Vaccinium coarctatum M.N.Tamayo & Fernando, 2023

Tamayo, Maverick, Fernando, Edwino & Fritsch, Peter, 2023, VACCINIUM COARCTATUM (ERICACEAE), AN ULTRAMAFIC-OBLIGATE NEW SPECIES FROM THE DWARF FOREST OF MOUNT REDONDO, DINAGAT ISLAND, PHILIPPINES, Edinburgh Journal of Botany 80 (1960), pp. 1-12 : 2-7

Vaccinium coarctatum M.N.Tamayo & Fernando , sp. nov.

Vaccinium coarctatum resembles V. hamiguitanense P.W.Fritsch but differs in having longer inflorescences (c. 4.5 cm vs c. 1.6 cm), shorter pedicels (2–3 mm vs 3–4 mm), longer bracteoles (6–8 mm vs 0.14–0.54 mm) that are persistent (vs caducous),

hirsutulous calyx lobes (vs glabrous), and shorter anther spurs (0.2–0.3 mm vs

0.2–0.4 mm). – Type: Philippines, Dinagat Islands Province, Dinagat Island, Municipality of Loreto, Mt Redondo , dwarf forest on ultramafic soil, 10°21′6.91′′N, 125°38′12.48′′E ,

878 m a.s.l., 1 ix 2016, E. S. Fernando 4202 (holotype PNH!; isotypes LBC 9623 !, PUH 21855 !) [acronyms follow Thiers (continuously updated)]. Figures 1 , 2 .

Shrubs, terrestrial, evergreen, 1–2 m tall, densely branched. Young branchlets reddish, white-hirsutulous with simple erect trichomes 0.2–0.3 mm long. Mature branchlets greyish or greenish brown, 1.5–4 mm wide, often ridged, lenticellate, glabrescent; perennating buds compressed-ovoid, 0.5–0.9 mm long, with several obscurely overlapping scales. Leaves persistent on older branchlets, densely crowded, spirally and evenly arranged, ± imbricate; petiole dark green, occasionally with a tinge of red, in cross section abaxially rounded, adaxially nearly flat, 1–2.2 × 0.8–1 mm, white-hirsutulous; leaf blade oblong, obovate, or narrowly elliptical, larger leaves on each branchlet 5.2–17 × 3–5 mm, coriaceous, abaxial surface pale green, light brown in sicco, adaxial surface glossy green (dark brown in sicco), glabrous, base cuneate, margin faintly crenulate to entire, thinly revolute, apex emarginate, ± white hirsutulous, marginal glands 4 or 5(6) per side, sunken, scattered along length of margin, c. 0.15 mm in diameter, midvein slightly raised abaxially, sunken adaxially or nearly so, secondary veins 2 to 3(4) on each side of midvein with basal pair arising from base and remainder along midvein, arc-ascending, obscure on both surfaces in situ, more evident abaxially in sicco, tertiary veins faintly evident or obscure. Inflorescences pseudoterminal or terminal, racemose, developing beyond confines of perennating bud, 1 per axil, c. 4.5 cm long, ± densely 3- to 8-flowered; peduncle and rachis green, puberulent, slightly ridged with erect trichomes same as branchlets, peduncle 1.5–2 cm, rachis 2–2.5 cm, bracts borne at base of pedicels, light green, involute, ± imbricate, foliaceous, elliptic or lanceolate, planar or occasionally cucullate, 10–13 × 3–4.5 mm, coriaceous, glabrous except sparsely white-hirsutulous on midvein, margin entire, thinly revolute, with 3–5(6) impressed and gland-tipped crenations per side, base cuneate, sparsely white-hirsutulous, apex obtuse or rounded. Flowers articulated at junction with pedicel, 1–1.2 cm long. Pedicel slightly nodding, 2–3 × 0.7–0.8 mm at anthesis, white-hirsutulous; bracteoles 2, persistent until fruit ripening, borne at base or c. 0.5 mm from pedicel, light green with a tinge of red, linearlanceolate to oblong or nearly so, 6–8 × 1–1.5 mm long, glabrous except the puberulent base, margin entire with faint gland-tipped crenations and simple erect trichomes, apex acute or rounded with occasional simple erect trichomes. Hypanthium orange with a tinge of pink or light green, cupuliform, 1.6–1.8 × 1.8–2 mm, glossy, slightly ridged, white-hirsutulous with simple erect trichomes c. 0.15 mm long; calyx limb 1–1.2 mm long, white-hirsutulous; calyx lobes broadly triangular, 0.8–1 × 1.5–1.7 mm, adaxially white-hirsutulous, margin entire, apex acute or obtuse, white-hirsutulous, with a ± sessile terminal gland. Corolla white with a tinge of pink, broadly urceolate, 6–7 × 5–5.5 mm, shallowly

