Terrapin Genus

The Diamondback Terrapin (Malaclemys terrapin) is an attractive medium sized, brackish water turtle of the family Emydidae. It is semi-aquatic in nature and ranges along the eastern and southern coasts of North America, from Cape Cod to Corpus Christi. Diamondbacks are the only U.S. turtles that inhabit estuaries, tidal creeks and saltwater marshes where the salinity comes close to or equals that of the ocean. It is in this type of environment that diamondbacks thrive, dining on delicacies such as crabs, snails, shrimp, fish, mussels, clams, and other assorted crustaceans.

Diamondback terrapins have proven to be one of the most physically variable of turtle species and even specimens within the same subspecies/populations can have vastly differing shell pattern, skin color, markings and shapes. However, one trait that is characteristic of all diamondbacks is their grooved, concentrically patterned, diamond-shaped scutes. It is from these intricate markings that the diamondback has derived its name. In addition, another descriptive feature of diamondbacks, shared with their common relatives the Map turtles (Graptemys sp.), is their sexual dimorphism. Females tend to be twice the size of males at sexual maturity. Male diamondbacks usually attain a carapace length of 5 inches, whereas females can attain a length of 9 inches. Females also possess larger and broader heads than males, adding to their stouter, bulkier look. A last distinguishing trait of diamondbacks is the large size of their hind feet in proportion to their bodies. This adaptation gives them greater mobility under the onslaught of strong tidal currents and undertows.

The color of diamondback carapaces can vary from black, brown, gray, orange, olive to tan; their patterns from concentric marbles, donuts, to patternless. In addition, their carapaces can be either deeply or slightly grooved, sporting either huge vertebral keels or slight knobs. Diamondback skin color and pattern are equally diverse with colors ranging from gray, white, olive, slate blue to even black; and patterns range from small dots, big spots, lines, bold stripes, combination of spots and lines, and patternless. To further complicate things, the intergrading of populations when commercial harvesting was at its peak further confounded taxonomical identification at the sub-specific level. Terrapin meat was once greatly esteemed as a delicacy from the late 1800s' into the Roaring Twenties; hence the reason for commercial harvesting (the word "terrapin" was actually derived from a french word meaning turtle soup). When the demand for terrapin meat finally waned due to the stock market crash and Prohibition (terrapin meat was usually cooked with wine), large shipments of diamondbacks from various parts of their range were reported to have been released into the wild. The introduction of these shipments compromised the purity of native populations and hence complicated the identification of the east coast subspecies.

There are currently seven recognized diamondback subspecies: the Northern Diamondback Terrapin (M.t. terrapin), the Carolinan Diamondback Terrapin (M.t. centrata), the Florida East Coast Diamondback Terrapin (M.t. tequesta), the Mangrove Diamondback Terrapin (M.t. rhizophorarum), the Ornate Diamondback Terrapin (M.t. macrospilota), the Mississippi Diamondback Terrapin (M.t. pileata) and the Texas Diamondback Terrapin (M.t. littoralis).

COMMON NAME LATIN NAME PICTURE RANGE DESCRIPTION

Northern Diamondback Terrapin Malaclemys terrapin terrapin
Cape Cod to Cape Hatteras. Carapace: lightly sculpted, black to light brown with slight dorsal keel and concentric markings.
Skin: light specks and/or streaks with brighter individuals possessing bold spots and dashes. Color varies from dark gray to white.
Distinguishing feature: the main subspecies available in herpetoculture.

Carolinan Diamondback Terrapin Malaclemys terrapin centrata
Cape Hatteras to Flagler County, Fl. Carapace: smooth, black, olive to ivory with dorsal keel almost absent. Sides of the carapace tend to run almost parallel to each other. Concentric markings are present and are sometimes faded, giving a marble effect.
Skin: light specks and/or streaks with brighter individuals possessing bold spots and dashes. Color varies from dark gray to white.
Distinguishing feature: carapace features and larger head.

