Classification of Amphibians: 3 Categories

In this article we will discuss about the classification of amphibians.

Sub Class (1) Labyrinthodontia (Folded Teeth):

1. The name Labyrinthodontia is derived for the structure of teeth.

2. In a cross-section the teeth shows a com­plete radiating infoldings of the enamel surface. This type of teeth is also present in rhipidistian crossopterygians.

3. The skull was massive and completely roofed by dermal bones and provided with heavily armoured bony plates.

4. The roof of the skull was composed of nasals, frontals and parietals.

5. The lower jaw was composed as many as ten elements.

6. The vertebral skeleton was composed of a series of bony vertebrae, each vertebra possessed a neural arch and zygapophyses and their vertebral construction indi­cates that they are the ancestors of rep­tiles and higher vertebrates.

7. Ribs were present in the neck vertebrae and the proximal part of the tail vertebrae.

8. The tail was absent but short and sturdy legs developed.

9. They were the first vertebrates which were able to walk on land.

The labyrinthodonts were present in Late Palaeozoic and Triassic fossils.

The labyrinthodonts were once thought to be an early tetrapod clade, now considered as a paraphyletic group.

The Subclass Labyrinthodontia is divided into two Orders.

Order (1) Anthracosauria; Order (2) Temnospondyli.

Order (1) Anthracosauria (Carboniferous — Permian):

1. The pleutpcentrum was the larger ele­ment than the intercentrum.

2. Moderately large tabular bone of the skull which articulates with the pari­etal.

The group became extinct at the close of the Permian and was represented by two groups (i) The water dwelling embolomeres e.g., Palaeoherpeton and the other group, more terrestrial seymouriamorph which had a large otic notch and a single occipital condyle (e.g., Seymouria).

They had strong limbs and had been able to walk. The intercentra were smaller than the early anthracosaurs. The terrestrial anthracosaurs gave rise to reptiles in the late Carboniferous period.

Order (2) Temnospondyli (Carboniferous— Triassic):

1. The pleurocentrum was the reduced element but the intercentrum was the dominant element in the centrum.

2. Tabular bone was small and had no contact with the parietal.

3. Tendency for the skull to become flattened and reduced through the loss of bone.

4. Double occipital condyle.

5. There were short-legged, heavy bodied, semi aquatic predators.

Examples:

Trematosaurus, Eryops (Fig. 7.33A), Rhinesuchus, Plagiosaurus, Cacops (Fig. 7.33B), Peltothorax, Gerrothorax.

Remarks:

Many authors like Colbert (1955), Romer and watson (1962), Young (1981), McFarland et al. (1985) have created a separate order Ichthyostegalia for the earliest known tetrapods—Ichthyostega, Ichthyostegopsis and Acanthostega but Duellman and Trueb (1986) placed them under different families—Ichthyostegidae for Ichthyostega and Ichthyoste gopsis, and Acanthostegidae for the genus Acanthostega without creating a separate order.

One of the earliest known tetrapods is Elpistostege, found in Upper Devonian of Canada. The known skull was intermediate between the rhipidistians and the earliest known tetrapod—Ichthyostega. Ichthyostega stensioei Saeve Soderbergh 1932, was found in the freshwater sediments in 1931 from Greenland of late Devonian or early Cretaceous.

It had a fish-like caudal fin, supported by fin-rays dorsal to the neural spines of the caudal vertebrae. Sutures are in the skull. A pre-opercular and a sub-opercular persisted on the back of the squamosal and quadratojugal bones.

The creatures were about 100 cm long and the jaws were provided with sharp, sturdy teeth, used for predation. They possessed a lateral line system. They had a short snout, strong legs and well- ossified rhachitomous vertebrae (the verte­brae possess two pairs of arch components; a larger anterior intercentrum and a smaller posterior centrum; the latter is the second “arch” component).

Subclass (2) Lepospondyli (Carboniferous — Permian) (Scale vertebrae):

1. The lepospondyles appeared in the mid­dle Carboniferous, flourished in the late Carboniferous and disappeared by the end of Permian without leaving any descen­dants.

2. They were small, ranging from less than 30 cm to 1 m in length.

3. They possessed a lepospondylous verte­bra (Gk. lepos = a scale; spondlylos = vertebra, or shell-like or spool-shaped ver­tebra).

4. The vertebra in which the centrum ossifies around the notochord is fused to the neu­ral and haemal arches.

The Subclass is divided into two Orders (i) Aistopoda and (ii) Nectridia.

Order (1) Aistopoda:

The aistopods are represented by two or three genera. They were snake-like creatures with legs reduced or lost, and probably were aquatic amphibians. They range from a few centimeters to about 1 m in length. The verte­brae were about 200. They were found in Mississippian and Pennsylvanian deposits

Example:

Ophiderpeton (Fig. 7.33C).

Order (2) Nectridia:

The group was rather a salamander-like form. Two types of lineages are discerned among nectridians. One type was a limbless or nearly limbless, snake like, with a long poin­ted skull (e.g., Urocordylus). They were fully aquatic. The other group possessed small limbs, a flattened body with horned skulls.

They were about 60 cm in length (e.g., Diploceraspis).

Order (3) Microsauria:

The group was more a salamander-like form and formerly included with aistopods and nectridians but Duellman and Trueb (1986) considered them a separate group for the following fea­tures: (i) Moderately elongated bodies with small, weak limbs, (ii) Three digits in the fore limbs and (iii) Supra temporal retained in the skull but tabular and interparietal lost (e.g., Euryodus).

Remarks:

Panchen (1972) and McFarland et al., (1985) have separated the microsaurs from lepospondyls and have suggested that they should be considered a separate group. Again this group is important because some authors postulate that the group is to be ances­tral to salamanders and apodans.

Subclass (3) Lissamphibia Haeckel, 1866 (Triassic—Recent) (Smooth amphibia) (Gk. lissos, smooth):

Characters:

1. They are smooth-skinned modern amphi­bians.

2. Vertebrae are monospondylous (i.e., want­ing separate intercentra).

3. Skull is broad and the orbits are enlarged into the cheek and temporal regions.

4. The teeth are pedicellate (fang-like).

5. A columella and operculum are present (secondarily absent in some taxa).

6. Papilla amphibiorum, a special sensory area in the inner ear, is present.

Distribution:

Lissamphibians are found throughout the tropical and temperate parts of the world.

The subclass include 3 extant orders.

Order (1) Caudata Oppel, 1811 or Urodela Latreille, 1825 [Upper Jurassic — Recent] (Gk. caudos, tail; oura, tail + delos, visible) Approx. 400 species.

Characters:

A. External:

1. Lizard-like body with a well-developed tail which assists in the progres­sion of the animal.

2. Distinct head.

3. Eyes are small and have no eyelids, but in cave dwellers (troglodytes), eyes are lost (e.g., Proteus).

4. Teeth may or may not be present.

5. Absence of tympanum but sala­manders are able to perceive the sound.

6. Many species have grooves on the sides of the body.

7. In aquatic urodeles they have lateral line system.

8. There are two pairs of weak limbs (hind limbs absent in Sirenidae).

B. Internal

Soft Parts:

1. The intestine forms several loops:

2. Respiration usually occurs by external gills in larval stages, but in adults by lungs and skin. The lungs are absent in Desmognathus where respiration is exclusively cutaneous and pharyngeal. Each lung is a simple sac-like struc­ture (Fig. 7.34).

3. The heart is amphibian type except terrestrial lung less plethodontids and in the permanently aquatic forms where inter-auricular septum and spi­ral valves are lost or reduced.

4. Usually four pairs of aortic arches are present. In cases where the gills persist in adults, accessory loops are present in the 3rd, 4th and 5th arterial arches. Fig. 7.35 shows the arrangement of the arterial arches in a larval and adult urodele.

5. An inter-ventricular septum is present in sirenids.

6. The brain is relatively simple (Fig. 7.36). The cerebral hemispheres are extremely elongated. The optic lobes are comparatively small in size.

7. The columella in the middle ear absent.

8. The kidney is opisthonephric type.

9. The urinary bladder is not bilobed.

10. The elongated testis often shows seg­mental nature.

11. The ovary is an elongated structure.

12. The oviduct is tubular. The posterior part is not dilated to form uterine chamber.

Hard parts:

1. In the skull, the cartilaginous elements are much reduced, only found in occipital region.

2. The vomer and palatine are fused forming vomero-palatine.

3. The frontal and parietal are separate.

4. An otic notch and middle ear are absent.

5. Postorbital, Jugal, post-frontal and post-parietal are absent.

6. Vertebrae may be amphicoelous or opisthocoelous.

7. The pectoral girdle is simple and com­posed mainly of cartilage (Fig. 7.37A). Two coracoids overlap one another. The scapulae are ossified.

8. There is an Y-shaped Ypsiloid bone or epipubis attached to the pubis (Fig. 7.37B).

9. Ribs are present.

Fertilization and Development:

1. Fertilization is generally internal but exter­nal in Cryptobranchoidea and presu­mably Sirenoidea. In case of internal fer­tilization, the male releases a sperm packet (spermatophore) on the ground; it has a gelatinous base and a sperm mass at the upper end. The females pick up this packet and store the sperm in cloaca.

2. A phenomenon, called paedomorphosis or paedogenesis, is found in several fami­lies which are recognised by the retention of larval characteristics including lateral line system, true teeth on both jaws, gill slits and external gills.

3. Larvae are aquatic in general but some are exclusively terrestrial (Spelerpes fuscus).

4. Some species of Salamandra and Mertensiella are ovoviviparous or viviparous.

Geographical Distribution:

Mostly in the temperate regions through­out the northern hemisphere and several are found in the tropical regions of Central and South America.

Content:

Four suborders are recognised provision­ally that include 9 living and 4 extinct families. The living families include 62 living genera with 352 species. McDiarmid (1993) reported the occurrence of 383 species under ten families. Pough, Janis and Heiser (2002) also mentioned 415 species and ten families.

