Map Turtles

Die Schildkröten-Gattung der Höckerschildkröten (Graptemys), die man in den Flüssen der östlichen USA findet, umfasst 12 Arten, die in zwei Artengruppen gegliedert werden, die breitköpfigen und die schmalköpfigen Höckerschildkröten. Ihre nächsten Verwandten sind die Schmuckschildkröten und die Zierschildkröten, mit denen sie den Chrysemys-Komplex bilden (benannt nach der Gattung der Zierschildkröten). Die im Brackwasser der Flussdeltas lebenden Diamantschildkröten (Malaclemys) hatten zusammen mit den Höckerschildkröten einen gemeinsamen Vorfahren. Somit handelt es sich in der Systematik um Schwesterntaxa.

Merkmale

Höckerschildkröten haben eine grünliche bis schwarze Haut, die mit hellgelben bis orangefarbenen Linien überzogen ist. Der olivgrüne bis dunkelbraune Rückenpanzer (Carapax) ist flach und entlang der Mittellinie mit einem auffälligen Kiel versehen. Bei allen Arten außer der Falschen Landkarten-Höckerschildkröte (Graptemys geographica) ist dieser Kiel auf den ersten drei Vertebralschilden artabhängig zu mehr oder weniger prominenten Höckern geformt. Auch die hinteren Ränder des Rückenpanzers sind gezackt. Der Bauchpanzer (Plastron) ist hellgelb und weist bei einigen Arten eine dunkle Zeichnung auf. Obwohl diese Gattung mehrere kleinbleibende Arten umfasst, erreichen manche Höckerschildkröten eine Panzerlänge von knapp 30 Zentimetern.

Lebensraum

Höckerschildkröten kommen vorwiegend in calciumreichen Flüssen mit je nach Art mäßiger bis starker Strömung vor. Die Ufer sollten mit dichter Vegetation bewachsen und unterhalb des Wasserspiegels verkrautet sein. Baumstämme oder Steine müssen als Sonnenplätze aus dem Wasser herausragen, da Höckerschildkröten vorzugsweise vom Wasser rundherum umgebene Stellen aufsuchen.

Körpergröße

Die maximale Körpergröße einiger breitköpfiger Arten beträgt 30 Zentimeter Panzerlänge. Manche adulten Männchen schmalköpfiger Arten hingegen wachsen auf gerade einmal 8 Zentimeter.

Geschlechtsunterschiede

Neben dem für Schildkröten typischen primären Geschlechtsmerkmal der unterschiedlichen Position der Kloake, fällt bei Höckerschildkröten besonders die Größendifferenz zwischen Männchen und Weibchen auf. Weibchen wachsen teilweise auf die dreifache Länge ihrer männlichen Artgenossen. Dadurch bedingt nehmen die Weibchen in ihrem Biotop über einen Großteil des Jahres eine gesonderte Ökologische Nische ein. Sie leben vorwiegend in den tiefen Bereichen in der Flussmitte, wogegen Jungtiere und Männchen die Uferzonen bewohnen. Zudem ist bei Schildkrötenweibchen der Schwanz deutlich dicker als bei Männchen. Ausgewachsene Männchen hingegen haben viel längere Krallen.

Lebenserwartung

Mangels genauerer Statistiken kann man aufgrund von Beobachtungen einzelner Tiere in Gefangenschaft davon ausgehen, dass Höckerschildkröten um die 60 Jahre alt werden können.

Mississippi-Höckerschildkröte (Graptemys pseudogeographica kohnii)

Lebensweise

Ihre Lebensweise ähnelt der aller Schildkröten (vgl. dort). Den Tag verbringen sie mit der Nahrungssuche und dem Sonnen zur Regulierung ihrer Körpertemperatur. Sobald die Temperaturen dauerhaft unter 20 °C bleiben, beginnen die Tiere zu überwintern, wobei es hier zu großen Unterschieden aufgrund der geographischen Herkunft kommt. Während sie im nördlichen Verbreitungsgebiet bei Temperaturen unter 10 °C in eine Starre fallen, bleiben sie im Süden den Winter über gemäßigt aktiv.

Ernährung

Höckerschildkröten sind mit ihren kräftigen Kiefern oft auf den Verzehr von Schnecken spezialisiert, nehmen aber sonst viele Arten von tierischer Kost auf, wie beispielsweise Fische, Weichtiere, Insekten. Vegetarische Kost ergänzt ihren Speisezettel.

Die Nahrungsaufnahme findet ausschließlich im Wasser statt. Allerdings ließ sich beobachten, dass einzelne Tiere Nahrung vom Land ins Wasser zogen.

Fortpflanzung

Im Herbst und im Frühjahr suchen sich die Männchen und Weibchen zur Begattung auf. Nach einer erfolgreichen Befruchtung bleiben die Weibchen für mehrere Jahre fruchtbar. Weichschalige Eier legen sie ab dem Frühjahr in oft vier Gelegen pro Jahr mit jeweils artabhängig um die vier Eier. Präferierte Eiablagestellen sind sonnige Uferzonen mit leicht sandigem Grund gut oberhalb der Wasseroberfläche. Das trächtige Weibchen sucht diese Stellen früh morgens oder bei Einbruch der Dunkelheit zur Oviposition (Eiablage) auf. Dort gräbt sie eine flaschenförmige Grube, die sie nach der Eiablage sorgfältig verschließt, so dass sie von der Umgebung nicht mehr zu unterscheiden ist. Die Eier werden rund drei Monate lang inkubiert. Das Geschlecht der Jungtiere ist von der Inkubationstemperatur abhängig, wobei artspezifisch häufig ein Wert von über 28 °C vorwiegend Weibchen hervorbringt.

Systematik

Breitköpfige Arten

Die breitköpfigen Höckerschildkröten wachsen größer als die übrigen Arten. Man findet sie vorwiegend in verkrauteten ruhigen Flussabschnitten mit Gelegenheiten des Sonnenbadens auf Steinen oder Baumstämmen, die aus dem Wasser ragen.

Barbours-Höckerschildkröte Graptemys barbouri Schlüpfling

• Barbours Höckerschildkröte (Graptemys barbouri Carr & Marchand, 1942)
• Escambia-Höckerschildkröte (Graptemys ernsti Lovich & Mccoy, 1992)
• Landkarten-Höckerschildkröte auch Landkartenschildkröte (Graptemys geographica (Le Sueur, 1817))
• Pascagoula-Höckerschildkröte (Graptemys gibbonsi Lovich & Mccoy, 1992)
• Ouachita-Höckerschildkröte (Graptemys ouachitensis Cagle, 1953)
  • Ouachita-Höckerschildkröte (Graptemys ouachitensis ouachitensis Cagle, 1953)
  • Sabine-Höckerschildkröte (Graptemys ouachitensis sabinensis Cagle, 1953) - manchmal auch als eigene Spezies Graptemys sabinensis aufgefasst
• Falsche Landkarten-Höckerschildkröte (Graptemys pseudogeographica (Gray, 1831)) - beide Unterarten sind häufig in Terrarien gehaltene Tiere
  • Missouri-Höckerschildkröte (Graptemys pseudogeographica pseudogeographica (Gray, 1831))
  • Mississippi-Höckerschildkröte (Graptemys pseudogeographica kohnii (Baur, 1890))
• Schmuck-Höckerschildkröte auch Alabama-Höckerschildkröte (Graptemys pulchra Baur, 1893)
• Graptemys pearlensis Ennen, Lovich, Kreiser, Selman & Qualls, 2010

Schmalköpfige Arten

Die schmalköpfigen Höckerschildkröten zählen zu den kleinsten Schildkröten überhaupt. Sie bewohnen kalkreiche Flussabschnitte mit zum Teil beachtlicher Strömung. Die Möglichkeit des Sonnenbadens auf Steinen oder aus dem Wasser ragenden Baumstämmen muss gewährleistet sein.

