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Taxonomy and Introduction to Common Species

Bob Doneley

Taxonomy

Class Reptilia is one of the largest groups of vertebrates, with over 10,000 species. It is also the oldest, evolving some 310-320 million years ago during the Carboniferous period. They share several common characteristics: all are covered with scales or scutes and are ectothermic. Most lay amniotic eggs (oviparity), although some are live bearers (viviparity, including ovovivaparity). They may be carnivorous, omnivorous or herbivorous.

Class Reptilia is made up of four orders: Squamata, Testudines, Crocodilia and Rhynchocephalia (Table 1.1). Each order is further divided into sub-orders, families, genera and species.

Table 1.1 Reptile orders.

Order and sub-order Common name Species (n) Squamata Squamates 9,671    Lacertilia Lizards 5,987    Serpentes Snakes 3,496    Amphisbaenia Worm lizards 188 Testudines Turtles, tortoises and terrapins 341 Crocodylia Crocodiles, gharials, caimans and alligators 25 Rhynchocephalia Tuataras 1

Squamata

Squamates are characterized by their scaled skin, which is shed periodically (ecdysis), and a moveable quadrate bone that allows the maxilla to open wide relative to the rest of the skull. The order is divided into three sub-orders: Lacertilia (the lizards), Serpentes (the snakes) and Amphisbaenia (the worm lizards), although some classifications place Amphisbaenia within Lacertilia.

Lacertilia has five infraorders based mainly on morphological similarities between family groups. These are the Diploglossa (including the glass lizards and the American legless lizards), Gekkota (the geckos, the blind lizards and the legless lizards), Iguania (including the agamids, chameleons, iguanas, anoles, collared lizards and the neotropical ground lizards), Platynota (varanids and Gila monsters) and Scincomorpha (including skinks, tegus, plated lizards and spiny-tail lizards). Most are omnivorous or carnivorous. They are primarily oviparous, although some are ovoviviparous.

Serpentes has two infraorders: Alethinophidia (including the boas, pythons, vipers, elapids, colubrids, file snakes and rattle snakes) and Scolecophidia (the blind snakes). All snakes are carnivorous. Most are oviparous, although some are ovoviviparous.

Amphisbaenia has five families found in the northern hemisphere, Africa and South America. They are largely legless squamates with rudimentary eyes capable of only detecting light (two species have rudimentary forelimbs). Their skin is loosely attached to the body, and appears to be their means of locomotion; the skin moves and 'drags' the body behind it. They are carnivorous, with strong jaws and interlocking teeth. Most species lay eggs, although some are known to be ovoviviparous.

Testudines

Testudines, sometimes known as Chelonia, are the turtles, tortoises and terrapins. They are characterized by a bony or cartilaginous shell developed from their ribs. There is some confusion in the terminology. In North America, 'turtle' is used to describe the whole order, while in Europe and Australia it refers to freshwater and sea-dwelling chelonians, with 'tortoise' used to describe terrestrial, non-swimming species. 'Terrapin' is a term used to describe several small species of turtle living in fresh or brackish water. Terrapins do not form a taxonomic unit and are not closely related. There are two suborders of Testudines: the Pleurodirans (three families), also called the side-necked or long-necked turtles, have long necks that are folded sideways to align them with the shell; the Cryptodirans (eleven families), or short-neck turtles and tortoises, pull their neck straight back to conceal their head within the shell. Sea turtles are Cryptodirans, although they have lost the ability to retract their heads.

Crocodylia

Crocodylia, an order of large, predatory, semi-aquatic reptiles, is divided into three families: Crocodylidae (the true crocodiles), Alligatoridae (the alligators and caimans) and Gavialidae (the gharial and false gharial).

Rhynchocephalia

Rhynchocephalia is a primitive order of lizard-like reptiles that includes only one living species, the Tuatara (Sphenodon punctatus) of New Zealand. There is debate as to whether S. guntheri is a separate species. They are slow-growing, reaching sexual maturity at 10-20 years, and breed until they are at least 60 years old. It takes the female between one to three years to develop eggs and up to seven months to form the shell. It then takes between 12 and 15 months from copulation to hatching. Thus, reproduction occurs at two- to five-yearly intervals, the longest of any reptile.

Tuatara lack external ears and possess a parietal eye (a light-sensitive spot located on the top of the animal's head, thought to play a role in setting circadian rhythms). They are capable of autotomy and have only rudimentary hemipenes. Tuatara have unique dentition, namely two rows of acrodont teeth in the maxilla and one row in the mandible.

Commonly Kept Species

Key

The following abbreviations are used in this section:

• d, days
• G, gestation
• I, incubation
• m, months
• O, oviparous
• OV, ovoviviparous
• PBT, preferred body temperature
• y, years

Tables

• Table 1.2 Lizards
• Table 1.3 Geckos
• Table 1.5 Chameleons
• Table 1.6 Snakes
• Table 1.7 Turtles
• Table 1.8 Tortoises

Table 1.2 Lizards.

Reptile Origin Species Habitat Diet Sexual maturity Mode of reprod. Incubation or
Gestation Thermal gradient (°C) PBT (°C) Relative humidity (%) Longevity (years) Bearded dragon (Figure 1.1) Australia Most common:
inland or central (Pogona vitticeps)
eastern (P. barbata)
blacksoil (P. henrylawsoni)
dwarf (P. minor)
Others include:
western (P. minima)
northwest (P. mitchelli)
Nullarbor (P. nullarbor)
Kimberley (P. microlepitoda) Terrestrial Omnivorous, although the juveniles are initially insectivorous but will eat vegetables and flowers as they grow 9-24 ma O (I) 61-74 d at 30-31 °C (P. vitticeps) 28-40 35 25-40 10-15 Blue-tongued skink (Figure 1.2) Australia eastern (Tiliqua scincoides scincoides)
pygmy (T. adelaidensis)
centralian (T. multifasciata)
blotched (T. nigrolutea)
western (T. occipitalis) Terrestrial Omnivorous 18-36 mb OV (G) 3-5?m 28-32 (higher for inland species) 25-35 25-40 10-15 Shingleback Australia Also known as bobtail lizard (T. rugosa) Terrestrial Omnivorous 18-36 mc OV (I) 4-5?m 36-40 25-45 25-40 10-15 Frilled lizard Australia Chlamydosaurus kingii Primarily arboreal Primarily insectivorous but will accept some vegetables 12-18?m (male) to 2-3 y (female) O (I) 60-90 d 32-37 28-38 50-70 10-15

a Depending on species (small species mature younger than larger species).

b Male matures earlier than female.

c This species forms close pair bonding and should be paired before sexual maturity.

Table 1.3 Geckos.

Reptile Origin Species Habitat Diet Sexual maturity Mode of reprod. Incubation or
Gestation Thermal gradient (°C) PBT (°C) Relative humidity (%) Longevity (years) Leopard gecko Pakistan, northern India and Asian desert regions Eublepharis...