Suborder (1) Karauroidea Estes, 1981:

The characters are as Karauridae Ivachnenko, 1978.

Family 1. Karauridae (Jurassic):

1. The angular is not fused with the prearticular.

2. The teeth are pedicellate.

3. Flattened skull.

4. The vertebrae are amphicoelous.

5. The ribs are bi-capitate.

Example:

Karaurus, only genus is repre­sented in the family and has collected from Kazakhstan, U.S.S.R.

Suborder (2) Sirenoidea Goodrich, 1930:

1. Eel-like aquatic salamanders.

2. They have only anterior limbs, lidless eyes and three pairs of external gills.

3. Posterior limbs and girdle are com­pletely absent.

4. They possess reduced pterygoids and prevomers and the prominent Jacob- son’s organ.

5. The angular is fused with the pre-arti­cular. Fertilization is probably exter­nal.

6. Vertebrae are amphicoelous.

7. Ribs bi-capitate.

Remarks:

The relationship is uncertain. Some authors assume that they have deve­loped from some hynobids.

It includes a single family Sirenidae.

Family 1. Sirenidae Gray, 1825:

1. Gill openings 1-3 pairs and 3 pairs external fringed gills.

2. Forelimbs with 3 or 4 toes.

3. Hind limbs and pelvic girdle absent.

4. Vertebrae amphicoelous.

5. Ypsiloid cartilage is absent.

It includes 6 fossil and 4 living paedomorphic species.

They are:

(i) Habrosaurus represented from Upper Cretaceous and Upper Palaeocene of North America.

(ii) Siren-3 gill clefts on each side and 4 fingers; two species.

Examples:

Siren lacertina (Mud eel) and S. intermedia.

Distribution:

It occurs in lakes and streams in South Eastern United States from South Carolina to Tomaulipus and North Eastern Mexico.

(iii) Pseudobranchus—is recognised by one pair of gill clefts and 3 fin­gers; single species.

Example:

Pseudobranchus striatus.

Distribution:

South Eastern United States.

Suborder (3) Cryptobranchoidea Dunn, 1922:

1. Aquatic, semiaquatic and terrestrial.

2. External gills are absent.

3. The angular and pre-articular bones of the lower jaw are not fused.

4. Vertebrae amphicoelous.

5. Ribs uni-capitate.

6. Fertilization external.

Distribution:

They occur in the eastern part of North America and in Asia including Japan, Korea, Ural Mountains to China and Turkestan.

Content:

The suborder includes 2 living families, containing 11 genera and 35 species.

Family 1:

Hynobiidae Cope, 1860 (Eastern Asiatic Land Salamanders)

1. The adults lack larval teeth, gills and gill-slits, and have eyelids.

2. Complete metamorphosis.

Distribution:

Hynobiids occur in Iran, China, Korea, Japan, Ural Mountains and Siberia.

Content:

It contains 9 genera including 36 species.

Examples:

(i) Hynobius:

Laterally com­pressed body; lungs present; teeth in both rows; feet may have 4 or 5 toes. 17 species. It occurs in Japan, Turkestan and Europe.

Examples:

H. keyserlingii occurs in Europe, Syktyvkar in the Soviet Union. Other examples are H. naevius, H. lichenatus and H. nebulosus, etc.

(ii) Onychodactylus:

Lungs absent. Larvae bear claw-like structure on their fingers and toes. Mountain stream forms; O. japonicus and O. fischeri. Both occur in North Eastern Asia. Other genera are Ranodon, Pachypalaminus, Batrachuperus, Pachynobius, Paradactylodon and Salamandrella.

Family 2. Cryptobranchiidae Fitzinger, 1826 (The Giant Salamanders):

1. Adults lack eyelids.

2. All are paedomorphic and spend entire life in water.

3. They have one pair of gill slits (absent in Andrias = (Megalobatrachus).

4. Incomplete metamorphosis.

Distribution:

Central China, Japan and eastern parts of the United States.

Content:

It contains 2 genera including 3 living and 2 extinct species.

Examples:

Andrias = (Megalobatrachus), 2 species occurs in China and Japan. The Japanese giant salamander (A. Japonicus) grows to a length of 5 feet. It is found in moun­tain streams of Japan. It possesses warts on the head and throat. It is the largest living amphibian.

The Chinese giant salamander (A. davidi- anus) is smaller and has warts on the head and throat. It occurs in the mountain stream of China.

Cryptobranchus (the Hellbender), found in the eastern parts of the United States, lives in mountain rivers. It is one and a half feet long and has no external gills. It has one species and two subspecies. C. alleganiensis with C.a. bishopi and C.a. alleganiensis.

Suborder (4) Salamandroidea Noble, 1931:

1. They are either aquatic (newts and Congo eels, Amphiuma) or terrestrial (plethodonts).

2. External gills in a few species.

3. Males have 3 sets of cloacal glands.

4. Fertilization internal.

5. No septomaxillary bone in the skull.

6. The angular is fused with the pre-­articular.

7. Vertebrae are usually opisthocoelous.

8. Ribs are bi-capitate.

Distribution:

They occur throughout the temperate Holarctic region and northern parts of South America.

Content:

The suborder includes 6 living and 3 extinct families.

Family 1. Prosirenidae:

They are known from the middle Jurassic to the middle Miocene of Europe and from the lower Cretaceous of North America.

1. The teeth are non-pedicellate.

2. Frontals fused.

3. They were small, aquatic or even fossorial salamanders.

Examples:

Prosiren, Albanerpeton, Nukusurus and Ramonellus.

Family 2. Batrachosauroididae:

They are known from Upper Cretaceous of North America.

1. The teeth are pedicellate.

2. Premaxillae are paired.

3. They were aquatic and reduced limbs.

Examples:

Batrachosauroides, Opisthotriton, Prodesmodon.

Family 3. Proteidae Gray, 1825:

1. They have 3 pairs of external fringed gills and two pairs of gill openings.

2. Appendages are provided with 3 fin­gers and 2 toes.

3. The teeth are pedicellate.

4. No maxillae.

5. Pigmented body and permanent larvae.

6. Paedomorphic aquatic salamanders.

Distribution:

The family includes two genera: (i) Proteus and (ii) Necturus. Proteus occurs in Eastern Europe and Necturus in east­ern part of North America.

Content:

2 genera including 6 living and 4 extinct species.

Examples:

Proteus anguinus (The Olm) and Necturus (the Mudpuppy). Necturus includes 5 species and one subspecies. N. maculatus (eastern half of the United States), N. punctatus (North and South Carolina).

The European olm (Proteus) is a cave sala­mander of Europe. It is found in Magdalene cave, near Adelsberg cave, Yugoslavia. They are usually viviparous, but if kept in warm place (about 15°C), sometimes they lay eggs.

The fossil genera are Mioproteus and Orthophyia.

Family 4. Dicamptodontidae:

1. They have developed limbs and eye­lids.

2. The larvae have 4 pairs of gill slits.

3. The teeth are pedicellate.

4. Semiaquatic salamanders.

Distribution:

North Western United States.

Content:

Two living genera including 8 living species.

Examples:

Dicamptodon and Rhyacotriton.

Family 5. Scapherpetontidae:

They are known from the upper Cretaceous of S. Western Asia.

Examples:

Eoscapherpeton, Horezmia, Scapherpeton.

Family 6. Amphiumidae Gray, 1825 (Congo eels or Congers):

1. Semiaquatic or aquatic forms.

2. Eel-like body and vestigial limbs.

3. They have no external gills but larval gills-slits and well-developed lungs.

4. The teeth are pedicellate.

5. They have no eyelids.

Distribution:

South Eastern United States.

Content:

There are three living and three extinct species.

Examples:

Proamphiuma (upper Creta­ceous of N. America); Amphiuma means, A. tridactylum etc.

Family 7. Salamandridae Gray, 1825:

1. Prevomerine teeth arranged in a S- shaped row on each side of the Para sphenoid.

2. Vertebrae generally opisthocoelous but a few amphicoelous.

3. Septomaxillae, lacrimals and the Ypsiloid cartilage are present.

4. The larvae have 4 pairs of gill-slits and large external gills.

5. Adults usually without gills; lungs pre­sent.

6. Eyelids present.

7. Terrestrial and aquatic salamanders.

Distribution:

They occur in N. America, Europe, N. Africa, Eastern Asia, and Asia Minor.

Content:

49 living and 15 extinct species are included in 15 genera.

Examples:

Archaeotriton (Upper Oligocene and lower Miocene of Czechoslovakia)

Brachycomus (Lower Miocene), Chioglossa (Spain and Portugal)

Martensiella (Greece, Turkey and Western Caucasus Mountains)

Pachytriton (South eastern China), Saltimandra (Europe and western Asia), S. salamandra (Central and Southern Europe, Western Asia).

Salamandrina (Northern Italy and Liguria), Taricha (North America), Triturus = Triton, 12 species (Europe, Asia Minor to Caspian sea, Ural Mountains).

Zagros newt (Neurergus) occurs in the Zagros Mountains of Ian (Fig. 7.38A). It has 3 species. N. crocatus occurs in the north­western Iran and Kurdistan provinces. N. microspilatus occurs in Lorestan Province. The habitat of these newts is closely related to shallow, cool, clear mountain streams and nearby vegetation.

In the breeding season, mating takes place close to the water. The females lay their eggs in aquatic medium. After a few weeks the larvae are found to swim in water. The duration of metamorphis from larvae to adults takes 2 months.

Tylototriton, 7 species (Darjeeling district of West Bengal to Southern China, Ryukyu Islands). Tylototriton verrucosus (Only Indian urodele).

T. andersoni occurs in the Okinawa islands in Loochoo Archipelago.

Tylototriton wenxianensis is found in China, gradually declining for the collection of medicinal purposes. It was once a common food item available in local markets, but its number at present has severely depleted.

The Chinhai Salamander (Echinotriton chinhaiensis) occurs in hilly forested areas, east of the Ningoo, Zhejiang, China (Fig. 7.38B). The salamander is completely terres­trial and they lay eggs on land, close to the ponds. The larvae develop in ponds (Cai and Fei (1984); Xie et al., (2000).