Die erstgenannten drei Arten haben sich nach der letzten Eiszeit aus einer Spezies entwickelt, die der rezenten Pracht-Höckerschildkröte ähnelte.

• Gelbtupfen-Höckerschildkröte (Graptemys flavimaculata Cagle, 1954)
• Schwarzknopf-Höckerschildkröte auch Schwarzbeulen-Höckerschildkröte (Graptemys nigrinoda Cagle, 1954)
  • Schwarzknopf-Höckerschildkröte auch Schwarzbeulen-Höckerschildkröte (Graptemys nigrinoda nigrinoda Cagle, 1954)
  • Delta-Schwarzknopf-Höckerschildkröte auch Südliche Schwarzbeulen-Höckerschildkröte (Graptemys nigrinoda delticola Folkerts & Mount, 1969)
• Pracht-Höckerschildkröte (Graptemys oculifera (Baur, 1890))
• Texas-Höckerschildkröte (Graptemys versa Stejneger, 1925)
• Cagles Höckerschildkröte (Graptemys caglei Haynes & Mckown, 1974)

o. Mississippi-Höckerschildkröte (Graptemys pseudogeographica kohnii) - u. Falsche Landkarten-Höckerschildkröte bzw. Missouri-Höckerschildkröte (Graptemys pseudogeographica pseudogeographica)

Literatur

• Carl H. Ernst, Jeffrey E. Lovich, Roger W. Barbour: Turtles of the United States and Canada. Smithsonian Books, New York 2000, ISBN 1-56098-823-1

Weblinks

– Sammlung von Bildern, Videos und Audiodateien

• Graptemys In: The Reptile Database

Graptemys is a genus of freshwater turtles containing 14 species, commonly known as map turtles.^[5] Graptemys are small to medium-sized turtles that are significantly sexually dimorphic, with females in some species attaining as much as twice the length and ten times the mass as males. Depending on the species, adult males range from 7–16 cm (2.75–6.25 in), adult females 10–29.5 cm (4–11.62 in), and hatchlings 2.5–3.8 cm (1–1.5 in),^{[6]: 202–209 p.} although some sources indicate female Barbour's map turtles (Graptemys barbouri) grow to 33 cm (13 in) in length.^[7] Most species have a distinctive dark pigmented keel that is often notched or serrated running down the center of the carapace and serrated scutes on the rear margin. The head, neck, and limbs exhibit bold patterns of yellow (occasionally orange or red) lines and spots against darker green, olive, or black base colors. The patterns on the head can be important characters in identifying the various species. The common name "map turtle" is derived from the intricate patterns on their shells that are suggestive of topographical maps, although the patterns are more apparent in some species than others, and often become obscure in older specimens. Some species are occasionally called "sawbacks", in reference to the serrated keels on their shell.^[8][9]

They are endemic to North America, where most species occur in the rivers of the Gulf Coast of the United States, although three species are more wide-ranging, dispersed throughout the eastern two thirds of the greater Mississippi River basin, into the Great Lakes region, and east to New York and southeast Canada. Most Graptemys are lotic (river) turtles, having a preference for moving water and larger lakes, and with long legs, broad feet, and long fully webbed digits they are well adapted for swimming in currents. They primarily feed on fresh water mussels, clams, snails, insects (including larva and eggs), bryozoans, sponges, algae, and various vegetation. Fish only appear in the diets of a few species and then only in a relatively small percentage of the diet. Within this spectrum of food items there is significant niche partitioning among the sexually dimorphic males and females, and microcephalic, mesocephalic, and megacephalic species occurring in the same river drainages. Like all turtles, map turtles are oviparous, typically laying eggs from late June to August. Females lay two to 15 eggs per clutch and depending on a number of variables such as species, size, and age among other factors, may skip a year between clutches, or lay as many four clutches a year.^[8][9]

Seven of the 14 species are listed as either near threatened, vulnerable, or endangered by the IUCN Red List as of 2021,^[10] and two species, the yellow-blotched map turtle (G. flavimaculata) and the ringed map turtle (G. oculifera) are listed as threatened by the U.S. Federal Government.^[11]

Species

Mississippi map turtles (Graptemys pseudogeographica kohni), adult female left, adult male right, photographed in situ, Trinity River, Liberty Co., Texas (20 April 2007)

The following species and subspecies are recognized as being valid (listed alphabetically by specific name and subspecific name). Nota bene: A binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than Graptemys.

Extant species

• Graptemys barbouri Carr & Marchand, 1942 – Barbour's map turtle^[12]
• Graptemys caglei Haynes & McKown, 1974 – Cagle's map turtle^[12]
• Graptemys ernsti Lovich & McCoy, 1992 – Escambia map turtle^[12]
• Graptemys flavimaculata Cagle, 1954 – yellow-blotched map turtle or yellow-blotched sawback ^[12]
• Graptemys geographica (Lesueur, 1817) – northern map turtle, formerly known as the common map turtle^[12]
• Graptemys gibbonsi Lovich & McCoy, 1992 – Pascagoula map turtle^[12]
• Graptemys nigrinoda Cagle, 1954 – black-knobbed map turtle^[12]
• Graptemys oculifera (Baur, 1890) – ringed map turtle^[12]
• Graptemys ouachitensis Cagle, 1953 – Ouachita map turtle^[12]
• Graptemys pearlensis Ennen, Lovich, Kreiser, Selman, Qualls, 2010 – Pearl River map turtle^[12][13]
• Graptemys pseudogeographica (Gray, 1831) – false map turtle^[12]
  • G. p. kohnii (Baur, 1890) – Mississippi map turtle^[12]
  • G. p. pseudogeographica (Gray, 1831) – false map turtle^[12]
• Graptemys pulchra Baur, 1893 – Alabama map turtle^[12]
• Graptemys sabinensis Cagle, 1953 – Sabine map turtle^[12]
• Graptemys versa Stejneger, 1925 – Texas map turtle^[12]

Fossil species

An extinct species from the Suwannee River drainage in Florida, Graptemys kerneri belonging to the female megacephalic subclade, was described in 2011 from Pleistocene fossil records.

