Vaccinium carmesinum M.N.Tamayo & P.W.Fritsch, 2022

Tamayo, Maverick N., Coritico, Fulgent P., Amoroso, Victor B., Penneys, Darin S., Tandang, Danilo N. & Fritsch, Peter W., 2022, Vaccinium carmesinum (Ericaceae), a new species of blueberry from Mt. Tago Range, Mindanao Island, Philippines, Phytotaxa 533 (3), pp. 173-180 : 174-178

Vaccinium carmesinum M.N.Tamayo & P.W.Fritsch , sp. nov. ( Figs. 1–2 )

Type:— PHILIPPINES. Mindanao Island, Bukidnon Province, Municipality [City] of Malaybalay , Barangay Kibalabag , Mt. Limbawon , [Mt. Tago Range,] accessory trail to peak, 8.26217°N, 125.18055°E, 1546 m elevation, 10 June 2019, Plants and Lichens of the Southern Philippines Survey 611 (holotype PNH!, isotypes A!, BRIT BRIT572077!, CAS!, CMUH!, NY!) .

Paratypes:— PHILIPPINES. Mindanao Island: Province of Bukidnon, Municipality [City] of Malaybalay , Barangay Kibalabag , Mt. Limbawon , [Mt. Tago Range,] open area with Pandanus , 8.27577°N, 125.18333°E, 1832 m elevation, 30 June 2015, Peter W. Fritsch 2081 (BRIT BRIT554025!, CAS 490415 !); Mt. Kiamo summit, [Mt. Tago Range,] on ridge of heathland scrub, 8.2563°N, 125.14799°E, 1760 m elevation, 7 May 2014, Darin S. Penneys 2377 (BRIT BRIT554030!, CAS 490401 !) .

Diagnosis:— Vaccinium carmesinum resembles V. platyphyllum Merrill (1917: 294) and V. luzoniense S. Vidal (1886: 168) , but differs from the former by longer and wider leaves, longer racemes, longer bracts, glabrous corollas, and glabrescent fruits, and from the latter by longer petioles, leaf glands distributed along the length of the blade margin, a glabrous inflorescence rachis, and lanate filaments.

