AmphibiaChina 中国两栖类.

Conservation Status (definitions)

IUCN Red List Status Account CITES No CITES Listing National Status None Regional Status None

Description
Theloderma khoii is a large, mossy frog described from one adult male and one adult female specimen. The snout-vent length of the male was 52.2 mm while the female’s was 59.4 mm, making this species one of the larger ones of the genus. Theloderma khoii demonstrates key characters of the Theloderma genus such as an obvious tympanum, head with skin not ossified to skull, and a round canthus rostralis with no bony ridge between it and the occiput. The species has a flattened body with a depressed head that is as long as it is wide, with a pointy, short snout that has oval shaped nostrils placed more terminally rather than close to the eyes. Their eyes are large and the space between them is about half of the snout length. Conical tubercles can be found on each eyelid. The distinct tympanum is smaller than the eyes and is set farther back from the eyes at a distance greater than its diameter. Starting from behind the eye, a distinct, unbroken supratympanic fold with irregular glandular ridges extends to the axilla. The strong forelimbs are shorter than the hind limbs. The hands of the male have large nuptial pads on the thumb’s side. The fingers have large rounded flat discs on the tips and slight webbing in between the finger bases that extends to the closest set of subarticular tubercles. The hind limbs are very long, with the tibia’s length being about 5x more than its width. The tibiotarsal articulation reaches the posterior edge of the eye or the tip of the nose when the hind limb is adpressed along the body. There is no metatarsal tubercle, but there are some small warts around the inner metatarsal area. The toes also also have discs, but they are smaller than the ones on the fingers. Also like the fingers, there is webbing as well as large subarticular tubercles on the toes. In life, the dorsal skin texture is rough, with enlarged glands in the following forms: a ridge near the center of vertebrae area, an x- shaped horn behind the head, and 3 - 4 conical shaped glands above each eye. Cone shaped tubercules lie on the back of the thighs near the vent as well as around the tympanum (Ninh et al. 2022).

DIAGNOSIS:

Theloderma khoii can look similar to other species that fall into the larger size category of the genus, such as T. bicolor, T. corticale, and T. gordoni. Using live color patterns is a good way to distinguish them. Theloderma khoii has distinct, dark brown speckles on its lateral sides that meet a yellowish-green band ventrally, while that entire area in T. bicolor is black with an asymmetrical yellowish-green pattern. Black thighs with yellowish-green bands and reddish brown warts also differentiate T. khoii from T. bicolor that has a thigh pattern of mixed black, yellow-green, and olive patches. Ventrally, T. khoii has a mixed black and yellow-green pattern with white warts and blue throat spots, while this area is a light whitish pattern with dark brown flecks in T. bicolor, lemon colored with black marks and cream warts in T. corticale, and dark blue with gray to white speckled patterns in T. gordoni. Lastly, T. khoii’s dorsal side resembles moss with a mix of mossy-green and light-olive colors, while T. gordoni’s is dark brown with light brown or orange spots falling on enlarged glands (Ninh et al. 2022).

Size and texture can also be used to differentiate these similar species. Theloderma corticale is larger in body size than T. khoii, and both T. corticale and T. gordoni have heads that are wider than they are long, unlike T. khoii’s roughly equal head width and length. The presence of developed foot webbing also differentiates T. khoii from T. bicolor and T. corticale. Lastly, T. khoii has a prominent tympanum and tympanic fold that T. gordoni lacks as well as a collection of large warts at the base of the head that T. cortale does not have (Ninh et al. 2022).

COLORATION:

In life, T. khoii has coloration resembling that of moss with intermixed mossy and olive green patterns and some magenta on its dorsal surface. The tips of the skin ridges and tubercles are reddish-brown. Dorsal areas of fore- and hind limbs have army green colored bands and some webbing patterns. The green fingers and toes have green discs with olive colored centers. The nuptial pad is ivory colored. The flank displays a dark brown pattern that moves ventrally to join a yellow-green band. The throat and chest is also dark brown with yellow-green warts, which lead into a belly with a large irregular black patch with yellow-green patterns and cream warts scattered throughout. The iris is yellow-green with irregular black reticulations. The tympanum is dark-olive colored (Ninh et al. 2022).

