Begonia anisoptera Merrill (1912: 398)

Ancheta, Donnafe J., Amparado, Olive A., Yu, Wen-Bin & Naive, Mark Arcebal K., 2023, Lectotypification and new data on the distribution of Begonia anisoptera (Begoniaceae, section Baryandra), a species endemic to the Zamboanga Peninsula, Phytotaxa 616 (2), pp. 189-194 : 190-193

Begonia anisoptera Merrill (1912: 398)

Type: PHILIPPINES. Mindanao, Province of Zamboanga, Zamboanga, elev. 0–100 m, 10 October 1906, ED Merrill 5482 (lectotype US [US00115242-image seen], designated here; isolectotypes B [ B100238058 -image seen], NY [ NY00118733 -image seen]). Figs. 1–2 .

Monoecious, epipetric to terrestrial, rhizomatous herb. Rhizome reddish green, glabrous to densely hirsute, creeping, ca. 3–5 mm in diameter, internodes to ca. 5.7 cm long. Stipules persistent, deltate to broadly deltate, concave, 9–10 mm long by 3.5–4.0 mm wide, subsucculent, keeled, green with reddish towards the margin, adaxially glabrous, abaxially densely white hirsute, margin, involute, apex aristate, arista 2–4 mm long. Leaves alternate, petiolate, 7.0– 15.5 cm long; petiole terete, succulent, 7–10 cm long, 2–4 mm in diameter, rufous to russet, densely white hirsute; lamina asymmetric, basifixed, obliquely ovate, 4.0– 14.7 cm long by 2.4–8.0 cm wide, subcoriaceous, succulent, adaxially green to brownish green, glabrous, abaxially pale reddish brown to pale green, puberulent, margin entire, revolute, ciliate, base asymmetrically cordate, apex obtusely acute to attenuate; venation basally palmate, with 6–7 majour lateral veins, actinodromous, branching dichotomously, green, adaxially channeled, glabrous, abaxially protruding, pubescent. Inflorescence axillary, paniculate, protandrous, bisexual, 10–20 cm long, erect, dichotomously branching; peduncle terete, tapering towards the apex, 8–18 cm long, 2–3 mm in diameter, pale red to bright red, hirsute; rachis terete, 5–10 mm long, 1.0– 1.8 mm in diameter dichotomously branching, greenish red, sparsely hirsute; bracts caducous, triangular, concave, reclinate, 1.5–2.5 mm long by 1–2 mm wide, hyaline, green to reddish green, sparsely hirsute, margin entire to repand, apex acuminate. Staminate flower numerous, bearing 4 tepals; pedicel terete, succulent, 5–6 mm long, 1.0– 1.5 mm in diameter, reddish green, hirsute, apically nodding; outer tepals 2, broadly ovate, 8–9 mm long by 6–7 mm wide, pink, adaxially glabrous, abaxially sparsely hirsute, margin entire, ciliate, apex obtuse; inner tepals 2, narrowly obovate, 4–5 mm long by 2.0– 2.5 mm wide, pink, glabrous both sides, margin entire, apex obtuse. Pistillate flower 1(–3), bearing 4 tepals; pedicel terete, succulent, 4–5 mm long, 1.0– 1.5 mm in diameter, reddish green, glabrous to hirsute, apically nodding; outer tepals 2, broadly ovate, 13–14 mm long by 5.0– 5.5 mm wide, pink, glabrous, margin entire, ciliate, apex obtuse; inner tepals 2, narrowly obovate, 9–10 mm long by 5–6 mm wide, pink, glabrous both sides, margin entire, revolute, apex obtuse; ovary stout, trigonous-ellipsoid, 9–10 mm long by 3–4 mm wide (wings excluded), 12–14 mm wide (wings included), pink with a hint of green in the edges of wings, sparsely hirsute, 2-locular, wings 3, strongly unequal, largest wing cucullate, apex obtuse to rounded, placentae bifid; style 3, ca. 2 mm long, bifid, apically forked; stigmas spirally twisted, papillose all around. Fruit up to 15 mm long, reclinate; pedicel terete, 4–5 mm long, glabrous; capsule trigonous-ellipsoid, 10–11 mm long by 3–4 mm wide (wings excluded), 13–14 mm wide (wings included), green to brown, hirsute, wings 3, strongly unequal, irregularly deltate, 8.0– 11.5 mm long by 5–6 mm wide, apex obtusely rounded, dosal wing cucullate.

