Ixora reynaldoi Banag, 2015

Banag, Cecilia I., Tandang, Danilo, Meve, Ulrich & Liede-Schumann, Sigrid, 2015, Two new species of Ixora (Ixoroideae, Rubiaceae) endemic to the Philippines, Phytotaxa 202 (2), pp. 155-160 : 158

Ixora reynaldoi Banag sp. nov. ( Fig. 2 )

Ixora reynaldoi differs from the other species of the genus by its pseudanthium type of inflorescence, with 9–15 flowers, long bracteoles (3.5–8 mm long) and keeled, foliaceous calyx lobes (8–10 mm long).

Type:— PHILIPPINES. Visayas: Eastern Samar: Maydolong, Borongan, 11°26’0.0888”N, 125°23’0.3336”E, 200 m, 28 August 2011, C. Banag, C. Cremen & N. Pinarok SA004 (Holotype PNH 254887, isotypes USTH, K, US).

Shrub, 1–2 m tall, glabrous; young internodes brown, older internodes grayish to brown. Stipule sheath subtruncate, 1–2 mm long, awn 4–6 mm long. Leaves with petioles 0.5–1 mm long, canaliculate; blades elliptic to obovate, 8–15 × 1–3 cm, coriaceous, drying olivaceous above, paler below; apex narrowly acute to acuminate; base acute to round; secondary veins 10–15 pairs on each side. Inflorescences terminal, sessile, pseudanthium type, consisting of 9–15 flowers; glabrous throughout; leaf-like bracts subtending the inflorescence absent; bracts triangular, 5–6 mm long, apices narrowly acute; bracteoles linear or narrowly triangular, keeled, 3.5–8 mm long, reaching half of the calyx lobes. Flower buds acute at apex. Hypanthium and calyx red, corolla white, filaments, anthers, style and stigma creamcolored; Hypanthium 1.2–2.3 mm long. Calyx tube 2–5 mm long; lobes foliaceous, triangular to narrowly triangular, keeled, 8–10 mm long, their bases overlapping. Corolla tube 20–22.5 mm long; lobes 4, 5.5–6.5 × 2–3.5 mm, elliptic to ovate, acuminate at apex. Stamens inserted at corolla mouth, filaments 0.5–1 mm long; anthers 5–7 mm long. Style exserted 2–2.4 mm beyond the corolla mouth, stigmatic lobes 1.5–2.5 mm long. Fruits unknown.

Distribution and Habitat:— Ixora reynaldoi is endemic in Eastern Samar and thrives in secondary forests, at 200–400 m elevation.

Etymology: —The specific epithet is dedicated to Reynaldo J. Banag, the late father of the first author of this paper.

Phenology: —Flowering specimens were collected in May.

Conservation Status: —IUCN Red List Category (2014): Critically Endangered (CR; B2a; B2b (i–v); D). B2: total area of occupancy less than 10 km 2; B2a: a single location known; b (i–v): continuing habitat decline inferred; D: less than 50 mature individuals. The suitable habitat for I. reynaldoi on Maydolong, Eastern Samar is indicated as an endangered environment, threatened by human activity (deforestation, agricultural expansion), reducing the extent of the forest, and the geographic location of Eastern Samar being one of the provinces in the Philippines frequently hit by typhoons. The rarity of the species is suspected by the authors based on the low number of mature individuals found after careful exploration of the area and several field surveys conducted in Samar .

Discussion: — Ixora reynaldoi has calyx lobes 8–10 mm long, whereas the other Philippine species of Ixora have calyx lobes 2–3.5 mm long. Calyces less than 2 mm long are also rare, and occur in, e.g., I. philippinensis Merrill (1910: 238) (0.8–1.5 mm long). The long bracteoles and calyx lobes observed in I. reynaldoi are rare features in Philippine Ixora , and are known to occur in some non-Philippine representatives, e.g., I. amplexicaulis Gillespie (1930: 30) from Fiji (bracteoles ca. 9 mm long, calyx lobes narrowly triangular, 7–8 mm long) and I. homolleae De Block (2014: 122) from Madagascar (bracteoles 8–10 mm long, calyx lobes 5–12 mm long). Ixora reynaldoi differs from I. amplexicaulis by having 9–15 flowers per inflorescence (vs. more than 30 flowers per inflorescence) and bracteoles reaching half of the calyx lobes (vs. bracteoles exceeding the calyx lobes). Furthermore, I. reynaldoi differs from I. homolleae by its 2-locular ovaries (vs. 4-locular ovaries).

Figures

FIGURE 2. Ixora reynaldoi. A. Flowering branch. B. Inflorescence. C. Open flower. D. Bracteoles. E. Calyx. F. Calyx with bracteoles attached. Drawn from C. Banag, C. Cremen & N. Pinarok SA004 by Arianne Zacarias (A, C–F) and Nemesio B. Diego, Jr. (B).