• †Graptemys kerneri Ehret & Bourque, 2011^[14]

Etymology

Cagle's map turtle (Graptemys caglei) hatchling

The generic name Graptemys is derived from two compounded Greek words, graptos, meaning inscribed or in writing, in reference to the patterns on the turtles shells, and emydos, meaning a freshwater turtle.^[2] The trivial names, or specific epithets, of four of the species in the genus are patronyms or eponyms, named in honor of prominent herpetologist, each of whom made significant contributions to studies on North American turtles: Thomas Barbour (G. barbouri); Fred Ray Cagle (G. caglei); Carl Henry Ernst (G. ernsti); J. Whitfield Gibbons (G. gibbonsi). One subspecies is named for the collector of the type specimen, Joseph Gustave Kohn (G. pseudogeographica kohnii).^[15] Three species are named for the rivers in which they were first discovered: Ouachita River (G. ouachitensis); Sabine River (G. sabinensis); Pearl River (G. pearlensis).^[16][13] The other species are all named for various aspects of the topographic map like patterns and other markings, colors, and contours of the carapace, that are most apparent in the juveniles and young adults of these attractive turtles: G. flavimaculata, flavus = yellow, maculatus = spotted or blotched;^[17] G. geographica, geographica = geographic map like;^[18] G. nigrinoda, niger = black, nodus = knot, node, or knob;^[19] G. oculifera, oculus = eye, fero = to bear (eye shape rings on the pleurals scutes);^[20] G. pseudogeographica, pseudo = false, geographica = geographic map like;^[21] G. pulchra, pulchra = beautiful;^[22] G. versa, vers = to change (probably referring to the contrasting head patterns compared to G. pseudogeographica).^[23]

Description

Northern Map Turtle (Graptemys geographica), plastron, Lac Leamy, Gatineau, Quebec, Canada (12 June 2011)

Graptemys species superficially resemble many other species of aquatic turtles, including sliders (Trachemys) and cooters (Pseudemys). However, they are distinguished by a keel that runs the length of the center of the carapace. In some southern species, the keel can result in vertebral spines, resulting in the map turtle's other common name — "sawback". They also typically grow to a smaller size at maturity. They are given the common name "map turtle" due to the map-like markings on the carapace. Map turtles are known for intricate head markings and strong sexual dimorphism with mature females twice the length and 10 times the mass of mature males.

Feeding morphology

Females of all map turtle species can be partitioned into three groups based on head (alveolar) width and corresponding ecology and phylogeny.

1. Microcephalic females are narrow headed, sympatric with a broader headed species, and consume few mollusks. Microcephalic species include yellow-blotched, black-knobbed, ringed, Ouachita, and Sabine map turtles.
2. Mesocephalic females have moderately broad heads and tend to eat mostly mollusks along with softer bodied prey. Mesocephalic species include Cagle's, northern, false, Mississippi, and Texas map turtles.
3. Megacephalic females have exceptionally broad heads, and feed almost exclusively on mollusks. Megacephalic females include Barbour's, Escambia, Pascagoula, Pearl River, and Alabama map turtles.

Males do not fit neatly into the three groups describing head width, with differences in head width likely not influencing diet. Due to these differences in head size and jaw strength, females tend to eat much larger prey than the males such as snails, clams, and crayfish whereas the males eat insects and smaller crustaceans.^{[8]: 237 p.} Including deadwood material inside of the Graptemys habitat then the chances of more Graptemys migrating or being born in that area is greater. The population can use a healthy habitat that can support a significant number of Graptemys and dead wood will help with this.

Distribution

The distribution of 11 Graptemys species and partial distribution of G. ouachitensis. The black dots and squares represent type localities.

Distribution of Graptemys geographica

Map turtles are endemic to North America. The genus ranges from the Great Lakes region and St. Lawrence River of southern Quebec and Ontario, Canada, south to the Gulf of Mexico, and the Hudson River and Delaware River basins on the Atlantic coast, west to the eastern margins of the Great Plains. Most species occur in rivers, moving waters, or larger lakes. Eleven of the 14 species have relatively limited distributions, restricted to river basins draining into the Gulf of Mexico, in the US states of Texas, Louisiana, Mississippi, Alabama, southwest Georgia, and the Florida panhandle. Three species are more wide ranging, include the Ouachita Map Turtle (G. ouachitensis) and the False Map Turtle (G. pseudogeographica) which range extensively in the Mississippi River drainage and its tributaries including much of the mid west, with the latter also ranging west into east Texas. The Northern Map Turtle (G. geographica) is the most widespread species, occurring in both Atlantic and Gulf of Mexico river drainages, from southern Quebec, Canada, west to Minnesota and eastern Kansas, south to New Jersey and above (north) of the fall line in Georgia, Alabama, and extreme northern Louisiana.^{[6]: 202–209 pp.}

Ecology and natural history

Habitat

Map turtles are predominantly lotic, living in moving water, such as rivers and larger creeks, streams, and bayous. The northern and wide-ranging Mississippi River species (G. geographica, G. pseudogeographica, G. ouachitensis) tend to inhabit more diverse habitats, including sloughs, oxbow lakes, and backwater areas of river bottoms, as well as lakes and occasionally even ponds and marshlands. Other species use these environments much less frequently, or as juveniles or during seasonal flooding, and a few species have never been reported from areas beyond the main channels of their respective river systems (e.g. G. gibbonsi, G. pearlensis, G. sabinensis). Several species will inhabit manmade reservoirs in their river systems, while other species are very uncommon in such impoundments (e.g. G. oculifera, G. versa), and still others are entirely absent from reservoirs (e. g. G. caglei). With few exceptions (G. barbouri, G. flavimaculata, G. nigrinoda), most species do not occur in tidally influenced waterways, estuaries, or brackish waters, which are occupied by their closest relative the diamondback terrapin (Malaclemys terrapin). The upstream distributional limits of many species are often associated with the level of sunlight penetration through the forest canopy. Larger, wider waterways allow sunlight to reach the surface, providing for the growth of aquatic vegetation and algae (food) and basking sites for Graptemys populations. Smaller streams in the shadow of forest canopies, or that receive brief patchy sunlight, are rarely inhabited by Graptemys.^{[8]: 84–87, 255–360 pp. [9]: 272–343 pp.}

Map turtles (Graptemys) typically select basking sites emerging from the water without any contact to land, Sabine map turtles (G. sabinensis), Orange Co. Texas (15 October 2016)

The ecology of many species of map turtles, particularly habitat use and diet, have been well studied. Specific habitat use often differs among males and females of the same species, as well as sympatric species sharing a river system, all inextricably linked to their diets in a somewhat complex example of niche differentiation. Ten of the 14 Graptemys species share a river basin with another Graptemys species, and three species occur in regions of Alabama, and portions of the Mississippi River. Generally the mesocephalic and megacephalic females occupy deeper areas with stronger currents and hard-bottom, limestone sections of rivers, and males inhabit slower, shallower areas of the rivers nearer to the shore, largely correlated with their respective diets and prey distribution. Graptemys rarely walk on land or move between waterways. Most species are reluctant to bask on river banks and are seldom seen even on fallen trees with one end resting on the bank. Basking sites are most often fallen tree and deadwood emerging from water with no direct contact to the banks. Although the wide-ranging, northern species (G. geographica, G. pseudogeographica, G. ouachitensis) tend to be more flexible in their basking habits.^{[8]: 84–87, 255–360 pp. [9]: 272–343 pp. [24]}

The natural meandering of rivers, riparian forest, and fallen trees and deadwood in the water are all key and vital elements to sustain most map turtle populations, particularly the Gulf Coast species. The outer bend in a river is typically the deeper side, with the stronger current of the main channel, eroding and cutting into the outer bank and falling trees of the riparian zone forest as it does. While the inside of the bend is shallower, with a slower current, dropping silt deposits and building beaches and sandbars. The meandering course maintains a diverse spectrum of water depths, temperatures, currents, soft and hardpan bottoms, as well as fallen trees and logs that get lodged in the bends. Beaches and sand bars are essential nesting sites. The presence of partially submerged deadwood and trees are critical, not only for basking, but for the growth of algae, bryozoans, sponges, snails, insects and their eggs larva that live in the growth, which are important food items for turtles.^{[8]: 84–87, 255–360 pp. [9]: 272–343 pp.}

