Ardisia kalimbahin Magtoto 2021, sp. nov.

Ardisia kalimbahin Magtoto, sp. nov. (Figs. 1 & 2)

Type:— PHILIPPINES. Luzon Island: Sitio Binbin, Municipality of Carranglan, Province of Nueva Ecija, Pantabangan-Carranglan Watershed Forest Reserve (PCWFR), ca. 920 m elevation, 13 March 2021, PTI-PCWFRI-96 with L. M. Magtoto & L. Udasco (holotype: PNH258564!; isotypes: CAHUP074214!; LBC9579!).

Paratypes:— PHILIPPINES. Palawan Island: Victoria Mountains, Municipality of Aborlan, Province of Palawan, 13 May 1950, M . D. Sulit 3817 (PNH 12374!); Mindoro Island: 25 April 1986, C. E . Ridsdale 1235 (PNH 62664!).

Diagnosis:— Ardisia kalimbahin closely resembles A. romanii in vegetative characters but can be distinguished by its shorter petiole (0.5–1.2 cm vs. 1.5 cm), shorter leaves (6–10.2 cm vs. 15 cm) that are elliptic (vs. ovate), racemose inflorescence (vs. umbel), longer pedicels (10–12 mm vs. 7.5 mm) that are sparsely puberulent (vs. glabrous), magenta corolla lobes (vs. deep lividus), basifixed anthers (vs. dorsifixed), shorter filaments (1.5 mm vs. 3 mm), and a beaked stigma (vs. pointed).

Description:—Tree, ca. 6 m high, stem terete, monopodial, branched from middle to top; branches forming dense crown. Leaves alternate; petiole 0.5–1.2 cm long, glabrous; lamina chartaceous, elliptic, apex obtuse, base subcuneate, entire, 6.0– 10.2 cm × 2.1–4.5 cm, paler on abaxial surface; glabrous; midrib prominent beneath, flat on the upper side with a shallow groove toward the base; secondary veins about 12 pairs with 1–3 intersecondary veins extending halfway to the midrib, reticulately anastomosing. Inflorescence arising from leaf axils; stalk pink, 1–2.5 cm long, bears relatively compact racemose flowers; pedicels 10–12 mm, ca. 2 mm thick, pink, sparsely puberulent. Flowers ca. 8, buds subglobose-ovoid. Calyx lobes 5, sparsely puberulent, same color as the pedicel, ovate, 3–5 mm × 2–3.5 mm, connate at the base, subrotund, margin thin and sparsely ciliate. Corolla lobes 5, magenta, 0.8–1 cm long, broadly ovate, slightly connate at the base, upper half margin rolled up upon the surface toward the apex, apex obtuse, glands sparse and denser near apex, spreading. Stamens 5, filaments white on the inner side and faint pink on the outer side, ca. 1.5 mm long; anthers 6 mm × 3 mm, yellowish and rugose on the inner side, gland-punctate on the outer side, with larger black glands toward the acute apex, basifixed. Style yellowish, gland-dotted, 6–8 mm long, glabrous, not exserted before anthesis; stigma beaked. Ovary yellowish, subglobose, glabrous. Fruits black when ripe, oblate, 1.0– 1.2 cm in diameter.

Distribution and habitat:— Ardisia kalimbahin is endemic to the Philippines and is currently distributed in the islands of Luzon (Municipality of Carranglan), Palawan (Victoria Mountains in Municipality of Aborlan), and Mindoro.

Etymology:—The epithet “ kalimbahin ” is derived from a Filipino word referring to a range of colors from pink to red-violet. This color range is a reminiscent of the flower color of the new species.

Phenology:—Flowering from May–April.

Proposed Conservation Status:—Only a single flowering individual was documented in one location within the vicinity of PCWFR. The paratypes which were collected at least three decades ago, also lack population and habitat descriptions. For these reasons, we propose the conservation status DD (IUCN Standards and Petitions Committee, 2019), as currently available information is inadequate to assess its risk of extinction using the IUCN guidelines.

Notes:—Apart from the characters mentioned in the diagnosis, Ardisia kalimbahin can be further distinguished from A. romanii by its pink (vs. greenish) inflorescence stalk, narrower calyx lobe basal portion (2–3.5 mm vs. 6.0 mm), shorter corolla lobes (0.8–1.0 cm vs. 1.25 cm), shorter filaments (1.5 mm vs 3 mm) that are white (vs. pink), and shorter style (0.6–0.8 cm vs 1.0 cm) that are yellowish (vs. whitish) in color.

There were previous collections purportedly attributed to A. romanii from Palawan [M.D. Sulit 3817 (PNH12374!)] and Mindoro [C.E. Ridsdale 1235 (PNH62664!)]. However, these specimens were mistakenly identified.The characters exhibited by these herbarium specimens confidently suggests that these materials belong to Ardisia kalimbahin mainly due to the elliptic leaves, racemose inflorescence, and longer pedicels in addition to some notes on the specimens’ flower color. The plant in Palawan was annotated in the herbarium sheet as “small tree ca. 5–6 m high, flower bright pink, fruit black when ripe, edible” while the specimen from Mindoro was annotated thriving on “ridge forest with some large Agathis, small monopodial treelet, branches swollen at junction orthotropic branch, detaching and leaving branch scar, flowers magenta”. The herein-listed paratypes are stored under the name A. romanii but these were not confidently determined as such by Stone when he made annotations on the above-cited PNH collections between 1991 and 1992.