118 urn:lsid:arphahub.com:pub:71cc5dc6-a767-5334-951f-ef6ae8936459 Plant Ecology and Evolution plecevo 2032-3913 2032-3921 Meise Botanic Garden and Royal Botanical Society of Belgium 10.5091/plecevo.196693 196693 Research Article Angiospermae Begoniaceae DNA barcoding Endemism Molecular systematics Phylogeny Species Inventories Systematics Taxonomy Asia Philippines Three new cryptic species of Begonia section Baryandra (Begoniaceae) from the Philippine archipelago supported by morphological and molecular evidence Naive Mark Arcebal K. mark@xtbg.ac.cn https://orcid.org/0000-0002-1548-9465 1 2 Conceptualization Writing - original draft Data curation Formal analysis Funding acquisition Investigation Validation Visualization Ancheta Donnafe J. 3 Writing - review and editing Data curation Investigation Cababan McArthur https://orcid.org/0000-0003-3786-9175 4 Writing - review and editing Data curation Investigation Mondejar Eddie P. 3 Writing - review and editing Data curation Investigation Buenvenida Harold O. 5 6 Writing - review and editing Data curation Investigation Hughes Mark https://orcid.org/0000-0002-2168-0514 7 Writing - review and editing Data curation Investigation Supervision Yu Wen Bin https://orcid.org/0000-0002-7643-2112 1 8 9 10 Writing - review and editing Data curation Formal analysis Funding acquisition Investigation Supervision Center for Integrative Conservation and Yunnan Key Laboratory for Conservation of Tropical Rainforests & Asian Elephants, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China Department of Biological Sciences, College of Science and Mathematics, Mindanao State University–Iligan Institute of Technology Iligan City Philippines https://ror.org/026441d17 University of Chinese Academy of Sciences, Beijing, China Center for Integrative Conservation and Yunnan Key Laboratory for Conservation of Tropical Rainforests & Asian Elephants, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China https://ror.org/02rz58g17 Department of Biological Sciences, College of Science and Mathematics, Mindanao State University–Iligan Institute of Technology, Iligan City, Philippines Yunnan International Joint Laboratory for the Conservation and Utilization of Tropical Timber Tree Species, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China https://ror.org/02rz58g17 Valencia National High School, Valencia City, Philippines Royal Botanic Gardens Edinburgh Edinburgh United Kingdom https://ror.org/0349vqz63 Capiz State University, Pontevedra Campus, Pontevedra, Philippines Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences Mengla China https://ror.org/034t30j35 Institute of Biology, University of the Philippines Diliman, Quezon City, Philippines Institute of Biology, University of the Philippines Diliman Quezon City Philippines https://ror.org/03tbh6y23 Royal Botanic Gardens Edinburgh, Edinburgh, UK University of Chinese Academy of Sciences Beijing China https://ror.org/05qbk4x57 Yunnan International Joint Laboratory for the Conservation and Utilization of Tropical Timber Tree Species, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China Capiz State University, Pontevedra Campus Pontevedra Philippines https://ror.org/05vm26792 Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Mengla, China Valencia National High School Valencia City Philippines Hainan Institute of National Park & Key Laboratory for National Park Protection and Development of Hainan Province, Haikou, China Hainan Institute of National Park & Key Laboratory for National Park Protection and Development of Hainan Province Haikou China

Corresponding authors: Mark Arcebal K. Naive (mark@xtbg.ac.cn) and Wen Bin Yu (yuwenbin@xtbg.ac.cn)

Academic editor: Brecht Verstraete

 2026 01 09 2026 159 3 520 535 42BCD5CD-6B9C-53E3-B4C2-FBD1F469A611 22 04 2026 02 07 2026 Mark Arcebal K. Naive, Donnafe J. Ancheta, McArthur Cababan, Eddie P. Mondejar, Harold O. Buenvenida, Mark Hughes, Wen Bin Yu This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Background and aims – The Philippine archipelago harbours the world’s greatest diversity of flowering plants, yet it is identified as a global plant diversity darkspot where much of this diversity remains poorly documented and inadequately sampled. To address this knowledge gap, extensive botanical explorations have been conducted, leading to the discovery of three new Begonia species from Panay and Mindanao Islands, which are described and illustrated herein.

Material and methods – All morphological descriptions and measurements are based on recently collected living and herbarium specimens. The new species are included in a phylogenetic analysis based on noncoding plastid regions (ndhA intron, ndhF-rpl32 spacer, and rpl32-trnL spacer) and the nuclear internal transcribed spacer (nrITS) region from the assembled plastome and nuclear ribosomal DNA sequences.

Key results – The newly described species from Mindanao (Begonia absiana sp. nov. and B. amorosoana sp. nov.) exhibit close morphological similarities to B. acuminatissima, while the novel species from Panay (B. panayica sp. nov.) shows affinity to B. biliranensis. The phylogenetic analyses confirmed the monophyly of B. sect. Baryandra but revealed significant cytonuclear discordance and unresolved relationships within the group. All three new species were placed in a well-supported clade, but their precise relationships remain uncertain, possibly reflecting rapid diversification.

Conclusion – These findings underscore an urgent need to intensify botanical exploration and conservation efforts in the Philippines to protect these unique evolutionary lineages before their habitats are lost.

