Differences between red-foot and yellow-foots

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matt41gb

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I'm re-posting these pictures so that they can be used as a sticky thread for faster viewing.

Differences between Geochelone Carbonaria (red-foot) and Geochelone Denticula (yellow-foot).

Dorsal view of male red-foot on left and male yellow-foot on right. Notice hourglass shape of red-foot.


Ventral view of male red-foot and male yellow-foot. Note wide anal scutes, concave plastron, and long tail.


Front view of males. Note scale coloration on legs.


Dorsal view of female red-foot on left and female yellow-foot on right. No hourglass shape.


Ventral view of females. No concavity on plastron, semi-circular anal scutes, and short tail.


Dorsal head view of red-foot (left) and yellow-foot (right). Red-foots have a single prefrontal scale at the tip of the nose, while yellows have two large prefrontal scales running parallel to one another.


Please add anymore information for others who want to know more about the differences between the two species.

-Matt
 

GeoTerraTestudo

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The scalation does tend to differ between the two species (one prefrontal on redfoots, two prefrontals on yellowfoots). My redfoot had only one, true to her type. However, every once in a while you do see a redfoot with two prefrontal scales.
 

domalle

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Note also that the inguinal (groin) scutes on redfoots are pronounced -
the inguinal scutes on yellowfoots are reduced.
This is the most consistent and uniform distinguishing characteristic of both.
And redfoots in some parts of their extensive range rival the yellowfoot in size, up to circa sixty centimeters (two feet).
 

Yvonne G

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Differentiating Geochelone denticulata and
Geochelone carbonaria


by Jack W. Hagan
Quite often there is confusion in identifying two of the three tortoises which are native to continental South America.

The Argentine tortoise, Geochelone chilensis, is quite easily distinguished from the other two South American tortoises, looking at first glance much like one of the tortoises belonging to the genus Gopherus.

Geochelone denticulata and G. carbonaria are the two tortoises which are often misidentified, particularly by many of the animal dealers who supply these attractive tortoises. Geochelone denticulata is commonly called "yellow leg" tortoise and G. carbonaria is frequently known as "red leg" tortoise. Use of these common names causes confusion, due to the fact that the so-called "red legs" sometimes have red legs, sometimes yellow and very often, any shade in between the two. Many dealers use coloring as their only means of identification, listing a G. carbonaria with yellow legs asG. denticulata.

No one characteristic can be used to identify these two tortoises; it takes a combination of differences to properly identify them. It is hoped that the following text and diagrams will be helpful in identifying these two South American tortoises.

Some of the characteristics are more constant and will hold true in the majority of specimens examined. Others are not as stable and will vary from specimen to specimen of species being examined.

G. denticulata, which appears to be the species less often displayed in collections, is the larger of the two. Specimens sometimes reach a length of nearly 26 inches. Carapace of both young and adult is a uniform light brown, with lighter yellow-brown centers in each shield. The young denticulate tends to show some concentric grooving or ringing of the shields on the carapace, but larger specimens show very little, if any.

The concentric grooving is a very predominant characteristic of G. carbonaria in both old and young specimens. The adult male denticulate appears to be somewhat bell-shaped when viewed dorsally, tending to flare out at the posterior third of the carapace in the area directly above the intergular. Females retain the more rounded shape of the young. Both young and adult, male and female, have a quite highly domed carapace with a gentle rounding from central to marginals when viewed anteriorly or posteriorly, with females having a higher dome.

G. carbonaria retains much the same shape throughout its life, having sides of the carapace quite parallel, giving it the appearance of a loaf of bread. In older, adult specimens, the shell can be seen to be indented slightly at mid-body when viewed dorsally, thus giving it a slight hour-glass shape. Carbonaria does not appear to reach the size of denticulata, large adult specimens obtaining an average carapace length of about 19 inches.

There is very little information on actual habitat of these two species. They both range over much of the same area of South America, both being found in forested areas where adequate shade is available, as neither appears to like to bask in full sunlight.Carbonaria seems to prefer the damper habitat, being found in wet, muddy dens in the wild, showing a tendency to drink and soak more in captivity thandenticulata.

The range of G. denticulata is as follows: southern Colombia (absent from the north), Venezuela, Island of Trinidad, Guyana (formerly British Guiana), Surinam, French Guiana, Peru and Brazil, being absent from Paraguay.

G. carbonaria has much the same range, but includes Colombia, only the western portion of Peru and is found in Paraguay.

Geochelone denticulata Geochelone carbonaria

*Gular shield even with posterior portion of carapace *Gular shield short of posterior portion of carapace
Humeral median suture usually longer than femoral median suture
Femoral median suture usually longer than humeral median suture
*Inguinal quite inconspicuous
*Inguinal quite conspicuous
Prefrontals elongated
Prefrontals small and broken up
*First marginals denticulated in young
*First marginals not denticulated in young
Very little if any concentric grooving of scutes
Concentric grooving quite predominant
*Most constant characteristics




When the scientists compared DNA from all four species of gopher tortoise they confirmed the close link between X. agassizii and X. berlandieri, and betweenG. flavomarginatus and G. polyphemus. Their results suggested that the Xerobates and Gopherus forms last shared a common female ancestor some 5-6 million years ago. The Texas tortoise, X. berlandieri, proved to be very closely related to the "eastern" agassiziigenotype. It is highly likely that berlandieri evolved from this eastern agassizii assemblage, probably fromXerobates stock inhabiting the north central region of Sonora. Perhaps the closeness of the relationship between the eastern agassizii assemblage andberlandieri explains the occasional occurrence of hybrids from matings between captive Texas and desert tortoises.

Article reprinted with permission from International Turtle and Tortoise Society Journal 2:4-5, 1968.
 
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