We describe a new species of megophryid frog from central Vietnam. Leptolalax croceus sp. nov. is most similar to L. tuberosus, but distinguished from this and all other Leptolalax species by its bright orange belly in life and by its unique, complex advertisement call consisting of 4–6 variably pulsed notes with a dominant frequency of 2635–3000 Hz. In contrast, L. tuberosus has an advertisement call consisting of a single, weakly pulsed note lasting 54–78 ms with a dominant frequency of 2584–2756.2 Hz. Leptolalax croceus sp. nov. can be further distinguished from its congeners by a combination of an indistinct tympanum, highly tuberculate dorsum, medium body size (22.2–27.3 mm in 16 adult males), head slightly wider than long, rudimentary webbing between toes I–III, no webbing between toes III–V, no lateral fringing on toes, and no ventrolateral glands. The new species is only known from a single locality in evergreen forest at 1316 m elevation. Males were found calling from leaf litter and low vegetation adjacent to a shallow, rocky stream. We suggest the species should be considered Data Deficient following IUCN’s Red List categories.
Key words: Acoustics, Anura, Leptolalax croceus sp. nov., Leptolalax tuberosus, Vietnam, Southeast Asia