Vaccinium gamay M.N.Tamayo & P.W.Fritsch

Tamayo, Maverick N., Amoroso, Victor B., Coritico, Fulgent P., Penneys, Darin S., Callado, John Rey C., Horner, John D. & Fritsch, Peter W., 2024, Three new species of Vaccinium L. (Ericaceae) from Mindanao Island, Philippines, Phytotaxa 647 (1), pp. 19-33 : 24-27

Vaccinium gamay M.N.Tamayo & P.W.Fritsch , sp. nov. ( Figs. 3–4 ).

Type:— PHILIPPINES. Mindanao Island, Province of Davao Oriental, City of Mati, Barangay Macambol , Mt. Hamiguitan Range Wildlife Sanctuary (MHRWS), 13–20 March 2022, J. R. C. Callado 2633 (holotype PNH!, isotypes BRIT!, CMUH!) .

Paratypes:— PHILIPPINES. Mindanao Island, Province of Davao Oriental, City of Mati , Barangay Macambol , Mt. Hamiguitan Range Wildlife Sanctuary (MHRWS), 13–20 March 2022, J. R. C. Callado 2628 ( PNH!) ; ibid. Nepenthes garden landslide area (lantawan), tropical lowland evergreen rain forest on SW-facing slope, 0–10% slope, trail to camp 4, 792 m, 6.72415°N, 126.15855°E, 21 June 2015, P. W. Fritsch 1969 ( BRIT BRIT554028 !, CAS 490403 !) ; ibid. Nepenthes garden landslide area (lantawan), tropical lowland evergreen rain forest on SW-facing slope, 0–10% slope, 1,181 m, 6.73169°N, 126.17803°E, P. W. Fritsch 1992 ( BRIT BRIT554023 !, CAS 490409 !) .

Diagnosis:— Vaccinium gamay most closely resembles V. gitingense Elmer (1912: 1490) but is distinguished by having shorter inflorescences (3–4 cm vs. 4–6 cm), early caducous inflorescence bracts (vs. persistent), shorter pedicels [8–9 mm vs. (7–) 10–15 mm], presence of clavate glands on the hypanthium (vs. absence), and an absence of anther spurs (vs. presence).

