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Keys to the Australasian members of the Family Chelidae: Austro/South American Side-Neck Turtles
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1. |
Manus with four claws; gulars in contact; intergular not on anterior edge of plastron; neck plus head length greater than two thirds of the carapace length (longnecked chelids) |
2. |
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Manus with five claws; gulars not in contact, intergular on anterior edge of plastron; neck plus head length less than half the carapace length (shortnecked chelids) |
3. |
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2. |
Plastron extensive and broad, posterior lobe partially covers carapace marginals when viewed from below; neck shorter than carapace length; dorsal surface of neck covered in blunt tubercles. |
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Plastron narrow and not extensive, posterior lobe does not cover carapace marginals when viewed from below; neck longer than carapace length; dorsal surface of neck without tubercles. |
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3. |
Intergular excludes both gulars and humerals from midline contact; temporal roofing of skull extensive; head shield covers most of head. |
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Intergular separates only gulars, humerals in contact; temporal roofing of skull substantially emarginate from below; head shield variable but never covering most of head |
4. |
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4. |
Alveolar ridge absent; first vertebral, maximum width, equal or subequal to the second and third vertebrals. |
5. |
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Alveolar ridge present; first vertebral wider than second and third in large adults. Shell deep and spacious; bridge long. Eye dark and lacking contrast at all ages; head shield well developed, restricted to top of skull. |
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5. |
Interlateral seams C and D contact posterior parts of marginals 6 and 8; rib tips of costals 2 to 4 articulate with gomphoses in centres of peripherals 4 to 6; a distinct white, ivory or silver iris at all ages. |
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Interlateral seams C and D contact marginals 7 and 8; rib tips of costals 2 to 4 articulate in or near interperipheral sutures ; iris variable, if pale then yellowish, not white or ivory. |
6. |
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6. |
Head shield present and well developed. |
7. |
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Head shield absent, or if present is fragmented, small and restricted to the parietal region; neck usually smooth, tubercles on neck, if present, small and rounded; barbels absent or small; rear edge of carapace never denticulate. |
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7. |
Head shield continues down the parietal arch to almost contact the tympanum. A well-defined head shield at all ages; dorsum of neck bearing many sharp tubercles; gular barbels always well-defined and longer than wide; rear edge of carapace may be denticulate at any age. Plastron highly variegated in colour; shell black to mottled. |
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Plastron white to cream; carapace uniform grey brown in colour. Tail distinctive and large: precloacal length greater than postcloacal length at all ages; tail laterally compressed; cloacal orifice a longitudinal slit; tail length up to 53% of carapace length in adult males. |
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