The Cape Verde giant skink was very large and robust compared to other skink species. Adults could attain a snout-to-vent length (SVL) of 32cm (13in).[8] The tail was less than half the length of the body.[9] It was described as prehensile and powerful, well adapted to climb trees, which surprised 19th century scientists who only knew Cape Verde giant skinks from denuded, arid islets.[3] However, other authors noted that the species was capable of autotomy, which would be contradictory for a prehensile tail. The long digits, equivalent to a SENI (Scincidae Ecological Niche Index) value of 0.13, are consistent with a low canopy arboreal niche.[9]
The teeth were located labiolingually, compressed, multicuspidate,[8] pleurodontid and pterygoid.[9]
There were three color morphs: grey, yellow, and intermediate. There was no banding but the body had dark stippled blotches and freckles with a yellow green-grey standard background. The underside was largely devoid of freckles, with a solid color lighter than the back. Dorsal scales were small and keeled in more than one hundred rows at the midsection but the osteodermal covering was less developed than in other skinks. The lower eyelid had a unique transparent "window" below.[9]
Males reached their maximum size quicker than females, had a larger head, more robust jaws, and longer hindlegs. Older males had thick, hanging dewlaps that are unusual for skinks.[9]
Distribution
Subfossil remains of Cape Verde giant skink were found in the northwestern islands of São Vicente and Santa Luzia, and the islets Branco and Raso, which along with the smaller islet Pássaros were united into the paleoisland "Mindelo" during the colder stages of the Pleistocene.[3] Testimonies of local fishermen also place giant skinks in São Nicolau island, but this remains unproven.[1] São Nicolau was not connected by land to other islands during the Pleistocene.[3]
Behaviour and ecology
Restoration of a Cape Verde giant skink on a rock of Branco or Raso, with other species native to the islands like giant wall gecko, Raso lark, and a shearwater.
The transparent lower eyelid may have been an adaptation to spot predators below while giant skinks slept on the lower canopy with their eyes closed. In that case the predator's extinction would have long preceded the Cape Verde giant skink's own. The need of light for this strategy would indicate that the giant skink was crepuscular and slept during the day.[9] The barn owl is known to have eaten skinks before and after human arrival.[3] The unusual dewlap of old males could have played some role in territoriality.[9]
The Cape Verde giant skink's long digestive track, abundant and varied helminthic community, and specialized dentition were well suited for a vegetarian diet.[3] Although most animals died early in captivity, some survived for years on a diet of fruit and vegetation. One was noted as eating a bird.[9] In Branco and Raso which are largely denuded of vegetation, the giant skinks adapted to live among large shearwater and petrel colonies and survived eating their regurgitations, feces, carrion, eggs, and hatchlings. Bones of skinks and seabirds are commonly found mixed together.[3]
Preserved giant skinks have belly-button slits indicative of viviparousmatrotrophy, yet a captive female was documented as laying a clutch of seven eggs over fifteen days in 1891, purely white colored and 1 1/2 inches in diameter. Other eggs are preserved at the Regional Museum of Turin. It is possible that the species used both modes of reproduction, like the sheen skink (Eugongylus albofasciolatus), where the same female was documented alternating between them.[9]
The species was very tame in captivity, and probably was long lived and reproduced slowly, like other island reptiles.[3]
The "Mindelo" island broke up when sea levels rose at the end of the Pleistocene, fragmenting the Cape Verde giant skink's population. The local climate also became more arid in the Holocene, replacing the primitive forest with shrubsavanna. Denudation increased after the Portuguese arrived in 1461, cut down the remaining tamarisk trees for firewood and construction, and introduced goats that ate the other vegetation. They also introduced mice, cats, and dogs, that ravaged the seabird colonies. Historical landfills show that settlers ate skinks themselves, but only occasionally and more rarely than seabirds. Examined owl pellets in Santa Luzia commonly contain skink bones before settlement, but lack any more recent than 1673, evidencing that they had become very rare in the island by then.[3]
