Description
This account was first written for Limnonectes ferneri (Siler CD, McVay JD, Diesmos AC, Brown RM 2009 A new species of fanged frog, genus Limnonectes (Amphibia: Anura: Dicroglossidae) from southeast Mindanao Island, Philippines. Herpetologica 65:105-114.) This is a large frog-- robust body, with head broader than body. Snout is rounded in both dorsal and lateral view. Canthus rostralis is laterally concave when viewed from above and the loreal region is flat. Nostrils oriented posterolaterally, with a slightly convex internarial region. Upper lip is somewhat swollen, forming a protuberant ridge towards the angle of the jaw. Tympanic annulus is distinct and bordered dorsally by a protuberant, rugose supratympanic fold. Interorbital region is rugose. Pupil is horizontally elliptical. Tongue is elongated and anteriorly tapered, and attached broadly at the anterior. Choanae are tear-shaped (with the narrow point posterolateral) and placed at the anterolateral edge of the palate, widely separated. Distinct dentigerous process of vomer, having seven teeth on each side. Odontoid process is distinct with pointed tips. Forearms are hypertrophied. Fingers are robust, lacking webbing, with slightly expanded terminal discs and relative finger length I=III>IV>II. Subarticular tubercles are prominent and convex, with one subarticular tubercle present underneath fingers I and II, and two tubercles underneath fingers III and IV. No supernumerary tubercles are present. Thenar and palmar tubercles are large, elongated, and ovoid. Toes have moderately expanded terminal discs, bearing circummarginal grooves. Well-developed subarticular tubercles are present. Relative length of toes IV>V>III>II>I. Webbing formula on foot I 0–0+ II 0–0+ III 0–0+ IV 0+–0+ V. Toe V has postaxial flap of skin running along entire outer edge. Inner metatarsal tubercle is prominent, elongated, and ovoid, with a sharp and spade-like ventral edge; the outer metatarsal tubercle is absent. The heel has white dermal asperities. No tarsal folds or flaps are present. Dorsal skin on head and trunk bears dermal asperities (concentrated on posterior 2/3 of dorsum and eyelids), ranging from tiny to large, and clustered tubercles capped with white-tipped dermal asperities. Irregular low ridges are found on the dorsum, particularly on the dorsolateral surfaces, but do not span the entire body length. Limbs are tuberculate dorsally and smooth ventrally and laterally. Flanks are shagreened. The cloacal area is wrinkled and has densely clustered white dermal asperities.

The coloration in life was not recorded. In preservative the head, body, and limbs are a uniform dark chocolate brown with white asperities. Dorsal surfaces of limbs have transverse, irregular light brown blotches. No interorbital bar is present. Tympanum is dark brown to black in the center. Lips are uniform brown except for irregular lighter brown blotches on the lower lip. Lower eyelid is light brown around the periphery and has a light blue-gray center. Flanks are dark brown. Venter is lighter and mottled. White blotches present on ventral surface across margin between upper arm and forearm. Dorsal surfaces of hands and feet are dark brown with light brown blotches present above each phalangeal articulation. Throat is marbled, lighter than dorsum. Anterior chest has light brown to tan bar. Forelimbs are mottled. Ventral thighs are mottled. Tibia and tarsus are darker brown. Palmar and plantar surfaces of hands and feet are dark brown with gray subarticular tubercles. Foot webbing is mottled.

Limnonectes ferneri can be distinguished from other species of Philippine Limnonectes and from L. kuhlii and L. asperatus (morphologically similar congeners from Indonesia) by the following combination of characters: moderately large body size (reaching 84.3 mm SVL for males, 69.3 mm SVL for the single female specimen); fully visible tympanum with a prominent, rugose supratympanic fold; foot webbing extensive and rugose; rounded snout; Finger I > Finger II; having smooth to rugose dorsal skin with radial dense clusters of white-tipped dorsal asperities; dorsal folds/ridges absent; odontoid process of moderate length (2.7 mm for males, 1.1 mm for females).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Philippines

View distribution map in BerkeleyMapper.

Limnonectes diuatus lives in high-elevation riparian habitats on Mindanao Island, the Philippines (above 900 m asl, and usually greater than 1200 m asl). It is known from Mt. Apo, Mt. Pasian, Mt. Hilong-hilong, Mt. Magdiwata, Mt. Balatucan, Mt. Lumot. It likely occurs at other montane sites in eastern and possibly central Mindanao Island and generally considered restricted to these "sky islands" (Abraham et al 2021).

The populations previously known as Limnonectes ferneri is known from the Simulaw River Drainage on Mt. Pasian, Municipality of Monkayo, Davao Del Norte Province, Mindanao Island, the Philippines. It was collected on rocks and muddy river banks in disturbed primary forest of the PICOP Forest Reserve (Siler et al 2009).

Life History, Abundance, Activity, and Special Behaviors
Breeding behavior has not yet been observed. Nuptial asperities were not present in the two males collected (in May 1994), but it is not known whether this is characteristic of the species or simply reflects sampling during non-breeding season. Other species found nearby were Ansonia muelleri, Kalophrynus pleurostigma, Limnonectes leytensis, Limnonectes magnus, Limnonectes parvus, Megophrys stejnegeri, Occidozyga laevis, Philautus leitensis, Platymantis cf. dorsalis, and Rana grandocula.

Trends and Threats
This species can tolerate some habitat disturbance, since it was found in selectively logged forest.

Comments
A reanalysis of the Mindanao Fanged Frogs, specifically the Limnonectes magnus complex made up of L. magnus, L. diuatus, L. ferneri, revealed that there were fewer species than previously believed (Abraham et al 2021). The authors, using fresh samples from a broad geographic sampling, concluded that L. ferneri is in synonymy with L. diuatus, and redescribed L. magnus, a widespread, generalist, highly variable giant Fanged Frog distributed throughout the low elevation region of Mindanao in the southern Philippines (Abraham et al 2021).

References

Abraham RK, Herr MW, Sterkhova VV, Otterholt R, Siler CD, Sanguila MB, and Brown RM. (2021). "Revisiting Linnaean and Wallacean Shortfalls in Mindanao Fanged Frogs: The Limnonectes magnus Complex Consists of Only Two Species. ." Herpetological Monographs, 35(1), 112-140. [link]

Siler, C. D., McVay, J. D., Diesmos, A. C., and Brown, R. M. (2009). ''A new species of fanged frog, genus Limnonectes (Amphibia: Anura: Dicroglossidae) from southeast Mindanao Island, Philippines.'' Herpetologica, 65, 105-114.

Species Account Citation: AmphibiaWeb 2022 Limnonectes diuatus: Tagibo Wart Frog <https://amphibiaweb.org/species/4752> University of California, Berkeley, CA, USA. Accessed Dec 28, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 Dec 2024.

AmphibiaWeb's policy on data use.