A large river toad, Phrynoidis asper (family Bufonidae) is one of the most common anurans species that occurs in almost all forest rivers in Malaysia (Yap et al., 2014). This toad can be found on large river banks and prefers fast-flowing or cascading stream areas in pristine rainforests as their breeding sites (Shahrudin, 2021). Phrynoidis asper is also known as Asian Giant Toad, Rough Toad, Giant River Toad, or Katak Puru Sungai in Malay language.
Phrynoidis asper has a stout dark brownish to blackish body with a broad and blunt head devoid of bony crests. The inconspicuous ‘x’ mark is present on the back between the round-to-oval-shaped paratoid glands at the juvenile stage. The snout-vent length (SVL) of the male Giant River Toad measures about 70-100 mm, while the females have a snout-vent length of 95-215 mm, which is longer than the males (Inger & Stuebing, 2005). The skin is covered with warty, irregularly sized, spinose tubercles where the vernacular name is derived from (Chan et al., 2019; AmphibiaWeb, 2022). It also has rounded or swollen fingertips and a pair of visible eardrums.
According to Amran et al. (2018), the mating call of male Giant River Toad produces hoarse low-frequency calls with two pulsed notes and four repetitive notes per 60 s. It has a low pitch with a frequency of 1 kHz and a low note repetition rate. Yap et al. (2014) also mention that this toad mainly feeds on Formicidae and Termitoidae as a higher proportion of ants and termites were found in their diets, perhaps due to the large availability of ants and termites in social aggregations.
Phrynoidis asper is distributed in Thailand, Malaysia, Brunei Darussalam, Indonesia, and Myanmar (Inger & Stuebing, 2005; Grismer, 2011; Goldberg et al., 2017). It is classified as Least Concern by the IUCN Red List as this species is widespread and has a presumed large population (IUCN SSC Amphibian Specialist Group, 2021).