A new species of Nanohyla (Anura: Microhylidae) from the lowland forests of southern Vietnam

We describe a new species of Nanohyla from the Song Hinh Protected Forest in Phu Yen Province, southern Vietnam, based on an integrative taxonomic approach. The new species represents a divergent lineage (16S rRNA gene uncorrected P-distance>5.3%), which clearly differs from any other Nanohyla species based on a series of morphological characters, most notably the presence of white spots on the top of its head. Morphologically, Nanohyla albopunctata sp. nov. is characterized by small body size (male snout–vent length (SVL) 18.2–20.2 mm); moderately slender body habitus; rounded snout; distinct tympanum; rounded canthus rostralis; loreal region slightly concave; skin on dorsum tubercular, ventral surfaces smooth; mid-vertebral skin ridge and dorsomedial stripe absent; superciliary tubercles absent; supratympanic fold indistinct; finger I reduced, less than half of finger II in length; II–IV fingers bearing discs with weak terminal grooves; two distinct palmar tubercles; two metatarsal tubercles; hindlimbs long, tibiotarsal articulation of adpressed limb reaching well beyond snout; fingers free of webbing; toe webbing formula: I 1–2 II 1–2 III 1–2 IV 1½–1 V; dorsum varying from dark gray to yellowish-gray, with darker "teddy-bear"-shaped brown marking; posterior surfaces of thighs and cloacal region with several brown stripes; chin, chest, and belly with gray mottling. We also report on the male advertisement call of the new species, characterized by a series of rattling sounds, consisting of 2–6 calls lasting 0.63 s, with 1–3 initial pulses and 5–9 successive pulses at a dominant frequency of ca. 3.02 kHz. To date, Nanohyla albopunctata sp. nov. is known only from the monsoon lowland tropical forest at the foothills of the Ca Mountain Range in Phu Yen Province of southern Vietnam at elevations of 200–400 m a.s.l., uncommon for the generally mountain-restricted Nanohyla genus. Our discovery brings the total number of Nanohyla species to 10, seven of which occur in Vietnam. We preliminary suggest the new species be considered as Data Deficient (DD) following the IUCN Red List categories.