Description:—Habit shrubs, terrestrial, evergreen, 0.4–3 m tall, densely branched. Young branchlets reddish in vivo, white-hirsutulous, with simple erect trichomes 0.1–0.2 mm long. Mature branchlets reddish in vivo, grayish brown in sicco, obscurely ridged, glabrescent, sparsely lenticellate, 3.0–5.0 mm wide; perennating buds compressedovoid or broadly triangular, 0.6–0.7 mm long, with several overlapping scales, scale apices acute, margin entire, minutely ciliolate, trichomes 0.2–0.3 mm long. Leaves persistent on older branchlets, densely crowded, spirally and evenly arranged; petiole dark green, occasionally tinged red, pubescent, with trichomes same as branchlets, in cross section abaxially rounded, adaxially nearly flat and slightly grooved, 1.0–1.5 × 0.8–1.0 mm; leaf blade elliptic to oblong, young leaves with sparse clavate glands ca. 0.10 mm long scattered on both surfaces, larger leaves on each branchlet 0.9–2.5 × 0.5–1.3 cm, coriaceous, abaxial surface light green in vivo, light brown in sicco, with scattered clavate glands, adaxial surface light green to reddish when young, glossy green and nitid at maturity, brown in sicco, glabrous except the puberulent base, base obtuse to rounded, margin entire, thinly revolute, with 5 or 8 impressed ± evenly distributed glands per side and scattered along length forming shallow crenations, first gland 0.5–1 from base, ca. 0.2 mm diameter, leaf blade apex acute, with occasional minute hairs and a terminal gland on tip, midvein slightly raised on both surfaces, secondary veins 3 to 6 on each side of midvein with first pair arising from base and remainder along midvein, arc-ascending, slightly raised or obscure abaxially, obscure adaxially, tertiary veins faintly evident. Inflorescences pseudo-terminal or terminal, racemose, developing beyond confines of perennating bud, 1 per leaf axil, densely 8- or 12-flowered, 3.0–4.0 cm long; peduncle and rachis light green with a tinge of red in vivo, slightly ridged, glabrous, peduncle ca. 1 cm long, rachis 2–3 cm long; bracts early caducous. Flowers with an articulation between the pedicel and hypanthium, 5.0– 6.2 mm long. Pedicel light green in vivo, nodding, puberulent, with occasional clavate glands ca. 0.1 mm long, 8.0–9.0 × 0.5–0.6 mm at anthesis; bracteoles 2, subulate, early caducous, ca. 1 mm long, margin entire, with a few simple trichomes ca. 0.2 mm long. Hypanthium green in vivo, cupuliform or broadly obconical, glossy, 1.0–1.2 × 1.3–1.5 mm, with scattered clavate glands; calyx limb 1.2–1.5 mm long; calyx lobes green, 5 or 6, semicircular, glabrous on both sides or with occasional clavate glands, callose-thickened, 0.8–1.0 mm long, margin entire, minutely ciliolate, apex rounded, with occasional sessile terminal gland. Corolla white or pale pink, darker pink at base, urceolate, broad at base, gradually constricted to the lower half, tapering distally, glabrous on both surfaces, 4.2–5.0 × 3.0– 3.5 mm; lobes 5 or 6, narrowly triangular, ca. 1.2 × 1.0 mm, apex rounded. Stamens 10 or 12, monomorphic, free from each other, 3.0– 3.5 mm long; filaments straight or slightly curved, 1.7–2.2 mm long, pubescent, trichomes simple, undulate, ca. 0.5 mm long, borne mainly at base, with a few scattered distally; anthers 1.5–1.8 mm long, opening by short introrse slits or terminal pores, slightly shorter than filaments, cells narrowly oblong, minutely echinulate, 0.9–1.3 mm long, tubules parallel, narrowly to broadly cylindric, 0.8–1.0 mm long, ± narrower than cells, opening by apically or ventrally oriented pores, pore apex rounded or truncate, spurs absent. Ovary 5- or 6-locular but appearing pseudo-10- to 12-locular with incomplete partitions extending 0.2–0.3 mm from inner wall; ovules in two columns per locule; disk bulky, annular, with ridges on margin, glabrous, ca. 1.5 mm in diameter; style not exserted from corolla, glabrous, 4.0– 4.5 mm long, stigma truncate or rounded. Fruit deep red turning dark purple at maturity, globose, glabrous or with occasional clavate glands, 3.0–4.5 × 3.0–5.0 mm, fruiting pedicels becoming longer, ca. 13 mm, disk becoming bulged outwards as fruit progresses to full maturity with calyx lobes appressed to disk.

Distribution and Habitat:— This new species is known only from the tropical lowland evergreen rainforest of MHRWS. Flowering and fruiting individuals were observed on a 0–30% southwest-facing slope near a landslide area adjacent to a lantawan (a small, cleared area serving as resting site, view deck, or natural landslide area) on ultramafic substrate. Individuals of Vaccinium gamay are restricted to ultramafic substrate and occur sympatrically with V. gitingense along ridges and lantawans in MHRWS.

Etymology:— The epithet “gamay ” is a Cebuano word meaning small. This refers to the relatively small and dainty flowers of the new species.

Phenology:— Flowering in March, fruiting in January.

Proposed conservation status:— Only a few mature individuals (<20) were observed in the type locality. The EOO = 21.573 km 2 and AOO = 20.0 km 2, suggesting a narrow distribution of this plant. Although the plant is in a protected area (PA) and an ASEAN Heritage Park, natural disasters such as typhoons may pose a threat and lead to a decline of its population. With this, we hereby assess the conservation status of Vaccinium gamay as Endangered [EN: B1b (i, ii, iii) + B2b (i, ii, iii)] (IUCN Standards and Petitions Subcommittee 2022).