5 to occasionally 6-sulcated, prominently ribbed along petal midveins, glabrous outside and inside, lobes 5 or occasionally 6, 1–1.2 × 1–1.5 mm, apex acute or obtuse. Stamens 8–10, monomorphic, distinct, 4.5–5.2 mm long; filaments straight or slightly curved, dorsoventrally slightly flat, gradually dilated toward base, 1.7–2 mm long, white-hirsutulous with trichomes 0.2–0.3 mm long, anthers 2.7–3 mm long, slightly curved, opening by short introrse slits or terminal pores, cells 0.9–1.1 mm long, minutely echinulate, tubules parallel, broadly cylindrical, 1.8–1.9 mm long, opening by oblique ventrally oriented apical pores, pore apex rounded or oblong, spurs present, borne ± midway along anther, dorsally to slightly laterally oriented, 0.2–0.3 mm long. Ovary 5- or 6-locular but appearing pseudo-10- or 12-locular with false partitions extending 0.2–0.3 mm from inner wall; ovules in two columns per locule, each column separated by false partition; disk annular with ridges on margin, c. 2 mm in diameter, glabrous; style tubular, not exserted from corolla, 5.5–6 mm long, glabrous, apex truncate. Fruit black at maturity, globose, 5–7 × 5–6 mm, trichomes persistent.

Distribution. Known only from two localities in the dwarf ultramafic forest of Mount Redondo, Dinagat Island ( Figure 3 ).

Habitat and ecology. The upper montane rain forest of Mount Redondo is considered a dwarf forest because it is composed of shrubs and small trees up to 3 m in height ( Lillo et al., 2019; Fernando & Wilson, 2021). Vaccinium coarctatum was observed flowering in September and fruiting in November.

Etymology. The epithet coarctatum (neuter) is Latin for ‘crowded’ or ‘pressed together’. This is in reference to the growth habit and the slightly appressed flowers of the new species.

Proposed IUCN conservation category. From the two excursions conducted, only two flowering plants of the new species were found at the type locality. Although the vicinity of Mount Redondo consists of a dwarf forest, there were no other occurrences of Vaccinium coarctatum detected in the surrounding area. Therefore, its occurrence is rare (extent of occurrence, 0.046 km 2; area of occupancy, 8.00 km 2). Moreover,

the eastern side of Mount Redondo is a chromium and nickel mining area. This anthropogenic disturbance adds to the pressure of possible extirpation. Therefore, in accordance with the criteria of the IUCN Standards and Petitions Committee (2022), we categorise the conservation status of Vaccinium coarctatum as Critically Endangered [CR: B1ab(i,ii,iii) + B2ab(i,ii,iii)].

Additional specimens examined (paratypes). PHILIPPINES. Dinagat Islands Province, Dinagat Island, Municipality of Loreto, Mt Redondo , dwarf forest on ultramafic soil, 820 m a.s.l., 9 ix 2015, E. S. Fernando 3821 ( LBC!) .

Figures

Figure 1. Vaccinium coarctatum M.N.Tamayo & Fernando, sp. nov. A, Flowering branchlets; B, inflorescence; C, leaf (adaxial view); D, bract (abaxial view); E, bracteole (adaxial view); F, corolla lobes; G, lateral view of stamen; H, dorsal view of stamen. Drawn from the holotype, E.S. Fernando 4202, by M. N. Tamayo.

Figure 2. Vaccinium coarctatum M.N.Tamayo & Fernando, sp. nov. A, Upper montane rain forest of Mount Redondo, Dinagat Island, showing the dwarf vegetation in the habitat of the species; B, flowering branchlets; C, leaves and inflorescence (ventral view); D, lateral view of the inflorescence, showing corolla ridges and sulci. All photographs: E. S. Fernando.

Figure 3. Distribution of Vaccinium coarctatum (green dot) and V. hamiguitanense (orange dot). Map created with ArcGIS version 10.5.