Abstract
Didymoplexiella laosensis is described as a new species from the limestone mountains of Vang Vieng District in central Laos. A detailed description, colour plate, line drawings and conservation assessment are provided, together with morphological comparisons with three allied species in tropical Asia, namely, D. ornata, D. siamensis and D. trichechus. With the leasing of its limestone habitat to a mining company for cement production, the threat to D. laosensis is already evident.