Turtles in Trouble: The World's 25+ Most Endangered - Wildlife ...

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Turtles in Trouble: Top 25+ Endangered Tortoises and Freshwater Turtles—2011Hoge’s Side-necked TurtleMesoclemmys hogei (Mertens 1967); Family ChelidaeSouth America: Brazil (Espírito Santo, Minas Gerais, Rio de Janeiro, São Paulo [?])IUCN Red List: EN, Endangered B1+2c; TFTSG Draft: CR, Critically EndangeredCITES: Not ListedThis moderate-sized species (carapacelength to 38 cm) was described basedon a single animal discovered in the serpentariumtanks of the Instituto Butantanin São Paulo, Brazil. This poorly knownBrazilian endemic species has one of thesmallest ranges of any of the South Americanmembers of the family Chelidae, restrictedto small portions of the states ofEspiríto Santo, Minas Gerais, and Rio deJaneiro. The range of this species appearsto be smaller than originally thought, as itdoes not apparently occur at its doubtfultype locality in São Paulo. If accurate, thetype locality would result in a fragmentedrange with an essentially impassable geographicbarrier of a large swath of landand forest at elevations higher than thisspecies is thought to occur.Originally described in the genusPhrynops, the species has since been reclassified as a memberof the closely related genus Mesoclemmys. Primitivein many of its osteologic features, it may instead representa distinct and monotypic genus with some similarities toAustralian chelid turtles. In females the lateral portions ofthe dorsal head have a variable area of dark wine red colorsuffusion, a unique feature among members of the generaPhrynops and Mesoclemmys.All confirmed collected specimens (only 10 in museumsfrom 9 localities), have been found in low-lying areasunder 500 m elevation along the Rio Paraíba drainagein the states of Rio de Janiero and southern Minas Gerais(notably the Rio Carangola basin), and north to coastal EspíritoSanto in Brazil. The Rio Paraíba is under heavy pressuresof habitat destruction due to human uses, includingpollution and deforestation and the resulting alteration ofwatercourses causing erosion and siltation.Distribution of Mesoclemmys hogei.Mesoclemmys hogei female from Espírito Santo, Brazil. Photo by Russell A. Mittermeier.The species is apparently omnivorous, feeding on meatand fish in captivity, but with stomach contents in the wildyielding leaves, seeds, and plant stems. Nothing is knownabout reproductive biology, and nesting, eggs, or hatchlingshave not been described. No data on growth are available.Currently, nothing is known regarding total populationsize —only localized populations are known, and noprotected areas occur within the range of this species. Thespecies appears to be rare throughout its range, and mayoccur as a series of disjunct populations with very lowoverall density. Concerted efforts at locating the speciesin the main Rio Paraíba drainage have often been unsuccessful.However, a few populations occur along the northernperiphery of the Rio Paraíba basin, such as in the RioCarangola in southeastern Minas Gerais. Unfortunately,even that river is threatened by habitat degradation and thepopulation of M. hogei there has decreased by over 15%annually over the last ca. 17 years.The species is in desperate need of studies to determineits actual distribution, population levels, specificthreats, and general ecology. Basic life history data are unavailable,and no rational management plans can be implementedunless more is known about the species. A protectedarea for the species has been recommended near FariaLemos on the Rio Carangola. Establishment of a captivepopulation at a research facility within the species’ naturalrange should be considered to allow for detailed reproductivebiology studies and to establish a breeding colony, butthe establishment of captive breeding colonies outside thespecies’ range should be discouraged.– 38 –
Turtles in Trouble: Top 25+ Endangered Tortoises and Freshwater Turtles—2011Geometric TortoisePsammobates geometricus (Linnaeus 1758); Family TestudinidaeAfrica: South AfricaIUCN Red List: EN, Endangered A1ac, B1+2c; SARCA/TFTSG Draft: CR, Critically EndangeredCITES: Appendix IThe Geometric Tortoise is an excellentexample of convergent evolutiondue to its striking resemblance to startortoises of India and Burma. However,this beautiful tortoise is not closely relatedto its Asian look-alikes, and canbe distinguished by the presence of anuchal scute on the anterior carapace. Asits Latin name suggests—psammos andbates means “inhabitant of the sands”—this species is found in low-lying areasof the Western Cape Province, South Africa,with acidic, sandy and nutrient-poorshale and alluvium soils with sparse vegetation,characterized by grasses and lowto medium-high shrubs.This species once occurred throughoutthe low-lying West Coast and inlandrenosterveld from Gordon’s Bay toPiketberg, and in the Upper Breede Riverand Ceres valleys. Although its historic range was nevervast, it now occupies only approximately 22 km 2 (8.5 sq.mi.)of highly fragmented remnants of suitable shale renosterveldand alluvium fynbos habitat in the Western Cape. Habitatdestruction for agriculture, mainly for vineyards and wheatfarming, degradation by invasive non-native plants and animals,coupled with fire suppression and increasing predatorpressure have been, and continue to be, the main threats tothe remaining habitat patches and populations.This small species does not exceed 20 cm in carapacelength, however, average adult sizes are more typically 10cm for males and 12.5 cm for females, exhibiting strongsexual dimorphism with females larger than males andpronounced differences in plastron concavity, shell shapeand tail size. Sexual maturity in females is reached in 8to 10 years. Generally active year-round, inactivity mayonly occur during the coolest months of the year (June toDistribution of Psammobates geometricus.Psammobates geometricus from South Africa. Photo by Atherton de Villiers.August). Breeding behavior and oviposition (1–5 eggs in1–3 clutches per year) occurs from September to Novemberwith hatchlings emerging 6–8 months later in March toMay. Geometric Tortoises may reach ages of up to 30 yearsand more.More than 90% of its former habitat has been destroyedand this species now occurs in a few small to medium-sizedpopulations in isolated patches of uncultivated land. Protectionmeasures include full legal protection, and populationsin both private and provincial nature reserves, as well asconservation stewardship contract nature reserves, occupyingareas of between 30 and ca. 1000 ha of suitable habitat.The most pressing conservation need for this species is theacquisition of more suitable native habitat, and more conservationstewardship nature reserves are being negotiatedwith private landowners. Management is required to preventhabitat alteration, and in this fire-adapted habitat, fireis required to maintain the open nature of the habitat and itsspecies diversity. However, small tortoise populations areextremely vulnerable to fires and up to 80% mortality canbe expected.This species does poorly in captivity and a highly managedin-situ breeding facility may be warranted. Becausethreats continue to operate in natural habitats, headstartingis, however, unlikely to improve the status of this species.A species conservation management plan is imminent, andthe South African Reptile Conservation Assessment has recentlydetermined the species to warrant Critically Endangeredstatus on the IUCN Red List, as noted by the Tortoiseand Freshwater Turtle Specialist Group.– 39 –
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