Allen's Horseshoe Bat

Allen's horseshoe bat is a small, large-eared horseshoe bat with generally light-brown upperparts and a paler buff underside. The broad horseshoe covers the muzzle and has small lateral leaflets and a distinct central notch; the long lancet has convex margins and a rounded or slightly pointed tip. Vietnamese animals belong to an unresolved regional form with a forearm around 4–4.6 cm, while the species complex weighs about 5–9.5 g (Handbook of the Mammals of the World 2019).

Genetic studies restored Allen's horseshoe bat from subspecies status within the big-eared horseshoe bat complex. North-eastern Vietnamese populations may represent an undescribed subspecies shared with Yunnan. A male measured in Xuan Nha Nature Reserve had a 4.21 cm forearm, 2.34 cm ears and weighed 6 g; a similar local bat differed genetically by roughly 2.5–3%, suggesting further regional structure. Until broader sampling resolves those lineages, identification in Vietnam should remain cautious (Handbook of the Mammals of the World 2019; Nguyen et al. 2025).