 Mindanao narrow-endemic Panay Southeast Asia threatened Introduction

Begonia L. belongs to the family Begoniaceae, alongside the monospecific genus Hillebrandia Oliver, and is ranked as the sixth largest genus in angiosperms, comprising over 2,200 species classified into 70 sections (Hughes et al. 2015a; Moonlight et al. 2018, 2024). These predominantly herbs, with a few soft-wooded shrubs exhibit a tropical and subtropical distribution, often occupying narrow ecological niches with highly specialized environmental preferences, such as exposed limestone outcrops (Doorenbos et al. 1998; Kidner et al. 2016; Radbouchoom et al. 2024; Thomas et al. 2024). In the Philippines, Begonia is represented by roughly 184 native species, classified into three sections, B. sect. Baryandra A.DC., B. sect. Petermannia (Klotzsch) A.DC., and B. sect. Platycentrum (Klotzsch) A.DC., of which 97% are endemic to the archipelago (Pelser et al. 2011; Ang et al. 2024). As circumscribed by Rubite et al. (2013), B. sect. Baryandra is a monophyletic group comprising ± 100 species characterized by having an ovary (and capsule) with two placentae per locule and boat-shaped, entire, sheathing bracts. It exhibits a Malesian distribution, with its centre of diversity in the Philippines, harbouring ± 90 species all of which are endemic (Pelser et al. 2011; Hughes et al. 2015a). The majority of the species is found in mid-elevation montane forests, whereas some occur at lower elevations near sea level, typically on karst limestone substrates (Ang et al. 2024). Particularly noteworthy are two species from Palawan (B. elnidoensis C.I.Peng, Rubite & C.W.Lin and B. wadei Merr. & Quisumb.) and one from eastern Mindanao (B. amparoae F.A.Blasco, Alejandro, Tandang & Rubite), all of which are restricted to exposed limestone sea cliffs. Beyond their ecological significance, Begonia species are also highly valued as ornamental plants, rendering them vulnerable to habitat loss as well as pressures from both legal and illegal horticultural trade (Tian et al. 2018).

Botanical expeditions to Panay and Mindanao Islands (2021–2024) resulted in the collection of three unknown Begonia sect. Baryandra species as part of the first author’s ongoing revisionary work on the genus Begonia in the Philippine archipelago. Two species from Mindanao had been frequently misidentified as B. acuminatissima Merr., while the Panay species was misidentified as B. biliranensis Merr. Comprehensive morphological investigations, supported by a literature review and examination of herbarium specimens of all known congeners in the section, confirmed that all three are distinct species new to science. Phylogenetic analyses based on nuclear ribosomal internal transcribed spacer (nrITS) and concatenated non-coding plastid regions further support their distinct taxonomic status and placement within B. sect. Baryandra. Here, we provide descriptions for the three new species, compare them with morphologically and phylogenetically closest taxa, and present information on their geographic distribution, conservation status, as well as photographic images and illustrations to aid species identification.

 Material and methods Taxon sampling and morphological description

Botanical expeditions were carried out on Capiz of Panay Island, and Iligan City and Bukidnon of Mindanao Island. All plant measurements and descriptions are based on recently collected specimens and living plants in the field, unless specified otherwise. Photographs were taken using a Canon EOS 800D camera, and coloured plates were prepared and edited using Affinity Photo software. Flowers were preserved in 70% ethyl alcohol and examined under a stereomicroscope. The descriptions follow Naive et al. (2025, 2026), with botanical terminology generally adhering to Beentje (2016). Type specimens and literature on Begonia species from the Philippines and neighbouring countries were reviewed using high-resolution images from Global Plants on JSTOR (https://plants.jstor.org), Begonia Resource Centre (Hughes et al. 2015a), and Global Biodiversity Information Facility (GBIF) (https://www.gbif.org).

 Conservation status assessment and distribution

The extent of occurrence (EOO) and area of occupancy (AOO) for each species were calculated using GeoCAT based on a 2-km cell width (Bachman et al. 2011) and each of their conservation statuses were assessed according to IUCN (2024) guidelines, using their terminology for categories, criteria, and subcriteria. The distribution map was produced using QGIS v.3.40 (QGIS Development Team 2024).

 DNA extraction and Illumina sequencing

To verify the phylogenetic placement of the three new species, total genomic DNA was extracted from silica gel-dried leaf tissues using a modified cetyltrimethylammonium bromide (CTAB) method (Doyle and Doyle 1987). The purified DNA was fragmented to approximately 350–500 bp in size for library construction following the manufacturer’s standard protocols (NEBNext Ultra II™DNA Library Prep Kit for Illumina). The 150 bp pair-end reads were generated using the Illumina NovaSeq 6000 platform (San Diego, CA, United States).

 Phylogenetic analyses

The GetOrganelle toolkit (Jin et al. 2020) was used for assembling circular plastomes and nuclear ribosomal DNA (nrDNA) sequences. The assembled plastome and nrDNA sequences were annotated in Geneious Prime v.2022.2.2 (Kearse et al. 2012) and non-coding plastid DNA regions (viz. ndhA intron, ndhF-rpl32 spacer, and rpl32-trnL spacer) used by Moonlight et al. (2018) and nrITS (including ITS1 and ITS2, along with 5.8S rRNA) were subsampled. Including sequences retrieved from the National Centre for Biotechnology Information (NCBI) database, our dataset consists of 52 accessions representing 50 species for nrITS, and 53 accessions representing 51 species for non-coding plastid regions, and the species B. kingiana Irmsch. from B. sect. Ridleyella Irmsch. was chosen as the outgroup (Suppl. material 1). Twelve samples representing 11 species were newly sequenced in this study. Sequences of each region were aligned in MAFFT v.7.526 (Katoh and Standley 2013) using default parameters, then three plastid matrices were concatenated into a plastid supermatrix. Nuclear and plastid datasets were analysed separately with no combined analyses performed. The models for ML analyses (TNe+G4 for nrITS and K3Pu+F+R2 for the plastid supermatrix) were selected by IQ-TREE 2 (Minh et al. 2020) based on the ModelFinder algorithm, which incorporates a broader range of models including those with FreeRate heterogeneity that are not available in MrBayes. The models for BI analyses (GTR+G4 for nrITS and GTR+I+G4 for the plastid supermatrix) were determined by ModelTest-NG (Darriba et al. 2020) and represent the best-fitting models available within the GTR family implemented in MrBayes v.3.2.7 (Ronquist et al. 2012). Each analysis ran for 20 million generations, with sampling every 5000 generations and a burn-in of 25%, and the remaining trees were used to construct a majority rule consensus tree with posterior probability values (PP). BS values ≥ 70 in ML analyses and PP values ≥ 0.95 in BI analyses were considered as strong support in this study. All trees were visualized using FigTree v.1.4.4.