Family 8. Ambystomatidae Hallowell, 1858:

1. The angular is /used with the prearticular.

2. The premaxillae are paired and enlarged.

3. Vertebrae amphicoelous.

4. The teeth are pedicellate.

5. Palatine teeth are arranged in a nearly straight, transyerse line.

6. Fertilization is internal by means of the male spermatophores.

7. Neotenic forms with gills and lungs.

8. Eyelids present.

9. Terrestrial salamanders with aquatic larvae.

Distribution:

United States and Mexico.

Content:

32 living species are included under 2 living genera.

Examples:

Ambystoma (= Amblystoma), Alaska to Mexico, the whole northern Asia, Southern part of China. Ambystoma per-simile, only non-American species, occurs on the higher mountains of Thailand and Upper Myanmar. Ambystoma lay eggs usually in water.

The larvae have broad body with caudal fins. A. tigrinum occurs in New York to Central Mexico. It has a depressed head with a wide mouth. The body is dark brown or bluish brown with numerous spots. The abdomen is greyish in colour. The eyes are golden brown. The famous larva of A. tigrinum is Axolotl.

During spring they lay eggs in water. A. opacum, the European spotted salamander, ranges from New Jersey to Florida and Texas. It is identified by broad body with rounded snout, gular fold in the neck region, larger hind limbs than the forelimbs, black pupil in the eyes and purplish-black body. A. opacum lays in the fall on land. After laying the female protects the eggs coiling around them.

Ryacosiredon, found in the streams and rivers of the southern Mexican Plateau. There are 4 species.

Family 9. Plethodontidae Gray, 1858:

1. Lung less salamanders. They rely entirely on cutaneous respiration for all gaseous exchanges. The skin allows passage of many environ­mental contaminates.

2. Eyelids present.

3. The teeth are pedicallate.

4. Vomerine teeth forming dentigerous patches over the Para sphenoid.

5. The vertebrae are opisthocoelous.

6. Small to moderate in size (4 – 30 cm).

7. They are either aquatic or terrestrial.

Distribution:

North America, Central America, most of the South America and Southern Europe.

Content:

There are 27 general and 265 species.

Examples:

Desmognathus:

It includes 11 species ranging from Eastern Canada to Kansas, (e.g., Desmognathus fuscus). Eurycea and Cyrinophilus (Eastern North America) are entirely neotenic. Nototriton (Guatamala to Costa Rica); Bolitoglossa and Chiropterotriton extend from Mexico to South America.

Plethodon occurs in eastern and western United States, and found by day under logs or within rock crevices. Typhlomolge, Texas Blind Salamander, is found in deep caves and wells of Texas, U.S.A. It has a single species T. rathbuni. Hydro mantes occurs in Italy and a part of southern France.

Systematic status of Urodela:

The systematic status of urodela is contro­versial due to their peculiar anatomical orga­nisation. Anatomically, urodeles form a transi­tional group between the fishes and amphi­bians. They show structural similarities with the fishes in one hand and with the amphi­bians on the other.

Relationship with fishes:

Urodeles exhibit the following piscine features.

These are:

(1) Presence of immo­vably fixed tongue.

(2) The lateral line sense organ is present.

(3) The gills are present.

(4) The circulatory and excretory systems show many similarities.

(5) The tympanum is absent.

Besides these typical piscine features, the urodeles show some similarities with crossopterygians.

The resemblances are:

(1) The presence of cutaneous gills,

(2) Similar girdles,

(3) Similarly venous system,

(6) First spinal nerve is without dorsal root and

(7) The ypsiloid bone of urodele is comparable to the epipubic bone of the Dipnoans. The similarities with the fishes in general and with the crossopterygians in parti­cular speak of their phylogenetic relationship.

Relationship with amphibians:

The urodeles are included in the Order Urodela under the Class Amphibia. This fact needs no consideration, because the organisa­tion of the brain, circulatory system, skull and visceral arches are typically amphibian in nature.

Amongst the amphibians, the urodeles are to be regarded as a most primitive group than the apodans and anurans because the position of the quadrate and walking gait jus­tify the truth. The primitive characters of the urodeles are due to their retention of the larval features.

Within the Order Urodela a gradation of organisation is observed:

Grade I:

Urodeles with persistent gills (Per-ennibranchiate condition), e.g., Necturus, Proteus and Siren.

Grade II:

Absence of gills and presence of only gill-slits in adults (Derotrematous condi­tion) represents the transitional stage, e.g., Amphiuma.

Grade III:

Absence of gills and gill-slits in adults (Cauducibranchiate condition) is the most advanced forms, e.g., Andrias, Salamandra, Triturus.

Order (2) Gymnophiona Rafinesque, 1814 (Apoda, Caecilia) (Jurassic — Recent) (Gk. gymnos, naked, ophioneos, of a snake; a, without +podos, foot) Approx. 165 species.

General Characters:

A. External Features:

1. Worm-like, elongated, limbless bur­rowing creatures.

2. Body smooth, slimy and segmented by a series of annular grooves within which small, granular dermal scales are embedded in many caecilians (e.g., Uraeotyphlidae, Typhlonectidae and Caeciliidae. Scales are not found in the Indian genus Cegenophis and in the American Siphonops, Typhlonectes, Chthonerpeton and Bdellophis.

3. The tail, if present, is short; conical but a flattened tail in American genus, Typhlonectes.

4. Lidless reduced eyes covered by the skin or by the maxillary bones.

5. A peculiar conical, flap-like, protrusible sensory tentacle in between nostril and eye and lodged in a small pit on each side of the head. The pits get secretion from well-developed harderian glands. The tentacle is likely a chemosensory organ and helps the animal to detect the presence of prey in underground condition.

6. A single median protrusible copulatory organ (Phallodeum) in males, can be protruded through the cloaca, an indication of internal fertilization.

7. Both the tympanum and tympanic cavity absent.

8. Tongue is fused with the floor of the mouth cavity.

B. Internal characters:

(a) Hard parts:

9. Vertebrae amphicoelous with persis­tent notochord and the number ranges from 200-300.

10. No sternum. Pectoral and pelvic gir­dles absent.

11. Skull solid, compact and fusion of some elements e.g. maxilla and pala­tine into maxillopalatine.

12. Maxilla large and broad. A prefrontal is present.

13. Squamosal fused with the quadratojugal.

14. Frontal and parietals separate.

15. Columella (stapes) absent or large and stirrup-shaped.

16. Teeth on the premaxilla, maxilla-pala­tine, vomer and dentaries.

17. The orbit is small and encircled by postfrontal.

(b) Soft parts:

18. Straight intestine in some forms.

19. Conus arteriosus lacks spiral valve and possesses one or two rows of valves.

20. Asymmetrical lungs; only the right part well-developed.

21. Only pulmonary and systemic arches persist. Carotid arises from the sys­temic.

22. Ductus arteriosus (connecting lateral vessel between systemic and pulmo­nary arches) is present.

23. Presence of functional Mullerian ducts in males.

24. Elongated sac-like paired ovaries.

Development:

25. Fertilization may be external (e.g., Rhinatrema) or internal (e.g., Caecilia (Fig. 7.39A and B), Hypogeophis, Ichthyophis (Fig. 7.40).

26. The eggs are large and yolky.

27. Cleavage is meroblastic.

28. Most of the primitive caecilians are oviparous but some advanced caeci­lians are viviparous (e,g., Typhlonectes). As the eggs are laid on land, the embryos grow by utilizing the yolk.

29. Free living larval stages are seen in the primitive family — Ichthyophidae.

30. Ichthyophis burrows near about a stream and larvae hatch from the eggs, and wriggle into the stream.

31. Larvae of Ichthyophis are characte­rized by the presence of long, fringed triramous gills.

32. A lateral line and an adult type dention is present in the larvae of Ichthyophis.

33. Egg laying of Ichthyophis glutinosus in Ceylon (Sri Lanka) occurs from July through September but Seshachar (1936) has recorded from December to March.

34. A phenomenon, called tachygenesis, (that is rapid elimination of ancestral characters by acceleration of develop­mental stages) is found in some apodans.

Fossil History:

Due to subterranean mode of life, no fossil representatives are found except single apodan fossil Eoceacilia, has been collected from the early Jurassic in western North America (Pough et al., 2000).

Habitat:

Caecilians generally occur in moist and damp areas under stones and rocks except Typhlonectes, which is an inhabitant of river. Chthonerpeton and Siphonops are found in the sites where human wastes are thrown. Some caecilians such as Ichthyophis, and Schistometopum are seen to live in the cleared land that is used for crop cultivations like tea and coffee plantations, and rice fields.

Generally it is difficult to find in their natural habitats. They may be seen when rains come. According to Honegger, caecilians prefer gra­vel ground which may be moist or thoroughly wet. He reported that all specimens are found at depths of 20 to 30 cm beneath the top soil.

Food:

Apodans feed on earthworms, arthropods, small vertebrates including snakes.

Geographical Distribution:

Gymnophionas are restricted throughout Tropics except Europe, N. America, Madagascar and Australasia. Unusually they are common in Seychelles Islands.

Content:

Neiden (1913) reported 19 genera and about 55 species. He included all caecilians under a single family Caecilidae. Recently American scientist E. H. Taylor (1969) revised the whole group.

He differentiated it into 4 families:

(i) Ichthyophidae

(ii) Caecili­dae

(iii) Typhlonectidae and

(iv) Scolecomorphidae.

Duellman and Trueb (1986) recog­nised 6 families including 34 living genera and 162 living and one extinct species.

Pough et al., (1996) classified caecilians into 6 families which include 165 species.

Remark:

Nassbaum (1979) considered that the subfamily Uraeotyphlinae of the fami­ly Uraeotyphlidae is the sister group of the higher caecilians (i.e., Scolecomorphidae, Caeciliidae and Typhlonectidae) and the Ichthyophiinae is the sister taxon of the Uraeotyphlinae and higher caecilians. But Frost (1985) suggested the rank of Uraeo­typhlinae as subfamily under Ichthyophidae.