Discussion:— During a floristic survey conducted by Central Mindanao University (CMU) and Botanical Research Institute of Texas (BRIT) in 2015, an unknown Vaccinium bearing flower buds and fruits was vouchered from one of the lantawans of MHRWS. This plant morphologically resembles V. gitingense in its shallowly crenate leaf blade margin and callose-thickened calyx lobes. Examination of the available material revealed the presence of clavate glands on the young leaves, pedicels, and hypanthium of this species, leading to consideration that this plant is undescribed, in part because neither of the other species of Vaccinium known from MHRWS exhibit this character. JRCC, during a floristic survey in MHRWS, encountered some flowering and additional fruiting individuals of this unknown Vaccinium . Photographs were also taken in situ and vouchers were made, thereby permitting thorough diagnosis and description of this new species.

In the key to the Malesian species of Vaccinium sect. Bracteata sensu Sleumer (1966 –1967), the new species best keys to V. apiculatum Sleumer (1961: 95) endemic to New Guinea. Vaccinium gamay can be distinguished from V. apiculatum by having shallow crenations throughout the length of the leaf blade margin (vs. crenulate only in the upper third), longer inflorescences (3–4 cm vs. 1.5–2.5 cm), a hypanthium with clavate glands (vs. glabrous), a rounded calyx lobe apex (vs. acute), and an absence of anther spurs (vs. presence).

In the artificial key to Philippine Vaccinium ( Copeland 1930) , V. gamay best keys to V. tenuipes Merrill (1908: 375) . Vaccinium gamay is distinguishable from V. tenuipes by having an acute leaf apex (vs. shortly caudate-acuminate), leaf glands distributed along the length of the leaf blade margin (vs. one pair confined to the leaf blade base), eglandular inflorescences (vs. bearing stipitate glands), shorter pedicels (0.8–0.9 cm vs. 1.0–2.0 cm), semicircular calyx lobes (vs. triangular-ovate), and a broadly urceolate corolla (vs. narrowly conical). In the key to Bornean Vaccinium ( Argent 2019) , V. gamay best keys to V. phillippsiae but differs by having a shallowly crenulate leaf blade margin (vs. entire), leaf glands distributed along the length of the leaf blade margin (vs. 1–2 pair/s confined to the leaf blade base), the presence of clavate glands on the pedicel (vs. absence of such glands), semicircular calyx lobes (vs. triangular), and the absence of anther spurs (vs. presence).

Vaccinium gamay is one of two micro-endemic blueberries documented in MHRWS, the other being V. hamiguitanense P.W. Fritsch (2020: 282) .Although these two species occur sympatrically in MHRWS, albeit at different elevations [ V. gamay restricted to elevations of ca. 700–1181 m (vs. ca. 1600–1641 m for V. hamiguitanense )], V. gamay can be distinguished by its acute leaf apex (vs. obtuse to rounded or emarginate), early caducous bracts (vs. persistent), absence of corolla sulci and ridges (vs. presence), semicircular calyx lobes (vs. broadly deltoid), and absence of anthers spurs (vs. presence). Vaccinium gamay is one of two Philippine species known to have distinct callose-thickened calyx lobes, the other being V. gitingense .

Figures

FIGURE 3. Vaccinium gamay. A. Fruiting branchlets in vivo. B. Fertile branchlets with flower buds and flowers in full anthesis. C. Lateral view of inflorescence.D. Fertile branchlet showing flowers in full anthesis and immature infructescence. E. Longitudinal section of flower showing stamens and style.All from J.R.C. Callado 2633; photos by J.R.C. Callado.

FIGURE 4. Vaccinium gamay. A. Flowering and fruiting branchlets. B. Abaxial surface of leaf. C. Lateral view of flower showing pedicel, hypanthium, calyx, and corolla. D. Longitudinal section of corolla showing stamens and style. E. Ventral view of stamen. F. Dorsal view of stamen. G. Infructescence. Illustration by M.N. Tamayo.