Ploughshare Tortoise

This species was originally described in 1885 by French zoologist Léon Vaillant, who named it Testudo yniphora ( ()|ploughshare||' ()|bearer}}) based on the distinguished shape of the gular scute in the front of the plastron. The angonoka tortoise (A. yniphora) and the radiated tortoise (A. radiata) are the only species in the genus Astrochelys. Astrochelys is attributed to John Edward Gray, who used the name in his 1873 book Hand-list of the specimens of shield reptiles in the British Museum. The parent family for Astrochelys is Testudinidae, the tortoise family. The name angonoka comes from the Malagasy word used as the local name of the species. The alternative common name, ploughshare tortoise, refers to the appearance of the gular scute of the plastron.

In the wild, this species is only found in Madagascar, where it is endemic to the dry forests in the Baly Bay area of northwestern Madagascar, near the town of Soalala (including Baie de Baly National Park). The distribution is in range around Baly Bay. The Baly Bay region is made up of savanna, mangrove swamps, and dry deciduous forest. They make use of bamboo-scrub habitat which is made up of different types of shrubs, savanna grasses, bamboo, and open areas with no vegetation. The flora includes shrubbery usually under in height, such as Bauhinia and Terminalia species, and Perrierbambus madagascariensis bamboo, which forms dense thickets. The elevation of this area is under above sea level.

The first population surveys of this species were performed by Juvik & Blanc in 1974 and Juvik et al. in 1981, in which they estimated the total wild population to be a few hundred, based on a population density of around five tortoises per km2 and a potential range of approximately in suitable habitat. In 1983 (published 1985) Curl et al. estimated a total population of 100–400 individuals in a range of , found in five subpopulations, two east and three west of the Andranomavo River. The two to the east were Beheta and Cape Sada; the three to the west were Ambatomainty, Andrafiafaly, and Betainalika. The most accessible and most studied area was on Cape Sada, and numerous surveys in the 1990s estimated a population there of around 30 individuals. In 1999 Smith et al. performed an exhaustive survey of the population on Cape Sada, counting 96 individuals, of which approximately half were adults. They concluded that the Cape Sada population, which was split into 3 subpopulations by Juvik et al. in 1997 on the basis of what they considered suitable habitat, was a single group because the animals utilized the more open habitat in the centre of the Cape and moved from between the three more forested areas. They also concluded the remote Ambatomainty and Andrafiafaly sites were in fact were two ends of an extensive tract of contiguous habitat. Smith et al. did not provide a total population estimate, but based on their research a population of 400–1500 tortoises could be extrapolated. In 2016 poaching intensified, including a foiled attempt to raid the captive breeding centre (a raid in 1996 had 75 tortoises looted). It was estimated in 2016 at a CITES conference that the wild population had dropped to 100 adults and the species would be extinct in the wild by 2018.

The angonoka tortoise has been observed feeding on grasses found in open rocky areas of bamboo scrub. It is also known to eat shrubs, forbs, and herbs. While it has been seen eating dead bamboo leaves, it has never been observed eating living bamboo. As well as these plants, the tortoise has also been seen eating the dried feces of bushpigs and carnivores. It is expected to become sexually mature once reaching 15 years old. The tortoise can produce one to six eggs per clutch and up to four clutches every season. The reproductive season is from 15 January to 30 May. With a 71.9% fertility rate and a 54.6% hatching success rate, about 4.3 hatchlings are produced per female tortoise. In captivity, males must be separated due to aggression towards each other, including ramming, pushing, and overturning with the enlarged gular scute. The aggression is used to establish dominance.

]] This species is one of the rarest land tortoises in the world, classified as Critically Endangered on the IUCN Red List. In addition to its Red List listing, the angonoka tortoise is now protected under the national law of Madagascar and listed on CITES Appendix I, commercial trade in wild-caught specimens is illegal (permitted only in exceptional licensed circumstances). For the conservation of the angonoka tortoise, the Durrell Wildlife Conservation Trust created Project Angonoka in 1986. The Water and Forests Department, the Durrell Trust, and the World Wide Fund for Nature work together on this project. The project ultimately was a success, achieving 224 captive-bred juveniles out of 17 adults in December 2004. After the 1990s, Project Angonoka started ecological research on the tortoise and the development of conservation plans that involved the communities surrounding the habitat. The work with the community involved local people in making firebreaks, along with the creation of a park proposed by the community to protect the tortoise and the forests. Monitoring of the angonoka tortoise in the global pet trade has continued to be advocated. On 20 March 2016, the Custom officials at Mumbai airport seized 146 tortoises from a mishandled baggage of a Nepal citizen. This bag was said to belong to a transit passenger, who arrived from Madagascar and flew to Kathmandu leaving this bag behind. Out of the 146 tortoises, 139 were radiated tortoises (Astrochelys radiata) and seven were angonoka tortoises (Astrochelys yniphora), both critically endangered tortoise species of Madagascar. Two radiated tortoises were found dead with broken shell. On 12 June 2016, it was reported that six angonoka tortoises and 72 radiated tortoises had gone missing from a breeding facility in Thailand.