Florida East Coast Diamondback Terrapin Malaclemys terrapin tequesta
East coast of Florida: Flagler County to the Upper Keys. Carapace: deeply sculpted, black to gray with sometimes lighter scute centers with slight dorsal keel. Concentric rings are generally absent.
Skin: thin, with mostly specks or large spots; and even patternless. Color is usually gray or white. Mustache is normally present.
Distinguishing feature: lack of concentric carapace markings.

Mangrove Diamondback Terrapin Malaclemys terrapin rhizophorarum Mangrove swamps of the Florida Keys and southern-most tip of the mainland. Carapace: smooth, black to light brown with slight dorsal keel and concentric markings.
Skin: spotted or streaked against a background of gray. Can also come with bold spots and dashes like the northern and carolinan subspecies.
Distinguishing feature: very rarely seen subspecies.

Ornate Diamondback Terrapin Malaclemys terrapin macrospilota
West coast of Florida: the Panhandle to Key Largo. Carapace: deeply sculpted, black to dark gray with high dorsal keel. Scute centers are typically orange or yellow. Concentric markings are almost completely absent. Marginals can be checkered or completely orange/yellow.
Skin: thin, making their heads appear pink at times. Light speckling is usually present although patternless individuals are also known to occur. Color is generally a shade of gray.
Distinguishing feature: arguably the most attractive and easily distinguishable subspecies. The contrast of orange/yellow scute centers against an otherwise dark carapace is very pleasing indeed.

Mississippi Diamondback Terrapin Malaclemys terrapin pileata Panhandle of Florida to Eastern Louisiana. Carapace: deeply grooved, black to dark gray with high dorsal keel. Concentric markings are absent against the dark background.
Skin: thin, with mostly light speckling against a black or gray background. Mustache often present.
Distinguishing feature: darkest subspecies.

Texas Diamondback Terrapin Malaclemys terrapin littoralis Eastern Louisiana to Corpus Christi, Tx. Carapace: deeply grooved, black to brown high dorsal keel. Scute centers are sometimes lighter and concentric markings are invisible due to the background color.
Skin: lightly speckled, dark gray with greenish or bluish heads.
Distinguishing feature: head color.

The Ornate Debate

No doubt the striking beauty of the above diamondback terrapin specimens warrants them being labeled as Ornate Diamondback Terrapins. Or does it? Recently, many diamondback breeders, wholesalers and collectors have adopted that name for specimens with striking teardrops, spots and dashes on white skin. These same individuals and herp establishments may be misled by publications that have themselves labeled this race as Ornate Diamondback Terrapins, even to the point of furnishing the scientific name Malaclemys terrapin macrospilota as captions for some of these pictures. Eg. in Pritchard's Encyclopedia of Turtles, p. 265 has a plate with the heads of 4 female M.t. tequesta showing the incredible variation that exists within a single population. However, the publisher erroneously labels them as Ornate Diamondback Terrapins. This has led some to believe that any white-headed Malaclemys specimen can be named Ornate Diamondback Terrapin. However, notice that the previous plate is one of an M.t. macrospilota from Tampa Bay but mysteriously the common name is not provided. Pritchard himself describes M.t. macrospilota as the Ornate Diamondback Terrapin (p. 154) in his summary of the genus, so it is doubtful that he would liberally apply the same common name to M.t. tequesta, no matter how beautiful or "ornate" they may look. Simple deduction concludes that the name Ornate Diamondback Terrapin was intended for the previous plate of M.t. macrospilota and not for the plate containing M.t. tequesta. Hence, to name the above specimens Ornate Diamondback Terrapins shows either a blatant disregard for accepted taxonomical identification, or ignorance due to the propagation of the mislabeling in literature and herp circles. Here is the true Ornate Diamondback Terrapin, Malaclemys terrapin macrospilota:

However, having resolved the issue of which is the true Ornate Diamondback Terrapin leaves us with another dilemma in regard to the white specimens with teardrops, spots and dashes - what are they? The answer may not be clear cut due to the intergradation of subspecies along the east coast. Field observations and research have concluded that such specimens exist in both the northern and carolinan ranges with the northern race sporting brown carapace and the carolinan race sporting yellow or orange. In addition, the Mangrove Diamondback Terrapin, M.t. rhizophorarum also shows similar skin markings. However, it is unknown where these specimens originated and whether or not they are a true race or the result of intergradation.

