AmphibiaWeb - Limnonectes magnus
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Limnonectes magnus (Stejneger, 1910)
Giant Philippine frog, Mindanao fanged frog, Mount Apo wart frog, bak-bak (local Higaonon), Palakang Kabkab (Tagalog)
family: Dicroglossidae
subfamily: Dicroglossinae
genus: Limnonectes
Species Description: Stejneger, L. (1910). Description of a new frog from the Philippine Islands. Smithsonian Miscellaneous Collections 52, 437–439.
Conservation Status (definitions)
IUCN Red List Status Account Near Threatened (NT)
CITES No CITES Listing
National Status Near Threatened (NT)
Regional Status Near Threatened (NT)
conservation needs Access Conservation Needs Assessment Report .

   

 
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Description

Limnonectes magnus is a large frog with an average snout-vent length range of 113 mm. It has a large, broad head and a short, rounded snout. The distance between its nostrils is approximately the same as the distance between its eyes. The interorbital space is wider than the upper eyelid. It has a distinct tympanum that is less than half the diameter of the eye. There are a few noticeable tubercles on the back of its upper eyelid and a sharp fold located behind the corner of its eye to above and behind its tympanum. An additional fold is found across the posterior part of its interorbital space. Limnonectes magnus is notable for its teeth. One vomerine set is situated in the mouth region behind the nasal cavity. The other set consisted of bony protrusions around 6 mm long; they are near the anterior end of the lower jaw and fit into deep hollows directly above them. Its first finger is longer than the second. When extended, the heel of its hind leg reaches the area between its eye and nostril. Limnonectes magnus has a tarsal fold. The foot has a long and narrow inner metatarsal tubercle, though it lacks outer metatarsal tubercles. The toes of L. magnus were fully webbed, and the fifth toe is lined with a dermal flap that is 2 mm wide. Its digits have well-developed knobs and multiple subarticular tubercles. Its skin is loose and smooth, with many pointed tubercles on its sacrum and the upper part of its tibia, and, in particular, concentrated around its heels (Stejneger 1910).

Limnonectes magnus is similar to L. macrodon from Java. However, it is larger than L. macrodon and has a wider interorbital space. Limnonectes magnus’ nostrils are farther apart than in L. macrodon; it has a smaller tympanum. Both species have vomerine teeth, however, L. macrodon’s teeth are located closer to its nasal cavity while L. magnus’ teeth are separated from the nasal cavity and shorter than those of its counterpart (Stejneger 1910).

In alcohol, L. magnus is a dark chocolate brown color. There is a black band from its nostrils to its eyes, and its lips have black blotches. Its hind legs have darker blotches that form obscure cross-bars. The back of its thighs are blackish with much lighter marbling throughout. While its belly is pale, there are dense brown markings all over the ventral surface of the legs and coarse, paler splotches on its abdomen. The latter splotches become fainter on the chest and throat. The tubercles on its feet are pale (Stejneger 1910).

Younger L. magnus have narrower heads and interorbital spaces as well as longer and more pointed snouts (Stejneger 1910).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Indonesia, Philippines

 
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View distribution map in BerkeleyMapper.
amphibiandisease logo View Bd and Bsal data (6 records).
Limnonectes magnus was found by Stejneger and associates on Mount Apo in Mindanao, Philippines, in 1910. This frog is also distributed throughout the Mindanao Pleistocene Aggregate Island Complex, which includes the cities of Basilan, Biliran, Bohol, Camiguin Sur, Dinagat, and Leyte; it also inhabits Sulawesi, Indonesia (Fabricante and Nuñeza 2012). It lives in forest stream systems at elevations up to 1800 m (Bursey et al. 2018).

Life History, Abundance, Activity, and Special Behaviors

Limnonectes magnus can often be observed sitting on rocks and the boulders of mountain streams. They also hide among leaf litter on the forest ground near stream banks (Dela Torre and Nuñeza 2021).

