taxonID	type	description	language	source
03B02A228B7DFFEFCC895292290B2977.taxon	diagnosis	Medinilla saxa is most similar to Medinilla whitfordii Merr. in its opposite, 3 - plinerved leaves and inflorescence of terminal, erect cyme. It differs, however, in its low shrub growth habit of 10 – 30 cm tall (vs erect shrub 3 – 5 m tall) and 4 - merous flowers (vs 5 – 6 - merous flowers).	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	materials_examined	Type: — PHILIPPINES. Luzon Island, Isabela Province, Dinapigue, in forest on ultramafic rocks and ultramafic-derived soils, along a stream, ca. 561 m elevation, flowers and fruits, 29 September 2023, E. S. Fernando 5591 (holotype PNH; isotypes CAHP, LBC + spirit coll., PUH, SING).	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	description	Low erect shrub, 10 – 30 cm tall, glabrous, multiple branching from the main stem base; the basal portions of some new branch growths prostrate on the rock surface, sometimes producing new roots. Stem 5 – 10 mm diameter at base; branch stems 3 – 5 mm diameter towards the base; internodes (4 –) 5 – 20 (– 26) mm long; nodes prominent, usually thicker than the internodes; young developing stems more or less angular. Leaves simple, opposite, decussate, shortly petiolate; petiole 1 – 2 (– 5) mm long, 2 mm thick, more or less flat on the adaxial side, convex on the abaxial side. Lamina distinctly 3 - plinerved, narrowly elliptic, sometimes lanceolate, (2 –) 3 – 5 (– 7) cm long × (0.5 –) 0.8 – 1.5 (– 2.0) cm wide, glabrous; apex obtuse; glossy on adaxial surface, lightly glaucous on abaxial surface; the pair of secondary veins distinct of the abaxial surface, distinct or sometimes only faintly visible on adaxial surface; transverse veins not distinct. Inflorescence terminal, erect, without prominent large bracts, lax and loosely branched, 3 – 5 - flowered cyme, ca. 4 cm long. Peduncle 14 – 20 mm long, up to 2.5 mm thick, dark red; bracts when present subulate, 1 mm long. Pedicel (7 –) 12 – 16 (– 18) mm long, 1.5 – 2 mm thick, dark red. Flower buds pointed at tips, the petals imbricate. Flowers 4 - merous, 3.4 – 4.7 cm wide when fully open. Hypanthium campanulate, pale green to dark reddish-brown, the rim generally truncate, 4 – 5 mm wide, 1 – 2 mm high, sometimes undulate, smooth with no distinct teeth. Petals pink, slightly darker along the edges and midvein, broadly elliptic, (17 –) 18 – 20 (– 22) mm long, (8 –) 10 – 11 (– 13) mm wide; apex obtuse. Stamens 8, usually positioned above the style, more or less equal in length and isomorphic; anthers linear-lanceolate, 7 – 10 mm long, purple, rather curved upwards, with a yellow dorsal spur of 0.5 mm on the connective; filament 8 – 10 mm long, pinkish. Ovary 4 - loculed, ovary wall ca. 0.2 mm thick in flower bud, 0.5 mm thick in juvenile fruit; style terete, tapering distally, 15 – 17 mm long, reddish in color; stigma punctiform, white; extra-ovarian chambers or anther pockets extending to about halfway down the ovary, or rarely a little bit farther. Fruit a subglobose berry, 10 – 13 mm long, 6.8 – 8.6 mm wide, pale green to pinkish-red, then purplish-black when ripe; pedicel red, 12 – 18 mm long. Seeds numerous, dull yellowish-brown, embedded in pulpy tissue, 1 – 1.2 mm x 0.8 mm with prominent lateral raphe.	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	biology_ecology	Habitat and ecology: — This species is unique among all Philippine species of Medinilla. It is the only species, thus far, known exclusively to grow directly on crevices or sometimes on concave surfaces of large ultramafic rocks along a shallow stream and in partial shade. In some cases, it shares the rock habitat together with the woody shrub Nymphanthus curranii (C. B. Rob.) R. W. Bouman (Phyllanthaceae) (Bouman 2022: 24) and with tall trees up to 10 m or more along the streambanks. The rocks are of ultramafic-rock type generally referred to as peridotite (Andal et al. 2005). The tall trees along the streambank include Tristaniopsis oblongifolia (Merr.) Peter G. Wilson & J. T. Waterh. (Wilson & Waterhouse 1982: 439). Three other species of Medinilla in the area at about the same elevation include Medinilla stenobotrys Merrill (1917: 350) with terminal, many-flowered, dense panicles, occurring as an epiphyte, or rarely as a terrestrial shrub; Medinilla cf. halconensis Merrill (1907: 287), a terrestrial shrub with white bracts and sometimes ‘ hairy’ hypanthium; and the very variable and widespread Medinilla quadrifolia Blume (1831: 509), a scandent epiphytic shrub or climber.	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	distribution	Geographical distribution: — Medinilla saxa is known, thus far, only in the Northern Sierra Madre Mountains in the Dinapigue area on the southern part of Isabela Province, Luzon Island, Philippines. This particular area forms part of the so-called Isabela ophiolite (Andal et al. 2005; Morishita et al. 2006), the northern end of the ophiolitic belts along the eastern coast of the Philippine archipelago with extensive exposure of peridotites (Andal et al. 2005).	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	etymology	Etymology: — The epithet saxa (from saxum, Latin for ‘ large rock’, in plural form) refers to the habitat of this new species. All plants were seen and observed to grow directly only on crevices or fissures and concave surfaces of large peridotite rocks along the river.	