References:

Bartlett, R.D. & Patricia (1999). A Field Guide to Florida Reptiles and Amphibians. Houston: Gulf Publishing Company.
Davenport, John (1992). The Biology of the Diamondback Terrapin, Malaclemys Terrapin (Latreille). Testudo volume 3 number 4.
Mara, W.P. (1996). Map Turtles and Diamondback Terrapins. Neptune: TFH Publications Inc.
No. 60. Hay, W.P. (1 904). A revision of Malaclemys, a genus of turtles. Bulletin of the U.S. Bureau of Fisheries 24: 1-20.
Pritchard, P.C.H. (1979). Encyclopaedia of Turtles. Hong Kong: TFH Publications Inc.

COMMON NAME	LATIN NAME	PICTURE	RANGE	DESCRIPTION
Northern Diamondback Terrapin	Malaclemys terrapin terrapin		Cape Cod to Cape Hatteras.	Carapace: lightly sculpted, black to light brown with slight dorsal keel and concentric markings. Skin: light specks and/or streaks with brighter individuals possessing bold spots and dashes. Color varies from dark gray to white. Distinguishing feature: the main subspecies available in herpetoculture.
Carolinan Diamondback Terrapin	Malaclemys terrapin centrata		Cape Hatteras to Flagler County, Fl.	Carapace: smooth, black, olive to ivory with dorsal keel almost absent. Sides of the carapace tend to run almost parallel to each other. Concentric markings are present and are sometimes faded, giving a marble effect. Skin: light specks and/or streaks with brighter individuals possessing bold spots and dashes. Color varies from dark gray to white. Distinguishing feature: carapace features and larger head.
Florida East Coast Diamondback Terrapin	Malaclemys terrapin tequesta		East coast of Florida: Flagler County to the Upper Keys.	Carapace: deeply sculpted, black to gray with sometimes lighter scute centers with slight dorsal keel. Concentric rings are generally absent. Skin: thin, with mostly specks or large spots; and even patternless. Color is usually gray or white. Mustache is normally present. Distinguishing feature: lack of concentric carapace markings.
Mangrove Diamondback Terrapin	Malaclemys terrapin rhizophorarum		Mangrove swamps of the Florida Keys and southern-most tip of the mainland.	Carapace: smooth, black to light brown with slight dorsal keel and concentric markings. Skin: spotted or streaked against a background of gray. Can also come with bold spots and dashes like the northern and carolinan subspecies. Distinguishing feature: very rarely seen subspecies.
Ornate Diamondback Terrapin	Malaclemys terrapin macrospilota		West coast of Florida: the Panhandle to Key Largo.	Carapace: deeply sculpted, black to dark gray with high dorsal keel. Scute centers are typically orange or yellow. Concentric markings are almost completely absent. Marginals can be checkered or completely orange/yellow. Skin: thin, making their heads appear pink at times. Light speckling is usually present although patternless individuals are also known to occur. Color is generally a shade of gray. Distinguishing feature: arguably the most attractive and easily distinguishable subspecies. The contrast of orange/yellow scute centers against an otherwise dark carapace is very pleasing indeed.
Mississippi Diamondback Terrapin	Malaclemys terrapin pileata		Panhandle of Florida to Eastern Louisiana.	Carapace: deeply grooved, black to dark gray with high dorsal keel. Concentric markings are absent against the dark background. Skin: thin, with mostly light speckling against a black or gray background. Mustache often present. Distinguishing feature: darkest subspecies.
Texas Diamondback Terrapin	Malaclemys terrapin littoralis		Eastern Louisiana to Corpus Christi, Tx.	Carapace: deeply grooved, black to brown high dorsal keel. Scute centers are sometimes lighter and concentric markings are invisible due to the background color. Skin: lightly speckled, dark gray with greenish or bluish heads. Distinguishing feature: head color.