Description
Xenorhina thiekeorum is a small-sized microhylid frog described from four male specimens with a snout-urostyle length range between 20.7 and 23.5 mm. The head is short; broader than long with an acuminated snout that protrudes in the profile. It has moderate, triangular spikes along each of its vomeropalatine bone. The dorsolaterally directed nostrils are located close to the snout-tip and are not visible from the ventral view. The internarial distance is smaller than the distance between the nostrils and the eyes. The loreal region has an oblique shape and there is no canthus rostralis. It has a relatively large, but poorly defined tympanum that is approximately ⅔ the size of its eye. The supratympanic fold does not reach the eye or the insertion of the forelimb. The entire dorsal side of the species is covered in low tubercles but the ventral surfaces are smooth. The palmer tubercles are poorly defined. The short, unwebbed fingers have a relative length of 3 > 4 = 2 = 1 and the tips do not expand into terminal discs, but do have circum-marginal grooves. The subarticular tubercles of the fingers are poorly defined. The tibia is moderately short, about 40 - 44% of the snout-urostyle length. The plantar tubercles are poorly defined. The relative toe lengths are 4 > 3 > 5 > 2 > 1, and the toes are unwebbed. The second through fifth toe have relatively large terminal discs and all toes have circum-marginal grooves. The subarticular tubercles of the toes are also poorly defined (Günther and Richards 2021).

DIAGNOSIS:

Xenorhina thiekeorum is similar in size to X. anorbis, X. brachyrhyncha, X. lanthanites, X. mehelyi, X. perexigua, X. pohleorum, X. schiefenhoeveli, and X. tumulus, but can be differentiated based on body ratios and advertisement call characteristics, although X. perexigua was only described from one specimen. Specifically, X. thiekeorum is smaller than X. mehelyi, X. schiefenhoeveli, and X. tumulus, but larger than X. perexigua. The head of X. thiekeorum is shorter and narrower than X. brachyrhyncha. The internarial distance relative to the body length is greater in X. mehelyi and X. tumulus. The ratio of the eye-to-nostrial distance and the internarial distance is smaller in X. anorbis, X. brachyrhyncha, X. lanthanites, X. pohleorum, X. schiefenhoeveli, and X. tumulus. The eye-to-nostril distance relative to the body length is shorter in X. tumulus. The eye size relative to the body length is smaller in X. pohleorum while the tympanum diameter relative to the eye diameter is larger and the fingers are shorter. The legs are shorter in X. anorbis but longer in X. brachyrhyncha and X. lanthanites. The presence of discs on the toes of X. thiekeorum sets it apart from X. anorbis, which lacks discs. With regards to call, the call length is longer in X. lanthanites, but shorter in X. perexigua, X. pohleorum, and X. tumulus. Xenorhina lanthanites also has longer call intervals and a lower repetition rate. Xenorhina mehelyi has a faster call rate and lower dominate frequency. And X perexigua and X. schiefenhoeveli have a longer call series with X perexigua having more calls per second and X. schiefenhoeveli having longer call intervals (Günther and Richards 2021).

COLORATION:

In life, X. thiekoreum has a reddish-brown dorsum with irregular light markings in the lumbar area, a narrow pale yellow mid-dorsal stripe, and white tips on the tubercles. The dorsal edge of the tympana and the dorsal surfaces of the limbs have a few dark brown spots and/or streaks. The anterior and posterior regions of the tympana and the lower region of the flanks have, off-white spots. The ventrum in life was not recorded. The irises are blackish but with golden veins and inner margin (Günther and Richards 2021).

In preservative, the reddish-brown background color is retained, but may pale slightly. The tubercles are still white tipped and blackish-brown spots are often associated with the structures. The limbs have lighter brown flecks. At the lower flanks the background color of the ventrum becomes ivory-white with orange-brown reticulation that can vary in density (Günther and Richards 2021).

VARIATION:

The phenotypic variation of the X. thiekoreum is usually only seen through slight color variation. Some individuals may have a beige-brown complexion rather than a red-brown complexion, the number of tubercules may vary, and the density of the orange-brown reticulation on the ventrum. No female specimens were collected so sexual variation could not be commented on (Günther and Richards 2021).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Papua New Guinea

View distribution map in BerkeleyMapper.

At the time of the species description, X. thiekoreum was only known from the type locality in the foothills of the Hindenburg Range near the Ok Tedi headwaters and Ok Menga (Ok meaning river) in the Western Province of Papua New Guinea, and was found at altitudes of 620 meters above sea level (Günther and Richards 2021).

Life History, Abundance, Activity, and Special Behaviors
Males were found at night, between 1 and 3 centimeters below the soil surface, calling from the base of ginger plants after rains. The calls were localized with all four individuals from the type series being found, by call, in a 4 m² area while calling was absent in adjacent areas that appeared suitable (Günther and Richards 2021).

Xenorhina thiekoreum have 6 - 8 repetitive, short, single, unpulsed “piping” calls that are very faint to the human ear. At an air temperature of 22.5 °C, individual calls last 133 - 162 ms with a call interval of 168 - 376 ms, while call series lasted 2.0 - 2.9 s at a rate of 2.5 - 3.0 calls/s. The calls had four harmonics with peak frequencies of 1.1, 2.2, 3.3, and 4.4 kHz. The third harmonic was the dominant frequency and the volume and the pitch of the calls slightly increased over the call series (Günther and Richards 2021).

Comments
This species was described based on morphology and advertisement call (Günther and Richards 2021).

References
Günther, R., and Richards, S. (2021). Description of six new species of Xenorhina Peters, 1863 from southern Papua New Guinea (Amphibia, Anura, Microhylidae). Zoosystematics and Evolution, 97(2), 355–382. [link]

Species Account Citation: AmphibiaWeb 2025 Xenorhina thiekeorum <https://amphibiaweb.org/species/9413> University of California, Berkeley, CA, USA. Accessed May 8, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 8 May 2025.

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