Description
Xenorhina waigeo is a medium-sized frog with a snout-urostyle length of 28.5 - 39.5 mm in males and 34.2 - 39.5 mm in females. The snout tapers to a point and has tiny depressions and laterally directed nostrils near the tip visible from above. In adult males, this species exhibits a head length to head width ratio of 0.79. The distance between the eye and naris is equal or mildly greater than the distance between nares, with an interval distance ratio of 1.28. Specimens were observed to have an oblique loreal region and lack a canthus rostralis. The tympanum is not easily visible in live individuals but becomes more visible in preservative, being nearly the same size as the eye (tympanic membrane diameter to eye diameter ratio is 1.08). A supratympanic fold is present from the posterior corner of the eye to the forelimb insertion. A constriction is noted at the neck, No vomerine spikes are present. The fingers are unwebbed and short with comparative finger lengths of 3 > 4 = 2 = 1. Despite the fingers lacking expanded discs, there are circum-marginal grooves present on all the fingertips. The toes are also unwebbed and have circum-marginal grooves along their tips. But in contrast to fingers, toes 2 - 5 have small, expanded discs that are wider than penultimate phalanges. The toes have comparative lengths of 4 > 3 > 5 > 2 > 1. There are weakly pronounced subarticular tubercles, as well as weak plantar and palmar tubercles. The dorsolateral surfaces of the body and dorsal hind legs have multiple tubercles, in contrast to the smooth ventral surfaces (Günther et al. 2020).

DIAGNOSIS:

Xenorhina waigeo is among a group of Xenorhina species that lack vomero-palantine spikes and was compared to the other species in this group by the species authority. This group includes X. adisca, X. arboricola, X. arndti, X. bouwensi, X. brachyrhyncha, X. eiponis, X. macrodisca, X. minima, X. oxycephala, X. parkerorum, X. similis, and X. varia, and finally Xenorhina salawati, which was described in the same article as X. waigeo and is the most morphologically similar. Xenorhina adisca and X. minima are smaller, have shorter legs, and lack expanded discs on toes compared to X. waigeo. Xenorhina arndti is also smaller, has a shorter internarial distance, and has narrower finger and toe tips. Xenorhina bouwensi is also much smaller than X. waigeo. Xenorhina arboricola and X. macrodisca, however, have strongly expanded finger discs, which are not present in X. waigeo. Xenorhina eiponis has much longer legs than X. waigeo. Xenorhina parkerorum and X. similus are much larger than to X. waigeo. While having shorter legs than X. waigeo, X. oxycephala, which is likely to be polyphyletic given mDNA studies, is also larger overall with slightly broadened discs on fingers, and smaller eyes. Xenorhina waigeo is most like X. salawati, although differs primarily in advertisement call series, with X. salawati’s series being greatly elongated and consisting of 2 - 4 times more calls per series compared to X. waigeo’s. Slight morphological differences between the two species include X. salawati having mildly shorter legs and 4th toes, as well as a greater distance between the eye and snout tip compared to X. waigeo. In preservative, compared to X. waigeo, X. salawati have lighter dorsal surfaces, strong mottling of the throat, and less intensely pigmented surfaces of fingers and toes (Günther et al. 2020).

COLORATION:

In life, the dorsal surface of the body and head are beige with dark brown spots around the lateral edges of the head, on the anterior and posterior limbs, and around the vent. The snout tip is grey or off-white with small grey indents. The eyes are colored with silver specks overlaid on golden irises. Dorsal and dorsolateral tubercles are noted to be lighter than the surrounding skin. Other dorsal surfaces are differing tones of bluish brown or beige, with ventral surfaces of pastel yellow with small white flecks. There are no spots present on the posterior chest or abdomen, however, there are grey-brown spots of varying prominence on the throat, anterior chest, and extremities. The abdomen has a prominent “pear-shape” formed by two very prominent zinc-yellow longitudinal stripes. There is also a pale lumbar spot visible. The ventral surface of the feet and hands are shades of grey-brown (Günther et al. 2020).

In preservative, the dorsal surfaces become a pale brown, with ventral surfaces changing to ivory white. Darker skin regions may remain the same color as in life, and the lumbar spot is no longer visible (Günther et al. 2020).

VARIATION:

Among adults, dorsal colorations can vary from brownish or blueish. There is also a yellowish mid-dorsal line present in half of the samples collected and described, 60% of which were among the blueish dorsal coloration group. Grey snout tips were present in most live specimens, which became more prominent when preserved (Günther et al. 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Indonesia

View distribution map in BerkeleyMapper.

Xenorhina waitgeo is only known only from one location on the southeastern tip of Waigeo Island in Indonesian New Guinea. They can be found in lowland rainforest at elevations between sea level and 20 m a.s.l. (Günther et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Xeborhina waigeo is a semi-fossorial species. Calling males were found beneath the soil surface or under vegetative debris. Females and non-calling males were found on the forest floor at night (Günther et al. 2020).

Thirty-one call series were recorded at 25^oC with an average length of 1.15 s with 2 - 6 calls per series lasting an average of 76 ms. Calls were unpulsed with approximately equal lengths and intervals except the last, which are often the longest. During each call series, the volume of calls commonly increased after starting abruptly. All calls recorded had between 6 - 8 harmonics between 0.25 and 3.8 kHz, with a dominant first harmonic often peaking at 0.45 kHz (Günther et al. 2020).

Trends and Threats
No threats were documented when the species was described (Günther et al. 2020). However, given the species’ limited known area of distribution, threats are likely to include destruction of habitat, decreased genetic variance due to small population size, and vulnerability to disease. More research is necessary to better understand the threats to this species’ continued existence.

Possible reasons for amphibian decline

General habitat alteration and loss

Comments
Xenorhina waigeo was described based on morphology alone (Gunther et al. 2020). Xenorhina includes species with one or more spikes on the vomero-palatine bone, which were previously referred to as Xenobratrachus, as well as another group lacking these spikes. Xenorhina salawati lacks these spikes, falling within the same category as X. adisca, X. arboricola, X. arndti, X. bouwensi, X. brachyrhyncha, X. eiponis, X. macrodisca, X. varia, X. minima, X. oxycephala, X. parkerorum, and X. similis, and finally X. salawati, which was described in the same article and is likely most closely related to due to similarities in morphology (Gunther 2010, Gunther et al. 2020). However, more research is required into this area

OTHER INTERESTING INFORMATION:

As of its first description in 2020, X. waigeo is one of only three members of its genus endemic to the Raja Ampat Islands, the other two being X. varia, and X. salawati (Günther et al. 2020).

References
Günther, R. (2010). Description of a new microhylid frog species of the genus Xenorhina (Amphibia: Anura: Microhylidae) from the Fakfak Mountains, far western New Guinea. Vertebrate Zoology, 60(3), 217-224. [link]

Günther, R., Richards, S., Tjaturadi, B., and Krey, K. (2020). Two new microhylid frog species of the genus Xenorhina Peters, 1863 from the Raja Ampat Islands, Indonesia. Vertebrate Zoology, 70(3), 333-347. [link]

Species Account Citation: AmphibiaWeb 2024 Xenorhina waigeo <https://amphibiaweb.org/species/9249> University of California, Berkeley, CA, USA. Accessed Mar 28, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 Mar 2025.

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