 Results and discussion

In this study, three new endemic species of Begonia sect. Baryandra from the Philippines are described and named as B. absiana, B. amorosoana, and B. panayica. Two of these new species were discovered in Mindanao, which, despite being the second largest island in the Philippine archipelago, had only 14 known species of B. sect. Baryandra compared with Luzon’s 38 (Hughes et al. 2015a). However, as a result of recent extensive field explorations, this number is steadily increasing with continued discovery of new species, including B. amparoae (Blasco et al. 2022), B. dorisiae Bucay, Tandang & K.F.Chung (Bucay et al. 2025), B. fritschiana Amoroso & Rubite (Amoroso et al. 2023), B. makuruyot M.G.Rule, Y.P.Ang, Rubite, Docot, R.Bustam. & A.S.Rob. (Rule et al. 2020), B. medinae Bucay, Tandang & K.F.Chung (Bucay et al. 2025), and B. sebodensis Mazo & Rubite (Mazo et al. 2023). The species discovered in Panay represents the 12th member of B. sect. Baryandra recorded from this island.

The discovery of these three new species underscores that the Philippines, a known megadiverse country, still contains major plant diversity darkspots, as identified by Ondo et al. (2024): areas of high predicted diversity that remain profoundly underexplored and under-documented. Our findings illuminate a small part of this darkspot, revealing that the true scale of Philippine plant diversity and endemism is likely vastly underestimated. This ongoing discovery process highlights an urgent paradox: we are describing unique evolutionary lineages at the very moment their habitats are vanishing. Consequently, there is a critical need to intensify botanical exploration in these darkspots and directly link discovery to conservation action, specifically by preserving remaining old-growth forest cover and strengthening the management of protected areas.

Phylogenetic relationships in <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Begonia">Begonia</tp:taxon-name-part></tp:taxon-name></italic> sect. <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Begonia"/><tp:taxon-name-part taxon-name-part-type="section" reg="Baryandra">Baryandra</tp:taxon-name-part></tp:taxon-name></italic> and placement of the new species

The aligned nrITS dataset is 884 bp in length with 287 parsimony informative sites, and the concatenated plastid dataset contains a total of 3,940 bp with 243 parsimony informative sites. Begonia sect. Baryandra was recovered as monophyletic (PP = 1.00, BS = 100), however, both ML and BI analyses recovered incongruent phylogenetic topologies between nrITS and plastid supermatrix datasets (Fig. 1; Suppl. material 2). Strong topological incongruences were detected between the two datasets, consistent with previous studies (e.g. Hughes et al. 2015b, 2018).

10.5091/plecevo.196693.figure1 6CEED2C2-5793-500D-A59F-49C6532931DA

Ultrametric ML trees of Begonia section Baryandra inferred from concatenated noncoding plastid regions (left) and nrITS (right). Bootstrap values and Bayesian posterior probabilities are shown above or below the branches. The corresponding ML phylograms are shown in the insets, while branch colours represent the geographic origin of each species (yellow: Borneo; brown: Biliran; orange: Luzon; pink: Mindanao; blue: Palawan; green: Panay; purple: Sibuyan). Clade labels (A–D) correspond to the four major clades recovered by Hughes et al. (2015b). Asterisk indicates the incongruent clades between ML and BI.

https://binary.pensoft.net/fig/1756096

The plastid phylogeny recovered four well-supported clades (A–D; Fig. 1), showing stronger backbone support values compared with the results of Hughes et al. (2015b). In the present study, Clade C was identified as the earliest-diverging lineage, sister to the remaining three clades, with strong support (PP = 1.00, BS = 100). Clade B was resolved as sister to Clades A and D, also with strong support (PP = 0.98, BS = 98). The sister relationship between Clades A and D was strongly supported by the ML analysis (BS = 90) but received only moderate support in the BI analysis (PP = 0.92). This topology differs from that reported by Hughes et al. (2015b), in which Clade A was recovered as the earliest-diverging lineage and Clades C and D were sister groups. Such discrepancies are likely attributable to differences in taxon sampling and the DNA regions analysed. Topological incongruence was also observed between the nrITS and plastid phylogenies. The nrITS phylogeny showed a poorly resolved backbone (PP < 0.95; BS < 70), and Clades A, C, and D were not recovered as monophyletic. This cytonuclear incongruence mirrors earlier reports (Hughes et al. 2015b, 2018), therefore, the nrITS dataset was deemed unsuitable for combination with the plastid supermatrix.