Family 1. Ichthyophidae Taylor, 1958:

The length of the body is about 500 mm. They have a tail and a sub-terminal mouth. The tentacular opening is in between the eye and nostril. Some are grey or black; others have pale stripes laterally. The aquatic larvae have one or two gill openings.

Geographical Distribution:

India, Sri Lanka, Philippines, Sumatra and Borneo.

Content:

2 genera and 36 species are included.

Caudacaecilia (5 species, Malaya, Phili­ppines, Sumatra and Borneo) and Ichthyophis (30 species; India, Sri Lanka, Philippines and Indonesia). I. sikkimensis = (I. glutinosus) (Darjeeling, Sikkim).

Family 2. Uraeotyphlidae Nussbaum, 1979:

The length of the body is about 300 mm. They have a tail and a ventral mouth. The ten­tacular opening is below the nostril. They are dull grey to brown. Oviparous.

Geographical Distribution:

South India, Sri Lanka.

Content:

Single genus with 4 species e.g., Uraeotyphlus. Uraeotyphlus malabaricus (S. India).

Family 3. Scolecomorphidae Taylor, 1969:

The length of the body is moderate, and it attains about 440 mm. They have no tail with a recessed mouth. The dorsal side of the body is black or brown. Possibly viviparous.

Geographical Distribution:

Mainly from Cameroon and Tanzania.

Content:

Single genus includes 5 species, e.g., Scolecomorphus = Bdellophis.

Family 4. Caeciliidae Gray, 1825:

The length of the body ranges from 100 mm to 1500 mm. They have no tail and a recessed mouth. The tentacular opening is ante­rior to the eye. Most are dull grey or black but some are striped. Oviparous and viviparous.

Geographical Distribution:

They are restricted to the Tropical regions of Central and South America, Sub-Saharan Africa, India and Seychelles Islands.

Content:

There are 24 living genera con­taining 89 living species. Some of the genera are Caecilia (Northern South America and eastern Panama); Microcaecilia (Guatmala); Parvicaecilia (Northern Colombia); Afrocaecilia (Kenya and Tanzania); Brazilotyphlus (Brazil); Dermophis (Southern Mexico to Colombia); Cegenophis (South India); Geotrypetes (Ethiopia and tropical south west Africa); Grandisonia (Seychelles Islands); Herpele (Tropical west Africa); Hypogeophis (Seychelles Islands); Indotyphlus (Maharashtra, India); Praslinia (Seychelles Islands); Siphonops (Tropical South America).

Family 5. Typhlonectidae Taylor, 1968:

The length of body is over 700 mm. They have no tail and the mouth is recessed. The body of the posterior part is laterally com­pressed. The colour of the dorsal part of the body is grey to brown or bluish black. The small tentacle is situated behind the nostrils. They are completely aquatic. Viviparous.

Geographical Distribution:

They are found in South America.

Content:

There are 4 genera with 22 species.

Chthonerpeton (Argentina and Brazil); Nectocaecilia (Amazon Basin); Potomotyphlus (South America); Typhlonectes (South America).

Family 6. Rhinatrematidae Nussbaum, 1977:

The length of the body is about 300 mm. They have a tail and a terminal mouth. The tentacle is adjacent to the eye. Yellow stripes are present on the lateral side of Rhinatrema.

Geographical Distribution:

South America.

Content:

There are 2 genera with 9 species. Epicrionops (Venezuela to Peru); and Rhinatrema (North Eastern South America).

Key to Genera of Gymnophiona in India (Revised by E. H. Taylor, 1961):

1. Tentacle closer to eye than to nostril or equal.

Tentacle closer to tip of snout than to eye.

2. Anal opening transverse; the tentacle cone shaped, on a level with a line between eye and nostril; no tail; 144 vertebrae; splenial teeth present.

……………. Indotyphlus Taylor, 1960.

Anal opening longitudinal; tentacle near edge of lip below level of a line between eye and nostril; tail present; vertebrae not over 125; splenial teeth present or absent.

……….. Ichthyophis Fitzinger, 1826.

3. Squamosal and parietal bones of skull separated by a diastema. Tentacle flap-like situated almost directly below nostril near mouth; orbit circular enclosed; tail region wider than body.

……….. Uraeotyphlus Peters, 1879.

Squamosal and parietal bones forming a common suture.

4. A single row of teeth in lower jaw. No splenials

………….. Gegenophis Peters, 1879.

Two rows of teeth in lower jaw; eyes covered over by bone; tentacle conical some­what behind nostril but below its lower level.

……………. Herpele Peters, 1879.

Hitherto known Herpele fulleri (Assam) is now transferred to the genus Gegenophis fulleri.

Key to Indian species of Ichthyophis [From E. H. Taylor, 1961]:

1. A lateral stripe of cream or yellow on each side of body from head to tail;

……………… 2

No lateral stripe of cream or yellow on side of body; usually less than 20 splenial teeth on each side. 4

2. Abdomen uniform brown lavender to plumbeous; position of tentacle variable.

……. 3

Abdomen with a broad white or yellow mid ventral stripe; tentacle near lip and nearly equidistant from eye and nostril; transverse folds 245 – 275; tail length is 56.5 times in males and 60 times in females as compared to the total body length tricolor Annandale, 1909

Distribution:

Maddathori, Western Ghats, Cochin.

3. Tentacle nearly equidistant from eye and nostril; lateral yellow stripe widens in region of throat; transverse folds about 240-293

……………… beddomii Peters, 1879

Distribution:

Nilgiris.

Tentacle near lip, much closer to eye than to nostril; lateral stripe not wider in region of throat; ventral folds about 300 – 400.

………… glutinosus vars

4. Number of folds on tail less than 10; body folds less than 300; tail length in total length about 50 times. 9 to 10 splenial teeth on each side; scales sparse or anteri­orly.

……………sikkimensis Taylor, 1960

Distribution:

Darjeeling.

No. of folds on tail more than 10, on body usually more than 300; tail length less than 30 times.

…………5

5. Splenial teeth 4 or less on each side; 18 transverse folds on tail; vertebrae 116; abdomen light coloured; total length, 330 mm.

………………….peninsularis Taylor 1960

Distribution:

Malabar Coast. Splenial teeth 5 or more on each side in adults; 14 – 18 tail folds.

……….6

6. Mandibular teeth 26-28; tail in total length about 23.5 times; vertebrae 111; abdomen creamish or yellowish; total length 494 mm.

……………. malabaricus Taylor, 1960

Distribution:

Maduvangard, Travancore.

7. Mandibular teeth 20 – 22; splenial teeth 9 – 9; 14 tail folds; tail length in total length 25.6; abdomen brownish; total length 390 mm.

………………. bombayensis Taylor, 1960

Distribution:

Waghai, Surat, Gujarat.

Mandibular teeth very large 17 – 17; sple­nial 10-10; 18 tail folds; transverse folds 356-364; scales anteriorly; abdomen dark lavender brown; total length 295 mm,

………… subterrestris Taylor, 1960

Distribution:

Kottayam, Travancore.

Number of Indian Caecilian species:

21 species of caecilians under 4 genera and 3 families so far known from India, mainly concentrate in the Western Ghats but also in the Eastern Ghats and N. Eastern India (Ravichandran, 2004).

20 species and 3 genera are Indian endemics, 13 of these endemic species are restricted to the Western Ghats and the majority species are found in the Kerala side of the South Western Ghats. Indian species represents 12.73% of the 165 species of the group reported globally.

Systematic position:

The systematic position of apodans has not been ascertained correctly because their fossil representatives are not enough due to subterranean mode of life. Sarasin supported Cope’s view that their nearest relatives are ‘Amphiuma’ in Urodela. They considered that Amphiuma represents a neotenic form of the Caeciliidae which they divided into Amphiumidae and Caecilidae, both of them under the Suborder Urodela.

Their conclusion is based on the following points:

(i) In both cases the mode of egg laying habit is same.

(ii) A vestigial tentacular structure occurs in Amphiuma.

(iii) An ethmoid bone is present in Amphiuma like the Caecilidae.

But Davidson (1895) did not support the above contention and pointed out that ethmoid bone is not found in Amphiuma.

Gadow, H. (1901) considers that caecil­ians retain both primitive and specialized characters.

The primitive characters are:

(i) cutaneous scales with calcareous incrustations resembling the Carboni­ferous Lepospondyli.

(ii) retention of post frontal (Ichthyophis), an ectopterygoid (Hypogeophis), lacrymal bone and gill clefts.

These primitive features suggest that apo­dans should not be included with other groups of amphibians. This group is more primitive than Urodela or Anura.

According to H. H. Newman (1939), the apodans are highly specialized for a burrow­ing life and are decidedly degenerate in many respects and they are regarded as the most primitive of modem Amphibia.

They resemble other amphibians for the structure of the heart, specially the conus arte­riosus in the heart, organization of the brain, absence of the tympanic cavity and the dispo­sition of urinogenital system.

But they differ from other groups of amphibians for the lack­ing of limbs, presence of dermal scales in the skin, presence of ductus Botalli and copulatory organ and a large macrolecittal egg with meroblastic cleavage, and the absence of gill- breathing larva.

They also possess some peculiar features by the absence of limbs and limb girdles, reduced eyes, presence of retractile sensory tentacle and the carotid artery arising from the systemic.

For the above features, recent herpetologists like Noble (1931), Colbert (1955), Coin and Goin (1960), Romer and Watson (1962), Young (1981), McFarland et al, (1985), Duellman and Trueb (1986), Pough et al, (1996) and Kardong (2002) have placed the apodans under a separate Order Gymnophiona (Apoda, Caecilia).

Superorder Salientia Laurenti, 1768 (L. saliens, leaping + ea, pi. suffix):

Characters:

1. Primitive salientians possess a short tail.

2. In anurans the caudal vertebrae are fused and form a rod-like structure, called urostyle.

3. The proximal tarsal elements are elon­gated.

4. Teeth are absent on the dentary in most forms except in one species.

5. Pterygoid usually triradiate.

Examples:

Triassic frog-like Triadobatrachus and the anurans.