Preserved specimens have indigo colored dorsal surfaces and upper flanks with irregular brown spots. The tympanum is lighter brown. The dorsal surfaces of the limbs are black with light bands. Below the vent, the posterior thigh is dark gray with ivory bands. The chin and throat areas are lighter gray with ivory spots. The chest and belly become dark, almost black, with irregular cream colored areas on the chest (Ninh et al. 2022).

VARIATION:

The male specimen of T. khoii was smaller in size than the female and had nuptial pads on the thumb and a single vocal sac (Ninh et al. 2022).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Viet Nam

View distribution map in BerkeleyMapper.

At the time of the species description, T. khoii had only been observed from the type locality in Ha Giang Province in northeastern Vietnam, although it is expected to extend to the evergreen forests of Yunnan Province, southern China. Individuals were found near cave entrances or in valleys within the limestone mountains of Mount Tung Vai between 1320 and 1750 m elevation. This species is associated with primary and secondary karst forests with mixed hardwoods, shrubs, and vines (Ninh et al. 2022).

Life History, Abundance, Activity, and Special Behaviors
Theloderma khoii was found at night between 19:00 and 23:30 hours near cave entrances and in valleys surrounded by limestone cliffs. These caves were about 5 - 6 meters away from water sources. One of the frogs was found on a leaf, about 0.5 - 1.2 m above the ground. Another frog was on a limestone cliff, about 0.5 - 1.2 m above the ground. The temperature of the air at the time of collection ranged from 18.3 to 23.2 ℃ and relative humidity was between 91 - 100% (Ninh et al. 2022).

Theloderma khoii is a cryptic species, thought to use its textured green-colored body to blend in with the leafy environment surrounding it (Ninh et al. 2022).

There is not much information is not known about T. khoii and its life history, abundance, or special behaviors since it is so difficult to come across. However, other species in the Theloderma genus have been observed laying eggs in water-filled cavities (Nguyen et al. 2015).

Theloderma kwangsiensis has been observed secreting defensive chemicals from its skin as protection against pathogenic microorganisms. There is a possibility that T. khoii could exhibit the same ability as well (Shen et al. 2016).

Trends and Threats
Theloderma khoii is associated with karst forests in Tung Vai that are now declining in quality due to effects of road construction, illegal timber logging, and agriculture. Due to this and its expected restricted range, T. khoii likely falls under the “Endangered” category according to the criteria of the IUCN Red List of Threatened Species (Ninh et al. 2022).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Habitat fragmentation

Comments

PHYLOGENETIC RELATIONSHIPS:

ETYMOLOGY:

Theloderma khoii is named to honor Professor Dr. Le Vu Khoi of the Vietnam National University-Hanoi University of Science, Ha Noi, Vietnam for his teaching, research, and conservation work in Vietnam (Ninh et al. 2022).

References
Nguyen, T., Matsui, M., and Eto, K. (2015). Mitochondrial phylogeny of an Asian tree frog genus Theloderma (Anura: Rhacophoridae). Molecular Phylogenetics and Evolution, 85, 59–67. [link]

Ninh, H. T., Nguyen, T. T., Nguyen, H. Q., Hoang, N. V., Siliyavong, S., Nguyen, T. V., Le, D. T., Le, Q. K., & Ziegler, T. (2022). A new species of mossy frog (Anura: Rhacophoridae) from Northeastern Vietnam. European Journal of Taxonomy, 794. [link]

Shen, Chen, Y., Yao, H., Du, C., Luan, N., and Yan, X. (2016). A novel defensin-like antimicrobial peptide from the skin secretions of the tree frog, Theloderma kwangsiensis. Gene, 576(1), 136–140. [link]

Species Account Citation: AmphibiaWeb 2023 Theloderma khoii: Khoi’s Mossy Frog (English); Ếch cây sần khôi (Vietnamese). <https://amphibiaweb.org/species/9515> University of California, Berkeley, CA, USA. Accessed May 7, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 7 May 2025.

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