The three new species were unequivocally placed into Clade D in both datasets (BS = 100, PP = 1.00). However, phylogenetic resolution within Clade D was weak, and the placements of the three new species were inconsistent between the two datasets. For instance, the plastid data weakly supported Begonia amorosoana as sister to B. merrilliana (PP = 0.93, BS = 63), whereas the nrITS phylogeny showed that B. amorosoana is sister to B. camiguinensis, although with no support (BS = 53). Morphologically, B. amorosoana is easily distinguished from B. merrilliana by its glabrous rhizome, petiole, and peduncle (vs densely appressed pink villous), irregularly orbicular to orbicular-ovate lamina with a repand-serrate margin (vs obliquely ovate with an angular-undulate margin); and capsules with unequal wings (vs subequal wings), and from B. camiguinensis in its stipule morphology (abruptly caudate vs gradually falcate apex), overlapping leaf basal lobes (vs non-overlapping), pistillate flowers with elongate ovate outer tepals (vs pistillate flowers with obovate outer tepals) and apically bluntly pointed and lemon green suffused with red (vs apically truncate capsule and pale pink to pinkish white). The phylogenetic positions of the other two new species, B. absiana and B. panayica, also showed inconsistency between plastid and nrITS phylogenies. The plastid phylogeny placed B. panayica as an early-diverging lineage within the B. biliranensis–B. rubiteae clade and B. absiana as sister to the B. sordidissima–B. rubiteae clade with no statistical support (BS < 70; PP < 0.95). Conversely, the nrITS phylogeny recovered B. panayica as sister to B. absiana–B. sykakiengii clade, although this relationship also lacked statistical support (BS < 70; PP < 0.95). Despite these topological differences, all three new species consistently formed a strongly supported lineage within Clade D. Their unresolved internal relationships may reflect rapid diversification, although incomplete taxon sampling, introgression, or incomplete lineage sorting cannot be excluded as alternative explanations (Hughes et al. 2018; Moonlight et al. 2018).

 Taxonomic treatment Plantae Cucurbitales Begoniaceae 970ADCB2-C0D2-5316-94BE-CD737E601D3D Begonia absiana urn:lsid:ipni.org:names:77395706-1 Naive sp. nov. Figs 1 , 2 , 3 , 4 Type

PHILIPPINES – Mindanao Island • Iligan City, Sikyop; 8°14’52”N, 124°25’25”E; 350 m; 16 Jan. 2026; E.P. Mondejar & D.J. Ancheta 206; holotype: PNH; isotypes: CLP, HNUL, HITBC.

10.5091/plecevo.196693.figure2 963C8405-9EB6-5A64-AAFB-89BCF72D17DD

Begonia absiana. A. Habit. B. Detail of abaxial leaf surface. C. Detail of node showing stipule and petiole attachment. D. Stipule. E. Cincinnus with immature flower. F. Staminate flower. G. Stamen. H. Pistillate flower. I. Pistil. J. Fruit. K. Cross-section of capsule. Illustrated from E.P. Mondejar & D.J. Ancheta 206 by Yuanito Eliazar.

https://binary.pensoft.net/fig/1756097 10.5091/plecevo.196693.figure3 4B357163-2911-5F55-8F6A-46B0D69FAF5B

Begonia absiana. A. Habitat. B. Plant habit. C. Rhizome. D. Stipule. E. Abaxial leaf. F. Inflorescence showing staminate flowers. G. Pistillate flower. H. Detail of ovary. I. Capsule. J. Dissected capsule. Photographs by Mark Arcebal K. Naive.

https://binary.pensoft.net/fig/1756098 10.5091/plecevo.196693.figure4 6601ADA4-7CE8-506C-A2FE-ED2263DD916F

Map showing the distribution of the three new species.

https://binary.pensoft.net/fig/1756099 Diagnosis

Morphologically similar to Begonia sordidissima Elmer but differs significantly in having sericeous rhizome (vs glabrous to sparsely hirsute rhizome), caducous, lanceolate stipule with caudate apex (vs persistent and broadly ovate stipule with aristate apex), sericeous petiole (vs hirsute to densely hirsute petiole), irregularly orbicular to orbicular-ovate leaf lamina with non-overlapping base lobes and 8 major lateral veins (vs elongate orbicular-ovate to broadly ovate with overlapping base lobes and 5–7 major lateral veins), inflorescence with glabrous peduncle and rachis (vs inflorescence with sparsely hirsute peduncle and glabrous to minutely glandular rachis), staminate and pistillate flowers with dorsoventrally glabrous tepals (vs staminate and pistillate flowers with dorsally glabrous to glandular outer tepals) and capsule wings with obtuse (dorsal wing) to rounded apex (lateral wings) (vs capsule wings with rounded apex).