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	discussion	Notes: — As no reliable infrageneric classification for Medinilla is available (Kartonegoro 2023), we tentatively follow Regalado’s (1995) informal groups for the Philippine species based on indumentum, leaf, stem, and inflorescence characters. Regalado’s (1995) Group 4 is defined as those whole plants that are glabrous and inflorescences of cymes that are terminal. Based on its overall morphology (Table 1), this new species, Medinilla saxa, belongs in Group 4 of Regalado (1995). This particular group includes Medinilla whitfordii Merrill (1905: 37), M. astronioides Triana (1871: 88), and M. coronata Regalado (1995: 149), all species endemic to the Philippines. Within this group, M. saxa is most similar to M. whitfordii in the 3 - plinerved leaves and inflorescence of simple 3 – 5 - flowered cyme. It differs, however, in its low shrub habit with multiple branches from the stem base, 4 - merous flowers, and in its unique low elevation (c. 500 – 600 m) ultramafic rock habitat. In contrast, Medinilla whitfordii occurs as a high elevation shrub or small tree species in montane forests reaching to 2600 m. Table 1 shows the diagnostic characters differentiating Medinilla saxa from species in Group 4 of Regalado (1995). A revised key to the Group is also provided. In the recent paper by Quakenbush et al. (2024) Medinilla whitfordii and M. astronioides clustered together as sister species when using nuclear genes, but not in the tree using plastid genes. However, both species were in the large Medinilla medinilliana (Gaudich.) Fosberg & Sachet (in Fosberg & Sachet 1980: 15) – alliance clade. Medinilla coronata was not represented in the large analyses of Quakenbush et al. (2024). Medinilla bolsteri Merrill (1906: 214) was regarded by Regalado (1995) as a synonym of M. astronioides. However, Quakenbush (in Pelser et al. 2011 onwards) had earlier indicated that Medinilla bolsteri may be a distinct species. Unlike in M. astronioides [Type: H. Cuming 758, L 0008942, MO 1940894, NY 00228811] the inflorescences in M. bolsteri are not terminal, but rather cauline. The isotype specimen of Medinilla bolsteri in NY [Ahern’s Collector FB 3262, NY 00221] has two detached lax inflorescences that appear to have been collected from the lower, leafless nodes of the stem below. The protologue also clearly states ‘ fascicled or solitary lax cymes 10 to 15 cm long from tubercles on the trunk’. Here, we support the resurrection of Medinilla bolsteri as a distinct species and its exclusion from Group 4 of Regalado (1995) as presently described. Medinilla saxa is the fifth species of Medinilla in the Philippines, thus far, restricted to ultramafic substrates. The four others are Medinilla ferruginea Merrill (1920: 297; Fernando et al. 2018), Medinilla theresae Fernando (in Fernando et al. 2018: 146) from Dinagat and Mindanao Islands, and Medinilla simplicymosa Malabrigo, A. G. Umali & A. B. Tobias (in Quakenbush et al. 2020: 867) and Medinilla ultramaficola Quakenbush, Y. P. Ang & R. Bustam. (2020: 868), both species from Palawan Island.	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	materials_examined	Additional specimens examined: — Philippines. Luzon Island, Isabela Province, Dinapigue, in forest on ultramafic rocks and ultramafic-derived soils, along a stream, c. 560 m elevation, flowers, 29 September 2023, E. S. Fernando 5589 (LBC, PNH), c. 545 m elevation, fruits, 30 September 2023, E. S. Fernando 5613 (LBC + spirit coll., PNH, SING).	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
03B02A228B7DFFEFCC895292290B2977.taxon	conservation	Provisional conservation assessment: — Medinilla saxa is known, thus far, only from its type locality and has a very small or restricted population along a rocky, riverine habitat. We estimate the number of mature flowering and fruiting individuals in the type locality, including a few hundred meters farther upstream and downstream, to be less than a thousand. Thus far, this is the only known and documented population. Using the GeoCAT conservation assessment tool (Bachman et al. 2011; http: // geocat. iucnredlist. org), this single location resulted in an Area of Occupancy (AOO) of less than 10 km 2 which is within the threshold for the Critically endangered (CR) category. It is possible that other populations of this species may also occur at lower or higher elevations along the same or other river systems in this mountainous area. The type locality, however, is near or within a new site being developed for a mining project. Habitat loss can be a real, plausible threat to this species in the very near future. A continuing decline in the number of mature individuals in the population is estimated, projected, or inferred. Following the IUCN Red List Categories and Criteria (IUCN 2012) and the Guidelines for Using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Subcommittee 2022), we provisionally assess Medinilla saxa as Critically endangered [CR B 2 ab (ii, iii) + C 2 a (i)].	en	Fernando, Edwino S., Quimado, Marilyn O., Quakenbush, J. Peter (2025): Medinilla saxa (Melastomataceae: Sonerileae), a new, ultramafic rock-dwelling species from the Philippines. Phytotaxa 718 (2): 144-152, DOI: 10.11646/phytotaxa.718.2.6, URL: https://doi.org/10.11646/phytotaxa.718.2.6
