Description

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).

bridge from its nose to its nostrils is well-defined, and the

DIAGNOSIS:

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).

COLORATION:

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).

VARIATION:

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

	View distribution map in BerkeleyMapper.
	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

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

PHYLOGENETIC RELATIONSHIPS: