Phou Khao Khouay Roundleaf Bat

When it was first encountered, researchers thought that it was the Laotian roundleaf bat, Hipposideros rotalis, as the two species are similar in appearance. The bats they found, however, were echolocating at a frequency 20 kHz above that of H. rotalis, utilizing frequencies of 87–91 kHz. In addition to its echolocation, the Phou Khao Khouay leaf-nosed bat has a smaller nose-leaf than H. rotalis. Its forearm is 45.5–48.5 mm (1.79–1.91 in) long; its tail is 35–37.5 mm (1.38–1.48 in) long; its ear is 24.4–25.2 mm (0.96–0.99 in) long. It weighs 7.7–9.6 g (0.27–0.34 oz), making it a moderate-sized species of the bicolor species group. The fur on its back is long and brown; individual hairs are tricolored, with white bases, dark brown middles, and light brown tips. Fur on its belly is lighter in color than the fur on its back. Its ears are long and broad with blunt tips; they are brown in color.

This species was first discovered in Phou Khao Khouay National Biodiversity Conservation Area. It has been captured at elevations ranging from 180–400 m (590–1,310 ft) above sea level. It has also been found near Vang Vieng, also in central Laos. It has been documented in both disturbed and intact evergreen forests. In 2008, the species was also captured in the mangrove habitat of Cat Ba Biosphere Reserve in Vietnam.

The Phou Khao Khouay leaf-nosed bat was described as a new species in 2006, based on specimens collected in central Laos in 1997 and 1998. The authors of the 2006 paper placed it in the bicolor species group of the genus Hipposideros. Its species name "khaokhouayensis" is a Neo-Latin derivative of Phou Khao Khouay, the conservation area where this species was discovered. The authors selected this name "to bring attention to the potential importance of the National Biodiversity Conservation Areas network for preserving natural areas in Lao PDR, as they contain highly distinctive ecosystems, hosting many endemic species such as this one." Its closest relative is the Laotian roundleaf bat; the two species have a genetic distance of 3.91–4.12%.