 Description

Monoecious, rhizomatous, succulent, perennial herb, up to 30 cm tall. Rhizome creeping, terete, 6.0–7.5 mm in diameter, sericeous, succulent, brownish to reddish green, with prominent petiolar scars, internode up to 1.5 cm long. Leaves 11–32 cm long, alternate, porrect; stipule caducous, lanceolate, 1.3–1.5 × 0.8–1.0 cm, prominently keeled throughout its length, pale reddish green, membranous, concave, glabrous, margin entire, slightly involute, apex caudate, cucullate, gradually tapering; petiole terete, 18.5–29.0 cm long, 2–8 mm in diameter, sericeous, reddish green; lamina asymmetric, irregularly orbicular to orbicular-ovate, 8.5–16.5 × 5.5–12.7 cm, subsucculent, dorsoventrally glabrous except the abaxial veins and margin, adaxially green to dull green, abaxially pale brownish green, margin irregularly and distantly repand-serrate, inconspicuously ciliate, base cordate, non-overlapping, apex acuminate; venation palmate, actinodromous, with 8 major lateral veins, branching dichotomously, adaxially green, glabrous, channelled, abaxially pale green, puberulous, protruding. Inflorescence erect, bisexual, axillary, protogynous, compound cymose, dichasial, longer than leaves, up to 30.8 cm long bearing many flowers; peduncle terete, 18–20 cm long, 3.5–5.0 mm in diameter, succulent, glabrous, reddish green; rachis terete, up to 12 cm long, 1.5–2.0 mm in diameter, glabrous, green to pale reddish green; floral bracts caducous, ovate, 5–9 × 3–5 mm, slightly concave, glabrous ventrally, glabrous to inconspicuously, sparsely punctate dorsally, reddish green, membranous, margin entire, apex acute. Staminate flower up to 1.3 cm long, 2 per cincinnus, 1 opening at anthesis, pedicellate; pedicel terete, 8–10 mm long, 0.5–0.8 mm in diameter, succulent, glabrous, pale red to reddish green; tepals 4, outer 2, broadly ovate, 8.5–9.5 × 7.0–7.5 mm, subsucculent, slightly convex, dorsoventrally glabrous, pale pink to whitish pink, margin entire, base subcordate, apex broadly obtuse, inner 2, narrowly obovate, slightly conduplicate, 7.0–7.5 × 3.5–4.0 mm, chartaceous, spreading, canaliculate, dorsoventrally glabrous, pale pink, margin entire, apex retuse; stamen ±40, 2.5–2.8 mm across, lemon yellow; filament 0.8–1.3 mm long; anther obovoid, 0.7–1.2 mm long. Pistillate flower up to 2.5 cm long, 1 per cincinnus; pedicel terete, 1.0–1.05 cm long, 0.8–1.0 mm in diameter, subsucculent, glabrous, pale green to pale reddish green; ovary trigonous-ellipsoid, 8.0–9.0 × 9.0–9.5 mm (wings included), 3.5–4.0 mm wide (wings excluded), glabrous, pale green to pale reddish green, apex truncate to slightly pointed, wings 3, equal, apex rounded, locules 3, placentae bilaminate; tepals 4, outer 2, obovate-orbicular, 10–11 × 8–9 mm, subsucculent, slightly concave, ventrally glabrous, pale pink, dorsally sparsely punctate, pink, margin entire, base subcordate, apex rounded, inner tepals 2, narrowly obovate, 7–8 × 3–4 mm, chartaceous, spreading, dorsoventrally glabrous, pale pink, margin entire, apex rounded; style 3, 3–4 mm long, shortly fused at base, bifid, apically forked; stigma spirally twisted, papillose all around. Fruit numerous, 1 per cincinnus, strongly recurved; pedicel terete, 1.3–1.5 cm long, 0.8–1.0 mm in diameter, succulent, strongly recurved apically, glabrous, pale green to pale reddish green; capsule trigonous-ellipsoid, 10–10.5 × 15–17 mm (wings included), 6–7 mm wide (wings excluded), glabrous to sparsely tomentose, lemon green suffused with pale red, apex blunt, shortly pointed, wings 3, unequal, apex obtuse (dorsal wing) to rounded (lateral wings).

 Distribution and habitat

This species is endemic to Mindanao Island, Philippines. It has so far only been found in its type locality (Fig. 4), where it grows in deeply shaded karst forest and moist limestone rocks near rivers and caves at elevations of up to 600 m a.s.l.

 Phenology

The species is observed to be flowering and fruiting from May to August, but it is assumed to flower and fruit all throughout the year.

 Etymology

The species is named in honour of the American Begonia Society (ABS), in recognition of their generous financial support for the first author’s fieldwork during this study’s conduct, as well as their enduring commitment to advancing Begonia research and conservation worldwide.

 Preliminary IUCN conservation assessment

This species is currently known only from its type locality, where fewer than 50 mature individuals were observed. The area is a tourist destination, and the population is threatened by ongoing anthropogenic activities. Following the guidelines of the IUCN Standards and Petitions Committee (2024), we propose that this species be classified as Critically Endangered: CR D.

 Morphological affinities

Aside from its morphological similarities with Begonia sordidissima, this species was previously misidentified as B. acuminatissima. However, it can easily be distinguished in having the following characters: sericeous rhizome (vs glabrous or nearly so rhizome), lanceolate stipules with caudate apex (vs oblong-ovate stipules with acuminate apex), sericeous petiole (vs with scattered brown hairs to ultimately glabrous), irregularly orbicular to orbicular-ovate leaf lamina (vs obliquely oblong-ovate to narrowly ovate leaf lamina), capsule with unequal wings (vs capsule with subequal wings), and dorsal and lateral wings with obtuse to rounded apex (vs dorsal and lateral wings with rounded apex).

 Plantae Cucurbitales Begoniaceae 7D23A6D9-29D2-5A5B-B11A-556782E7FED8 Begonia amorosoana urn:lsid:ipni.org:names:77395707-1 Naive sp. nov. Figs 1 , 4 –6 Type

PHILIPPINES – Mindanao Island • Bukidnon, Impasug-ong, Impalutao, The Center for Ecological Development and Recreation (CEDAR); 8°15’12”N, 125°02’10”E; 750 m; 19 Jun. 2024; MA Cababan & M.A.K. Naive 205; holotype: PNH; isotypes: CLP, HNUL, HITBC.

10.5091/plecevo.196693.figure5 8EB0CF5E-1F67-5739-8E86-A6820D103357

Begonia amorosoana. A. Habit. B. Detail of abaxial leaf surface. C. Detail of node showing stipule and petiole attachment. D. Stipule. E. Cincinnus. F. Floral bract. G. Staminate flower. H. Stamen. I. Pistillate flower. J. Pistil. K. Fruit. L. Cross-section of capsule. Illustrated from M.A. Cababan & M.A.K. Naive 205 by Yuanito Eliazar.

https://binary.pensoft.net/fig/1756100 10.5091/plecevo.196693.figure6 9649A7E6-D049-526C-BE8B-4AE4405FD6D7

Begonia amorosoana. A. Habitat. B. Plant habit. C. Rhizome. D. Stipule. E. Detail of leaf lamina apex and margin. F. Inflorescence showing young staminate flowers. G. Staminate flower. H. Pistillate flower. I. Detail of ovary. J. Inflorescence showing young fruits. K. Detail of capsule. Photographs by Mark Arcebal K. Naive (A, C–G & I–K) & McArthur Cababan (B, H).

https://binary.pensoft.net/fig/1756101 Diagnosis

Closely related to Begonia acuminatissima by having inflorescence as long or equal to the length of the leaves. However, B. amorosoana differs significantly in having broadly ovate stipule with abruptly tapering apex (vs lanceolate stipules with gradually tapering apex), irregularly suborbicular to orbicular-ovate leaf lamina with slightly falcate, acuminate apex and 5–7 major lateral veins (vs obliquely oblong-ovate to narrowly ovate leaf lamina with attenuate apex and 7–8 major lateral veins), staminate flowers with elongate ovate outer tepals with rounded apex and oblanceolate inner tepals with retuse apex (vs staminate flowers with broadly elliptic outer tepals with obtuse apex and narrowly obovate inner tepals with rounded apex), and capsule with unequal wings (vs capsule with subequal wings).

