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| Begonia ilinensis Bucay, Tandang & M.A.Reyes, in Bucay, Tandang, Reyes, Mundo et Chung, 2026. Taiwania. 71(1); |
Abstract
Begonia ilinensis is a newly described species of Begonia sect. Baryandra, first found in the coastal areas of Ilin Island, off the southwestern coasts of Mindoro Island in the Philippines. The species resides in exposed to semi-exposed limestone areas on the coast. The species is notable for its dormancy during the dry months, where it is limited to its minute rhizomes. It only starts growing its foliage and flowers during the wet season of June to November. Morphologically, the species is relatively small compared to most Baryandra species in the Philippines, but resembles Begonia luzonensis, a resident of nearby Luzon Island, mainly by its leaf margins. However, the species is much smaller compared to B. luzonensis specifically in terms of lamina, inflorescences, and capsules, and it lacks the characteristic rusty villous indumentum of B. luzonensis on its leaves, peduncles, and petioles. We also documented and mapped other Begonia sect. Baryandra that we have found thriving on the same habitat as B. ilinensis on other portions of the Philippines to shed further insights on the ecology of these coastal Begonias based on their habitat preferences.
Keyword: archipelago, Begonia ilinensis, Begonia luzonensis, biogeography, karst ecosystems, species radiation
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| Begonia ilinensis Bucay, Tandang & M.A.Reyes. A. Habitat showing limestone formations near the coast; B. Habit; C. Individual state recovering from dormancy stage, showing young leaves; D. petioles; E. stipules; F. Young leaves; G-H. leaves abaxial and adaxial side; I. Inflorescences; J. Male flowers and some young female flowers; K. Ovary; L. Female flower. |
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| Begonia ilinensis Bucay, Tandang & M.A.Reyes. A. Habit; B. Pistillate flower showing the ovary; C. Pistillate flower showing the stigmas; D. Ovary lateral view; E. Staminate flower; F. Staminate flower with the ventral view of androecium; G. Fresh capsules ventral view and cross-section; and H. stipules. |
Begonia ilinensis Bucay, Tandang & M.A.Reyes, sp. nov.
§ Baryandra
Diagnosis: The plant is observed to be most similar to B. luzonensis, particularly on leaf margins; both species of which may exhibit dentate leaves. However, B. luzonensis foliage is glabrous on both sides (vs. densely villous). Its peduncles are also glabrous (vs. longer villous), and the petioles are glabrescent (vs. sparsely villous). B. ilinensis is also significantly smaller than the more robust B. luzonensis and to most Begonia sect. Baryandra species. To scale, the range of lamina dimension of B. ilinensis is only at 4–6 × 2–5 cm (vs. 12–16 × 7–10 cm in B. luzonensis) and its capsules are very minute with lengths of 1.1–1.2 cm (vs. 2–2.5 cm). B. ilinensis also has more obtuse base on abaxial wing on the ovaries compared to a more truncated and extended abaxial wing of B. luzonensis.
Mark Angelo C. Bucay, Danilo N. Tandang, Mikko Angelo G. Reyes, Neil Anthony A. Del Mundo, Kuo-Fang Chung. 2026. New Begonia Species from Ilin Island, Occidental Mindoro Province, Philippines and insights to the coastal species of Begonia sect. Baryandra. Taiwania. 71(1); 42-48 DOI: 10.6165/tai.2026.71.42 [2026 January 06] https://taiwania.ntu.edu.tw/abstract/2143