Roa rumsfeldi, a new butterflyfish (Teleostei, Chaetodontidae) from mesophotic coral ecosystems of the Philippines.

A new species of the butterflyfish genus Roa is herein described from the Verde Island Passage in the Philippines, West Pacific Ocean. Roa rumsfeldisp. n. was found on mesophotic coral ecosystems at Puerto Galera and Batangas, and sampled through technical mixed-gas rebreather diving at 100-130 m depth. This represents the fifth known species of Roa. The main differences between Roa rumsfeldisp. n. and its congeners are the lower number of pored scales in the lateral line, longer snout, longer caudal peduncle, shorter caudal fin, pelvic fin color (dark first spine vs. white in all other Roa), and genetics (8.4% divergence from its closest relative Roa modesta in the mitochondrial COI gene). Roa spp. are usually seen in pairs, but the two specimens we collected were solitary individuals. We have kept one of the specimens alive in the California Academy of Sciences' Twilight Zone exhibit for more than one year, where it thrives and is feeding on a variety of dried and fresh food.