, C.J.P.Dela Cruz & Y.P.Ang , sp. nov.

§ Baryandra ( Figures 1–3 )

Type:— PHILIPPINES. Luzon Island, Aurora Province, Municipality of Maria Aurora, Barangay Villa Aurora , Sitio Dimani , primary forest, ca. 560 m elevation, 15°41’ 32.175”N, 121°21’ 29.79”E, 30 June 2022, AAMNP2 (holotype PNH, isotypes BRIT, CAHUP) .

Diagnosis:— Begonia masilig belongs to B. sect. Baryandra A. de Candolle (1859: 122) in having a rhizomatous habit, axillary protandrous inflorescences with boat-shaped bracts, and an ovary with bifid placentation. Begonia masilig is similar to B. droseroides C.I Peng et al. ( Rubite et al. 2018) in having brown-appressed-sericeous petioles, inflorescences with glandular trichomes, and 5-tepaled pistillate flowers with lunate ovary wings. It differs by having adaxially glabrous stipules (vs. hirsute), an ovate to narrowly ovate lamina (vs. widely ovate) up to 26 × 15 cm (vs. up to 8.2 × 7 cm), usually with a darker green tinge in the middle (vs. entirely green), and a margin with sparse minute white trichomes (vs. dense red trichomes), longer peduncle (19–50 cm long vs. 7–19 cm long), and staminate flower tepals with scattered glandular hairs abaxially (vs. glabrous) ( Table 1 ).

Description:— Lithophytic herb, monoecious, rhizomatous. Rhizome creeping, maroon with white spots, up to ca. 30 × 0.5–0.9 cm in diam., glabrous, internodes 4–10 mm long, with conspicuous petiolar scars. Stipules deciduous, herbaceous, brownish red, ovate, 12–15 × 7–9 mm, keeled, keel subtended by 1 to 5 fleshy aristate trichomes fused at base, other parts glabrous, margin entire, apex apiculate, apiculae ca. 1 mm long. Leaves alternate; petiole terete, maroon at base, turning pale green towards lamina, 9–26 × 0.3–0.5 cm, brown-appressed-sericeous, glabrescent at maturity; lamina basifixed, ovate to narrowly ovate, asymmetrical, 13.5–26 × 7.5–15 cm, adaxially glabrous, waxy, uniformly light green, usually with a deep purplish brown or dark green tinge in middle; abaxially pale green with reddish brown tinge on variegation, brown-tomentose on veins, glabrescent, base cordate, basal lobes slightly overlapping, margin sparsely serrulate to entire, shallowly undulate, ciliate with sparse white simple trichomes (ca. 0.5 mm long), apex acute; venation basally ca. 9-palmate, branching dichotomously or nearly so, veins sunken adaxially and raised abaxially. Inflorescence axillary, protandrous, cymosely branching 3 to 5 times, panicle 22–58 cm long; peduncle 19–48 cm long, the lower half of primary peduncle sparsely brown-pubescent, rest of peduncle scattered (to densely scattered) with simple white glandular trichomes ca. 0.5 mm long. Bracts caducous, pale brown to green, broadly ovate, boat-shaped, hyaline, lowest bract ca. 5 × 4 mm, adaxially glabrous, abaxially scattered with simple glandular trichomes (ca. 0.5 mm long), margin entire, apex cuspidate. Staminate flower: pedicel 8–12 mm long, scattered with simple glandular trichomes; tepals 4, white, outer tepals elliptic, abaxially scattered with simple glandular trichomes, 10–11 × 9–10 mm, apex rounded, inner tepals obovate, 9–10 × 5–6 mm, glabrous, apex rounded; androecium ca. 4 mm diam., stamens ca. 55, filaments free, 1.5–2.0 mm long, anthers yellow, ca. 1 mm long, obovate, with 2 lateral slits running lengthwise from base to apex, apex rounded. Pistillate flower: pedicel 10–11 mm long, sparsely scattered with simple glandular trichomes, tepals 5, pale pink, outer tepals 2, orbicular to broadly elliptic, 7–8 × 8–9 mm, abaxially scattered with simple glandular trichomes, apex rounded, inner tepals 3, obovate, 7–8 × 5–6 mm, glabrous, apex rounded; styles 3, yellow, shortly fused at base, ca. 2.5 mm long, spiral and papillose all around; ovary trigonous-ellipsoid, greenish pink, 7–8 × 3–4 mm (wings excluded), densely scattered with simple white glandular trichomes, locules 3, placenta bifid; wings 3, unequal, largest wing lunate, distally truncated, proximally rounded, cucullate, 7–8 mm wide, 2 lateral wings narrowly oblong to lunate, 2–3 mm wide. Capsule pendent, shape similar to ovary, 8–9 × 4–6 mm, glabrous, largest wing 11–12 × 13–15 mm, lateral wings 9–12 × 4–6 mm, recurved with largest wing pointing towards the ground, dehiscing along the attachment of the 2 lateral wings.

Etymology:— The epithet masilig is a Tagalog-Baler (Balereño) word that translates to fast, rapid, or heavy water flow. Begonia masilig was discovered in an area where there is fast-flowing water, hence the name.

