Scholarly and authoritative book on

‘Amphibians of Sri Lanka’

By Ifham Nizam

Nearly 69 per cent of 112 amphibian species described in Sri Lanka to date are Endotrophic -completing the tadpole stage within the egg and emerging metamorphosed. Amphibian is a collective name given to frogs, toads, caecilians, salamanders and newts, says Dr. Anslem de Silva, Sri Lanka’s top herpetologist.

In general an amphibian is defined as a vertebrate animal with a moist or dry glandular skin, toes devoid of claws and usually passes through an aquatic stage before metamorphosing into the adult form.

The amphibians of Sri Lanka exhibit four habits: aquatic (e.g. Nyctibatrachidae and Ranidae), terrestrial (e.g. Bufonidae), fossorial (e.g. Ichthyophiidae and Microhylidae) and arboreal (Rhacophoridae). Nevertheless, the terrestrial forms may exhibit fossorial or aquatic tendencies and vice versa. Most endemic species belonging to these four groups are mainly found in wet zone forests, rainforests and montane forests.

Breeding activity in amphibians usually begins with some male species calling either singly or in groups at breeding sites. While each species has its own call (this is presently used as one taxonomic criterion to identify species), some do not call at all, says Dr. De Silva.

A mature female will respond to this call and approach the male (which is usually smaller than the female). The male mounts her and clasps her tight with his forelimbs; this is known as amplexus. Most males (e.g. Bufonids) usually develop a nuptial pad during the breeding season which helps them to get a firm grip of the female.

Amplexus is usually carried out in two ways: auxiliary amplexus where the male holds or grips the female just behind the fore limbs or inguinal amplexus where the male holds the female near the hind limbs. When the female begins laying eggs, the male simultaneously releases sperm to fertilize the eggs. In Sri Lanka all amphibians are known to breed through external fertilization.

Frogs, toads and caecilians have diverse ways of reproducing. According Duellman & Trueb (1986) there are at least 36 modes of reproductions known. In Sri Lanka, some lay eggs in stagnant water either as a single embryo embedded in a separate gelatinous mass and the egg cluster floats on the surface for about 24-35 hours or as long strands in water which get entangled with the aquatic vegetation (e.g. toads).

Some species of the genus Polypedates and Taruga make a foam nest above water level or on the ground close to water level and deposit their eggs in it so that the emerging larvae can drop or wriggle into the water below. Some Microhylids deposit their eggs a few centimetres above the water level inside tree holes (e. g. Uperodon nagaoi).

All toads, ranids and some species of tree frogs have an aquatic phase; these free-living larvae are known as tadpoles. Tadpoles are either surface, mid-water or bottom feeders of vegetation or scavengers. However, all known species of the Genus Pseudophilautus are endotrophic (i.e., they undergo the tadpole stage within the egg, emerging as metamorphosed imagos or diminutive frogs), with nesting taking place on the forest floor or on trees (Kirtisinghe, 1946; de Silva, 2007; Bossuyt & Dubois, 2001; Meegaskumbura et al., 2001; Bahir et al., 2005).

Most of these frogs deposit their eggs in a hole dug into the humus or under leaf litter. Pseudophilautus femoralis attaches its eggs to the underside of a leaf. Caecilians lay their eggs inside earth cavities under stones, or decaying logs and the female remains with the eggs to ‘guard’ or ‘incubate’. Meegaskumbura et al. (2007) reported a bush frog (Pseudophilautus maia) from Sri Lanka that attaches its eggs on to the ventral side of its body. However, this species is listed as an extinct species (Meegaskumbura et al., 2007).

Frogs and toads (including tadpoles) have various interesting strategies to defend themselves from predators like birds, mammals, snakes and possibly other large frogs. The most common method used by frogs is to leap away from danger. Some species even squirt a jet of ‘urine’ on the predator during the leap. On several occasions this has happened to Dr De Silva.

Dr De Silva says some frogs, especially toads, have toxins in their parotoid glands; some microhylids exude toxic, sticky and smelly white secretions from the surface of their body. Another interesting defense technique is to camouflage themselves. Some species inflate their body appearing to be several times larger than their normal size, good examples being Uperodon systoma, the Balloon frog, and the two species of genus Sphaerotheca .

Some frogs (e.g. Uperodon taprobanicus) virtually sink their head into their lower jaw and hide their head and face. Some frogs have deceiving body patterns, like Taruga eques and T. longinasus, whose cloaca appear like a mouth, the white tubercles around the cloaca appear like teeth and the spur-like calcars on the heels look like two eyes. The posterior side of Microhyla mihintalei has dark brown spots which resemble a ‘face’. Some species feign death.

Latest book on Amphibians hit the market last week

Project is lead by Regional Chairman of Crocodile Specialist Group (IUCN) for South Asia and Iran, Chairman Snake Specialist Group for South Asia and Sri Lanka Co-chair of Amphora Specialist Group, Sri Lanka Dr, Anslem de Silva, the co authors Nayana Pradeep Daundasekara and Suranjan Karunarathna also members of many IUCN Specialist Groups.

Amphibians of Sri Lanka (An annotated bibliography and a checklist of the herpetofauna of Sri Lanka) Volume 2, a hard cover book with 334 pages, 216 colour photos.

This monograph is not only a bibliography of published papers on various aspects of the amphibians of Sri Lanka, but a treasure trove for herpetologists, wildlife researchers, wildlife managers, biologists and conservationists. This monograph consists of 10 chapters with one on the biographical accounts of the three pioneer workers on amphibians of Sri Lanka: Edward Fedrick Kelaart (1819–1860), William Ferguson (1820–1887) and Parakrama Kirtisinghe (1903–1981).

The book also includes a chapter on Archaeological and Historical aspects of the amphibians of Sri Lanka, and brief accounts of locals and foreigners who have contributed to various aspects of the study of amphibians of the country. This work constitutes a key introduction to the amphibians of Sri Lanka and includes brief accounts of all known amphibians of the country, with most illustrated with a colour photograph. Additionally, it includes a list of Joint Authors] and a Systematic Index.