Graptemys versa

Geographic Range

Texas map turtles ( Graptemys versa ) are a Nearctic species endemic to west-central Texas. Populations of Texas map turtles are located primarily in the Colorado River watershed around the Edwards Plateau, including the tributaries of the Ilano, San Saba and Concho Rivers. Texas map turtles do not typically inhabit waters southeast of Bastrop County, Texas.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Texas map turtles inhabit shallow, clear streams and muddy rivers with moderate currents (although exact current rates are not reported). They are most commonly found in open-canopied lotic habitats with dense vegetation. It is uncommon to find Texas map turtles on land, but they do bask on partially submerged logs or rocks. Texas map turtles spend most of their time underwater, at depths from 0 to 75 cm below the surface, emerging only to bask or come up for air. There is no reported elevation range for Texas map turtles.

Female Texas map turtles nest on sandbars and shorelines, typically in open areas. If the river they live in does not have a prominent, exposed shoreline, females will move farther inland to build nests in sandy areas.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• freshwater freshwater

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• riparian riparian

Physical Description

Texas map turtles have flattened carapaces, which help them move quickly through the water. They have olive or olive-brown coloration on their heads, feet, and tails, with orange markings on their carapaces and orange vertical lines on their heads, arms, and legs. The orange lines along their bodies create patterns that resemble the lines on topographical maps. Directly posterior to their eyes, Texas map turtles have orange patches that often create "J" shapes. There are also two vivid orange spots on their chins. Their plastrons are yellow and orange, with dark seams. The sides of their shells have five or six thin, dark lines.

Texas map turtles exhibit sexual dimorphism, with females being larger than males. Adult females range in carapace length from 12.70 to 20.32 cm and weigh 2.3 to 2.6 kg (average 2.5 kg). In contrast, adult males range in carapace length from 6.35 to 10.16 cm and weigh 0.2 to 0.7 kg (average 0.4 kg). Male Texas map turtles also tend to have thicker tails and more vivid colors compared to females.

As juveniles, Texas map turtles of both sexes range in size from 2.3 to 3.5 cm. Juvenile Texas map turtles have brighter markings compared to adults. As they age and reach maturity, the orange markings on their bodies and carapaces become duller.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• male more colorful

Development

Female Texas map turtles can lay as many as four egg clutches during the mating season, with 4 to 14 eggs in each clutch. Although the incubation period for Texas map turtle eggs has not been reported, other species in the genus Graptemys have an average incubation period ranging from 50 to 80 days. Texas map turtle hatchlings have carapace lengths of 2.3 to 2.5 cm. Texas map turtles exhibit indeterminate growth, although their growth rate slows down when they reach adulthood. Males reach maturity between 2 to 3 years of age, at which point their plastrons average 57 mm in length. Females reach maturity at 7 years, with their plastrons measuring an average of 115 mm.

The incubation temperature of Texas map turtle nests exhibit temperature-dependent sex determination. Males develop at cooler temperatures, around 25 to 30 °C, whereas females develop at warmer temperatures, above 32 °C. Between 30 and 32 °C, eggs may develop into either males or females.

• Development - Life Cycle
• temperature sex determination
• indeterminate growth indeterminate growth

Reproduction

There is limited information regarding the mating system of Texas map turtles specifically. However, many other species in the genus Graptemys have monogamous mating systems. Male Texas map turtles engage in courtship behavior by sticking their noses near the cloacas of females. Males then usually drum their claws on the faces of females, although they may go directly into mating after performing the cloaca-sniffing behavior. Texas map turtles release pheromones that communicate their sex and reproductive status to nearby conspecifics.

Texas map turtles are iteroparous, breeding between February and June. Females produce an average of 4 clutches in every breeding season, and each clutch contains 4 to 14 eggs. There are no reports of egg gestation period or hatchling birth mass of Texas map turtles. However, research on other species in the genus Graptemys suggest that females can store sperm and delay fertilization, and it is probable that Texas map turtles can do the same. Female Texas map turtles abandon their nests after laying eggs, so juveniles are independent upon hatching. Hatchlings have carapaces (top portion of their shells) that measure 2.3 to 2.5 cm in length.