Description: — Terrestrial leaning shrub or tree, evergreen, 2–5 m tall, sparsely branched. Branchlets glabrous, red when young, grayish brown at maturity, terete, 3–8 mm wide, lenticellate; perennating buds compressed-ovoid, 1.5–2.5 mm long; bud scales overlapping with minutely ciliate margins. Leaves persistent on older branchlets, spirally and evenly arranged, slightly overlapping, internodes 1–5 cm long; petiole crimson red, in cross section rounded abaxially and slightly raised adaxially, 10–18 × 1–5 mm, glabrous; lamina broadly elliptic, ovate, or rarely subrounded, with the larger leaves on each branchlet 7–15 × 0.4–9 cm, coriaceous, both surfaces reddish when young turning pale green abaxially and glossy adaxially, in sicco both surfaces light brown to ferrugineous, without punctae, glabrous; midvein flattened or sunken adaxially, strongly raised abaxially, secondary veins 3 or 4 on each side of midvein with first pair arising from base and remainder along midvein, arc-ascending, abaxially raised, adaxially sunken, tertiary veins faintly evident or obscure, base cuneate to truncate, margin entire, weakly revolute, apex slightly acuminate, marginal glands sunken, 10–18 per side, scattered along length of margin but more concentrated towards the apex, 0.3– 0.5 mm wide. Inflorescence pseudo-terminal or terminal, racemose, developing beyond confines of perennating bud, 1 per axil, 6–8 cm long at anthesis, densely 10- to 12-flowered; peduncle and rachis crimson red, slightly ridged, terete, glabrous; flower bracts caducous, crimson red, dark brown in sicco, foliaceous, ovate to elliptic, planar or occasionally cucullate, 6–15 × 2.5–3.5 mm, coriaceous, glabrous, margin entire, ciliolate, with several yellowish or reddish globose glands, 0.15–0.20 mm diameter mainly on basal half and with cilia ca. 0.1 mm mainly on apical third, apex acute to obtuse with a terminal gland. Pedicel 3.5–15 × 0.5–0.9 mm at anthesis, terete, spreading, glabrous, occasionally with 1 or 2 globose glands near base or occasionally on apical half, ebracteolate. Flowers articulated at junction with pedicel, 3.5–12 mm long. Hypanthium crimson red, cupuliform, 1.5–2 × 2–2.5 mm, white-hirsutulous with trichomes 0.10–0.15 mm long; calyx limb 1.0– 1.2 mm long, white-hirsutulous; calyx lobes broadly triangular, 0.8–1.2 mm long, white hirsutulous, margin entire, often ciliolate, apex acute, with a prominent greenish (reddish in sicco) globose sessile terminal gland ca. 0.25 mm diameter. Corolla broadly acute, lustrous white, conical-urceolate, 7–12 × 2.5–6 mm, outside glabrous, inside white-lanate especially on upper and lower third, trichomes 0.5–1 mm long; corolla lobes 5 or 6, 1–2 × 1–1.5 mm, apex acute to obtuse. Stamens 8 to 10, monomorphic, distinct, 5.5–7.2 mm long; filaments white, straight, gradually dilated at base, 3.5–4.8 mm long, pink towards base, densely white-lanate with trichomes 0.5–1 mm long; anthers 2–2.4 mm long, cells 1.4–1.6 mm long, echinulate, tubules parallel, narrowly cylindrical, distinctly narrower than cells, opening by oblique ventrally oriented apical pores, 0.6–0.8 mm long, pore apex rounded, spurs absent. Ovary 5- or 6-locular but appearing pseudo-10- to 12-locular with false partitions extending ca. 1.5 mm from inner wall; ovules in two columns per locule. Disk disciform, ca. 2 mm in diameter, puberulent, margin shallowly ridged. Style reddish, not exserted from corolla, 10–12 mm long, glabrous. Fruit on pedicels 1.4–2.1 cm long, deep purple, dark brown or reddish in sicco, globose, slightly ridged, 4–6 × 4–6 mm, glabrescent except for minute cilia on calyx lobe margins; persistent calyx lobes erect; disk ca. 4.5 mm in diameter. Seeds numerous, minute, brown, ca. 0.8 mm long.

Distribution and Habitat:— Vaccinium carmesinum is endemic to two mountains (Mt. Kiamo and Mt. Limbawon) in Mt. Tago Range, Mindanao, growing in tropical lower montane rainforest to upper montane rainforest. Populations of V. carmesinum were mostly found near summits where they thrive on volcanic-igneous or clay substrate with abundant humus. They also occur in areas of open shaded mossy forests, or on ridges covered in heathland scrub. Paratypes of the new species were collected on ca. 10–30% west-facing slopes.

Etymology:— The epithet carmesinum is derived from the Greek word for crimson (blood red), as depicted by its crimson red petioles, floral bracts, peduncle, rachis, pedicels, hypanthium, and calyces. Moreover, a crimson red stain is extracted in notable quantity when the plants are soaked in a denatured alcohol solution.

Phenology: — Flowering in June. Fruiting from January to May.

Proposed Conservation Status:— Mt. Tago Range has not been extensively explored botanically, which results in uncertainty as to the conservation status of the species. This range is a non-protected area; thus, the extent of occurrence and area of occupancy for the species cannot be assessed. There are only two populations currently known. Hence, we recommend a conservation status of data deficient (DD) ( IUCN Standards and Petitions Committee 2019).

Discussion:— In its combination of morphological characters, Vaccinium carmesinum matches no other species treated in relevant taxonomic treatments. In the artificial key to the species of Philippine Vaccinium ( Copeland 1930) , V. carmesinum keys to V. platyphyllum . The new species differs from V. platyphyllum by having longer and wider leaves (7–15 × 0.4–9 cm vs. 11–14 cm × 5–7 cm), longer racemes (6–8 cm vs. 4–6 cm), longer bracts (6–15 mm vs. ca. 8 mm), longer pedicels (3.5–15 mm vs. ca. 8 mm) that are glabrous (vs. slightly pubescent) and ebracteolate (vs. bracteolate), a glabrous (vs. sparsely pubescent) corolla outside, longer anthers (2.0– 2.3 mm vs. ca. 1.5 mm), and longer (4.0–6.0 mm vs. ca. 3 mm) and glabrescent (vs. pubescent) fruits ( Merrill 1917).