Order (3) Proanura:

The characters are similar to Protobatrachidae.

Family Protobatrachidae:

This Family is represented by an impres­sion of the skeleton from the Lower Triassic of Madagascar.

Characters:

1. The skull was broad and frog-like with large orbits.

2. Short vertebral column.

3. Ilium extends forward.

4. There is no urostyle by the fusion of the posterior vertebrae.

Example:

Triadobatrachus.

Order (4) Anura Rafinesque, 1815 (Salientia) [Jurassic — Recent] [Gk. an = without + oura = tail] Approx. 3850 species.

Characters:

The modern extant toads and frogs are included under this order.

A. External:

1. Anurans are short, four legged and stout bodied animals.

2. Post anal tail is absent.

3. The posterior limbs are longer that possess 4 segments and help in long leap.

4. Well-developed eyelids.

5. Distinct tympanum.

6. Tongue may be present or absent (Family Pipidae).

7. Wide mouth and large eyes that are situated well ahead of the head, giv­ing binocular vision.

8. There is no trace of external gills and gill-slits.

B. Internal:

Hard Parts:

1. Mandible is devoid of teeth.

2. Frontal and parietal bones are joined to form a single bone, called fronto­parietal.

3. Pterygoid is usually triradiate and para- sphenoid bears lateral alae posteriorly.

4. The vertebral column consists of 5-9 pre-sacral vertebrae.

5. Vertebrae always bear zygapophyses and transverse processes except the first-atlas.

6. The post sacral vertebrae are fused into a rod, urostyle.

7. The tibia and fibula (= astragulus and calcaneum) are fused at least proximally and distally.

8. The ilium is elongated and extends far anteriorly.

Life History:

1. Fertilization is external except Ascaphus, Eleutherodactylus and Nectophrynoides.

2. Reproductive behaviour is associated with vocalizations, mostly in males.

3. Most anurans breed only during or shortly after a rain and deposit their jelly-encapsu­lated eggs in water-filled ditches or ponds.

4. Some species lay eggs on land but have aquatic tadpoles. .

5. Terrestrial eggs develop directly into frogs.

6. Many species of adult anurans exhibit parental care by guarding or transporting the eggs or tadpoles.

7. Tadpoles of some anurans are filter-fee­ding herbivores and some are carnivorous.

Distribution:

Throughout world except extreme cold and drier parts.

Fossil History:

The fossil record beginning in the Jurassic of Madagascar, Europe, North America and South America extends through the Pleistocene.

Content:

Noble (1922, 1931) based his classification of anurans chiefly on the nature of the intervertebral joints that were derived from the work of Nicholls (1916). The classi­fication of anurans here includes 21 living and one extinct family that contain 301 living genera with 3438 species (Duellman and Trueb, 1986). Pough, janis and Heisor (2002) mentioned 4300 species under 27 families.

Family 1. Liopelmidae Mivart, 1869:

1. Most primitive anurans.

2. Vertebrae is amphicoelous.

3. Interdorsal and interventral remain cartilaginous.

4. Nine free presacral vertebrae.

5. Tail waggling muscles are present, though tail is not found.

6. No tympanum.

7. Semiaquatic, aquatic or terrestrial frogs.

Distribution:

New Zealand and North Western United States.

Content:

The Family contains two living and two extinct genera.

Examples:

Liopelma, an endemic genus of New Zealand includes three species. Small, greyish, sometimes scattered browns, yellow or pinks. It occurs in the montane uplands of New Zealand. They lay eggs on the damp ground and the frog lets develop within the egg.

Liopelmid frogs are very secretive and scarce. Of three species Archey’s frog (Liopelma archeyi) is declining in Coromondal Range, and on Tapu Ridge. Another species L. hochstetteri is also more or less available in the breeding grounds of New Zealand.

Ascaphus is known as “Bell toad” and includes a single species and possesses a cloacal extension, apparently acts as an intromittent organ during copulation. They are found in the cold mountain streams of Western North America. A. truei is about 3-10 mm in length.

Fertilization internal:

The extinct genera are Notobatrachus (Late Jurassic of Argentina) and Vieraella (Jurassic of Argentina).

Family 2. Discoglossidae Giinther, 1859 (Disc tongued):

1. Free sacral vertebrae with biconvex centrum.

2. Pre-sacral vertebrae always 8.

3. Vertebrae opisthocoelous.

4. Tongue and eyelids present.

Distribution:

They are found in Eurasia, Philippines and Borneo.

Content:

5 living genera contain 14 spe­cies and 8 extinct genera include 11 species.

Examples:

Alytes (Western Europe), 2 species, A. obstetricans is known as Midwife toad. A. cisternasi is also called Spanish mid­wife toad. Baleaphrysie (Spain, Balearic islands), 1 species. Bombina (= Bombinator) [Europe, Turkey, Western U.S.S.R. and Eastern Asia), 6 species, B. igneus (Fire bellied toad) is restricted to northern parts of Europe.

They are recognised by dark or olive black in upper parts, and lower parts olive black or orange.

Males are smaller than the females and have internal vocal sacs. Discoglossus is recognised by indistinct tympanum. Pupil round or triangu­lar, long legs, tapered head and smooth shiny skin, 3 species restricted to Southern Europe and Northern parts of Africa. Barbourula is found in Northern Borneo and Philippines.

Family 3. Rhinophrynidae Giinther, 1859 is known as ‘Mexican burrowing frog’, recognised by stout body, smooth skin, short limbs and small head. The well-developed inner metatarsal tubercle is employed in burrow. 1 species, Rhinophrynus, Texas and Mexico to Costa Rica.

Family 4. Palaeobatrachidae, (5 extinct ge­nera). Examples Palaeobatrachus (Europe), Albionbatrachus (England), Lithobatrachus (Europe), Pliobatrachus (Germany).

Family 5. Pipidae Gray, 1825:

1. Presacral opisthocoelous vertebrae are 5 to 8.

2. Sacrum fused to the coccyx (Urostyle).

3. Tongue absent, hence called aglossal toad.

4. Eyelids ill developed or absent.

5. Free ribs in the larva but joins to the diapophyses during metamorphosis.

6. Some species of Pipa have aquatic larvae. Direct development is seen in some other species of Pipa.

7. Specialized aquatic frogs.

Distribution:

They are found in Africa (South of Sahara) and South America.

Content:

30 living species are included under 4 living genera. 6 extinct genera also reported.

Examples:

Cordicephalus (Cretaceous of Israel); Eoxenopoides (Upper Eocene or Oligocene of South Africa); Hymenochirus (4 species, found in tropical Africa); Pipa (7 species; Venezuela to Brazil and Peru, Eastern Panama). Pseuhymenochirus (Western Africa), 1 species; Saltenia (Upper cretaceous of Argentina); Shomronella “(Lower Cretaceous of Israel); Thoraciliacus (Lower Cretaceous of Israel); Xenopus (SubSaharan Africa, 14 species).

Xenopus is used in the diagnosis of human pregnancy. After the injection of the patient’s urine, the female frog will respond by spawning within a few hours. Xenopus laevis is known as ‘Clawed toad’. The three inner hind toes provide black horny claws. Other species are X. mueileri, X. calcaratus, X. tropicalis, etc.

Xenopus laevis spends the whole life in aquatic medium and a question may arise in the meaning of “Amphibibia” (spends life in both different media).

Family 6. Pelobatidae Bonaparte, 1850 (Spade foot toads):

1. 8 pre-sacral vertebrae.

2. Pre-sacral vertebrae is uniformly procoelous.

3. Sacrum fused to coccyx (mono-condylar articulation with the coccyx) in megophryines.

4. Arciferal pectoral girdle (with the pro-coracoid cartilages overlapped) with a cartilaginous omosterum and sternum.

5. Tongue protrusible.

6. Astragalus and calcaneum fused com­pletely and three tarsalia.

Distribution:

Pelobatines occur in Europe, Western Asia, North Africa, North America to Southern Mexico. Megophryines (about 80 species) are restricted to India, Sri Lanka, Western China and Philippines.

Content:

3 subfamilies are recognised of which two are living and one is extinct. Two living subfamilies contain 9 genera that include 83 living species. The extinct sub­family contains three genera.

Examples:

Subfamily 1:

Eopelobatinae includes (i) Aralobatrachus (Cretaceous of Uzbekistan) (ii) Eopelobates (Early Eocene to early Oligocene of North America) and Kizylkuma (Cretaceous of Uzbekistan).

Subfamily 2:

Megophryninae contains 7 gen­era. Atympanophrys (1 species, China); Brachytarsophrys (1 species, South Western China, Myanmar and Thailand); Leptobrachella (6 species, Borneo) and Leptobrachium (11 species; India, Southern China, Philippines, Sunda Islands to Bali).

In India, Leptobrachium is represent­ed by a single species; L. hasselti, recorded from Khasi Hills. Lepto- lalax (4 species, Southern China, Malaya and Borneo); Megophrys (21 species; South-eastern Asia includ­ing India); Scutiger (29 species; India to Southern China) and Megophrys is represented by 4 species in India, namely M. parva, M. lateralis, M. monticola and M. boettgeri. Megophrys is found in W. Bengal, Arunachal Pradesh, Assam and Sikkim. Scutiger occidentalis, S. sikimmensis occur in Jammu and Kashmir, Sikkim and W. Bengal. Megophrys monticola nasula is known as horned toad.

Subfamily 3:

Pelobatinae includes 3 genera of which one is extinct. Macropelobates (Oligocene of Mongolia); Pelobates (4 species, Europe, Western Asia and North Western Africa) is recognised by inner tarsal tubercle shovel shaped, toes webbed and tympanum absent. P. fuscus insubricus (Northern Italy), P. syriacus (Asia Minor). Scaphiopus (6 species, N. America and Mexico) is recognised by subgular vocal sac and hidden tympanum.

