SUBORDER AMPHISBAENIA
This suborder contains a single family found in Paraguay. Amphisbaenians are legless, burrowing lizards with a superficial resemblance to earthworms. The common name is derived from "Amphisbaena" a mythical serpent said to have a head at either end of its body, and referring to the poorly-defined external head morphology of the species in this group. The body is elongated and cylindrical and the skull elements are fused and modified as an adaptation for a fossorial lifestyle. There is a single median tooth in the upper jaw. They lack external ears and the eyes are covered with scales. Annuli (folds of skin) circle the body with or without granular scales. Skin is only loosely-attached to the body, and movement is accordion-like, the skin moving first and the body being dragged along. They are also capable of performing this motion in reverse. Osteoderms are absent.
Amphisbaenians lack temporal arches and a postorbital bar. The quadrate is fixed and slants forwards, whilst the epipterygoid is reduced or absent. The jaw is short. There are no palatal teeth and there are a few large teeth in the upper and lower jaws. Splenial is absent and limb girdles are reduced. Limbs are completely absent in all Paraguayan genera. The extra-columella is enlarged. There are no intercentra and no parasternum.
FAMILY AMPHISBAENIDAE - AMPHISBAENIANS
This Paraguayan branch of this family includes representatives of two subfamilies, the Amphisbaeninae and the Rhineurinae. The cranium is in the frontal plane of the body and the snout is rounded or laterally compressed. Nostril is laterally-located. Vertical processes of the premaxilla are narrow and no postarticular process is present. Preanal pores are present. Premaxilla and dentary are small and moderate. Skin lacks pigment or is only slightly pigmented dorsally, giving a mostly pinkish colour. Skin somewhat permeable. Limbs are lacking and tail tapers abruptly. Teeth are pleurodont. Oviparous.
SUBFAMILY AMPHISBAENINAE
Eleven species in two genera have been documented in Paraguay - Amphisbaena and Cercolophia. Characters are typical of those of the family
SUBFAMILY RHINEURINAE
One species in the genus Leptosternon recorded in Paraguay. Members of this subfamily have the cranium tilted to the frontal plane of the body. The face is flattened and the snout is spade-like with a sharp horizontal edge. Nostrils are inferior, the vertical process of premaxilla being broad and triangular. Preanal pores may be present or absent. Other characters are typical of those of the family. This subfamily is occasionally raised to family level.
Key to Adults of Paraguayan Amphisbaenids
Identification to species level in this family is complex and requires careful examination of the specimen in addition to scale counts. This key is adapted from Montero & Terol (1999).
1a Snout shovel-shaped and somewhat phallic in appearance....................................... Leptosternon microcephalum
1b Snout rounded or slightly laterally compressed ............................................................................................. 2
2a Tail tip with vertical keel. Snout rounded or slightly laterally compressed................................ "Cercolophia" 3
2b Tail tip without vertical keel. Snout rounded ..........................................................................Amphisbaena 4
3a Snout slightly laterally compressed. Four preclocacal pores.........................................Amphisbaena steindachneri
3b Snout rounded. Two precloacal pores.................................................................................. Amphisbaena roberti
4a No autotomy of the tail................................................................................................................................ 5
4b Shows autotomy of the tail (tail detaches a defense mechanism).................................................................. 6
5a Head rounded with large temporal protruberances. Tail of same diameter as the trunk. Terminal tail rings weakly delimited. More than 65 scales making up the medial body ring. ................................ Amphisbaena alba
5b Head elongated and pointed with spade-shaped tip to snout. Temporal protruberances not prominent. Tail thinner than the trunk with tail rings well-defined. autotomy of the tail. Less than 65 scales making up the medial body ring............................................................................................................... Amphisbaena angustifrons
6a More than 54 scales making up the medial body ring................................................................................... 7
6b Less than 50 scales making up the medial body ring.................................................................................... 8
7a Generally less than 200 scale rings along body. When more body rings plus tail rings are less than 220. Up to 86 scales making up the medial body ring. Head dark, sometimes with white band, but never completely pale.......................................................................................................................................... Amphisbaena camura
7b Generally more than 205 scale rings along body. When less body rings plus tail rings are more than 224. Less than 70 scales making up the medial body ring. Head dark, with white band or completely pale......................................................................................................................................... Amphisbaena bolivica
8a Two precloacal pores. ........................................................................................................ Amphisbaena leeseri
8b Four or more precloacal pores. ...................................................................................................................... 9
9a Five or more precloacal pores. Pigmentation visible on the anterior part of body scales only........................................................................................................................................ Amphisbaena mertensii
9b Four or less precloacal pores. ...................................................................................................................... 10
10a 23 or less scales on the tail ring immediately anterior to the autotomic constriction ................................ 11
10b 24 or more scales on the tail ring immediately anterior to the autotomic constriction. Tail smooth or tuberculated. ........................................................................................................................ Amphisbaena darwinii
11a Head short. Medial body ring with 24 to 35 scales. Pigmentation disappears ventrally. Postmalar scale row. .......................................................................................................................................... Amphisbaena prunicolor
11b Head relatively elongated. Medial body ring with 27 to 30 scales. Pigmentation uniform dorsally and ventrally. Postmalar scale row absent. .......................................................................... Amphisbaena albocingulata
REFERENCES
Fouquette MJ (unpublished) - Synopsis of Recent Reptiles to Genus - Arizona University
Montero R, Terol GJ 1999 - Los Amphisbaenidae en Paraguay, Listado Geográfico - Cuadernos de Herpetologia 13: p85-95.
Whitfield P Ed.1984 - Longman Illustrated Animal Encyclopedia - Guild Publishing, London.
