Description
Hoplobatrachus litoralis is a large frog with a snout-vent length in males of 81.3 - 102.1 mm and of 83.2 - 121.3 mm in females. The head is pointy and longer than it is wide. The tongue tip is forked. There are small bulbous warts on both the dorsal and lateral sides. The fingers are free with rounded fingertips. The relative lengths of the fingers are 3 > 1 > 2 > 4. The toe tips are rounded and have a wide web. The relative toe lengths are 4 > 5 > 3 > 2 > 1 (Hasan et al. 2012).

DIAGNOSIS:

Hoplobatrachus litoralis is morphologically similar to its sympatric sister species H. tigerinus and the related H. rugulosus. However, H. litoralis have more distinct dark bands running from the anterior corner of the eye to the upper jaw through the nostril, and along the lateral margin of the upper jaw (Hasan et al. 2012). Hoplobatrachus litoralis was also reported to have a shorter snout to vent length than H. tigerinus. The few findings of H. litoralis individuals in India were confirmed using genetic comparisons rather than solely morphology (Hasan et al. 2012; Kundu et al. 2020).

COLORATION:

In life, the dorsum is yellow to dark brown and is marked with dark brown to black spots. There is a yellow to white vertebral stripe that extends from the tip of the snout to the vent. Black bands extend from the anterior eye to the lateral margin of the upper jaw as well as under the eyes. The tympanum is dark gray with a pale center. The hind limbs have large black bands and black spots with yellow reticulations connecting them. The ventrum is white, except for black spots around the lower jaw and at the base of the forelimbs. In preservative, the patterning remains the same, but the dorsal coloration becomes gray (Hasan et al. 2012).

VARIATION:

Males have a pair of gray subgular vocal sacs on the underside of the jaw and a well-developed nuptial pad on the base of the first finger. Some frogs lack stripes down the middle of the dorsal side. The number and size of dark spots along the region of the lower jaw varies or are even sometimes completely lacking (Hasan et al. 2012).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Bangladesh

View distribution map in BerkeleyMapper.

Hoplobatrachus litoralis is distributed from the southeastern coast of Bangladesh to northeast India. It was first recorded in Cox’s Bazar in Bangladesh (Hasan et al. 2012), and later in the further inland regions of Panisagar (Purkayastha and Basak 2018) and the Dampa Tiger Reserve (Kundu et al. 2020) in India. Though initially thought to be limited to low elevation regions (3 m above sea level) near the coast, the specimens collected in India indicate an elevational range expansion to approximately 268 m above sea level (Kundu et al. 2020). Hasan et al. (2012) also suggest that H. litoralis may exist in regions of Myanmar that neighbor Cox’s Bazar, though sampling for this species has not been done in that region.

Hoplobatrachus litoralis is found in coastal marshes, ponds, and wetlands, as well as river edges. They have thus far been found in moist, vegetated habitats. Cox’s Bazar is the upper region of the Teknaf-Ukhia peninsula of Bangladesh, which is characterized by hill streams, estuaries adjacent to mountains, and forest (Hasan et al. 2012).

Life History, Abundance, Activity, and Special Behaviors
Like other Hoplobatrachus, H. litoralis are semi-aquatic and generally found by water edges of wet habitats such as ponds, marshes, rivers, etc. (Hasan et al. 2012). Being the lesser-known Indian bullfrog, due to being recently distinguished among the genus Hoplobatrachus, H. litoralis is likely to exhibit similar reproductive behavior as its sister species, H. tigerinus (Purkayastha et al. 2018).

To attract females, male H. litoralis emit a low-pitched sound that occurs in four second intervals that generally last for thirty seconds, which sound like rapidly repeating pulses. The frequency of their call is within 0.30 kHz, which is a low frequency sound suggesting that they are more sensitive to vibration to recognize conspecifics (Hasan et al. 2012).

Hoplobatrachus litoralis has been bred with H. tigerinus in the lab to produce viable young, however, their hybrids yield lower densities of spermatozoa. Viable, fertile hybrids - although less fit - suggest that a behavioral reproductive isolation method is occurring between these two sympatric species. Crosses between these species and their close relative H. rugulosus did not produce viable offspring, aligning with the greater genetic difference between H. rugulosus and H. litoralis than between H. tigerinus and H. litoralis. Due to the overlap in distribution of H. litoralis and H. tigerinus, the separation of these two species is less distinct, and possibly more recent (Hasan et al. 2017).

Hoplobatrachus litoralis have indirect development in its reproductive cycle (Hasan et al. 2017).

Tadpoles from the genus Hoplobatrachus are known for being mainly carnivorous, and feed on eggs of Microhylid frogs (Vitt and Caldwell 2014).

Trends and Threats
As of 2022, H. litoralis has not been assessed by the IUCN Red List. However, migration of H. litoralis from coastal areas in Bangladesh to higher altitudes in northeastern India suggests that selection pressure is acting on them (Kundu et al. 2020). Potential threats are urbanization and other human activities decreasing the type of habitats they’re endemic to. However, the conservation of globally threatened marine turtle habitat in the coastal belt of Bangladesh may benefit H. litoralis (Hasan et al. 2017). Furthermore, H. litoralis also occur and remain protected in the Dampa Tiger Reserve. Further studies needed to better determine their range distribution (Kundu et al. 2020).

Relation to Humans
Hoplobatrachus litoralis is likely hunted for use as food and medicine, and being captured for pet trade (Kundu et al. 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Subtle changes to necessary specialized habitat
Habitat fragmentation
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

PHYLOGENETIC RELATIONSHIPS:

Divergence in Cytb and 16s rRNA sequences of the mitochondrial genome were used to confirm a significant enough genetic distance between H. litoralis and H. tigerinus to warrant a new species description. Maximum Likelihood and Bayesian analyses placed H. litoralis as sister to H. tigerinus; these two species together are sister to H. rugulosus (Hasan et al. 2012; Kundu et al. 2020).

ETYMOLOGY:

The species epithet, “litoralis” means “coastal” or “seashore” in Latin and is a reference to where the species was first found (Hasan et al. 2012).

References

Hasan, M., Islam, M.M., Khan, M.R., Wanichanon, R., Kurabayashi, A., Sumida M. (2017). “Reproductive isolating mechanisms in the Bangladesh coastal bullfrog Hoplobatrachus litoralis and its congeneric species revealed by crossing experiments and examination on spermatogenesis of the hybrids.” Asian Herpetological Research, 8(1):27-38. [link]

Hasan, M., Kuramoto, M., Islam, M.M., Alam, M.S., Khan, M.R., Sumida, M. (2012). “A new species of genus Hoplobatrachus (Anura, Dicroglossidae) from the coastal belt of Bangladesh.” Zootaxa, 3312, 45-48. [link]

Kundu, S., Lalremsanga, H.T., Purkayastha, J., Biakzuala, L., Chandra, K., Kumar, V. (2020) “DNA barcoding elucidates the new altitude record and range-extension of lesser-known bullfrog (Hoplobatrachus litoralis) in northeast India.” Mitochondrial DNA Part B: Resources, 5(3), 2668-2672. [link]

Purkayastha, J., Basak, S. (2018). “Hoplobatrachus litoralis (Anura: Dicroglossidae) in India.” Hamadryad, 38(1&2), 25-26. [link]

Vitt, L.J., Caldwell, J. P. (2014). Herpetology: An Introductory Biology of Amphibians and Reptiles (4th ed.). Academic Press, Elsevier, San Diego, CA.

Species Account Citation: AmphibiaWeb 2022 Hoplobatrachus litoralis: Bangladesh Coastal Bullfrog <https://amphibiaweb.org/species/7826> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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