Family 7. Pelodytidae Bonparte, 1850:

1. 8 presacral vertebrae with procoelous centra.

2. Arciferal pectoral girdle with a carti­laginous omosternum and bony ster­num.

3. Sacrum is not fused with the coccyx and has a bicondylar articulation with the coccyx.

4. Small terrestrial frogs with aquatic lar­vae.

Distribution:

They are found in Western Europe and South Western Asia.

Remarks:

Some authors like Noble (1924) placed Pelodytes under the family Pelobatidae. Boulenger (1899) and Noble (1924) traced that Scaphiopus, Pelobates and Pelodytes are closely allied.

Content:

Two extinct genera and one extant genus with two living species.

Examples:

Miopelodytes (Miocene of U.S.A); Pelodytes (2 species, Western Europe and Caucasus Mountains). Pelodytes is recog­nised by lacking of tarsal digging spur; tympa­num not fully disposed and long hind limbs with toes frog-like. P. punctatus (France and Portugal).

Family 8. Myobatrachidae Schlegel, 1850:

1. 8 presacral vertebrae.

2. Arciferal pectoral girdle with a carti­laginous omosternum (absent in Myobatrachus and Notaden) and ster­num.

3. Astralgalus and calcaneum fused proximally and distally, and two tarsalia.

4. Aquatic and terrestrial frogs.

Distribution:

They inhabit in Tasmania, New Guinea and Australia.

Content:

The family includes two subfam­ilies, 20 living genera and 120 species.

Examples:

Adelotus (1 species, Australia); Heleioporus (6 species, Australia); Kyarranus (3 species, Australia); Lechriodus (4 species, New Guinea, Australia); Limnodynastes (12 species, Tasmania, New Guinea and Australia); Megistolotis (1 species, Australia); Mixophys (4 species, Australia); Neobatrachus (7 species, Australia); Notaden (3 species, Australia); Philoria (1 species, Australia). The above ten genera are included under the sub­family Limnodynastinae.

The other subfamily Myobatrachinae includes 10 genra. These are Arenophryne (1 species, South Western Australia); Assa (1 species; Australia); Crinia (13 species, Australia); Geocrinia (5 species, Tasmania, Australia); Myobatrachus (1 species, Australia); Paracrinia (1 species, Australia); Pseudophryne (10 species, Tasmania, Australia); Rheobatrachus (2 species, Australia); Taudactylus (5 species, Australia); Uperoleia (18 species, Australia). From India a fossil frog has been recorded during Eocene period and named Indobatrachus.

Family 9. Heleophrynidae Noble, 1931:

1. 8 pre-sacral vertebrae.

2. Arciferal pectoral girdle with a carti­laginous omosternum and sternum.

3. Solid procoelous vertebrae.

4. T-shaped terminal vertebrae.

5. Maxillary teeth.

6. Aquatic larvae.

Distribution:

South Africa.

Content:

The family contains single genus with 3 species.

Example:

Heleophryne.

Family 10. Sooglossidae Noble, 1931:

1. 8 presacral vertebrae.

2. Free coccyx.

3. A cartilaginous omosternum and bony sternum.

4. Digits terminating in small, pointed discs.

Distribution:

Seychelles Islands.

Content:

2 genera contain 3 species.

Examples:

Nasomantis (1 species); Sooglossus (2 species).

Family 11. Leptodactylidae Werner, 1896 (1838):

1. 8 presacral vertebrae with procoelous centra.

2. Coccyx free.

3. Sacrum has rounded diapophyses.

4. Ribs are absent.

Distribution:

They occur in most of the South America, Southern North America and the West Indies.

Content:

51 living genera contain more than 900 living species.

Examples:

Some of the genera are — Ceratophrys, Lepidobatrachus, Eleutherodactylus, Crossodactylus, Leptodactylus, Physalaemus, Pleurodema etc.

Family 12. Bufonidae Gray, 1825:

1. Warty skin with parotoid glands behind the eyes.

2. 5-8 pre-sacral vertebrae.

3. Free sacrum.

4. Transverse process absent in coccyx.

5. Sternum bony or cartilaginous.

6. Omosternum absent (except Nectophrynoides, Werneria and Bufo).

7. Most species are terrestrial and have short legs.

8. Presence of Bidder’s organ except in Dendrophryniscus.

9. Jaws are toothless except Notaden which has vomerine teeth.

Distribution:

Cosmopolitan in temperate and tropical regions except Madagascar, Australia, some Oceanic Islands and Antarctica, though Bufo marinus has been introduced into Australia by man.

Content:

There are 25 genera that include 400 living and 20 extinct species.

Examples:

Some of the genera are — Ansonia (17 species, South India, Malay Peninsula, Philippines and Borneo). A. ornata and A. rubigina occur in Karnataka and Kerala. Bufo (205 species; cosmopolitan except New Guinea, New Zealand, Australia).

16 species have been recorded in India of which B. viridis, a migrant of Europe, is abun­dant in Kashmir and also occurs at an eleva­tion of 500 m in the Himalayas. B. melanostictus is very common throughout India. Bufoides (1 species, Meghalaya, India).

Nectophrynoides (8 species, East Africa) is only viviparaous anurun in the world. Pedostibes (6 species; South India, Malay Peninsula, Sumatra and Borneo). P. kempi occurs in Meghalaya and P. tuberculosus is also found in Kerala. Bufo taitanus beiranus (.94″) of Mazambique (Africa) is the smallest toad in the world.

Family 13. Brachycephalidae Gunther, 1859:

1. 7 procoelous presacral vertebrae.

2. Free coccyx without transverse pro­cesses.

3. Omosternum and sternum absent.

4. Pectoral girdles fused partially or fully in the midline.

5. Aquatic tadpoles presumably absent.

Distribution:

Southeastern Brazil.

Content:

2 genera with five species.

Examples:

Brachycephalus and Psyllophryne.

Family 14. Rhinodermatidae Bonaparte, 1850:

1. Procoelous presacral vertebrae.

2. Omosternum and sternum cartilagi­nous.

3. Lacking digital scutes or dilatations.

4. Coccyx free with transverse processes.

5. Skull weakly ossified.

6. Indistinct tympanum.

Distribution:

Chile and Argentina.

Content:

Single genus contains two species.

Example:

Rhinoderma darwini.

Family 15. Pseudidae Fitzinger, 1843:

1. 8 solid procoelous presacral vertebrae.

2. Cylindrical dilated sacral diapophyses.

3. A cartilaginous sternum.

4. Maxillary teeth.

5. Aquatic frogs with large tadpoles.

Distribution:

South and Central America, and West Indies.

Content:

Two genera contain 4 species.

Examples:

Lysapsus (2 species); Pseudis (2 species).

Family 16. Hylidae Gray, 1825:

1. 8 procoelous presacral vertebrae.

2. Coccyx free.

3. Claw shaped phalanges.

4. Dilated sacral diapophyses.

5. The phalanges are increased by the addition of a short, cartilaginous inter­calary element between the penulti­mate and terminal phalanges (ossified or absent in Cyclorana).

6. Teeth in the upper jaw.

7. Distinctive toe pads present.

8. Some are aquatic, terrestrial and arbo­real.

9. Larvae are mostly aquatic.

Distribution:

North and Central America, South America, West Indies, India, Austra­lasian region, Japan and Northern Africa.

Content:

37 living genera contain 760 species.

Examples:

Some of the genera are Cyclorana (= Chiroleptes) (13 species; Australia); Litoria (106 species; New Guinea, Solomon Islands, Australia, Tasmania, Timor, Bismarck Archipelago); Pachymesuda (1 species; Mexico); Phyllomedusa (33 species, South America); Hyla (251 species; North, Central and South America, India, North of Sahara); Castrotheca (37 species; Venezuela to northern Argentina, Brazil and Panama), etc.

Hyla annectans (Only Indian Hyla, found in some parts of Meghalaya and Assam).

Family 17. Centrolenidae Taylor, 1951:

1. 8 procoelous presacral vertebrae.

2. Free coccyx without transverse pro­cesses.

3. Pectoral girdle with a sternum but no omosternum.

4. Terminal phalanges are T-shaped.

5. Skin of the abdomen is transparent.

6. Mostly small arboreal frogs with aquatic larvae.

Distribution:

Mexico to Bolivia, Argentina and Panama.

Content:

Two genera containing 130 species.

Examples:

Controlene and Centrolenella.

Family 18. Dendrobatidae Cope, 1865:

1. 8 procoelous presacral vertebrae.

2. Omosternum present.

3. A pair of dermal scutes on the upper surface of each digit forming adhesive pads.

4. Eggs are laid on land that hatch into tadpoles and are transported to water by an adult.

Distribution:

Northwestern South America.

Content:

There are 4 genera containing 117 species.

Examples:

Dendrobates, Phyllobates, Atopophrynus and Colostelhus. Dendrobates are brightly coloured with warning colou­ration and are called “South American arrow poison frogs”. They are extremely toxic.

The arrow poison frog (Phyllobates latinasus) of Columbia whose 1/100,000 of a gram poison is enough to kill a man.

Family 19. Ranidae Grey, 1825:

1. 8 procoelous presacral vertebrae.

2. Eighth presacral vertebra biconcave and the sacrum biconvex.

3. Sacrum has cylindrical diapophyses.

4. Free coccyx without transverse pro­cesses.

5. Pectoral girdle is generally firmisternal (The epicoracoidal horns are absent, the sternum is fused to the pectoral arch and the epicoracoidal cartilages of each half of the pectoral girdle are fused to one another). Omosternum and stemu bony in most genera.

6. The pupil is horizontal in most taxa.

7. Toothed upper jaw.

8. Usually bifid tongue.

9. Smooth slimy skin.

10. Aquatic or semiaquatic.

11. Most have aquatic tadpoles.

Distribution:

Cosmopolitan except Green land, New Zealand, Southern South America, the West Indies and the Australian region.

Content:

The family contains 47 genera with about 700 species.

