Description
Limnonectes phuyenensis is a small to medium-sized, robust frog with a snout-vent length range of 40.8 - 61.8 mm in females and 49.8 - 77.9 mm in males. Both sexes have a fang-like odontoid process on the lower jaw. Males have enlarged heads, but both sexes have a head that is broader than long. In the dorsal view the short snout is rounded and in the lateral view it projects over the jaw. The lateral nostrils are closer to the snout tip than the eye. The canthus rostralis is indistinct and the loreal region is slightly concave and oblique. The interorbital distance is both greater than the internarial distance and the upper eyelid width. The eye diameter is smaller than the snout length. There is no visible tympanum. The distinct supratympanic fold extends from the eye to the angle of the jaw. There is no external vocal sac. The dorsal surface of the head and body, including the flanks, is tuberculate and has ridges. Small tubercles can also be found on the upper eyelids and cloaca. There is no dorsolateral fold. The dorsal surface of the forelimbs and thighs is smooth but the dorsal surface of the tibia and feet are covered in small, low tubercles that are relatively dense. The ventral surfaces of the throat, body, and limbs are smooth. The forearms are short with the upper arm being much shorter than the forearm. The inner metatarsal tubercle is elongated and oval. The outer metatarsal tubercle is small. The unwebbed fingers have a relative finger length of I < II < IV < III, one prominent, round subarticular per finger, and end in blunt finger tips that do not expand. The fingers do not have dermal ridges. Males have a nuptial pad on finger I that presents as minute spines on the medial edge and dorsal surface. When the hind limb is adpressed along the body the tibiotarsal articulation extends to just behind the eye. The tibia is shorter than the thigh. The inner metatarsal tubercle is elongated and there is no outer metatarsal tubercle. The relative toe lengths are I < II < V < III < IV and they have a webbing formula of I0 - 0II0 - 0III0 - 0IV0 - 0V0. Unlike the fingers, the toes have a dermal ridge on the outer surfaces of toes I and V. The subarticular tubercle formula is 1, 1, 2, 3, 2. The toe tips are blunt, but slightly rounded (Pham et al. 2020).

DIAGNOSIS:

Limnonectes phuyenensis differs from Limnonectes fastigatus by L. phuyenensishaving a robust (versus thin) odontoid process and a nostril closer to the tip of the snout than to the eye. It differs from Limnonectes kiziriani and Limnonectes fragilis by having a head that is broader than long compared to longer than wide (Pham et al. 2020).

COLORATION:

In life, the dorsal surface of adult L. phuyenensis is mottled brown and yellow with dark crossbars on the dorsal surface of the limbs. The head has a pale yellow bar between the eyes with a dark brown bar directly posterior to it. The lip has dark bars. The irises are bicolored with the upper half being dark gray and the lower half being light gray. The supratympanic fold is dark brown. Like the dorsum, the flanks and limbs also have yellowish-brown markings, with the limbs also having dark crossbars. The ventral surface of the belly, throat, and limbs is white with brown markings and the toe webbing of the feet is brown. Juveniles exhibit lighter yellow coloration. When preserved in 70% ethanol, the yellow coloration fades to light brown but the patterning largely remains (Pham et al. 2020).

VARIATION:

Limnonectes phuyenensis exhibits sexual and developmental variation. Males are larger than females and have a larger head, larger fangs, and a nuptial pad on finger I. One juvenile was observed to have a mostly pale yellow dorsum with few brown markings, compared to the mottled brown-yellow appearance of the adults (Pham et al. 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Viet Nam

View distribution map in BerkeleyMapper.

At the time of the species description, L. phuyenensis was only known from the headwater pools and banks of small, rocky streams at elevations above 300 meters in the Phu Yen Province of Vietnam. The habitat surrounding the streams is hardwood evergreen forest mixed with shrubs and vines. The air temperature in this area is around 20.5 - 26.3^oC and the relative humidity was 73 - 96% (Pham et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Limnonectes phuyenensis is a semi-aquatic frog that is found in small rocky pools and along stream banks. Adults are active during the evening into the night. Males have been observed in the water with two or three females nearby (Pham et al. 2020).

At the time of the species description, advertisement calls were not recorded (Pham et al. 2020).

Gravid females were found in March, August, and September. Their internal eggs were yellow cream colored and of varying size (Pham et al. 2020).

Sympatric amphibian species included Leptobrachella macrops, Megophrys elfina, Limnonectes poilani, Odorrana morafkai, Rhacophorus annamensis, and a species that is presumed to be Kurixalus banaensis (Pham et al. 2020).

Larva
Larvae were not collected or observed at the time of the species description (Pham et al. 2020).

Trends and Threats
Limnonectes phuyenensis is considered locally common, but the surrounding habitat is threatened by habitat loss to agriculture, timber logging, and hydro-power construction. Large frogs, including this species, in this area are also collected for food (Pham et al. 2020).

Relation to Humans
Limnonectes phuyenensis is collected for food (Pham et al. 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Dams changing river flow and/or covering habitat
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

PHYLOGENETIC RELATIONSHIPS:

References
Pham C. T., Do, D. T., Le, M. D., Ngo, H. T., Nguyen, L. T., Ziegler, T., Nguyen, T. Q. (2020). A new species of Limnonectes (Amphibia: Anura: Dicroglossidae) from Vietnam. Zootaxa 4894, 387–402. [link]

Species Account Citation: AmphibiaWeb 2024 Limnonectes phuyenensis: Phu Yen Wart Frog (English); Ếch nhẽo phú yên (Vietnamese) <https://amphibiaweb.org/species/9300> University of California, Berkeley, CA, USA. Accessed May 5, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 5 May 2025.

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