Three new species of Vaccinium L. (Ericaceae) from Mindanao Island, Philippines

Three new species of Vaccinium endemic to the island of Mindanao, Philippines are here described and illustrated. Vaccinium fallax most closely resembles V. myrtoides, but differs by having smaller leaves, caducous bracts, shorter pedicels, a broadly obconical hypanthium, broadly triangular calyx lobes, and a deep pink and broadly urceolate corolla. It grows on exposed areas and among sulfur vents at and near the summit of Mt. Apo. Vaccinium gamay most closely resembles V. gitingense, but differs in having shorter inflorescences, early caducous inflorescence bracts, shorter pedicels, presence of clavate glands on the hypanthium, and an absence of anther spurs. It grows on exposed areas in the ultramafic forest of Mt. Hamiguitan. It is one of only two Philippine Vaccinium species possessing distinctly callose-thickened calyx lobes, the other being V. gitingense. Vaccinium vomicum most closely resembles V. carmesinum, but differs by having smaller leaves, presence of glands on the extreme end of the leaf blade base, presence of clavate glands on the hypanthium, shorter stamens, and presence of stalked glands on the dentate apex of the tubules. It grows in the mossy rainforest of Mt. Kitanglad, and it is the only Philippine species of Vaccinium with glands on the extreme end of its leaf blade base. Following IUCN guidelines, we propose a conservation status of Critically Endangered for V. fallax, Endangered for V. gamay, and Data Deficient for V. vomicum. With these discoveries, the number of Vaccinium species in Mindanao Islands increases to 22 and in the Philippines to 44. Furthermore, the Mindanao Islands can now be considered the center of Vaccinium diversity in the Philippines.