Examples:

Some of the genera are Arthroleptis (11 species; Sub-Saharan region); Astylosternus (11 species; Western Africa); Mantella (4 species; Madagascar); Mantidactylus (53 species; Madagascar); Amolops (23 species; North-eastern India, Nepal, Southern China, Greater Sunda Islands). In India Amolops is represented by 3 species.

They are A. afghanus, Gunther, 1858 (Himachal Pradesh and Arunachal Pradesh, W. Bengal); A. formosus, Meghalaya, West Bengal, Sikkim and Punjab; A. montico­la, West Bengal. Ceratobatrachus (1 species, Solomon Islands); Micrixalus (13 species; India, Sri Lanka, China, Philippines and Borneo).

In India, Micrixalus is represented by seven species of which M. borealis Annandale, 1912 is found in Arunachal Pradesh and the rest occur in Kerala and Tamil Nadu. Nannobatrachus (3 secies; South India); Nannobatrachus bed- domii Boulenger, 1882 (Kerala and Tamil Nadu) is 20 mm in length and smallest frog of Indian subcontinent.

Nannophrys (3 species; Sri Lanka); Nannorana (1 species, China); Nyctibatrachus (4 species, India); Occidozyga (9 species; W. Bengal to Southern China, Greater and Lesser Sunda Islands); O. lima Kuhl and Van Hasselt, 1822, only Indian species, found in W. Bengal; Platymantis (38 species; Philippines, New Guinea, Palau, Fiji and Solomon Islands). Rana (258 species; All over world except southern part of South America and Australia).

In India, 55 species have been recorded. Among Indian species. R. limnocharis (Rice Frog), R. cyanophlyctis (Skipper frog) are commonly distributed throughout India. R. tigerina is known as Indian bull frog. R. verrucosa is found at Malabar hills up to 230 m in the Nilgiris and 1300 m above in Kerala.

The common frogs in different countries are — R. japonica (Japan, Korea and China); R. cancrivora (Thailand and Northern parts of Malay Peninsula); Italian springing frog (R. latastei); Spanish frog (R. iberica); Creek frog (R. graeca); American bull frog (R. catesbiana); American wood frog (R. sylvatica).

Hairy frog (Trichobatrachus robustus), found in Eastern Africa, is famous for hair like projections on the sides of the abdomen and thighs during breeding seasons in males. Cigantorana goliath is famous for its gigantic size and found in Tropical Sub Saharan region in Africa. The frog is about 60 cm in length and is the largest frog in the world.

Family 20. Hyperoliidae Laurent, 1943:

1. 8 procoelous presacral vertebrae.

2. Presacral 8th vertebra is biconcave and sacrum biconvex.

3. Free coccyx without transverse pro­cesses.

4. Pectoral girdle is firmisternal; a carti­laginous or bony omosternum and sternum.

5. Tooth upper jaw.

6. The pupil vertically elliptical in most genera.

7. Mostly arboreal frogs with aquatic larvae.

Distribution:

Sub-Saharan region in Africa.

Content:

There are 14 genera with 230 species.

Examples:

Some of the genera are Afrixalus (23 species); Callixallus (1 species).

Hyperolius (109 species); Tachycnemis (1 species, Seychelles Islands).

Family 21. Rhacophoridae Hoffman, 1932:

1. 8 presacral procoelous vertebrae.

2. Presacral 8th vertebra is biconcave and the sacrum biconvex.

3. Pectoral girdle is firmisternal. The omosternum and sternum are bony.

4. Phalanges are increased by the addi­tion of short, cartilaginous (bony in some taxa) elements between the penultimate and terminal phalanges.

5. Highly webbed on the hands and feet.

6. Fingers and toes are provided with adhesive disc-like pads.

7. Most of the arboreal except Aglyptodactylus which is terrestrial.

Distribution:

Old world tropics.

Content:

There are 10 genera with about 315 species.

Examples:

Some of the genera are — Boophis (28 species, Madagascar); Chiromantis (3 species, Tropical Africa); Philautus (63 species; India, Sri Lanka to China, the Philippines and Greater Sunda Islands). In India, Philautus is represented by 28 species, comparatively greater in number than the genus Rhacophorus.

All the species under the genus Philautus are characterised by a hori­zontal pupil, and fingers and toes are provided with adhesive pads and the absence of vome­rine teeth. They are restricted to South India and Eastern Himalayas.

Polypedates (11 species, Tropical Asia). In India Polypedates leucomystax Graven- horst 1829 (W. Bengal, Assam and Sikkim) P. maculatus (throughout India) and P. pseudocruciger Das and Ravichandran, 1998, are recorded. Rhacophorus (56 spices; India, China, Japan and Greater Sunda Islands). In India Rhacophorus is represented by 11 species.

They occur more or less throughout India, Rhacophorus malabaricus Jerdon 1870, (Kerala and Karnataka) is famous for gliding from the top of one tree to the base of another tree by using its webbed feet as parachutes. Rhacophorus is famous in making foam nests, sometimes placed in vegetation over water and the eggs hatch into tadpoles within it.

Remarks:

Liem, S. (1970) has reported 56 species under the genus Rhacophorus Kuhn and Van Hasselt, 1822 from India, China to Japan and the Greater Sunda Islands, and Polypedates Ischudi, 1838 (11 species) from Japan and E. China throughout tropical Asia to Java, Bornes and Philippines. Boulenger (1890), Daniel (1963, ’75), Duellman and Trueb (1986), Pillai and Murthy (1986) also reported the occurrence of only genus Rhacophorus from Indian region.

But Frost (1985), Inger and Dutta (1986) in their list of amphibians, mentioned Polypedates leuco- mystax and Polypedates maculatus (1834) in the Indian region. The two species were previously under the genus Rhacophorus.

Family 22. Microhylidae Gunther, 1859:

1. 8 proceolous presacral vertebrae.

2. Ribs are absent.

3. Coccyx is free.

4. Pectoral girdle is firmisternal.

5. Omosternum is absent in most genera.

6. A cartilaginous sternum is present.

7. Palatines are reduced or absent in most genera.

8. Toothless upper jaw is in most genera but present Calluela, Dyscophus, Cophyla, Mantipus, Plethodontohyla, Platypelis, Paracophylla, Stumpffia.

9. Fingers of some species are dilated and phalanges are ‘T’ shaped.

10. Pupil is horizontal or round (vertically elliptical in Calluela and Dyscophus).

11. Skin is smooth or warty.

12. Body is small, stout and small headed to globular, short-legged terrestrial or arboreal toads.

13. Presence of two to three palatal folds.

Distribution:

Cosmopolitan in temperate and tropical regions, except in Palaearctic region and most of Australia.

Content:

61 genera and about 315 species.

Examples:

Some of the genera are Pseudohemisus (6 species, Madagascar); Calluela (5 species, South eastern Asia and Malay Archipelago); Dyscophus (3 species, Madagascar); Mantipus (7 species, Madagas­car); Pherohapsis (1 species, Papua and New Guinea); Xenobatrachus (9 species, New Guinea); Breviceps (12 species, South Africa); Callulina (1 species, Tanzania); Melanobatrachus (1 species, South India); Kaloula (9 species, India, Sri Lanka, Korea, Northern China and Philippines); Microhyta (21 species, India, Sri Lanka, Bangladesh, South East Asia); Ramnella (8 species, India and Sri Lanka); Uperodon (2 species, India and Sri Lanka).

Melanobatrachus indicus Beddome, 1878 (Kerala) is recognised by the absence of palatal ridges and is represented by a single species. Microhyla is represented by 5 species in India and found all over the country including Andaman.

It is recognised by circular pupil, entire oval tongue, palatal ridges and with or without terminal dilatations in the digits. Kaloula is represented by a single species. K. pulchra taprobanica is the most beautiful frog of all living Indian anurans.

Ramanella is rep­resented by 6 species in India and recognised by the dilatation of fingers and toes, colour pattern, and the presence or absence of web. Another genus Uperodon is represented by U. globulosus and U. systoma and known as “Baloon frogs”.

They are recognised by narrow mouth, rotund shaped body and a ridge ending behind or between the nostrils. They occur in W. Bengal, M.P., Orissa, Gujarat, Maharashtra and South India.

Interrelationship of living orders:

From the analysis of collected fossils and structural peculiarities of the living representatives it is considered that urodeles have evolved independently from the fish porolepis, suggested to have an internal nostril and this group acts as an intermediate in between fish and amphibians.

Due to sub­terranean mode of life the fossils of apodans are not enough, though a few fossils of Jurassic beds have been collected recently and are considered the most primitive group.

Their fossorial habit has influenced their mor­phological features to some extent and the retention of dermal scales in the skin also indicates the primitiveness. Anurans are the most advanced group among amphibians and have adjusted to various environments by increasing their adaptive value.

Phylogeny:

The fossil track does not confirm firmly that primitive amphibians have evolved from Devonian rhipidistians because a gap of sequence of fossil record prevails in between middle Devonian rhipidistians and the late Devonian amphibians.

Yet a major part of herpetologists are in favour of Devonian rhipidistians, as the ancestor of amphibians. They consider that early amphibians have evolved from groups of crossopterygians — may be specially mentioned Osteolepis and Eusthenopteron.

At present, a newly defined lineage of late Devonian crossopterygians, the Panderichthyidae is considered to be the ancestor of earliest amphibians.

The rhipidistians became successful to come to land from aquatic medium.

On coming to land these fishes trans­formed into earliest amphibians — Ichthyostega, is included under the Subclass Labyrinthodontia. From Ichthyostega two major lines of evolution, the Orders Anthracosauria and Temnospondyli, can be assumed. The anthracosaurs gave rise to reptiles in the late Carboniferous period and completes the first part of amphibian history.

The second lineage includes the lepospondyl amphibians (Subclass Lepospondyli) that appeared in the mid-Carboniferous and dis­appeared by the end of Permian. The third part of amphibian history includes the modern amphibians, which is under Subclass Lissamphibia, and represents the diversified fossils of the Jurassic bed.

