Big-eared Odorous Frog – Odorrana gigatympana – (Orlov, Ananjeva & Ho, 2006)

Science name: Odorrana gigatympana – (Orlov, Ananjeva & Ho, 2006)

Taxonomic:  Animalia>> Chordata>> Amphibia>> Anura >> Ranidae >> gigatympana

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

Description:

Physical Characteristics:
Odorrana gigatympana is a medium-sized frog species. Males have a snout-vent length (SVL) of approximately 39.0 to 46.7 mm, while females are larger, with an SVL ranging from 53.4 to 63.3 mm. The species is characterized by its narrow head, distinct round tympanum, and expanded finger and toe discs. The skin on the dorsum is smooth, and males have gular pouches that appear as skin folds at the corners of the throat. The dorsal surface is dark green with brownish lips and scattered dark spots, while the ventral surface is ivory with some brown pigmentation.

Coloration:
In life, the dorsum of O. gigatympana is dark green to brown, sometimes with scattered dark spots. The ventral surface is ivory, with brown pigmentation on the throat, chest, and legs. The species exhibits darker coloration during the day and becomes paler, sometimes fading to yellow or yellowish-green at night.

Distribution and habitat:

Altitude:
Odorrana gigatympana is found at elevations ranging from 412 to 1,420 meters above sea level (asl). It inhabits both lowland and montane regions, particularly within moist evergreen forests in central Vietnam.

Range:
The species is currently known from several provinces in central Vietnam, including Kon Tum, Dak Nong, Ninh Thuan, Quang Nam, Gia Lai, Phu Yen, Thua Thien-Hue, Khanh Hoa, and Dak Lak. However, its range may extend beyond these areas, as similar habitats are present in adjacent regions. The estimated extent of occurrence (EOO) for O. gigatympana is approximately 82,288 km².

Habitat:
Odorrana gigatympana is primarily associated with streams of varying flow speeds within evergreen forests, where it is commonly found on rocks, fallen trunks, and wide leaves near streams. The species is also observed in secondary forests, although its tolerance to disturbed habitats remains unclear. Reproduction is believed to occur in streams, as with many of its congeners.

Behaviour and ecology:

Lifestyle:
Odorrana gigatympana is a semi-aquatic species that inhabits streams in forested regions. It is commonly found perched on rocks, branches, and leaves along streams, particularly during the breeding season.

Reproduction:
Reproduction occurs between March and July, with males calling from tree branches or large leaves along streams. Gravid females and amplexing pairs have been observed during this time. Although oviposition has not been reported, it is presumed that eggs are laid in streams, where the tadpoles develop.

Feeding:
Like other species in the genus Odorrana, O. gigatympana is likely insectivorous, feeding on small invertebrates found near streams.

Conservation and status:

IUCN Red List Category and Criteria:
Odorrana gigatympana is listed as “Least Concern” on the IUCN Red List, as the species is widespread, and its population is not considered to be severely fragmented. However, the population trend is currently decreasing.

Threats:
The primary threats to O. gigatympana include habitat loss and degradation due to expanding agriculture, logging, and deforestation. These activities are reducing the quality and extent of the species’ forest and stream habitats, particularly in lower-elevation areas.

Conservation Actions:
There are no specific conservation measures in place for O. gigatympana. However, it is found in several protected areas, which may provide some degree of habitat preservation. Further research is needed to assess the species’ tolerance to habitat disturbance and to better understand its population trends and ecological requirements. Conservation efforts should focus on maintaining forest ecosystems and protecting stream habitats from degradation.