Texas map turtles exhibit indeterminate growth. Males reach maturity between 2 to 3 years, at a minimum recorded plastron length of 5.7 cm. Females reach maturity at 6 to 7 years, at a minimum plastron length of 11.5 cm. Females grow to be 12.70 to 20.32 cm in carapace length, while males grow to be 6.35 to 10.16 cm.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Texas map turtles do not exhibit high levels of parental investment. Females build nests for their eggs in sandbars or shorelines, which provide some level of protection from predators. It is possible that females also guard their nests to some extent, as other species in the genus Graptemys exhibit this behavior, although nest guarding has not been directly observed in Texas map turtles. Regardless, females exhibit no further parental investment once juveniles hatch. Male Texas map turtles provide no parental investment beyond the act of mating.

• Parental Investment
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

There is limited information regarding the lifespans of Texas map turtles, but other species in the genus Graptemys are reported to live 14.5 to 35.4 years. For instance, ringed map turtles ( Graptemys oculifera ) live up to 20.3 years, false map turtles ( Graptemys pseudogeographica ) live up to 35.4 years, and Cagle's map turtles ( Graptemys calegi ) live up to 14.5 years. It is likely that Texas map turtles have similar lifespans, both in the wild and captivity.

Behavior

Texas map turtles are diurnal and spend most of their time submerged in the shallow water of streams or rivers. However, as they are endothermic, they also bask on partially submerged logs or rocks to heat their bodies. While basking, they are highly vigilant and will quickly return to the water if they perceive a threat. There is limited information regarding Texas map turtle behavior, but other species of map turtle (genus Graptemys ) feed in the late morning, then alternate between basking and feeding throughout the day. Other map turtle species also decrease feeding activity in mid-September, but basking behaviors continue throughout the middle of October. Other map turtle species are also known to brumate from the middle of October until the middle of April. Texas map turtles are not known to migrate, so it is likely that they also brumate during winter, when temperatures are low and food is not as abundant.

Although little is known about specific Texas map turtle behavior, the basking behavior of Texas map turtles is thought to be similar to that of other map turtle species. Map turtles are known to be extremely aggressive and competitive when it comes to basking. In cases where basking space is limited, larger individuals will either attempt to bask on top of smaller individuals or bite their legs and heads to get them to move. Some individuals avoid competition for basking spots by moving away, but others will defend their basking areas by moving their bodies back and forth abruptly to knock off any individuals trying to climb on top of them. In some cases, both competing turtles can end up falling off of basking locations due to this competition. Texas map turtles exhibit courtship and mating behaviors in April, July, October, and November.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary

Home Range

Texas map turtles are mostly sedentary, although specific home range sizes have not been reported. Other members of the genus Graptemys have reported home ranges of 18.9 to 283.8 ha. It is likely that the average home range size of Texas map turtles falls within this same range of values. There are no records of Texas map turtles defending specific territories.

Communication and Perception

There is limited information regarding the specific communication and perception strategies of Texas map turtles. However, the other species in the genus Graptemys have been more thoroughly studied. When map turtles hatch from eggs, hatchlings exhibit a behavior known as phototaxis, where they move towards light sources. Because map turtles hatch at night, the brightest natural light source comes from the reflection of the moon off of nearby water sources. Map turtles also rely on visual stimuli to detect predators while they are above water and to hunt for prey while they are submerged. Map turtles can also sense prey or approaching threats by detecting scent chemicals or vibrations propagating through water.