Courtship behavior

Adult Graptemys males have greatly elongated claws on the front feet, which are used in courtship behavior. The male faces the considerably larger female and "fans" her face, vibrating his foreclaws against her head to induce her to cooperate in mating.^[25]

Longevity

Complete and accurate longevity records for map turtles are lacking. A review of zoo records published in 1992 identified the maximum period of time that many species of Graptemys lived in captivity in North American zoos, ranging from eight to 35 years, including: Barbour's map turtle (G. barbouri) 31 years 8 months; false map turtle (G. pseudogeographica ssp.) 32 years and 6 months; Mississippi map turtle (G. pseudogeographica kohnii) 35 years 5 months. However, it is important to note that in every example these records involve turtles that were acquired by the zoos as adults from the wild, or of unknown origins and of undetermined ages. Therefore the records only reflect the period of time that an individual turtle was maintained at the institutions before it died, not the full lifespan of the individual.^{[26]: 13 p.} Subsequently, the longevity of two female Barbour's Map Turtles (G. barbouri) of unknown ages and origin at the Columbus Zoo were reported at 37 and 43 years. Herpetologist Carl Ernst noted northern map turtles (G. geographica) and Alabama map turtles (G. pulchra) likely live well over 20 years in the wild,^{[9]: 300 & 339 p.} and ringed map turtles (G. oculifera) are known to live at least 30 years in the wild.^[27] Based on records of other turtles in the Emydidae family, it is likely Graptemys longevity exceeds these records significantly, perhaps by decades.^{[8]: 114 p.}

Conservation

The most frequently cited and best-documented threats to map turtle and sawback populations involve modifications of the rivers and lakes they inhabit and their take for the pet trade.^{[8]: 198 p.}

Top: A satellite view of the Sabine River showing the natural meandering course, producing a diverse spectrum of water depths, fast and slow currents, temperatures, soft and hardpan bottoms, sand beaches, and other habitats and microhabitats, all supporting a diverse spectrum of flora and fauna. Bottom: A channelized tributary of the Sabine River, maintained at a uniform depth, eliminating a spectrum of the habitats (e.g. beaches), and reducing or eliminating a spectrum of native flora and fauna.

The limited ranges and restricted habitats of most species make Graptemys particularly vulnerable to conservation issues. The destruction and fragmentation of habitat through the engineering of rivers and lakes, such as channelization, dams and impoundments, gravel and sand mining, pollution, clearing and development of riparian zones, and the removal of logs and deadwood from waterways are among the foremost conservation threats to map turtles. These activities degrade or destroy nesting sites (sandbars), prey species and prey habitat, and basking sites that are essential for thermoregulation and the turtles survival. The pet trade is another significant threat to the survival of map turtles. In the year in 2000 alone, 200,000 live Graptemys were exported from the USA, predominantly to Europe, and this does not take into account the domestic market.^{[8]: 192–206 p.}

A variety of human activities such as bycatch in gillnetting and fyke nets, injuries form boat propellers, and "plinking", the practice of shooing turtles for target practice, or for the misinformed idea that they are significant competitors for game fish, all contribute to mortalities. Seemingly benign activities such as the regular use of sandbar beaches for recreation, swimming, and heavy boat traffic are known to cause turtles to abandon stretches of rivers and nesting sites. Some lesser threats include invasive species such as fire ants (Solenopsis invicta) which are known to prey on eggs and hatchlings. Invasive plants such as water hyacinth (Eichhornia crassipes), alligator weed (Alternanthera philoxeroides), congon grass (Imperata cylindrica), cocklebur (Xanthium stramarium), and the Chinese tallow tree (Triadica sebifera) are all known to degrade Graptemys habitat and nesting beaches. Hydrilla (Hydrilla verticillata) has been associated with steep declines of black-knobbed map turtles in some areas. Conversely, maps turtles are known to feed on some non-native species of clams (Corbicula) and mussels (Dreissena).^{[8]: 210–214 p.}

The United States Federal Government list two species, the yellow-blotched map turtle (G. flavimaculata) and the ringed map turtle (G. oculifera) as threatened species.^[11] In Texas the state government list the Cagle's Map Turtle (G. caglei) as a threatened species.^[28] The state of Louisiana list the ringed map turtle (G. oculifera) as threatened and the Ouachita map turtle (G. ouachitensis) and Sabine Map Turtle (G. sabinensis) as vulnerable.^[29] The state of Mississippi list the yellow-blotched map turtle (G. flavimaculata) as threatened and the ringed map turtle (G. oculifera) and black-knobbed map turtle (G. nigrinoda) as endangered.^[30] In Alabama, all six species of map turtles occurring in the state are classified as nongame species protected by the state.^[31] In Georgia the Barbour's map turtle (G. barbouri) is as threatened and the northern map turtle (G. geographica) and Alabama map turtle (G. pulchra) are considered rare species ranked S1 and S3 respectively.^[32] In Florida Barbour's map turtle (G. barbouri) is state-designated as threatened.^[33] The Government of Canada list the Northern Map Turtle (G. geographica) is a species of special concern.^[34] Seven of the 14 Graptemys species are listed as either, near threatened, vulnerable, or endangered by the IUCN Red List as of 2021^[10] As of 2021, all Graptemys are listed as Appendix III by CITES.^[35]

Pet trade

Throughout the pet trade, the Mississippi map turtle, the northern map turtle, and Ouachita map turtle were bred and hatched out by the thousands in the 1970s. Various other turtles were available, but as the salmonellosis Four-inch Law was established, map turtles and others slowly decreased in popularity. Today, these same three still hold the title for most common among the pet trade. Other species being captive-bred more often include the Texas map turtle, Cagle's map turtle, and the black-knobbed map turtle. Some harder-to-find map turtles include the yellow-blotched map turtle and the Pearl River map turtle.

Gallery

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  Barbour's map turtle (Graptemys barbouri), megacephalic female in zoo exhibit

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  Barbour's map turtle (Graptemys barbouri), male

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  Escambia map turtle (Graptemys ernsti)

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  Northern map turtle (Graptemys geographica), juvenile, Meramec River, Franklin County, Missouri (August 2020)

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  Northern map turtle (Graptemys geographica) from Shannon County, Missouri (27 August 2017)

• 

  Pascagoula Map Turtle (Graptemys gibbonsi)

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  Black-knobbed map turtle (Graptemys nigrinoda), two hatchlings

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  Black-knobbed map turtle (Graptemys nigrinoda), adult in an aquarium display

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  Ringed map turtle (Graptemys oculifera), juvenile

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  Ouachita map turtle (Graptemys ouachitensis), juvenile from St. Louis County, Missouri (26 May 2018)

• 

  Ouachita map turtle (Graptemys ouachitensis) in situ, Red River, Fannin Co., Texas (24 June 2021)

• 

  Pearl River map turtle (Graptemys pearlensis)

• 

  Northern false map turtle (Graptemys p. pseudogeographica), juvenile, St. Louis County, Missouri (27 June 2015)

• 

  Northern false map turtle (Graptemys p. pseudogeographica), adult

• 

  Mississippi map turtle (Graptemys pseudogeographica kohnii), juvenile from Pulaski County, Arkansas (28 April 2016)

• 

  Mississippi map turtles (Graptemys pseudogeographica kohnii) in situ in Big Cypress Bayou, Harrison Co., Texas (13 April 2017)

• 

  Sabine map turtle (Graptemys sabinensis) in situ, Viilage Creek (Neches River), Hardin Co., Texas (12 October 2021)

• 

  Texas map turtle (Graptemys versa) in situ, Colorado River, Travis Co., Texas (12 April 2012)

• 

  Texas map turtle (Graptemys versa) Kimble Co., Texas (7 October 2018)

References

Las tortugas mapa (Graptemys) son un género de tortugas de la familia Emydidae. Son tortugas acuáticas originarias del este de Norteamérica. Se parecen a muchas otras especies de tortugas acuáticas, incluyendo Trachemys y Pseudemys, de las que se distinguen por desarrollar una quilla que se extiende a lo largo del centro del caparazón, y también porque suelen alcanzar un tamaño menor. Se les da el nombre de tortuga mapa por a las marcas que tienen en el caparazón. La esperanza de vida media de las tortugas mapa es de entre 15 y 30 años.