 Description

Monoecious, rhizomatous, epipetric to terrestrial, succulent, perennial herb, up to 45 cm tall. Rhizome creeping, terete, 1.0–1.3 cm in diameter, glabrous, succulent, green to brownish red, with prominent petiolar scars, internode up to 1.1 cm long. Leaves up to 25 cm long, alternate, porrect; stipule caducous, broadly ovate, 11–13 × 7–8 mm, prominently keeled except the basal 1/4, pale reddish green, membranous, concave, glabrous except the villous keel, apex abruptly tapering, caudate; petiole terete, up to 23.5 cm long, 5–8 mm in diameter, sparsely lenticellate, glabrous, succulent, red to greenish red; lamina asymmetric, irregularly suborbicular to orbicular-ovate, 15.0–18.2 × 10.0–11.7 cm, dorsoventrally glabrous except the abaxial veins and margin, adaxially green to dull green, abaxially pale green, margin entire to occasionally distantly serrate, sparsely ciliate, base cordate, overlapping, apex attenuate to acuminate, slightly falcate; venation palmate, actinodromous, 5–7 major lateral veins, citrine, adaxially channelled, glabrous, abaxially protruding, puberulous. Inflorescence erect, bisexual, axillary, protogynous, compound cymose, dichasial, as long as or shorter than the leaves, up to 19.5 cm long; peduncle terete, up to 14.0–15.3 cm long, 4.0–4.5 mm in diameter, succulent, glabrous, pale reddish green; rachis terete, up to 5–7 cm long, 1.0–1.3 mm in diameter, dichotomously branching, glabrous, pale green suffused with red; floral bracts caducous, ovate, 5–10 × 5–10 mm, slightly concave, glabrous ventrally, sparsely glandular dorsally, green, margin entire, apex obtuse. Staminate flower up to 1.2 cm long, 2 per cincinnus, 1 opening at anthesis, pedicellate; pedicel terete, 8–9 mm long, 0.5–1.0 mm in diameter, succulent, glabrous, pinkish red to pale red; tepals 4, outer 2, elongate ovate, 1.1–1.3 × 0.9–1.0 cm, subsucculent, slightly convex, dorsoventrally glabrous, pale pink to whitish pink, margin entire, base subcordate, apex rounded, inner 2, oblanceolate, flat, 8.0–9.5 × 5.0–6.5 mm, chartaceous, spreading, canaliculate, dorsoventrally glabrous, pale pink, margin entire, apex retuse; stamen ±35, 3–4 mm across, lemon yellow; filament 1.0–1.5 mm long; anther obovoid, 1.0–1.5 mm long. Pistillate flower up to 3 cm long, 1 per cincinnus; pedicel cylindrical, inconspicuously corrugated, 4–5 mm long, 1.0–1.5 mm in diameter, succulent, glabrous, reddish green; ovary trigonous-ellipsoid, 9–11 × 9–10 mm (wings included), 4–5 mm wide (wings excluded), glabrous, reddish green, apex bluntly pointed to truncate, wings 3, unequal, apex obtuse (median wing) to rounded (lateral wings), locules 3, placentae bilaminate; tepals 4, outer 2, broadly ovate, 10–11 × 9–10 mm, slightly succulent, glabrous both sides, margin entire, apex rounded, inner 2, oblanceolate, 5.0–6.5 × 2–3 mm, chartaceous, glabrous both sides, margin entire, apex rounded; style 3, 3–4 mm long, shortly fused at base, bifid, apically forked; stigma spirally twisted, papillose all around. Fruit 1.8–2.0 cm long, solitary in cincinnus, strongly recurved; pedicel cylindrical, terete, 1.0–1.2 cm long, 1.0–1.3 mm in diameter, strongly recurved, glabrous, yellowish green suffused with red; capsule trigonous-ellipsoid, 1.0–1.1 × 1.3–1.5 cm (wings included), 5.5–7.0 mm wide (wings excluded), lemon green suffused with red, apex bluntly pointed, wings 3, unequal, apex obtuse (dorsal wing) to rounded (lateral wings).

 Distribution and habitat

This species is endemic to Mindanao Island, Philippines. It has so far only been found in its type locality (Fig. 4), where it grows in shaded forest and moist rocky cliffs near rivers and waterfalls (Natigbasan and Gantungan Falls) at 700–760 m a.s.l.

 Phenology

The species was observed to be flowering and fruiting from April to December, but it is assumed to flower and fruit all throughout the year.

 Etymology

The species is named in honour of Dr Victor B. Amoroso, Professor Emeritus of Central Mindanao University and a Filipino Academician, in recognition of his lifelong commitment to the documentation and conservation of Philippine biodiversity. This tribute specifically acknowledges his pioneering botanical explorations and foundational taxonomic work in Mindanao—a region of exceptional endemism where his fieldwork has been instrumental in documenting its unique flora and where this new species was discovered.

 Preliminary IUCN conservation assessment

Begonia amorosoana is proposed to be classified as Critically Endangered: CR D, following IUCN Standards and Petitions Committee (2024). It is currently known only from the type locality, where the population size is estimated to be fewer than 50 mature individuals. The population is inferred to be declining due to ongoing anthropogenic pressures from tourism, which threaten its habitat.