The origin of lepospondyls and lissamphibians still remains an unanswered question due to yet undiscovered fossils.

Possible views regarding the origin of Amphibia:

1. Polyphyletic View [Carroll and Currie, 1975; Jarvik, 1980-81]:

They hypothesized that the three living orders, e.g., Urodela, Apoda and Anura have evolved separately. Jarvik (1980) also pointed out that the amphibians originated indepen­dently from more than one group of rhipidistian fish.

Remark:

This view is not accepted to all.

2. Diphyletic View [Romer, 1949, 1962; Romer and Watson, 1962]:

They suggested that both salamanders and caecilians share a common ancestor and anurans were developed separately. By emphasizing on the vertebral column similar­ities in the different groups it is considered that anurans have evolved from labyrintho- donts and urodeles and apodans from lepospondyls.

But Romer (1931) considered that sala­manders and anurans share a common ancestor, with caecilians having been evolved separately.

3. Monophylelic View [Noble, 1931; Bolt, 1979; Mc Farland et al., 1985; Duellman and Trueb, 1986]:

They considered that all living amphibians have evolved from the earliest amphibians, the Ichthyostega and this group also derived from Osteolepid fish (Osteolepis sp.).

Amphibian discoveries:

New species of the class Amphibia are being discovered at a greater rate than many other vertebrate taxa. The number of species is expected to reach 5000 by the year 2000. It was 4003 in 1985. Rapid increase in num­ber can be accounted for by the application of molecular techniques to the separation of morphologically cryptic species.

Global Amphibian Assessment:

About one third (32.5%) of the world’s amphibian population representing 1856 species has been enlisted in the Red Data Book as Critically Endangered (CE), Endangered (En) and Vulnerable (Vu).

At least 34 amphibian species are going to be extinct, 134 amphibian species might possibly be extinct, 9 amphibian species are known to have died out since 1980, and at least 113 additional species might have disappeared during this period.

Salamanders and newts show significant­ly higher threat levels which include about 234 species (46%) among the whole uro­deles. Frogs and toads comprise 1635 species (32.6%) as threatened and rest of the cacilians have poorly known data.

Research on Indian Amphibians:

Since 19th century herpetologists carried out research work mainly on taxonomy and distri­bution of Indian amphibians. Some of the notable works done by Gunther (1861), Cope (1865), Jerdon (1870), Anderson (1871), Stoliczka (1872), Boulenger (1883, 1890, 1892 and 1920) and Sclater (1892), etc.

Among the above mentioned wokers, Boulenger (1890) published a comprehensive work on Indian amphibians in the “Fauna of British India inclu­ding Ceylon and Burma”. In 1920, Boulenger published a monograph of the genus Rana of S. E. Asia. Ferguson (1904) published on Travancore batrachians.

Annandale (1908), the first Director (Superintendent) of the Zoological Survey of India, published the breeding habits of Tylototriton verrucosus. In 1912, he reported the amphibian fauna of Abor Expedition (Abor Hills).

C. R. N. Rao(1915-37) published about different South Indian Batrachians and also described the different forms of larvae found in different groups of amphibians. Hora (1921-1922) studied about the amphibian larval forms of the torrential- streams.

Kampan (1923) gave an account of Indian amphibains in his treatise “Amphibia of the Indo-Australian Archipelago”. Parker (1934) published about the microhylid frogs.

Bhaduri (1944- 45, 1955) reported the breeding behaviour of Rhacophorus and also gave an account of behaviour of narrow-mouth frog, Uperodon giobulosus. Acharjee and Kripalini (1951) studied the amphibian fauna of Western Himalayas. E. H. Taylor of Kansas University (1961-1962) revised the Indian Caecilians. Murthy (1964) studied the fauna of Rajasthan.

In 1973, he published the distribution of micro­hylid (Ramanella variegata) frogs. Pillai (1976-1981) studied the amphibian fauna of South India with reference to Silent Valley.

Daniel (1962-1999) published a series of writ­ings on distribution, taxonomy and ecology of amphibians of Darjeeling district of West Bengal, and specially of Western Indian amphibians. In 1997, he reported the frogs and toads of Western Ghats.

Dubois (1978-1997) studied the amphibians of Central and Western Himalayas. He also revised the Indian amphi­bian fauna, specially the family Ranidae. Chanda (1981-1994) studied the amphibian fauna of N. E. India and also of Sikkim. He has also published in 1994 a detailed account of 54 species known from N. Eastern region. Mahanti- Hejmadi (1985) published the amphibian fauna of Orissa.

Sarkar and Sanyal (1985) published the report on amphibians of Namdapha National Park, Arunachal Pradesh. Dutta (1985) published some observations of the habits of burrowing frogs, found in Orissa. He also pub­lished a checklist and bibliograph of Indian and Sri Lankan amphibains in 1997.

Ingerand Dutta (1986) gave an overview of the Indian amphi­bian fauna. On Indian salamander (Tylototriton verrucosus) various authors like Singh (1987), Roy (2002) reported the new occurrence and habits of this endangered species. Sekar (1991, 1992) described the amphibian fauna of Goa.

Mallick and Mallick (-1982) published the foam-nest formation in Polypedates. Mallick, Mallick and Das (1980) published the spawning behaviour of 4 salientians in West Bengal. Krishnamurthy (1999) studied the amphibian fauna of Western Ghats.

Ravichandran (1996) studied the amphibian fauna in Kalakad wild life Sanctuary in Tamil Nadu and also in 2002, 2004 he reported about the caecilian diversity in India with reference to Western Ghats, Eastern Ghats and in North-east India. Padhye and Ghate (2002) overviewed the amphi­bian fauna in Maharashtra state. Meren, Bordoloi and Ohler (2003) reported the amphibian fauna of Nagaland with new records from India.

Banerjee and Chakrabarty (2003) studied the chromosmal sex determination in Anuran amphibians. Biju (2002) conducted field survey of Western Ghats. He recorded 104 species, out of 206 species of anurans reported from India. Biju and Bossuyt (2003) created a new frog family from India that reveals an ancient biogeographical link with the Seychelles.

Molecular phylogeny of Indian amphibians is in early stage but phylogenetic relationships based on molecular level are improving gradually.

Indian Species:

The amphibian fauna is represented by 3960 living species, occurring all over the world except Antarctica and some Oceanic Islands. In India, a faunal review of the amphibians was first published in 1890 by Boulenger in the book, Fauna of British India – Reptilia and Batrachia which contained only 77 species. The literature of last hundred years has added many names for

Dilemma of Herpetologists:

Herpetologists or amphibian biologists face a dilemma regarding the nomenclatural changes in different groups. Taxonomists or field biologists are unable to cope with the changes of scientific names of different groups. If we analyse the case of Indian bull frog, Rana tigerina, the condition can be understood.

First the specific name was misspelt and corrected from tigrina to tigerina. Then the generic name was replaced from Rana to Occidozyga which the studies of the Indian amphibians.

Pillai and Murthy (1986) reported 142 species in all three orders of which Gymnophiona contains 15 species, urodeles-1 and anurans-126. Inger and Dutta (1986) also published a list in which they have mentioned 186 species.

The only species of urodeles Tylototriton verrucosus Anderson, 1871 (Darjeeling District, West Bengal, Sikkim and Arunachal Pradesh), and 4 genera of Caecilians: (i) Ichthyophis (7 species) (ii) Uraeo­typhlus (4 species) (iii) Gegenophis (3 species) and (iv) Indotyphlus (1 species) ‘have been recorded.

The species of four genera of apodans are:

(i) Ichthyophis bombayensis Taylor, 1960 (Maharashtra);

(ii) I. subterrestris Taylor, 1960 (Maharashtra and Kerala);

(iii) I. beddomei Peters, 1879 (Kerala, Karnataka and Tamil Nadu);

(iv) I. malabarensis Taylor, 1960 (Kerala);

(v) I. penisularis Taylor, 1960 (Kerala and Tamil Nadu);

(vi) I. sikkimensis Taylor, 1960 (West Bengal and Sikkim);

(vii) I. tricolor Annandale, 1909 (Kerala);

(viii) Uraeotyphlus malabaricus (Beddome, 1870) (Kerala);

(ix) U. menoni Annandale, 1913 (Kerala);

(x) U. narayani Seshachar, 1939 (Kerala);

(xi) U. oxyunvs(Dumeril and Bibron, 1841) (Kerala);

(xii) Gegenophis carnosus (Beddome, 1870) (Kerala);

(xiii) G. fulleri (Alcock, 1904) (Assam);

(xiv) G. ramaswamii Taylor, 1964 (Kerala);

(xv) Indotyphlus battersbyi Taylor, 1960 (Khandala, Maharashtra).

The anu­rans are represented by the following genera — Amolops, Nannobatrachus, Nyctibatrachus, Micrixalus, Rana, Tomopterna, Rhacophorus, Chirixalus, Polypedates, Philautus, Theloderma, Uperodon, Kaloula, Ramnella, Microhyla, Melanobatrachus, Bufo, Bufonoides, Ansonia, Pedostibes, Megophrys, Leptobranchium Scutiger and Hyla.

Dilemma of Herpetologists:

Herpetologists or amphibian biologists face a dilemma regarding the nomenclatural changes in different groups. Taxonomists or field biologists are unable to cope with the changes of scientific names of different groups. If we analyse the case of Indian bull frog, Rana tigerina, the condition can be understood. First again was changed into Euphlyctis, and at pre­sent the generic name is Hoplobatrachus.

Rare and Endangered Indian species:

Indian salamander (Tylototriton verruco­sus), Malabar tree-toad (Pedostibes tuberculosus), Garo Hills tree toad (Pedostibes kempi) have been declared rare or endangered. Family Hylidae is represented by a single species Hyla annectans Jerdon, 1870 which is an inhabitant of some parts of Assam and Meghalaya.

Indian viviparous toad (Nectophryne tuberculosa = Pedostibes tuberculosus), a very rare amphibian, is found in the Malabar rain forest tracts.