Especies

• Graptemys barbouri (Carr y Marchland, 1942)
• Graptemys caglei (Haynes y McKnown, 1974)
• Graptemys ernsti (Lovich y McCoy, 1992)
• Graptemys flavimaculata (Cagle, 1954)
• Graptemys geographica (Le Sueur, 1817)
• Graptemys gibbonsi (Lovich y McCoy, 1992)
• Graptemys nigrinoda (Cagle, 1954)
• Graptemys oculifera (Baur, 1890)
• Graptemys ouachitensis Cagle, 1953
• Graptemys pearlensis (Ennen, Lovich, Kreiser, Selman, Qualls, 2010)
• Graptemys pseudogeographica (Gray, 1831)
  • Graptemys pseudogeographica kohnii
• Graptemys pulchra (Baur, 1893)
• Graptemys versa (Stejneger, 1925)

Referencias

• An Overview of map turtles in the United States, Reptile & Amphibian Magazine, November/December 1993, p. 6-17.

Graptemys Emydidae familiako narrasti genero bat da. Ipar Amerikan bizi dira.

Espezieak

• Graptemys barbouri Carr & Marchand, 1942
• Graptemys caglei Haynes & McKown, 1974
• Graptemys ernsti Lovich & McCoy, 1992
• Graptemys flavimaculata Cagle, 1954
• Graptemys geographica (Lesueur, 1817)
• Graptemys gibbonsi Lovich & McCoy, 1992
• Graptemys nigrinoda Cagle, 1954
• Graptemys oculifera (Baur, 1890)
• Graptemys ouachitensis Cagle, 1953
• Graptemys pearlensis Ennen, Lovich, Kreiser, Selman & Qualls, 2010
• Graptemys pseudogeographica (Gray, 1831)
• Graptemys pulchra Baur, 1893
• Graptemys versa Stejneger, 1925

Graptemys est un genre de tortue de la famille des Emydidae^[1].

Répartition

Ces tortues se rencontrent en Amérique du Nord^[1].

Description

Ce sont des tortues aquatiques et carnivores.

Liste des espèces

Selon TFTSG (27 mai 2011)^[2] :

• Graptemys barbouri Carr & Marchand, 1942
• Graptemys caglei Haynes & McKown, 1974
• Graptemys ernsti Lovich & McCoy, 1992
• Graptemys flavimaculata Cagle, 1954
• Graptemys geographica (Lesueur, 1817)
• Graptemys gibbonsi Lovich & McCoy, 1992
• Graptemys nigrinoda Cagle, 1954
• Graptemys oculifera (Baur, 1890)
• Graptemys ouachitensis Cagle, 1953
• Graptemys pearlensis Ennen, Lovich, Kreiser, Selman & Qualls, 2010
• Graptemys pseudogeographica (Gray, 1831)
• Graptemys pulchra Baur, 1893
• Graptemys versa Stejneger, 1925

Publication originale

• Agassiz, 1857 : Contributions to the Natural History of the United States of America. Little, Brown & Co., Boston, vol. 1, p. 1-452 (texte intégral).

Notes et références

Le tartarughe geografiche (Graptemys Agassiz, 1857) sono un genere di testuggini appartenente alla famiglia degli emididi, originarie del Nord America.

Specie

• Graptemys barbouri Carr & Marchand, 1942 – tartaruga geografica di Barbour
• Graptemys caglei Haynes & McKown, 1974 – tartaruga geografica di Cagle
• Graptemys ernsti Lovich & McCoy, 1992 – tartaruga geografica del fiume Escambia
• Graptemys flavimaculata Cagle, 1954 – tartaruga geografica dalle macchie gialle
• Graptemys geographica (Lesueur, 1817) – tartaruga geografica settentrionale
• Graptemys gibbonsi Lovich & McCoy, 1992 – tartaruga geografica del fiume Pascagoula
• Graptemys nigrinoda Cagle, 1954 – tartaruga geografica dalle gobbe nere
• Graptemys oculifera (Baur, 1890) – tartaruga geografica dagli anelli
• Graptemys ouachitensis Cagle, 1953 – tartaruga geografica meridionale
  • G. o. ouachitensis Cagle, 1953 – tartaruga geografica del fiume Ouachita
  • G. o. sabinensis Cagle, 1953 – tartaruga geografica del fiume Sabine (a volte considerata una specie a sé: Graptemys sabinensis)
• Graptemys pearlensis Ennen, Lovich, Kreiser, Selman & Qualls, 2010 – tartaruga geografica del fiume Pearl
• Graptemys pseudogeographica (Gray, 1831) – falsa tartaruga geografica
  • G. p. pseudogeographica (Gray, 1831) – tartaruga geografica del fiume Missouri
  • G. p. kohni (Baur, 1890) – tartaruga geografica del fiume Mississippi
• Graptemys pulchra Baur, 1893 – tartaruga geografica dell'Alabama
• Graptemys sabinensis Cagle, 1953 – tartaruga geografica del fiume Sabine (a volte considerata una sottospecie: G. ouachitensis sabinensis)
• Graptemys versa Stejneger, 1925 – tartaruga geografica del Texas

Etimologia

Giovane esemplare di Gratemys caglei. Si notino i motivi concentrici sugli scuti del carapace

Questa illustrazione del 1872 evidenzia le linee sul carapace di una Graptemys geographica

Il nome comune "tartaruga geografica" (in inglese map turtle; in franco-canadese tortue géographique) fa riferimento ai motivi concentrici del carapace, visibili soprattutto negli esemplari più giovani, che richiamano le curve di livello di una carta topografica.^[1]

Il nome scientifico Graptemys^[2] è una latinizzazione del greco antico γραπτός ‑ή ‑όν (graptós ‑ḗ ‑ón, «delineato, iscritto, disegnato»; derivato di γράφω, trascr. gráphō) ed ἐμύς ‑ύδος (emýs ‑ýdos, «tartaruga d'acqua dolce»; cfr. Emys) e, secondo Seidel & Ernst (2017), fa riferimento alle sottili linee chiare che decorano il carapace degli esemplari adulti.^[3]

Distribuzione e habitat

Le tartarughe appartenenti al genere Graptemys si trovano in fiumi e torrenti di tutta la parte orientale del Nord America, dagli Stati Uniti alle regioni sudorientali del Canada.

La maggior parte delle specie predilige acque caratterizzate da correnti abbastanza forti, ma le si trova anche in specchi d'acqua più calmi come invasi artificiali e lanche.