Giant skinks survived for longer in Branco and Raso, as they were not settled and remained free of introduced mammals. In 1783, Feijó wrote that the inhabitants of the Islands used the skins of Branco lizards to make shoes.[3] Their fat was also used as medicine.[9] According to an elderly resident interviewed by Hopffer, around 1833 a drought-induced famine struck Cape Verde and the government cut expenses by marooning thirty prisoners from Santo Antão in Branco, who survived by eating fish and skinks. This story is often quoted in sources discussing the giant skink's extinction, but is questioned by some authors because Branco has no freshwater sources.[3]
The rediscovery of the species, its rarity, large size and tameness drove up the demand of specimens for European museums, zoos, and collectionists. In 1874 vulcanologist Alphons Stübbel discovered the Raso population. In 1890, the wildlife traffickers Thomas Castle and José Oliveira captured up to two hundred skinks in Branco and sold them in England, Germany, and Austria. The ItalianherpetologistMario Giacinto Peracca bought 40 skinks in London and held them for several years in his vivariums of Chivasso near Turin, where he made important observations on the reproduction and nutrition of the species. By 1896 Bocage feared that the species was being driven to extinction and requested Francisco Newton of the Museum of Lisbon to not import any more giant skinks. Boyd Alexander visited the islets in 1898 and noted that the giant skink was still common in Raso but had become very rare in Branco; Leonardo Fea, who visited in the same year, found no skinks in Branco at all. However captures continued in Raso by Fea himself and by Francisco Newton in 1900 (who didn't give the collected skinks to the Museum, and perhaps sold them to private collectors). In 1902, Prince Albert I of Monaco set traps in Branco for a week before he captured the first of six specimens.[3]
Despite Peracca's efforts, no breeding colony was successfully established in captivity.[9] By the early 20th century it was commonly assumed that the extinction of the Cape Verde giant skink was imminent. Peracca offered a high sum to Newton for capturing as many skinks as he could, planning to release them in an islet near Tuscany, but this never went through. In 1909 the entomologist and botanist Giacomo Cecconi claimed to have collected one individual in São Vicente, but this was deemed dubious by many. In 1915, an official of the Cape Verde colony wrote the Museum of Lisbon to inform that fishermen from Santo Antão had released some dogs in Raso and that they had quickly killed all skinks on the islet. Some animals survived in the possession of German and Austro-Hungarian zoos and collectionists even with the additional difficulties brought by World War I and the interwar period, until the species was declared extinct in 1940.[3] An individual was reportedly seen in Branco in 1985, but several expeditions in the 1990s failed to find any.[9] The IUCN red list classified it as extinct in 1996. In 2005, a juvenile jaw was claimed to have been found in feral cat droppings from Santa Luzia, but a 2006 survey of the island found no animals.[1]
Related Research Articles
Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Skinks are characterized by their smaller legs in comparison to typical lizards and are found in different habitats except arctic and subarctic regions.
Santa Luzia is an island of the Barlavento archipelago in Cape Verde located between São Nicolau and São Vicente, the channel of Santa Luzia separates the island of São Vicente and is 8 km wide. The area is 34.2 km2. Like all Cape Verdean islands, it is of volcanic origin. The highest point is Topona. Santa Luzia is 12.4 km long and 5.3 km wide.
Ilhéu Raso is an uninhabited 5.76 square kilometres volcanic island in the Barlavento archipelago of Cape Verde. It is flanked by the smaller Branco islet to the west and by São Nicolau island on its eastern side. The distance from the island of São Nicolau is 15 kilometres. Together with Santa Luzia and Ilhéu Branco, Ilhéu Raso is on the tentative list of UNESCO's World Heritage Sites. Since 1990, the islet is part of the protected area Reserva Natural Integral de Santa Luzia.
Ilhéu Branco is an uninhabited 278-hectare (690-acre) islet in the Barlavento group of the Cape Verde archipelago off the coast of north-west Africa in the Atlantic Ocean. Ilhéu Branco is flanked by the islands of Santa Luzia to the north-west and Ilhéu Raso to the south-east. Since 1990, the islet is part of the protected area Reserva Natural Integral de Santa Luzia. Together with Santa Luzia and Ilhéu Raso, Ilhéu Branco is on the tentative list of UNESCO's World Heritage Sites.