Distribution and habitat:— The species is known within Aurora Memorial National Park ( Figure 6 ). It was found most abundantly perching over lowland rivers on rocks. It inhabits inclined to almost vertical surfaces that are perpetually wet or moist throughout the year. Plants exposed to pockets of light were observed to grow much larger with ample flowering and fruiting. Smaller individuals scattered in deep shade and flowering and fruiting with the same frequency as the larger individuals. Because the mountains in the type locality form a continuum, further exploration and documentation may yield additional individuals from the nearby mountains and rocky outcrops.

Phenology:— Flowering and fruiting in June.

Proposed conservation assessment:— The area in which Begonia masilig occurs is an initial component of the National Integrated Protected Area Systems (NIPAS) Law, a Philippine Law that governs the protection, conservation and management of Protected Areas (DENR-BMB 2018). Nonetheless, the species faces natural and anthropogenic threats, e.g.,landslides and illegal collection of forest resources.The trail where the species occurs is frequently disturbed by tourists visiting a nearby waterfall. Moreover, local reports on the unregulated collection of B. masilig have led to the extirpation of some easily accessible subpopulations. In our surveys, the population count was estimated to be <250 mature individuals within an Extent of occurrence (EOO) of <200 km 2 and Area of occurrence (AOO) of about 10 km 2. In situ observations indicate that there has been a recent decline that is projected to continue. Consequently, the criteria for IUCN 15.1 Red List EN (Endangered) Criteria B1ab (ii,iii,iv)+2ab(ii,iii,iv) are satisfied ( IUCN Standards and Petitions Subcommittee 2022).

Notes:— A plant of what is now considered Begonia masilig was first documented in 2012 by Pelser et al. (2011 – Present) with a photograph stored in Phytoimages ( Nickrent et al. 2006 –Present). Subsequently, the same photograph by Pelser et al. (2011 –Present) was included by Tandang et al. (2016), albeit identified as B. neopurpurea nom . inval., based on the earlier published name B. purpurea ( Elmer, 1939) , which is a later homonym and also a nomen nudum as it lacked a Latin diagnosis. The description of B. purpurea was based on a single collection by Elmer from elevations of ca. 230 m on Mount Bulusan, Irosin, Sorsogon, on July 1916 (A.D.E. Elmer 16565). There are some morphological similarities between B. masilig with the species in Tandang et al. (2016), with both bearing ovate leaves with a dark purplish center, 4-tepaled staminate flowers, 5-tepaled pistillate flowers, as well as occuring in the same region as AMNP. Although B. masilig is similar to B. neopurpurea , as based on the literature ( Elmer 1939) and the specimen there are some morphological distinctions and we do not consider them to represent the same taxon. It differs from B. masilig by having a more prominent rhizome up to ca. 1 m long (vs. up to ca. 30 cm long), elongated internodes ca. 7 cm long (vs. 4–10 mm long), smaller lamina (ca. 12 × 7 cm vs. 13.5–26 × 7.5–15 cm), lower half of peduncle sparsely ciliate (vs. sparse brown pubescent), and upper half of peduncle glabrous (vs. densely white glandular) ( Elmer, 1939).

Begonia masilig is a member of a group of Luzon begonias that develop glandular trichomes on their inflorescences. This group includes B. droseroides , B. caramoanensis Rubite et al. (2020) , B. tayabensis Merr. and B. depressinerva Pranada et al. (2019) . As more areas in Luzon are explored, additional Begonia species with such characters may be discovered.

Other specimen examined:— PHILIPPINES. Luzon, Aurora Province, Municipality of Maria Aurora, Barangay Villa Aurora, Sitio Kamatis , Mt. Kamatis , primary forest, elevation 683 m, 15°40’24.96”N, 121°18’42.4188”E, 27 February 2022, PTI-AMNP-1-148 ( PNH, CAHUP, PPC) .

Figures

FIGURE 1. Begonia masilig. A. Habit; B. Stipule; C. Leaf adaxial surface showing margin; D. Leaf abaxial surface showing veins; E. Bract; F. Peduncle; G. Staminate flower ventral view; H. Stamens dorsal and lateral view, from left to right; I. Pistillate flower ventral view; J. Ovary lateral view; K. Ovary cross section. Illustrated by Y.P. Ang based on AAMNP2 (PNH, BRIT, CAHUP).

FIGURE 2. Begonia masilig. A. Habitat and habit; B. Leaf adaxial (left) and abaxial (right) surfaces; C. Rhizome showing stipule and base of petiole; D. Petiole and leaf abaxial surface; E. Panicle; F. Peduncle showing glandular trichomes; G. Bracts; H. Staminate flower lateral and ventral view; I. Pistillate flower lateral and ventral view; J. Capsule; K. Ovary cross section. Photos: A by M.N. Tamayo; B–E, H–J by Y.P. Ang; F, G & K by R. Bustamante.

FIGURE 3. Begonia masilig. A, B, C. Color variation in lamina adaxial surface at the type locality. All photos by Y.P. Ang.

FIGURE 6. Map of Aurora Province showing the locality of B. masilig and B. akaw (star).