Descrizione

Il carapace, che presenta una corazione che va dal verde scuro al bruno, è caratterizzato da una cresta dorsale seghettata (carena) che viene mantenuta anche negli individui adulti, a differenza delle altre tartarughe della famiglia Emydidae. Ha un margine posteriore seghettato e presenta vari motivi di linee o chiazze gialle.

Il piastrone ha una colorazione chiara con dei motivi scuri, anche molto intricati.

Dimorfismo sessuale

Coppia di G. pseudogeographica. Notare la differenza tra le dimensioni del maschio (sopra) e della femmina

Le Graptemys presentano un dimorfismo sessuale fortemente accentuato: le femmine sono notevolmente più grandi dei maschi, con una lunghezza all'incirca doppia e una massa corporea anche 10 volte maggiore di quella di un maschio adulto.

Inoltre, il cranio dei maschi è più piccolo e stretto di quello delle femmine; i maschi hanno una coda molto più lunga, e spessa a causa della presenza degli organi riproduttivi; la cloaca è in prossimità della punta della coda; e unghie dei maschi sono molto sviluppate in lunghezza, specialmente sulle zampe anteriori.

Le femmine hanno invece un cranio più grosso e spesso molto largo, coda tozza con apertura della cloaca entro il bordo posteriore del carapace e unghie corte.

Il sesso non si può riconoscere prima dei 4-5 anni di età.

Morfologia del cranio

Le femmine di tutte le specie possono essere ripartite in tre gruppi in base alla larghezza del cranio e corrispondente modalità di nutrizione^[4]:

1. femmine microcefale: hanno un cranio relativamente stretto e consumano pochi molluschi conchigliati. Includono la G. flavimaculata, la G. nigrinoda, la G. oculifera, la G. ouachitensis e la G. (o.) sabinensis.
2. femmine mesocefale: hanno un cranio moderatamente largo e la loro dieta si compone prevalentemente molluschi conchigliati oltre ad altre prede più morbide. Includono la G. caglei, la G. geographica, la G. pseudogeographica, la G. p. kohni e la G. versa.
3. femmine macrocefale: hanno un cranio estremamente largo e si nutrono esclusivamente di molluschi conchigliati. Includono la G. barbouri, la G. ernsti, la G. gibbonsi, la G. pearlensis e la G. pulchra.

Riproduzione

Corteggiamento

Tutte le tartarughe del genere Graptemys presentano un ben strutturato rituale di corteggiamento che fa da preludio alla copulazione. Si ritiene che questo comportamento abbia come obiettivo primario quello di immobilizzare la femmina.

Il rituale di corteggiamento ha inizio con il maschio che si posiziona faccia a faccia con la femmina e, mentre questa si sposta in avanti, comincia a nuotare all'indietro per mantenere l'approccio frontale.

A questo punto, il maschio (che presenta degli artigli estremamente lunghi) vibra le zampe anteriori attorno alla regione oculare della femmina. Questo comportamento, chiamato "titillamento", è condiviso con le specie nordamericane e caraibiche del genere Trachemys.

La femmina, se è disposta all’accoppiamento, nuota verso il maschio per poi scendere sul fondo. Lì avviene l'accoppiamento vero e proprio, con il maschio che afferra il carapace della femmina con tutti e quattro gli arti, e la monta.

Deposizione e incubazione

Differenti temperature di incubazione hanno effetti sul motivo delle macchie presenti sulla testa dei nascituri.

Note

Graptemys ialah genus kura-kura akuatik yang dikenali sebagai Kura-kura Peta, dan endemik (berasal) dari Amerika Utara .

Taburan

Spesies daripada genus Graptemys ini boleh dijumpai sepanjang timur Amerika Syarikat hingga ke utara dan tenggara Kanada.

Ciri-ciri

Spesies Graptemys ini mempunyai ciri-ciri yang hampir serupa dengan kura-kura akuatik yang lain seperti Trachemys dan Pseudemys. Bagaimanapun, ia dibezakan dengan kewujudan lunas pada bahagian tengah karapas (tempurung). Sesetengah spesies, terutamanya dari daerah selatan, mempunyai lunas yang menonjol sehingga nampak seperti mata gergaji dan ia digelar "sawback". Kura-kura ini Mempunyai saiz yang lebih kecil apabila dewasa. Ia dipanggil kura-kura Peta kerana mempunyai corak seakan-akan kontur peta di bahagian karapasnya. Kura-kura betinanya mempunyai saiz yang lebih besar berbanding kura-kura jantan.

Spesies

Senarai spesies dan subspesies berikut telah disahkan berdasarkan Trinomen.^[2]

• Graptemys barbouri (Carr & Marchand, 1942) – Kura-kura Peta Barbour
• Graptemys caglei (Haynes & McKown, 1974) – Kura-kura Peta Cagle
• Graptemys ernsti (Lovich & McCoy, 1992) – Kura-kura Peta Escambia
• Graptemys flavimaculata (Cagle, 1954) – Kura-kura Peta Tompok Kuning
• Graptemys geographica (Lesueur, 1817) – Kura-kura Peta Utara
• Graptemys gibbonsi (Lovich & McCoy, 1992) – Kura-kura Peta Pascagoula
• Graptemys nigrinoda (Cagle, 1954) – Kura-kura Peta Bonggol Hitam
• Graptemys oculifera (Baur, 1890) – Kura-kura Peta Cincin
• Graptemys ouachitensis (Cagle, 1953) – Kura-kura Peta Ouachita
  • G. o. ouachitensis (Cagle, 1953) – Kura-kura Peta Ouachita
  • G. o. sabinensis (Cagle, 1953) – Kura-kura Peta Sabine
• Graptemys pearlensis (Ennen, Lovich, Kreiser, Selman, Qualls, 2010) – Kura-kura Peta Sungai Pearl^[3]
• Graptemys pseudogeographica (Gray, 1831) – Kura-kura Peta Palsu
  • G. p. kohnii (Baur, 1890) – Kura-kura Peta Mississippi
  • G. p. pseudogeographica (Gray, 1831) – Kura-kura Peta Palsu
• Graptemys pulchra (Baur, 1893) – Kura-kura Peta Alabama
• Graptemys versa (Stejneger, 1925) – Kura-kura Peta Texas

Rujukan

Pautan luar

• An Overview of Map Turtles in the United States, Reptile & Amphibian Magazine, November/December 1993, p. 6-17.
• ARKive - images and videos of the Cagle's map turtle (Graptemys caglei)
• Ouachita map turtle - Graptemys ouachitensis Species account from the Iowa Reptile and Amphibian Field Guide.
• False map turtle - Graptemys pseudogeographica Species account from the Iowa Reptile and Amphibian Field Guide.
• Common map turtle - Graptemys geographica Species account from the Iowa Reptile and Amphibian Field Guide.

Bacaan lanjut

• Agassiz, L. (1857). Contributions to the Natural History of the United States of America. Vol. I. Boston: Little, Brown and Company. li + 452 pp. (Graptemys, new genus, p. 252).
• Smith, H.M., and E.D. Brodie, Jr. (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3 (paperback). (Genus Graptemys, p. 48, including identification key to species).

Portal Kura-kura

Graptemys is een geslacht van schildpadden uit de familie moerasschildpadden.^[1] De groep werd voor het eerst wetenschappelijk beschreven door Louis Agassiz in 1857.

