Description

Xenophrys truongsonensis is a rather large sized frog species with males exhibiting a robust snout-vent length of 58.8 - 71.4 mm, and females of 65.6 - 87.3 mm. The head is rather wide in comparison to the size. The snout is obliquely truncate in profile and projecting beyond the lower jaw so that the mouth is much behind the tip of the snout. The tympanum is small, oval in shape and distinct. An apparent dermal ridge runs from behind the eye over the tympanum and ends in a thickened bud over the fore arm. The hind limbs are long; the webbing between the toes is rudimentary (e.g. four phalanges of fourth toe are free of web), but narrow, lateral fringes extend along the toes to their tips. The subarticular tubercles of fingers and toes are absent and replaced by a faint dermal ridge under digits. The inner metatarsal tubercle is flat, the outer metatarsal tubercle is absent. The dorsal body is covered with weak granules and with a pair of dorsolateral ridges, and a X-shaped ridge that is behind the head on the middle of the back. Several incomplete ridges run across the limbs. The upper eyelid is topped by a small, distinctly pointed tubercle. The flanks are stippled with small tubercles. The underside of body and limbs is smooth. There are pairs of white glands on the side of the breast and the thighs. Males do not have nuptial spines or external vocal sacs (Luong et al. 2022).

DIAGNOSIS:

Xenophrys truongsonensis has previously been part of X. maosonensis (Luong et al. 2022). Mahony et al. (2018) recognized several distinct lineages within the later species. Xenophrys truongsonensis can be distinguished from X. maosonensis by flanks showing small tubercles and small white spots (vs. having large tubercles and larger white spots in X. maosonensis) (Luong et al. 2022).

COLORATION:

In life, the dorsal side of head and body is brown or grey-brown, with darker brown, lighter-edged symmetrical markings, including a triangular spot between eyes and a more or less complete hour-glass pattern between shoulders. The sides of the head show a dark band that caps the tip of the snout and extends over the nostrils and the loreal and temporal regions to the shoulders. A discontinuous white stripe stretches from behind nostril to below tympanum. The limbs are brown with dark brown cross-bands; the posterior thighs are orange brown. The throat and chest are tinted violet brown, with whitish, dark-edged spots on the lower lip, the lateral pair extending as curved, interrupted bands to the side of the chest. The belly and shanks are egg-yellow and the groins orange-reddish brown. These toads have brown webbing and light grey tips of the fingers and the toes. Their iris is copper in its upper part and brown in its lower part (Luong et al. 2022).

In preservative, the dorsal body has dark brown patterns on a greyish background. The greyish flanks are speckled with a few whitish spots. The throat and chest are brown, the whitish belly is speckled with brown flecks. The dorsal side of the fore- and hind limbs are greyish with brown bands, their posterior thighs are dark brown. They have whitish glands on the shanks. The foot and webbing are dark brown (Luong et al. 2022).

VARIATION:

There is some variation in coloration and some sexual dimorphism. Specifically, the dorsal coloration that can be greyish or reddish brown in life. Adult females reach larger body size than males (Luong et al. 2022).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Viet Nam

View distribution map in BerkeleyMapper.

Xenophrys truongsonensis is distributed in Laos and Vietnam in the southern part of Annamite Range. In Laos it is found in Champasak and Sekong provinces (according to genetic data of Chen et al. 2017), and in Vietnam in Dak Lak, Dank Nong, Kon Tum, Lam Dong, Ninh Thuan, Quang Nam and Thua Thien Hue Provinces (Luong et al. 2022). The species dwells secondary evergreen forests with medium and small trees and shrubs. It occurs from 530 to 1605 m above sea level (Luong et al. 2022).

Life History, Abundance, Activity, and Special Behaviors
The species is nocturnal and has been observed at early night from 19:00 to 23:00 h. It is locally common (Luong et al. 2022). As of 2023, no observations on breeding behaviour are available.

Larva
Taxonomically confirmed larvae from this species have not been described. Assumptions are based on phylogenetically close species of the genus Xenophrys. These species have larvae with an elongated body and a strong tail muscle but low fins. They have special anatomical structures at the mouth, including an expanded umbelliform oral disc that is orientated upward. They have no keratodonts (tooth-like structure made of keratin implicated in grazing) and are considered suspension feeders. These tadpoles live in forest streams (Tapley et al. 2020).

Trends and Threats
Although the species is present in nature reserves and national parks, X. truongsonensis seems to be threatened by habitat degradation through timber logging, road and hydropower construction, and harvesting for human consumption (Luong et al. 2022).

Relation to Humans
These large sized frogs are locally collected for food (Luong et al. 2022).

Comments

PHYLOGENETIC RELATIONSHIPS:

References
Chen, J.-M., Zhou, W.-W., Poyarkov, N. A. Jr., Stuart, B. L., Brown, R. M., Lathrop, A., Wang, Y.-Y., Yuan, Z.-Y., Jiang, K., Hou, M., Chen, H.-M., Suwannapoom, C., Nguyen, S. N., Duong, T. V., Papenfuss, T. J., Murphy, R. W., Zhang, Y.-P. and Che, J. (2017). A novel multilocus phylogenetic estimation reveals unrecognized diversity in Asian horned toads, genus Megophrys sensu lato (Anura: Megophryidae). Molecular Phylogenetics and Evolution, 106, 28-43. [link]

Luong, A. M., Hoang, C. V., Pham, C. T., Nguyen, T. T., Orlov, N., Ziegler, T. and Nguyen, T. Q. (2022). A new species of Xenophrys (Amphibia: Anura: Megophryidae) from Truong Son Range, Vietnam. Zootaxa, 5150(3), 333-356. [link]

Mahony, S., Kamei, R. G., Teeling, E. C. and Biju, S. D. (2018). Cryptic diversity within the Megophrys major species group (Amphibia: Megophryidae) of the Asian Horned Frogs: Phylogenetic perspectives and a taxonomic revision of South Asian taxa, with descriptions of four new species. Zootaxa, 4523(1), 1-96. [link]

Tapley, B., Nguyen, L., Cutajar, T., Nguyen, C., Portway, C., Luong Van, H. and Rowley, J. (2020). The tadpoles of five Megophrys Horned frogs (Amphibia: Megophryidae) from the Hoang Lien Range, Vietnam. Zootaxa, 4845(1), 35–52. [link]

Species Account Citation: AmphibiaWeb 2024 Xenophrys truongsonensis: English: Truongson Horned Toad; Vietnamese: Cóc mắt trường sơn <https://amphibiaweb.org/species/9555> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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