Vaccinium vomicum 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 : 27-30

Vaccinium vomicum M.N.Tamayo & P.W.Fritsch , sp. nov. ( Figs. 5–6 ).

Type:— PHILIPPINES. Mindanao Island, Province of Bukidnon, Municipality of Impasug-ong, Sitio Intavas , La Fortuna , Mt. Kitanglad , 2090 m, 6 September 2007, JMS 117 (holotype PNH!, isotype CMUH 2173 !) .

Diagnosis:— Vaccinium vomicum most closely resembles V. carmesinum M.N.Tamayo & P.W. Fritsch (2020: 174) but differs by having smaller leaves (5.0–9.0 × 1.8–5.2 cm vs. 7–15 × 0.4–9 cm), the presence of glands on the extreme end of the leaf blade base (vs. ca. 1–2 cm from the leaf blade base), the presence of clavate glands on the hypanthium (vs. absence), shorter stamens (4.5–5.5 mm long vs. 5.5–7.2 mm long), and the presence of stalked glands on the dentate apex of the tubules (vs. glandless, entire).

Description:—Habit shrubs, terrestrial, evergreen, sub-densely branched. Young branchlets reddish brown in sicco, glabrous. Mature branchlets light brown, obscurely ridged, glabrous, lenticellate, 3.0–8.0 mm wide; perennating buds acute, 1.2–2.0 mm long, with several obscurely overlapping scales. Leaves persistent on older branchlets, not densely crowded, spirally and evenly arranged; petiole reddish brown in sicco, glabrous, in cross section abaxially rounded, adaxially nearly flat, 0.6–1.0 × 0.18–0.28 cm; leaf blade narrowly to broadly elliptic, larger leaves on each branchlet 5.0–9.0 × 1.8–5.2 cm, coriaceous, abaxial surface light reddish brown in sicco, glabrous, adaxial surface dark reddish brown in sicco, glabrous, base cuneate, margin entire, thinly revolute, leaf blade glands 10 to 13 on each side, impressed ± evenly distributed, 0.2–0.3 mm diameter, the first pair of glands immediately at junction with petiole, 1.0– 1.2 mm diameter, leaf blade apex acuminate, acumen 1.5–1.7 cm long, midvein raised abaxially, flattened adaxially or nearly so, secondary veins 2 to 4 on each side of midvein with first pair arising from base and remainder along midvein, arc-ascending, slightly raised abaxially, obscure adaxially, tertiary veins faintly evident or obscure. Inflorescences pseudo-terminal or terminal, racemose, developing beyond confines of perennating bud, 1 per leaf axil, densely flowered, 10- to 12-flowered, 6.0– 6.5 cm long; peduncle and rachis reddish brown in sicco, slightly ridged, glabrous or with occasional clavate glands 0.15–0.2 mm long, peduncle ca. 1 cm long; rachis 5.0– 5.5 cm long; bracts dark brown in sicco, narrowly elliptic, planar or occasionally cucullate, coriaceous, glabrous, caducous, ± foliaceous, 10.0–12.0 × 5.0–6.0 mm, margin entire, apex acuminate. Flowers with an articulation between the pedicel and hypanthium, 1.6–2.3 cm long. Pedicel reddish brown in sicco, nodding, with occasional clavate glands, 8.0–16 × 0.9–1.2 mm; bracteoles 2, borne at base of pedicel, early caducous. Hypanthium reddish brown in sicco, cupuliform, broadly obconical, 1.2–2.0 × 2.0– 2.5 mm, with clavate glands; calyx limb 1.3–1.5 mm long, with clavate glands same as hypanthium; calyx lobes 5 or 6, broadly triangular or slightly rounded, glabrous on both sides, 0.7–0.8 mm long, margin entire, minutely ciliolate, with several scattered long clavate glands, with a sessile terminal gland. Corolla red, tubular-ampullaceous, gradually narrowed toward lobes, glabrous or occasionally with a few clavate glands outside, glabrous inside, 8.0– 11.0 × 3.5–4.0 mm; lobes 5 or 6, narrowly triangular, ca. 0.8 × 0.7 mm, apex acute to rounded. Stamens 10 or 12, monomorphic, free from each other, 4.5–5.5 mm long; filaments straight, 3.5–3.8 mm long, sparsely white-pubescent, trichomes filamentous, 0.8–1.0 mm long, mainly at base and sparsely scattered distally; anthers opening by short introrse slits or terminal pores, 2.3–2.5 mm long, shorter than filaments, cells narrowly oblong, minutely echinulate, 1.2–1.5 mm long, tubules parallel, cylindric, 1.5–1.7 mm long, slightly longer than cells, opening by oblique ventrallyto laterally-oriented apical pores, pores obliquely cut, apex serrate with a few scattered glandular trichomes ca. 0.2 mm long, spurs absent. Ovary 5- or 6-locular but appearing pseudo-10- to 12-locular with incomplete partitions extending ca. 0.20 mm from inner wall; ovules in two columns per locule; disk, slightly bulky, annular with obscure ridges on margin, 1.5–2.0 mm in diameter, glabrous; style not exserted from corolla, glabrous, 9–10 mm long, stigma truncate. Fruits not observed.