Uiterlijke kenmerken

De soorten staan bekend als de landkaartschildpadden maar worden ook wel zaagrugschildpadden genoemd. De eerste naam slaat op de tekening van de volwassen dieren, die enigszins lijkt op een landkaart vanwege de complexe lijnentekeningen. De naam zaagrugschildpad slaat op de juvenielen van veel soorten, die een opstaande, getande kiel op het midden van het schild hebben, vaak met een afstekende zwarte kleur. Deze structuur doet enigszins denken aan de tanden van een zaag.

Verspreiding en levenswijze

De verschillende Graptemys-soorten leven uitsluitend in de Verenigde Staten, alleen de 'echte' landkaartschildpad (Graptemys geographica) komt ook voor in zuidelijk Canada, en dan alleen in Zuid-Quebec. Het zijn wat meer naar een carnivoor neigende schildpadden die veel vlees eten en actief jagen op slakken en weekdieren en andere ongewervelden. Alle soorten zijn sterk seksueel dimorf; mannetjes blijven aanzienlijk kleiner dan de vrouwtjes. Mannetjes blijven rond de 12 centimeter, vrouwtjes bereiken een lengte van 30 centimeter, hoewel de exacte afmetingen per soort iets verschillen. Ook zijn mannetjes eerder geslachtsrijp en te herkennen aan de relatief dikkere en langere staart. Drie soorten hebben ieder twee ondersoorten die wat verschillen in verspreidingsgebied, kleuren en patronen.

Taxonomie

Onderstaand een lijst van soorten. Er zijn dertien verschillende soorten, inclusief de pas in 2010 beschreven soort Graptemys pearlensis.^[1]

• Soort Barbours landkaartschildpad (Graptemys barbouri)
• Soort Graptemys caglei
• Soort Graptemys ernsti
• Soort Graptemys flavimaculata
• Soort Landkaartschildpad (Graptemys geographica)
• Soort Graptemys gibbonsi
• Soort Graptemys nigrinoda
• Soort Geringde zaagrugschildpad (Graptemys oculifera)
• Soort Graptemys ouachitensis
• Soort Graptemys pearlensis
• Soort Onechte landkaartschildpad (Graptemys pseudogeographica)
• Soort Graptemys pulchra
• Soort Graptemys versa

Externe link

• Veel Nederlandstalige informatie over de Graptemys-soorten.

Bronvermelding

Referenties

Bronnen

• (en) Peter Uetz & Jakob Hallermann - The Reptile Database – Graptemys - Website Geconsulteerd 20 mei 2015
• (en) - Peter Paul van Dijk, John B. Iverson, Anders G. J. Rhodin, H. Bradley Shaffer & Roger Bour - Turtles of the World, 7th Edition: Annotated Checklist of Taxonomy, Synonymy, Distribution with Maps, and Conservation Status - ISSN 10887105 (2014) - Website
• (en) C.H. Ernst, R.G.M. Altenburg & R.W. Barbour - Turtles of the World - Website

Graptemys – rodzaj żółwi błotnych. Rodzaj ten łatwo rozpoznać, ponieważ żółwie te mają wielki garb na pancerzu.

Charakterystyka

Za okiem mają żółtą pręgę podobną do tej, która odróżnia żółwia żółtobrzuchego od innych żółwi, czasem bardziej widoczną, czasem mniej. Karapaks szaro-zielony, czasami z pomarańczowymi okręgami.

Rozmiary

Samce dorastają do 12-15 cm, a samice do 28-30.

Występowanie

Występują w Missisipi i jej dorzeczach.

Systematyka

• Graptemys barbouri
• Graptemys caglei – mapnik Cagle'a
• Graptemys ernsti
• Graptemys flavimaculata
• Graptemys geographica
• Graptemys gibbonsi
• Graptemys nigrinoda
  • Graptemys nigrinoda delticola
  • Graptemys nigrinoda nigrinoda
• Graptemys oculifera – mapnik piłogrzbiety
• Graptemys ouachitensis
  • Graptemys ouachitensis sabinensis
  • Graptemys ouachitensis ouachitensis
• Graptemys pearlensis
• Graptemys pseudogeographica
  • Graptemys pseudogeographica kohnii
  • Graptemys pseudogeographica pseudogeographica
• Graptemys pulchra
• Graptemys versa

Linki zewnętrzne

• Hodowla żółwia ostrogrzbietego (pol.)

Graptemys (também conhecido por Tartarugas mapa) refere-se a um género de testudinatas pertencente à família Emydidae. Trata-se de tartarugas aquáticas que se distribuem por toda a parte oriental e norte dos Estados Unidos assim como a sul do Canadá. De aparência superficialmente idêntica a outras espécies de tartarugas aquáticas, nomeadamente Trachemys e Pseudemys, esta espécie distingue-se por possuir uma quilha que se estende longitudalmente ao longo da carapaça na zona medial. As graptemys tendem a alcançar um tamanho relativamente pequeno em comparação com outras espécies de tartaruagas aquáticas. A esperança média de vida destas tartarugas ronda entre os 15 e 30 anos.^[1]

Espécies

• Graptemys barbouri (Carr e Marchland, 1942)
• Graptemys caglei (Haynes e McKnown, 1974)
• Graptemys ernsti (Lovich e McCoy, 1992)
• Graptemys flavimaculata (Cagle, 1954)
• Graptemys geographica (Le Sueur, 1817)
• Graptemys gibbonsi (Lovich e McCoy, 1992)
• Graptemys nigrinoda (Cagle, 1954)
• Graptemys oculifera (Baur, 1890)
• Graptemys ouachitensis Cagle, 1953
• Graptemys pearlensis (Ennen, Lovich, Kreiser, Selman, Qualls, 2010)
• Graptemys pseudogeographica (Gray, 1831)
  • Graptemys pseudogeographica kohnii
• Graptemys pulchra (Baur, 1893)
• Graptemys versa (Stejneger, 1925)

Referências

Sågryggar (Graptemys)^[2] är ett släkte av sköldpaddor som beskrevs av Louis Agassiz 1857.^[1] Släktet ingår i familjen kärrsköldpaddor.^[2]

Kladogram enligt Catalogue of Life^[2]:

Graptemys barbouri

Graptemys caglei

Graptemys ernsti

Graptemys flavimaculata

Graptemys geographica

Graptemys gibbonsi

Graptemys nigrinoda

Graptemys oculifera

Graptemys ouachitensis

Graptemys pseudogeographica

Graptemys pulchra

Graptemys versa

Chrysemys

Clemmys

Deirochelys

Emydoidea

Emys

Glyptemys

Malaclemys

Pseudemys

dossköldpaddor

Trachemys

Källor

1. ^ [a b] Agassiz, L. 1857. Contributions to the natural history of the United States of America, vol. 1, 2. Little, Brown and Co., Boston. 452 pp.
2. ^ [a b c] Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D. (red.) (28 april 2011). ”Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist.”. Species 2000: Reading, UK. http://www.catalogueoflife.org/annual-checklist/2011/search/all/key/graptemys/match/1. Läst 24 september 2012.