 Morphological affinities

This species was historically misidentified as Begonia acuminatissima, much like B. absiana, without subsequent taxonomic verification. Aside from B. acuminatissima, this species closely resembles B. absiana. However, B. amorosoana can be readily recognized by having broadly ovate stipules, prominently keeled except the basal 1/4 with abruptly tapering apex (vs lanceolate stipules, prominently keeled throughout their length with gradually tapering apex), glabrous, sparsely lenticellate petiole (vs sericeous, non-lenticellate petiole), inflorescence shorter than or equal to the leaves (vs inflorescence longer than leaves), ovary wings unequal with obtuse (median wing) to rounded (lateral wings) apex (vs ovary wings equal with rounded apex). Ecologically, the two species occupy distinct niches: B. absiana is strictly karst-dependent, while B. amorosoana inhabits rock walls or terrestrial environments.

 Plantae Cucurbitales Begoniaceae D343CF17-9744-5B2C-B9D9-DD31D61EA758 Begonia panayica urn:lsid:ipni.org:names:77395708-1 Naive sp. nov. Figs 1 , 4 , 7 –8 Type

PHILIPPINES – Panay Island • Capiz, Yating; 11°23’35”N, 123°00’17”E; 390 m; Aug. 2021; HO Buenvenida 2021-032; holotype: PNH; isotypes: Capiz Ecology and Conservation Centre, CAHUP, SING.

10.5091/plecevo.196693.figure7 5AA212DF-8251-55D2-8D6C-F40770AE602C

Begonia panayica. A. Habit. B. Detail of abaxial leaf surface. C. Detail of node showing stipule and petiole attachment. D. Stipule. E. Cincinnus with a staminate flower. F. Floral bract. G. Stamen. H. Pistillate flower. I. Pistil. J. Fruit. K. Cross-section of capsule. Illustrated from H.O. Buenvenida 2021-032 by Yuanito Eliazar.

https://binary.pensoft.net/fig/1756102 10.5091/plecevo.196693.figure8 2A7D68F0-AC66-532D-9A3F-0081D0CCA843

Begonia panayica. A. Climbing habit. B. Detail of rhizome and stipule. C. Adaxial leaf (top) and abaxial leaf (bottom). D. Inflorescence. E. Staminate flower (front view). F. Staminate flower (back view). G. Detail of ovary. H. Pistillate flower. I. Detail of style and stigma. J. Detail of capsule. Photographs by Mark Arcebal K. Naive.

https://binary.pensoft.net/fig/1756103 Diagnosis

Morphologically similar to B. biliranensis Merr., however, this new species can be easily recognized by having deltate stipule (vs ovate stipule), glabrous and lenticellate petiole (vs prominently brown-setose petiole), leaf lamina with entire to repand-serrate margin and 8–9 major lateral veins (vs leaf lamina with undulate or somewhat undulate-lobed and about 10 major lateral veins), inflorescence longer than leaves with glabrous peduncle and lax flowers (vs inflorescence as long as leaves with tomentose peduncle and crowded flowers), staminate and pistillate flowers with oblanceolate inner tepals (vs oblong-ovate inner tepals), and capsules with unequal wings (vs capsules with subequal wings).

 Description

Monoecious, creeping to climbing on the lower trunk of trees, epipetric to terrestrial, succulent, herbaceous plant, up to 65 cm tall. Rhizome creeping, terete, lenticellate, glabrous to occasionally sparsely sericeous, green to reddish green, up to 1.5 cm in diameter, internode up to 1–6 cm long. Leaves up to 38 cm long, alternate, porrect; stipule caducous, deltate to broadly ovate, 10–17 × 6.0–8.5 mm, slightly concave, succulent, keeled, red to pinkish red, glabrous except the pilose keel, margin entire, revolute, apex cuspidate, recurved; petiole cylindrical, terete, up to 26 cm long, 1.0–1.2 cm in diameter, succulent, lenticellate, sparsely strigose, green to reddish green; lamina asymmetric, ovately orbicular, up to 25.5 × up to 18.2 cm, subsucculent, glabrous both sides except the abaxial veins and ciliate margin, adaxially green, abaxially pale green to pale green suffuse with magenta near veins, margin entire to repand-serrate, base cordate, lobes overlapping, apex acuminate, slightly falcate; venation palmate, actinodromous, with 8–9 major lateral veins, branching dichotomously, adaxially green, glabrous, channelled, abaxially whitish green to magenta-green, sparsely strigose. Inflorescence bisexual, axillary, protogynous, compound cymose, dichasial, longer than leaves, up to 64 cm long, bearing over 10 flowers; peduncle terete, up to 49 cm long, 5.5–8.5 mm in diameter, glabrous, pale green to maroon; rachis terete, up to 5–9 cm long, 1.0–1.5 mm in diameter, dichotomously branching, glabrous, pale green to maroon; floral bracts caducous, broadly ovate, 5.0–5.5 × 4.0–4.5 mm, translucent, glabrous ventrally, sparsely glandular dorsally, reddish green, margin entire, apex obtuse to rounded. Staminate flower up to 1.7 cm long, 2 per cincinnus, 1 opening at anthesis, white to pale pink; pedicel cylindrical, terete, 1.1–1.3 cm long, 0.8–1.0 mm in diameter, succulent, glabrous, pale green to whitish green; tepals 4, outer 2, broadly ovate, 1.1–1.3 × 1.1–1.2 cm, succulent, glabrous both side, margin entire, apex rounded, inner 2, oblanceolate, 9–11 × 5.0–5.5 mm, chartaceous, glabrous both sides, margin entire, apex rounded; stamen over 45, 4.5 mm across, golden yellow; filament 2 mm long; anther obovoid, 1.0–1.8 mm long. Pistillate flower up to 2.8 cm long, arising below the staminate flowers, 1 per cincinnus, white to pale pink; pedicel cylindrical, terete, up to 1.4 cm long, 0.8–1.0 mm in diameter, succulent, glabrous, green to reddish green; ovary trigonous-ellipsoid, 8–9 × 11–13 mm (wings included), 4.0–5.5 mm wide (wings excluded), glabrous, green, apex bluntly pointed to truncate, wings 3, unequal, apex obtuse to rounded, locules 3, placentae bilaminate; tepals 4, outer 2, broadly ovate, 1.0–1.2 × 1.0–1.15 cm, succulent, glabrous both sides, margin entire, apex rounded, inner 2, oblanceolate, 8.5–9.0 × 5.5–6.0 mm, chartaceous, glabrous both sides, margin entire, apex rounded; style 3, 4–4.5 mm long, shortly fused at base, bifid, apically forked; stigma spirally twisted, papillose all around. Fruit numerous, 1 per cincinnus, strongly recurved; pedicel cylindrical, terete, up to 1.7 cm long, 0.8–1.0 mm in diameter, glabrous, green to reddish green; capsule trigonous-ellipsoid, 1.1–1.2 × 1.2–1.8 cm (wings included), 5.0–7.5 mm wide (wings excluded), green to reddish green, apex truncate to bluntly pointed, wings 3, unequal, apex rounded.

