Orlov’s Vietnamese Frog – Vietnamophryne orlovi – Poyarkov, Suwannapoom, Pawangkhanant, Aksornneam, Duong, Korost & Che, 2018

Science name: Vietnamophryne orlovi – Poyarkov, Suwannapoom, Pawangkhanant, Aksornneam, Duong, Korost & Che, 2018

Taxonomic:  Animalia>> Chordata>> Amphibia>> Anura >> Microhylidae >> orlovi

Species status: Endemic ; IUCN status: LC (Least Concern)

Description:

Physical Characteristics:
Vietnamophryne orlovi is a miniaturized frog species, with the single male holotype measuring 15.4 mm in snout-vent length (SVL). It has a stout body, with a head that is longer than wide. The snout is comparatively long and rounded in both dorsal and lateral views, being longer than the eye length. The eyes are medium-sized, with a small, rounded tympanum well separated from the eyes.

The skin on the dorsal and lateral surfaces is smooth anteriorly but slightly shagreened (rough) posteriorly with small, flat pustules scattered on the posterior dorsum and hindlimbs. The ventral surface is completely smooth. The coloration of the dorsal side is reddish-brown with small red speckles, while the ventral side is bright lemon-yellow with fine brown marbling.

Distribution and habitat:

Altitude:
Vietnamophryne orlovi inhabits montane regions at an elevation of approximately 1,200 meters above sea level.

Range:
This species is currently known from a single locality on Phia Oac Mountain in Phia Oac-Phia Den National Park, located in Cao Bang Province, northern Vietnam. Its estimated extent of occurrence (EOO) is only 75 km². However, it is likely that its range could extend to adjacent areas with similar habitats, and further surveys may reveal its presence in other locations.

Habitat:
The species is associated with primary evergreen forest. The only observed individual was found under soil in the roots of a tree fern on a steep mountain slope, about 20 meters from a small cascading stream. This suggests a semi-fossorial (partly subterranean) lifestyle. The forest in which V. orlovi is found is a subtropical montane broadleaf evergreen forest with thick bamboo undergrowth and large trees. This species is not known to occur in disturbed areas and is likely dependent on undisturbed forest habitats. There is a continuing decline in the extent and quality of forest habitat due to human activities such as agriculture.

Behaviour and ecology:

Lifestyle:
Vietnamophryne orlovi appears to have a semi-fossorial lifestyle, spending much of its time burrowed in soil. The only known specimen was found at night, under heavy rain, in the soil around the roots of a tree fern on a steep slope, indicating a preference for moist, forested environments. The reproductive biology of the species is unknown, but it is hypothesized that it may reproduce via direct development, bypassing the tadpole stage, as seen in closely related species. No calling activity has been recorded.

Reproduction:
Nothing is currently known about the reproductive habits of this species. Given the behavior of related genera, it is possible that V. orlovi reproduces via direct development, meaning eggs hatch directly into juvenile frogs without a free-swimming tadpole stage.

Conservation and status:

IUCN Red List Category and Criteria:
Vietnamophryne orlovi is listed as “Data Deficient” on the IUCN Red List due to a lack of sufficient information about its population, distribution, and ecology. The species was discovered only recently, and further studies are needed to determine its conservation status.

Threats:
The primary threat to Vietnamophryne orlovi is habitat loss due to deforestation and land conversion for agriculture. The species is dependent on primary evergreen forests, which are in decline due to human activity in the region. The habitat of Phia Oac-Phia Den National Park is fragmented, and much of the forest below 1,000 meters has been degraded or converted to plantations, making the species vulnerable to habitat destruction.

Conservation Actions:
Further research is needed to assess the population size, distribution, and ecology of Vietnamophryne orlovi. Surveys in adjacent areas of similar habitat are crucial to understanding the species’ range. Protecting the primary montane forests of Phia Oac-Phia Den National Park and implementing conservation measures in nearby areas could help ensure the species’ long-term survival.