Externa länkar

• Wikimedia Commons har media som rör Sågryggar.
  Bilder & media

• Wikispecies har information om Graptemys.
  Artförteckning

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地圖龜屬（学名：Graptemys）又名圖龜屬，通称地圖龜，为龟鳖目泽龟科鸡龟亚科的一属，是淡水龜，分佈在美國東部及加拿大南部。牠們的外表很像其他泽龟科龟类，如伪龟属（Pseudemys）及彩龜屬（Trachemys），但較為細小及在龜殼中央有一道鋸齒狀突出物，牠們的龜殼紋像地圖，故得此名。壽命可達15-20歲。

寵物

密西西比地圖龜、偽地圖龜在寵物市場為最常見的地圖龜種，其他的如德州地圖龜、卡氏地圖龜及黑瘤地圖龜都有被飼養繁殖但價格高出許多。一些地圖龜則較為稀有，如黃斑地圖龜及三角地圖龜。

地圖龜的價格與背上的鋸齒突出程度成正比，故最常見的密西西比地圖龜是突出最不明顯的，而高價的黑瘤等背部突起之鋸齒巨大許多。

地圖龜與巴西龜相同，成龜偏向肉食性，雖然也吃植物不過更愛吃魚蝦或昆蟲，故性情為常見寵物龜中較兇猛好動的物種，搶食能力很高，與其他龜種混養時容易發生攻擊行為，就算同種一起養也會攻擊。

種

• 巴氏地圖龜 （Graptemys barbouri）
• 卡氏地圖龜 （Graptemys caglei）
• 恩氏地圖龜 （Graptemys ernsti）
• 黃斑地圖龜 （Graptemys flavimaculata）
• 北部地圖龜 （Graptemys geographica）:又名地圖龜、地理圖龜
• 吉氏地圖龜 （Graptemys gibbonsi）
• 黑瘤地圖龜 （Graptemys nigrinoda）
  • 三角地圖龜（G. n. delticola）
• 眼斑地圖龜 （Graptemys oculifera）
• 沃希托地圖龜 （Graptemys ouachitensis）
  • 薩賓地圖龜 （G. o. sabinensis）
• 珍珠河地圖龜（Graptemys pearlensis）
• 偽地圖龜 （Graptemys pseudogeographica）
  • 密西西比地圖龜（G. p. kohni）
• 亞拉巴馬地圖龜 （Graptemys pulchra）
• 德州地圖龜 （Graptemys versa）

参考文献

外部連結

• ARKive
• （英文）瓦失陶地圖龜的資料
• （英文）擬地圖龜的資料
• （英文）地理圖龜的資料

• バーバーチズガメ
• ケイグルチズガメ
• アーンストチズガメ
• キマダラチズガメ
• ヒラチズガメ
• ギボンズチズガメ
• ミシシッピチズガメ
• クロコブチズガメ
• ワモンチズガメ
• フトマユチズガメ
• ニセチズガメ
• アラバマチズガメ
• テキサスチズガメ

チズガメ属（チズガメぞく、Graptemys）は、カメ目ヌマガメ科に含まれる属。

分布[編集]

アメリカ合衆国東部、カナダ南東部^[1][2]

形態[編集]

最大種はバーバーチズガメで最大甲長33センチメートル^[1]。甲長の性的二型が顕著で例としてバーバーチズガメはメス甲長17-33センチメートルなのに対し、オスは甲長9-13センチメートル^[1]。甲板の表面は滑らかで、成長輪はあまり発達しない^[3]。属名Graptemysは「浮き彫りされたカメ、彫刻されたカメ」の意で、背甲や四肢に入る筋模様に由来する^[1]。ヒラチズガメの種小名geographicaおよび英語圏で本属の構成種を指す総称map turtle、和名は背甲の甲板に入る模様が、地図の等高線のように見えることに由来する^[1]。

後述するようにヒラチズガメを除くと属内でもあまり大型化しない種と、頭部が大型化する種に分けられる^[1]。上顎の先端は凹まず、その両脇が牙状に突出しない^[3]。頸部は短く、頭部と頸部の長さは腹甲の直線距離よりも短い^[3]。頭部や頸部に筋模様が入る^[3]。

分類[編集]

形態やミトコンドリアDNAの塩基配列の分子系統学的解析から、キスイガメ属と単系統群を形成すると推定されている^[1]。本属とキスイガメ属の2属からなる単系統群は、アカミミガメ属の一部から分化し単系統群を形成すると推定されている^[3]。

ヒラチズガメが約8,000,000-6,000,000年前と最も初期に分化した種と考えられている^[2]。またミトコンドリアDNAの塩基配列の分子系統学的解析から頭部が小型なキマダラチズガメ、クロコブチズガメ、ケイグルチズガメ、テキサスチズガメ、ニセチズガメ、フトマユチズガメ、ミシシッピチズガメ、ワモンチズガメの8種と、大型化するアラバマチズガメ、アーンストチズガメ、ギボンズチズガメ、バーバーチズガメの4種はそれぞれ単系統群を形成すると推定されている^[1]。これらの2つの単系統群は約3,000,000-2,500,000年前に分岐したと考えられ、それぞれの単系統群で数十万から数万年前にかけて急激に種分化したと考えられている^[2]。

• Graptemys barbouri　バーバーチズガメ　Barbour's map turtle
• Graptemys caglei　ケイグルチズガメ　Cagle's map turtle
• Graptemys ernsti　アーンストチズガメ　Escambia map turtle
• Graptemys flavimaculata　キマダラチズガメ　Yellow-blotched sawback turtle
• Graptemys geographica　ヒラチズガメ　Common map turtle
• Graptemys gibbonsi　ギボンズチズガメ　Pascagoula map turtle
• Graptemys kohnii　ミシシッピチズガメ　Mississippi map turtle
• Graptemys nigrinoda　クロコブチズガメ　Black-knobbed map turtle
• Graptemys oculifera　ワモンチズガメ　Ringed sawback turtle
• Graptemys ouachitensis　フトマユチズガメ　Ouachita map turtle
• Graptemys pseudogeographica　ニセチズガメ　False map turtle
• Graptemys pulchra　アラバマチズガメ　Alabama map turtle
• Graptemys versa　テキサスチズガメ　Texas map turtle

生態[編集]

主に河川の上流域から中流域にかけての流水域に生息する^[3]。昼行性。水棲傾向が強いが、水辺にある岩や倒木の上などに登り日光浴を行うことも好む。

食性は雑食。大型個体（メスの成体）は貝類、小型個体（幼体やオスの成体）は昆虫を食べる傾向がある^[1]。

繁殖形態は卵生。

人間との関係[編集]

生息地では食用とされる種もいる。

開発による生息地の破壊、水質汚染、食用やペット用の乱獲、娯楽としての殺傷などにより生息数が減少している種もいる^[1][2]。2006年にアメリカ合衆国の個体群が属単位でワシントン条約附属書IIIに掲載された^[4]。

ペットとして飼育されることもあり、日本にも輸入されていた。1980年代（1980年代後半以降は主にニセチズガメ、フトマユチズガメ、ミシシッピチズガメ、後にはほぼミシシッピチズガメ）には種が特定されず「グレーマップタートル」や「ハイイロチズガメ」の商品名で販売されることもあった^[2]。ニセチズガメ、フトマユチズガメ、ミシシッピチズガメは流通量が多く、野外での発見例があること、定着した場合の影響が懸念されることから要注意外来生物に指定されている^[3]。

画像[編集]

• アーンストチズガメ
  G. ernsti

• キマダラチズガメ
  G. flavimaculata

• ワモンチズガメ
  G. oculifera

参考文献[編集]

関連項目[編集]

• ヌマガメ科
  • アミメガメ亜科

外部リンク[編集]