Vaccinium carmesinum can be distinguished from all other species of Philippine Vaccinium by its leaves, which are the widest of any Vaccinium in the Philippines. The pedicels are also notably ebracteolate and have 0 to 2 globose glands near the base or occasionally on the apical half. These glands might be homologous with bracteoles (typically two per pedicel in Vaccinium ) with a reduction in size and/or number. Copeland (1930) mentioned pedicel glands in V. luzoniense . Unfortunately, this character was not thoroughly described for the other Philippine species in former publication where the absence of bracteoles in a specimen is noted as “unobserved” (i.e. Sleumer 1966 –1967).

Vaccinium carmesinum is a member of V. section Bracteata Nakai in Nakai & Koidzumi (1927: 234) sensu Sleumer ( Sleumer 1966 –1967) as based on the combination of many-flowered racemose inflorescences, caducous foliaceous bracts, absence of a membranaceous wing at the sinuses of the corolla, and anthers that open by short introrse slits or terminal pores ( Sleumer 1966 –1967; Co et al. 2002; Salares et al. 2018). In Sleumer’s (1966 –1967) key to the Malesian V. section Bracteata , V. carmesinum keys to V. luzoniense . Vaccinium carmesinum differs from V. luzoniense , however, by having longer petioles (10–18 mm vs. ca. 10 mm), longer and wider leaves (7–15 × 0.4–9 cm vs. 7–9 cm × 3–4.5 cm), with leaf glands distributed along the length of the leaf margin (vs. with merely a pair of glands near the base), glabrous rachis (vs. with capitate-glandular trichomes), white (vs. red) corollas, and densely lanate (vs. sparsely pubescent) filaments ( Vidal 1886; Copeland 1930).

In the key to the Bornean species of Vaccinium ( Argent 2018) , V. carmesinum keys to V. sarawakense subsp. montanum Argent (2018: 108) but differs from it by having an inflorescence with fewer flowers (10- to 12-flowered vs. 7- to 20-flowered), glabrous rachis (vs. densely covered by short brown curved glandular trichomes), calyx lobes with a sessile terminal gland (vs. absent), white (vs. pale pink) corollas, and the absence of anther spurs (vs. presence).

In the sectional treatment of Vaccinium ( Vander Kloet and Dickinson 2009) , V. carmesinum can be treated as a member of V. section Euepigynium Schlechter (1919: 174) by its evergreen habit, monomorphic perennating buds, each with more than two scales, one perennating bud per leaf axil, plinerved leaf blade venation, entire leaf blade margin, peduncle longer than pedicels, calyx tube completely fused to the ovary, and pseudo-10-locular ovary. However, the boundaries of V. section Euepigynium and other sections of Malesian Vaccinium delimited by Vander Kloet and Dickinson (2009) were vaguely defined (i.e. the species included in each section are not provided). Hence, the sectional limits of Vaccinium in Malesia need further study.

During the process of diagnosing Vaccinium carmesinum as distinct from other Philippine species, we have become cognizant of problems in the taxonomy of the Philippine species. For example, V. ilocanum Merrill (1919: 441) and V. rizalense Merrill (1925: 43) were synonymized under V. platyphyllum by Copeland (1930) but characters seem divergent among these species and the justification relied mainly on macroscopic characters. A detailed study of this complex is currently in progress with emphasis on, e.g., ovary indumentum, corolla surfaces, and stamen characters.

Figures

FIGURE 1. Vaccinium carmesinum. A. Leafy branchlet. B. Inflorescences showing flower buds and foliaceous bracts. C. Corolla. D. Dissected flower showing stamens, style, ovary, hypanthium, and calyx. E. Dorsal view of stamen. F. Ventral view of stamen. G. Fruit cross section. Illustration by MNT.

FIGURE 2. Vaccinium carmesinum. A, B. Flowering branchlet. C. Leafy branchlet. D. Inflorescences showing flower buds and foliaceous bracts. E. Longitudinal section of flower showing corolla, style and stamens. F. Immature fruits. Photographs: A, D by DSP; B, E, F by MAKP; C by DNT.