 Distribution and habitat

This species is endemic to Panay Island, Philippines. It has so far been recorded in the provinces of Aklan, Antique, and Capiz (Fig. 4), where it grows on dry stream banks as an epipetric plant, and occasionally as a climber on lower tree trunks in deeply shaded forest slopes at 300–400 m elevations.

 Phenology

The species is observed to be flowering and fruiting in the wild in April, May, and August, but it is assumed to flower and fruit all throughout the year.

 Etymology

The specific epithet refers to Panay Island, the type locality where the species was discovered and collected. The choice of epithet serves to emphasize the biogeographic importance of this central Philippine island, which functions as a distinct centre of diversity and endemism within the West Visayas. This discovery adds to the growing list of taxa unique to Panay, reinforcing the need for focused conservation efforts in its remaining forest fragments.

 Preliminary IUCN conservation assessment

At present, the species is found to occur in three localities where < 60 mature individuals were observed with an estimated EOO of 396 km2 and AOO of 12 km2. Two localities are in unprotected areas with observed anthropogenic activities such as cow and goat grazing and expansion of agricultural land. One locality was found within Northwest Panay Peninsula Natural Park, a designated protected area since 2002 under the National Integrated Protected Areas System Act, Philippines (UNEP-WCMC 2022). Following IUCN Standards and Petitions Committee (2024), we propose B. panayica to be classified as Endangered: EN B1ab(i,ii,iii)+2ab(i,ii,iii).

 Morphological affinities

Among Begonia sect. Baryandra in Panay Island, this new species is comparable to B. collisiae Merr. (Merrill 1919) but it can easily be recognized by having sparsely strigose petioles (vs sericeous petioles), ovately orbicular leaf lamina with entire to repand-serrate margin (vs broadly ovate leaf lamina with irregularly and coarsely dentate-serrate or lobulate margin), glabrous peduncle (vs sparingly glandular), and ovary with unequal wings (vs ovary with equal wings). It is also similar to B. titoevangelistae Tandang & Rubite from southeastern Luzon (Tandang et al. 2016), however, B. panayica differs significantly in having deltate stipule with cuspidate apex (vs ovate stipule with acuminate apex), sparsely strigose, lenticellate petiole (vs sericeous, non-lenticellate petiole), and ovary/capsule with unequal wings (vs ovary/capsule with equal wings).

 Conclusion

The discovery of these three new, narrowly endemic species underscores the remarkable, yet still underexplored, biodiversity of the Philippines. As members of the rapidly diversifying Begonia sect. Baryandra, which is renowned for its high degree of microendemism, these species exemplify the ongoing evolutionary processes within the archipelago’s isolated forests. As a megadiverse nation, the continued description of endemic taxa necessitates a race against time to fast-track species discovery and documentation, thereby preventing the dark extinction of unknown lineages. This effort highlights the urgent need to conserve its remaining forest fragments and ensure the effective, long-term management of protected areas.

 Acknowledgements

We extend our appreciation to DENR Region VI and X for the issuance of gratuitous permits (R6-2021-003, R10-2024-115, R10-2025-112), and Yuanito Eliazar for the beautiful illustrations. MAKN’s Ph.D. is sponsored by University of Chinese Academy of Sciences (UCAS) Scholarship for International Students and Xishuangbanna Tropical Botanical Garden (XTBG), Chinese Academy of Sciences. DJA’s PhD is sponsored by Department of Science and Technology–Science Education Institute (DOST–SEI) under the Accelerated S&T Human Resource Development Program (ASTHRDP). This work is generously funded by the following: International Association for Plant Taxonomy through their ‘IAPT Research Grant 2024’, American Begonia Society through their ‘2024 Conservation and Research Fund Grants’, and the Society of Systematic Biologists’ Graduate Student Research Award (Spring 2025) awarded to MAKN and the 14th Five-Year Plan of Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences (E2ZKFF1K01) awarded to WBY.

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Plant Diversity 40: 75–90. https://doi.org/10.1016/j.pld.2018.06.002 Supplementary materials 10.5091/plecevo.196693.suppl1 9361ED6B-9FAC-5A69-AB3E-F06D66EE2C64

GenBank accession numbers of sequences for four molecular markers (ndhA intron, ndhF-rpl32 intergenic spacer, rpl32-trnL intergenic spacer, and ITS) used in this study. Species marked with an asterisk (*) represent newly generated sequences for this study.

 https://binary.pensoft.net/file/1756104 10.5091/plecevo.196693.suppl2 5F4299B2-CD8B-5C00-8B3E-370165C6673A

Conflicting nodes produced by Bayesian Inference tree as indicated by asterisks. A. Noncoding plastid genes. B. nrITS.

 https://binary.pensoft.net/file/1756105