Family- Bufonidae (True Toads)

The members of the family bufonidae are characterized by having thick, warty dry or glandular skin with shortened forelimbs and hindlimbs used for walking or hopping. There is a concentration of glands in the temporal-neck area forming the prominent parotid gland which stores an alkaloid secretion. The bufonids are generally called toads. Adult toads lack teeth in the upper jaw. The pupil of the eye is horizontal. They reproduce by depositing strands of eggs in water and the eggs hatch in to tadpoles. The tadpoles have keratinized mouthparts. In most species fertilization is external but few are known to fertilize internally. The family Bufonidae is distributed worldwide except Antarctica and Australia. More than 610 species are known throughout the world that belongs to 52 genera (Amphibiaweb).

Bufonidae of Sri Lanka

Sri Lanka is home to 6 species of bufonids (Meegaskumbura et al., 2015; Jayawardena et al., 2017). The bufonidae in Sri Lanka consists of two genera: Adenomus and Duttaphrynus. The genus Adenomus is endemic to Sri Lanka.

Genus - Adenomus Cope, 1860

Adenomus species are characterized by their slender habitus and moist warty skin (Manamendra-Arachchi and Pethyagoda,1998). They have comparatively long limbs with smooth finger edges. Species of Adenomus also lack the supra-orbital ridge which is prominent in Duttaphrynus species. Two species of Adenomus are found in Sri Lanka (Meegaskumbura et al., 2015a).

Species of Adenomus in Sri Lanka

Adenomus kandianus (Gunther, 1872)^E
Adenomus kelaartii (Gunther, 1858)^E

Adenomus kandianus can be distinguished from A. kelaartii by the absence of cranial ridges (vs present in A. kelaartii). Both species are normally found close to water bodies. Out of the two species, A. kandianus was thought to be extinct until it was recently rediscovered from the Sripada Sanctuary (Peak Wilderness Sanctuary) (Wickramasinghe et al., 2012) and Piduruthalagala range (Gabadage et al., 2014). It is restricted to the submontane and montane forests of the Sripada sanctuary and Piduruthalagala range and is found associated with clear fast flowing shallow mountain streams covered by a thick canopy (Meegaskumbura et al., 2015b, Karunarathna et al., 2016). Adenomus kelaartii is distributed in the lowland and sub-montane rainforests of Sri Lanka.

Genus - Duttaphrynus Frost et al., 2006

They have a stout, stocky appearance with short legs. Their skin is dry and warty with prominent parotid glands on the head. Duttaphrynus species have prominent bony ridges, such as a canthal, a pre-orbital, a supraorbital, and a postorbital ridge, and a short orbito-tympanic ridge. Their snout is short and blunt, the interorbital space is broader than the upper eyelid and the tympanum is very small. The first finger of these toads extend beyond the second and the toes are half webbed. The finger edges of Duttaphrynus are granular (rough). Four species are known from Sri Lanka. These four species were previously placed in the genus Bufo. But in 2006 they were placed in the new genus Duttaphrynus based on molecular evidence (Frost et al., 2006). Two species are endemic to Sri Lanka.

Species of Duttaphrynus in Sri Lanka

Duttaphrynus kotagamai (Fernando and Dayawansa, 1994)^E
Duttaphrynus melanostictus (Schneider, 1799)
Duttaphrynus noellertii (Manamendr-Aarachchi and Pethyagoda,1998)^E
Duttaphrynus scaber (Schneider, 1799)

Duttaphrynus melanostictus is the commonest of all toads and maybe the commonest amphibian in Sri Lanka and it is easily seen in home gardens and even inside houses. Duttaphrynus melanostictus can be distinguished by the other Duttaphrynus species of Sri Lanka by the absence of a parietal ridge and by the presence of a large tympanum and large inter-paratoid warts that run up to the anterior level of parotid glands. Duttaphrynus scaber is distributed in the lowlands of Sri Lanka and can be distinguished by the other Duttaphrynus species by the presence of a parietal ridge and rounded parotid glands. Duttaphrynus kotagamai and D. noellertii are distributed in the lowland rainforests of Sri Lanka (Fernando et al., 1994; Manamendra-Arachchi and Pethyagoda,1998). Duttaphrynus kotagamai is distinguished by all the other Duttaphrynus species of Sri Lanka by the presence of a parietal ridge and and elongated and unlobulated parotid glands. Duttaphrynus noellertii can be differentiated by the other Duttaphrynus species of Sri Lanka by the absence of a parietal ridge and by the presence of a small tympanum and small inter-paratoid warts that are limited to the mid level of parotid glands.

Abbreviations in superscript

E- Endemic Species, Ex- Extinct species, Cr- Critically Endangered Species

References

Fernando, P., Dayawansa, N., Sirwardhana, M. (1994) Bufo kotagamai, a new toad from Sri Lanka. Journal of South Asian Natural History, 1: 119–124.

Frost, D.R., Grant, T., Faivovich, J., Bain, R.H., Haas, A., Haddad, C.F.B., de Sá R.O., Channing A, Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P.E., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M., Wheeler, W.C. (2006). The amphibian tree of life. Bulletin of American Museum Natural History, 297: 1-370. (Available at: http://digitallibrary.amnh.org/dspace/handle/2246/5781)

Gabadage, D.E., de Silva, A., Botejue, W.M.S., Bahir, M.M., Surasinghe, T.D., Madawala, M.B., Amarasinghe, A.A.T., Karunarathna, D.M.S.S. (2014) On the discovery of second living population of Adenomus kandianus (Günther, 1872) from Sri Lanka: with the bioecology, and detailed redescription to the species. Herpetotropicos,10: 37-49.

Jayawardena, B., Senevirathne, G., Wijayathilaka, N., Ukuwela, K., Manamendra-Arachchi, K., Megaskumbura, M. (2017) Species boundaries, biogeography and evolutionarily significant units in dwarf toads: Duttaphrynus scaber and D. atukoralei (Bufonidae: Adenominae). Ceylon Journal of Science, 46: 79-87. (DOI: http://doi.org/10.4038/cjs.v46i5.7455)

Karunarathna, .S., Henkanaththegedara, S., Gabadage, D., Botejue, M., Madawala, M., Surasinghe, T.D. (2016) Ecology and demography of the Critically Endangered Kandian torrent toad Adenomus kandianus: a long-lost endemic species of Sri Lanka. Oryx, 52: 619- 626. (https://doi.org/10.1017/S0030605316000594)

Manamendra-Arachchi, K., Pethiyagoda, R. (1998) A synopsis of the Sri Lankan Bufonidae (Amphibia: Anura) with description of new species. Journal of South Asian Natural History, 3: 213–248.

Meegaskumbura, M., Senevirathne, G., Wijayathilaka, N., Jayawardena, B., Bandara, C., Manamendra- Arachchi, K. and Pethiyagoda, P. (2015a) An assessment of the species boundaries of the Sri Lankan torrent toads (Bufonidae: Adenominae: Adenomus) Zootaxa, 3911: 245-261.

Meegaskumbura, M., Wijayathilaka, N., Abayalath, N., Senevirathne, G. (2015b) Realities of rarity: climatically and Ecology ecologically restricted, critically endangered Kandian Torrent Toads (Adenomus kandianus) breed en masse. PeerJ PrePrints, 3: e1964. (https://doi.org/10.7287/peerj.preprints.1575v1)

Wickramasinghe, L.J.M., Vidanapathirana, D.R., Wickramasinghe, N. (2012) Back from the dead: the world’s rarest toad Adenomus kandianus rediscovered in Sri Lanka. Zootaxa, 3347: 63–68.