ID based on diagnostic descriptions in:

• Frederic Henry Gravely (1914) An account of the Oriental Passalidae (Coleoptera) : based primarily on the collection in the Indian Museum, Baptist Mission Press, p. 232−239 DOI: 10.5962/bhl.title.9406.
• Christoph Neumann, Masahiro Kon, & Kunio Araya (2013). "Checklist of Passalidae Leach, 1815 (Coleoptera, Scarabaeoidea) of Laos with a key to their identification and a description of Leptaulax pacholatkoi mutoniatus ssp. nov.". Entomologica Basiliensia et Collectionis Frey 34: 207-235.
• Masahiro Kon, Koji Mizota, & Kunio Araya (2005). "Passalidae (Coleoptera) recorded from the Crocker Range, Sabah, Malaysia". Journal of Tropical Biology and Conservation 1 (31): 31-46.
• Kazuo Iwase (1998). "Some new Passalid Beetles (Coleoptera, Passalidae) from Southeast Asia". Elytra, Tokyo 26 (1): 131-139.

Basis for ID:

• Distribution range (Philippines)
• Size (~40mm)
• Antennae with six long lamellae
• Upper and lower teeth of left mandible large, dentition not clear on right mandible, probably incomplete.
• Labrum concave, slightly asymmetrical, with left anterior edge further forward than right
• Head asymmetrical, left outer tubercle larger than right
• Supraorbital and supraoccipital ridges form open semicircle,
• Pronotum with indistinct median groove
• Pronotum with crescent-shaped scars on sides, more dense on front edge, finely punctured
• Pronotum anterior angle protrudes forward
• "Shoulders" of elytra hairy