This suborder contains a single family found in Paraguay. Amphisbaenians are legless, burrowing lizards with a superficial resemblance to earthworms. The common name is derived from "Amphisbaena" a mythical serpent said to have a head at either end of its body, and referring to the poorly-defined external head morphology of the species in this group. The body is elongated and cylindrical and the skull elements are fused and modified as an adaptation for a fossorial lifestyle. There is a single median tooth in the upper jaw. They lack external ears and the eyes are covered with scales. Annuli (folds of skin) circle the body with or without granular scales. Skin is only loosely-attached to the body, and movement is accordion-like, the skin moving first and the body being dragged along. They are also capable of performing this motion in reverse. Osteoderms are absent.
Amphisbaenians lack temporal arches and a postorbital bar. The quadrate is fixed and slants forwards, whilst the epipterygoid is reduced or absent. The jaw is short. There are no palatal teeth and there are a few large teeth in the upper and lower jaws. Splenial is absent and limb girdles are reduced. Limbs are completely absent in all Paraguayan genera. The extra-columella is enlarged. There are no intercentra and no parasternum.
FAMILY AMPHISBAENIDAE - AMPHISBAENIANS
This Paraguayan branch of this family includes representatives of two subfamilies, the Amphisbaeninae and the Rhineurinae. The cranium is in the frontal plane of the body and the snout is rounded or laterally compressed. Nostril is laterally-located. Vertical processes of the premaxilla are narrow and no postarticular process is present. Preanal pores are present. Premaxilla and dentary are small and moderate. Skin lacks pigment or is only slightly pigmented dorsally, giving a mostly pinkish colour. Skin somewhat permeable. Limbs are lacking and tail tapers abruptly. Teeth are pleurodont. Oviparous.
SUBFAMILY AMPHISBAENINAE
Eleven species in two genera have been documented in Paraguay - Amphisbaena and Cercolophia. Characters are typical of those of the family
SUBFAMILY RHINEURINAE
One species in the genus Leptosternon recorded in Paraguay. Members of this subfamily have the cranium tilted to the frontal plane of the body. The face is flattened and the snout is spade-like with a sharp horizontal edge. Nostrils are inferior, the vertical process of premaxilla being broad and triangular. Preanal pores may be present or absent. Other characters are typical of those of the family. This subfamily is occasionally raised to family level.
Key to Adults of Paraguayan Amphisbaenids
Identification to species level in this family is complex and requires careful examination of the specimen in addition to scale counts. This key is adapted from Montero & Terol (1999).
1a Snout shovel-shaped and somewhat phallic in appearance....................................... Leptosternon microcephalum
1b Snout rounded or slightly laterally compressed ............................................................................................. 2
2a Tail tip with vertical keel. Snout rounded or slightly laterally compressed................................ "Cercolophia" 3
2b Tail tip without vertical keel. Snout rounded ..........................................................................Amphisbaena 4
3a Snout slightly laterally compressed. Four preclocacal pores.........................................Amphisbaena steindachneri
3b Snout rounded. Two precloacal pores.................................................................................. Amphisbaena roberti
4a No autotomy of the tail................................................................................................................................ 5
4b Shows autotomy of the tail (tail detaches a defense mechanism).................................................................. 6
5a Head rounded with large temporal protruberances. Tail of same diameter as the trunk. Terminal tail rings weakly delimited. More than 65 scales making up the medial body ring. ................................ Amphisbaena alba
5b Head elongated and pointed with spade-shaped tip to snout. Temporal protruberances not prominent. Tail thinner than the trunk with tail rings well-defined. autotomy of the tail. Less than 65 scales making up the medial body ring............................................................................................................... Amphisbaena angustifrons
6a More than 54 scales making up the medial body ring................................................................................... 7
6b Less than 50 scales making up the medial body ring.................................................................................... 8
7a Generally less than 200 scale rings along body. When more body rings plus tail rings are less than 220. Up to 86 scales making up the medial body ring. Head dark, sometimes with white band, but never completely pale.......................................................................................................................................... Amphisbaena camura
7b Generally more than 205 scale rings along body. When less body rings plus tail rings are more than 224. Less than 70 scales making up the medial body ring. Head dark, with white band or completely pale......................................................................................................................................... Amphisbaena bolivica
8a Two precloacal pores. ........................................................................................................ Amphisbaena leeseri
8b Four or more precloacal pores. ...................................................................................................................... 9
9a Five or more precloacal pores. Pigmentation visible on the anterior part of body scales only........................................................................................................................................ Amphisbaena mertensii
9b Four or less precloacal pores. ...................................................................................................................... 10
10a 23 or less scales on the tail ring immediately anterior to the autotomic constriction ................................ 11
10b 24 or more scales on the tail ring immediately anterior to the autotomic constriction. Tail smooth or tuberculated. ........................................................................................................................ Amphisbaena darwinii
11a Head short. Medial body ring with 24 to 35 scales. Pigmentation disappears ventrally. Postmalar scale row. .......................................................................................................................................... Amphisbaena prunicolor
11b Head relatively elongated. Medial body ring with 27 to 30 scales. Pigmentation uniform dorsally and ventrally. Postmalar scale row absent. .......................................................................... Amphisbaena albocingulata
REFERENCES
Fouquette MJ (unpublished) - Synopsis of Recent Reptiles to Genus - Arizona University
Montero R, Terol GJ 1999 - Los Amphisbaenidae en Paraguay, Listado Geográfico - Cuadernos de Herpetologia 13: p85-95.
Whitfield P Ed.1984 - Longman Illustrated Animal Encyclopedia - Guild Publishing, London.
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