Distribution and Habitat:— This new species is restricted to the upper montane rain forest of Mt. Kitanglad range.

Etymology:— The epithet “vomicum ” is Latin meaning abscess or sore. This is in reference to the conspicuous pair of glands on the extreme end of the leaf base of this species.

Phenology:— Flowering in September.

Proposed Conservation Status:— The species has been collected only once, during an inventory of flowering plants in 2007 at Mt. Kitanglad mountain range; a protected area and a designated ASEAN Heritage Park. The lack of population data hinders assessment of this species in accordance with IUCN guidelines. Thus, we provisionally assess this species as data deficient (DD) ( IUCN Standards and Petitions Committee 2022).

Discussion:— Vaccinium vomicum is the only species of Philippine Vaccinium bearing glands on the extreme end of the leaf blade base. Normally, marginal glands on the leaves of Philippine Vaccinium are located some distance from the petiole along the margin, or spread throughout the length of the leaf margin, but never at the extreme end of the leaf blade base. These glands in Vaccinium and other species in the tribe Vaccinieae may serve as extrafloral nectaries to attract pollinators ( Argent 2019). The clavate glands on the hypanthium of V. vomicum resemble those of V. nitens Sleumer (1961: 97) , endemic to Mindoro Island, Philippines. Vaccinium vomicum differs from V. nitens by having larger leaves [5–9 × 1.8–5.2 cm vs. (4–)5–7 × 2.4–4 cm], an eglandular adaxial leaf surface (vs. bearing clavate glands), leaf marginal glands distributed along the length of the leaf margin (vs. bearing only a single a pair of basal glands), longer pedicels [8–16 mm vs. 5–6(–7) mm], and a serrate anther tubule apex (vs. non-serrate).

The stipitate glands borne at the apex of the tubules of Vaccinium vomicum are usually not observed in Philippine Vaccinium but do occur in some other Malesian species ( Sleumer, 1966 –1967; Mustaqim et al. 2022; Argent & Wilkie 2020). The only Philippine Vaccinium known to have such glands on its anther tubules is V. palawanense Merrill (1908: 373) ( Sleumer 1966 –1967). Vaccinium vomicum differs from V. palawanense by having longer petioles [0.6–1 cm vs. 0.2–0.4(–0.6) cm], larger leaves [5–9 × 1.8–5.2 cm vs. (4–)5–7 × 1.5–2(–3) cm], a tubular-ampullaceous corolla (vs. urceolate), an absence of anther spurs (vs. presence), and a glabrous disk (vs. pubescent).

In the key to the Malesian species of Vaccinium sect. Bracteata sensu Sleumer (1966 –1967), the new species best keys to V. muriculatum J.J. Smith (1914: 161) endemic to New Guinea but differs by having petiolar glands (vs. absent), longer petioles (0.6–1 cm vs. 0.2–0.5 cm), longer pedicels (8–16 mm vs. 3–6 mm), and a longer (8–11 mm vs. 6–7 mm) tubular-ampullaceous corolla (vs. urceolate).

In the artificial key to Philippine Vaccinium of Copeland (1930), V. vomicum best keys to V. tenuipes . Vaccinium vomicum differs from V. tenuipes by having longer petioles (0.6–1 cm vs. ca. 0.3 cm), larger leaves (5–9 × 1.8–5.2 cm vs. 3–5 × 1–2.5 cm), an inflorescence and a hypanthium with clavate glands (vs. stipitate), and anthers with stipitate glands (vs. eglandular). In the key to Bornean Vaccinium ( Argent 2019) , V. vomicum best keys to V. sarawakense subsp. montanum Argent (2019: 108) but differs by having longer petioles (0.6–1 cm vs. 0.5–0.6 cm), fewer flowers per inflorescence (10–12 vs. 7–20), longer pedicels (8–16 mm vs. 2–3 mm), a long-tubular (ampullaceous) corolla (vs. ovoid-urceolate), and anthers without spurs (vs. with spurs).

Figures

FIGURE 5. Vaccinium vomicum. A. Flowering branchlet. B. Abaxial view of leaf. C. Glands on the extreme end of the leaf blade base (red arrows). D. Adaxial view of leaf blade margin showing marginal glands. E. Inflorescence.All from JMS 117; photos by M.N. Tamayo.

FIGURE 6. Vaccinium vomicum. A. Flowering branchlet. B. Petiole showing glands on the extreme end of the leaf blade base. C. Flower showing pedicel, hypanthium, calyx, and corolla. D. Ventral view of stamen. Illustration by M.N. Tamayo.