This frog has an invertebrate-based diet, and its most frequent food item is Orthoptera. Plant debris was also found in the stomach contents. However, it us unclear if plant debris consumption is accidental, as L. magnus has difficulty digesting fiber (Fabricante and Nuñeza 2012). It is parasitized by the nematode A. samarensis, which attaches to the intestines of L. magnus (Bursey et al. 2018), as well as the cestode D. latum (Fabricante and Nuñeza 2012). Moreover, L. magnus are sometimes predated by the crab species Isolapotamon mindanaoense on Mt. Magdiwata (Magdua et al. 2022).

Trends and Threats

Overharvesting for consumption is a threat to the survival of L. magnus. The species is considered “Near Threatened” (Solania and Fernandez-Gamalinda 2018, IUCN 2020).

Relation to Humans

Limnonectes magnus is overharvested for consumption (Solania and Fernandez-Gamalinda 2018, IUCN 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

The phylogeny of L. magnus was derived from Bayesian and likelihood analyses of mitochondrial DNA sequences and inferred that is sister to the clade composed of the L. woodworthi complex and the L. modestus complex (Evans et al. 2003).

Limnonectes magnus was first identified as Rana magna (Stejneger 1910), but was later classified into its own genus.

References
Bursey, C. R., Goldberg, S. R., Siler, C. D., and Brown, R. M. (2018). Endoparasites in Limnonectes magnus (Anura, Dicroglossidae) from Samar Island, Philippines with description of a new species of Aplectana (Nematoda, Cosmocercidae). Acta Parasitologica, 63(3), 474–478. [link]

Dela Torre, V. C. P., and Nuñeza, O. M. (2021). Species diversity, distribution, and microhabitats of anurans on Mt. Kalo-Kalo of the Mt. Kalatungan Range Natural Park, Bukidnon, Philippines. Asian Herpetological Research, 12, 58–75. [link]

Evans, B. J., Brown, R. M., McGuire, J. A., Supriatna, J., Andayani, N., Diesmos, A., Iskandar, D., Melnick, D. J., and Cannatella, D. C. (2003). Phylogenetics of fanged frogs: Testing biogeographical hypotheses at the interface of the Asian and Australian Faunal Zones. Systematic Biology, 52(6), 794–819. [link]

Fabricante K. M. B., and Nuñeza O. M. (2012). Diet and endoparasites of Rana grandocula (Amphibia, Ranidae) and Limnonectes magnus (Amphibia, Dicroglossidae) in Mt. Sambilikan, Diwata Range, Agusan del Sur, Philippines. AES Bioflux 4(3),113-121. [link]

IUCN SSC Amphibian Specialist Group. 2020. Limnonectes magnus (amended version of 2019 assessment). The IUCN Red List of Threatened Species 2020: e.T58353A176620668. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T58353A176620668.en. Accessed in January 2024.

Magdua, A., Sanguila, M., Manuel-Santos, M., and Fernandez, Jason. (2022). Predation on the Mindanao Fanged Frog, Limnonectes magnus (Stejneger, 1910), by an endemic freshwater crab at Mt. Magdiwata, eastern Mindanao Island, Philippines. Herpetology Notes. 15. 559-563. [link]

Solania, C. L., and Fernandez-Gamalinda, E. V. (2018). Species composition and habitat association of anurans within water systems of Andanan watershed, Agusan del Sur, Caraga Region, Philippines. Environmental and Experimental Biology, 16(3). [link]

Stejneger, L. 1910. Description of a new frog from the Philippine Islands. Smithsonian Miscellaneous Collections 52, 437–439. [link]



Originally submitted by: Sophie dela Cruz (2024-02-05)
Description by: Sophie dela Cruz (updated 2024-02-05)
Distribution by: Sophie dela Cruz (updated 2024-02-05)
Life history by: Sophie dela Cruz (updated 2024-02-05)
Trends and threats by: Sophie dela Cruz (updated 2024-02-05)
Relation to humans by: Sophie dela Cruz (updated 2024-02-05)
Comments by: Sophie dela Cruz (updated 2024-02-05)

Edited by: Ann T. Chang (2024-02-05)

Species Account Citation: AmphibiaWeb 2024 Limnonectes magnus: Giant Philippine frog <https://amphibiaweb.org/species/4774> University of California, Berkeley, CA, USA. Accessed Jun 18, 2024.



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Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Jun 2024.

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