Distribution: Endemic to the Zamboanga Peninsula ( Map 1 ).At present the species can be found in Zamboanga del Norte (Municipality of Sindangan), Zamboanga del Sur (Municipality of Dimataling) and Zamboanga City (Pasonanca Natural Park). Rubite and Madulid (2009) previously reported Begonia anisoptera as present in Northern Mindanao. However, upon examining their voucher specimens deposited at HAST (HAST121005, HAST121006, HAST120558) we discovered that the collection site mentioned is Zamboanga City Water District Watershed, rather than Northern Mindanao.

Habitat: Begonia anisoptera was found growing in partially shaded to totally shaded tropical lowland rainforest. In Pasonanca Natural Park, it was observed growing with bamboo, ferns and other plants species along the riverside at approximately 140–220 m a.s.l. and was assessed as locally abundant in the area.

Phenology: Flowering and fruiting all throughout the year.

Provisional conservation status: At present, the Begonia anisoptera can be found in five localities and is herein assigned a provisional status of Least Concerned (LC), following the Red List criteria of the IUCN Standards and Petitions Subcommittee (2022). Although considered as Endangered (EN) based on the combined extent of occurrence (EOO) of 1,154.571 km 2 and area of occupancy (AOO) of 20 km 2, the species is abundantly growing in Pasonanca Natural Park with over 1000 mature individuals. Furthermore, Pasonanca Natural Park is one of the protected areas in the Philippines declared in 1999 through Proclamation No. 132, issued by then President Joseph E. Estrada. This species was also found abundantly growing in Barangay Dagatan, Sindangan, Zamboanga del Norte (Rule, pers comm.).

Specimen examined: PHILIPPINES, Southwestern Mindanao , Zamboanga City, Pasonanca Natural Park, elev. 180 m, 13 April 2023, MAK Naive 138 ( HNUL); Zamboanga City Water District Watershed , elev. 140–220 m, 15 December 2007, R. Rubite 479 ( HAST 121006 -image seen, HAST 121005 -image seen, HAST 120558 -image seen); District of Zamboanga (now Zamboanga City), Nov.-Dec. 1911, E. D. Merrill 8304 ( B, BM, K); Zamboanga Del Sur, Dimataling, Baluno, 650 m, 14 March 1992, Reynoso et al. PPI4288 ( PNH); Zamboanga Del Sur, Dimataling , Baluno , 650 m, 14 March 1992, Reynoso et al. PPI4292 ( PNH) .

Taxonomic notes: Begonia anisoptera was originally described by Elmer D. Merrill in 1912 based on specimens from Zamboanga collected by himself (E. D. Merrill 5482) and from Port Banga of Zamboanga by Hutchinson (W.I. Hutchinson FB12342 ). Herein, we choose the most complete sheet of Merrill’s collection [ US 00115242] as the lectotype, which was also fully examined by himself.

The species has a wide range of variability most especially on its leaves. Leaf colour varies from adaxially green to brownish green and from abaxially pale reddish brown to pale green ( Fig. 2 ). Lamina size ranges from 4.0– 14.7 cm long by 2.4–8.0 cm wide and leaf margin ranges from entire to repand ( Fig. 1D and Fig. 2 ). According to Hughes et al. (2015), B. anisoptera is closely related to the Palawan endemic species with B. blancii M.Hughes & C.I Peng as its sister species. The relatedness of the species somehow agrees to the hypothesis that Zamboanga Peninsula was once a part of the Palawan microcontinental block, thus representing the southernmost continental margin of China ( Yumul et al. 2004). Based on our current investigation, we found B. anisoptera morphologically similar to the Palawan endemic species B. acclivis Coyle (2010: 125) which was not included in the phylogenetic tree of Begonia sect. Baryandra by Hughes et al. (2015). However, B. anisoptera differs in having deltate to broadly deltate stipules (vs. lanceolate to broadly lanceolate in B. acclivis ), triangular, 1.5–2.5 mm long bracts (vs. obovate, 4 mm long bracts in B. acclivis ), and 5–6 mm long pedicel in male flowers (vs. up to 10 mm long pedicel in male flowers in B. acclivis ).

Figures

FIGURE 1. Begonia anisoptera A. Habitat and habit B. Stipule C. Detail of petiole D. Leaf (left, adaxial surface; right, abaxial surface) E. Staminate flower F. Pistillate flower G. Profile view of pistillate flower showing the ovary H. Capsule. Based on MAK Naive 138. Photos by: MAK Naive.

FIGURE 2. Two colour variations of the leaves observed at Dos Rio BMS, Pasonanca Natural Park, Zamboanga City A. Left, abaxially pale green; right adaxially green B. Left, adaxially reddish brown; right, abaxially brownish green. Photos by: MAK Naive.

MAP 1. Map showing the distribution of Begonia anisoptera with its type locality as indicated by the red circle. Prepared by: MAK Naive.