Texas map turtles are solitary with the exception of their breeding season, when they communicate with prospective mates. They use pheromones to identify the sex and reproductive status of other individuals, and also to alert others to danger. Males also use tactile communication as part of courtship. Males use their noses to nudge the cloacas of females and then adjust themselves so that they are face-to-face. Then, males bob their heads vertically and vibrate their foreclaws near the ocular regions of their potential mate. Following this courtship behavior, sexually receptive females will allow males to mount them and copulate. Other map turtle species also exhibit biting as a precopulatory behavior, wherein males bite the necks of females. It is likely that Texas map turtles engage in similar biting behaviors.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Texas map turtles are omnivores, feeding on insects, molluscs, crustaceans, worms, and plant matter. They eat a wide variety of insects, including beetles (order Coleoptera ), caddisflies (order Trichoptera ), damselflies and dragonflies (order Odonata ), moths and butterflies (order Lepidoptera ), mayflies (order Ephemeroptera ), net-winged insects (Order Neuroptera ), grasshoppers (order Orthoptera ), and true bugs (order Hemiptera ). Texas map turtles eat molluscs, such as Asian fingernail clams ( Corbicula fluminea ) and snails (order Gastropoda ). They also eat worms and leeches (phylum Annelida ), freshwater sponges (family Spongilidae ), and aquatic crustaceans, such as crayfish (family Cambaridae ) and isopods (order Isopoda ). Male Texas map turtles typically eat a variety of insects including caddisflies, mayflies, and beetles, whereas females primarily consume Asian fingernail clams. The diets of juvenile Texas map turtles are similar to adult diets, including sex-based differences in diet.

In addition to animal prey, Texas map turtles eat stoneworts (order Charales ), filamentous algae from a variety of taxa, and vascular plants. They have been observed eating stems, leaves, flowers, and seeds of both dicots and monocots.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
  • vermivore
• herbivore herbivore
  • folivore folivore
  • granivore granivore
  • lignivore
• omnivore omnivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms
• aquatic or marine worms
• aquatic crustaceans

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts
• flowers
• algae

Predation

Texas map turtles have few predators as adults. The majority of known predators that eat Texas map turtles are specifically nest predators, eating unhatched eggs. Primary nest predators include raccoons ( Procyon loctor ), herons and egrets (family Ardeidae ), and gars (genus Lepisosteus ). Humans ( Homo sapiens ) eat both adult and juvenile Texas map turtles.

Texas map turtles share parts of their geographic range with Texas river cooters ( Pseydemys texana ), which also experience nest predation from Virginia opossums ( Didelphis virginiana ), skunks (family Mephitidae ), and fire ants ( Solenopsis invicta ). It is likely that these nest predators also opportunistically prey on Texas map turtle eggs.

Texas map turtles have cryptic coloration and hard shells, which protect them from being detected and attacked by predators, respectively. They spend most of their time at the bottom of shallow water, often near aquatic vegetation, which further disguises them from predators. When basking, they are highly vigilant and will return to the water if they detect predators.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Texas map turtles consume a variety of aquatic invertebrates, as well as basal animals like freshwater sponges (family Spongilidae ). Texas map turtle eggs serve as food items for raccoons ( Procyon loctor ), herons (family Ardeidae ), and gars (genus Lepisosteus ).

Texas map turtles are hosts for the apicomplexan species Eimeria graptemydos and Eimeria mitraria . They are also hosts for acanthocephalans, such as Neochinorhynchus emydis and Neoechinorhynchids stunkardi .

Economic Importance for Humans: Positive

Texas map turtles are tolerant of poor water quality and have a flexible diet, and thus are popular in the pet trade. Texas map turtles typically cost between 40 and 299 USD.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

Other species in the genus Graptemys are known to carry salmonella on their skin and shells. When kept as pets or handled in the wild, map turtles have the potential to transfer salmonella to humans. Although it has not been confirmed that Texas map turtles carry salmonella, it is likely that they do.

Conservation Status

Texas map turtles are listed as a species of "Least Concern" on the IUCN Red List. They are listed in Appendix III of CITES, which prohibits the export of any specimen from any location without a permit. Texas map turtles have no special status on the U.S. Fish & Wildlife Service Endangered Species list or Michigan's Rare Animals list.

Although there are no reported threats to Texas map turtles, other species in the genus Graptemys are threatened by commercial fishing nets and water pollution. It is likely that Texas map turtles are experiencing similar threats in their habitats. Texas map turtles have a limited geographic range, meaning any threats to areas in this range have the potential to strongly affect Texas map turtle populations.

Texas map turtle habitats are federally protected by Texas Parks and Wildlife Services. Additionally, certain areas within their geographic range are part of protected state parks, including the Fort McKavett State Historical Park on the San Saba River, San Angelo State Park on the Concho River, and the South Llano River State Park.

Additional Links

Encyclopedia of Life

Contributors

Candice Amick (author), Radford University, Sierra Felty (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.

References

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