The Cape Verde Islands dry forests is a tropical and subtropical dry broadleaf forests ecoregion in the Cape Verde Islands, which constitute the country of Cabo Verde. The islands lie off the western coast of Africa.
The wildlife of Cape Verde is found across its archipelago of ten islands and three islets, albeit in smaller numbers of species than mainland Africa. Each volcanic island within the archipelago is unique, and each of them have parks under their jurisdiction, by decree promulgated by the Cape Verde government. Located just off the west coast of Africa, the total land area of the island nation is 4,564 square kilometres (1,762 sq mi). With the exception of bats, there are no truly endemic species of mammal on Cabo Verde; historically, the archipelago was only accessible to creatures with the ability to fly or swim, or to be brought by humans. The islands were first explored in 1456, but not actually settled until 1462; humans brought their livestock with them, including donkeys, pigs, cattle and goats—many of the latter are now so wild, they resemble mainland ibex, and are considered endemic “by default”. In the centuries since settlement began, more mainland species would make their way with waves of settlers. There are no snakes present on the archipelago, which has allowed for the proliferation of many other species of other herpetiles, such as geckos, frogs and lizards. The main predators of these reptiles and amphibians would be the various birds of prey and raptors present, including the Egyptian vulture, Eurasian buzzard, kestrel, osprey, peregrine falcon, and the rare Cape Verde kite. This kite species is currently threatened by extinction but may yet be observed on Boa Vista and Maio.
Trachylepis is a skink genus in the subfamily Mabuyinae found mainly in Africa. Its members were formerly included in the "wastebin taxon" Mabuya, and for some time in Euprepis. As defined today, Trachylepis contains the clade of Afro-Malagasy mabuyas. The genus also contains a species from the Brazilian island of Fernando de Noronha, T. atlantica, and may occur in mainland South America with Trachylepis tschudii and Trachylepis maculata, both poorly known and enigmatic. The ancestors of T. atlantica are believed to have rafted across the Atlantic from Africa during the last 9 million years.
Chioninia is a genus of skinks, lizards in the subfamily Lygosominae. For long, this genus was included in the "wastebin taxon" Mabuya. The genus Chioninia contains the Cape Verde mabuyas.
Chioninia delalandii is a species of skink, a lizard in the family Scincidae. The species is endemic to the Cape Verde Islands.
Chioninia spinalis is a species of skink in the family Scincidae. It is endemic to the Cape Verde Islands, and has been found on the islands of Sal, Boa Vista, Maio, Santiago, Fogo and several smaller islets.
Chioninia stangeri is a species of lizard in the family Scincidae. The species is endemic to the Cape Verde Islands.
Chioninia vaillantii, also known commonly as Vaillant's mabuya or Vaillant's skink, is a species of skink in the family Scincidae. The species is endemic to the Cape Verde Islands. There are two recognized subspecies.
Chioninia nicolauensis is a species of skinks in the family Scincidae. It is endemic to the Cape Verde island of São Nicolau. Until around 2010, it was treated as a subspecies of Chioninia fogoensis.
Trachylepis ozorii is a species of skink, a lizard in the family Scincidae. The species is endemic to the island of Annobón in Equatorial Guinea.
There are two species of skink named Bibron's skink:
Jean-Théodore Cocteau (1798–1838) was a French herpetologist, who was associated with Duméril, Cuvier, and Bibron, and corresponded with other workers in zoology around the world. Cocteau published a volume on skinks, Etudes sur les Scincoïdes, and named a number of new taxa. Cocteau is commemorated in the scientific name of a species of giant skink, Chioninia coctei, which is now extinct.
Trachylepis gravenhorstii, also known commonly as Gravenhorst's mabuya, is a species of skink, a lizard in the family Scincidae. The species is endemic to Madagascar.
Trachylepis perrotetii, also known commonly as the African red-sided skink, the red-sided skink, and the Teita mabuya, is a species of lizard in the family Scincidae. The species is endemic to Africa.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mateo, J. A., Barone, R., Hernández-Acosta, C. N., & López-Jurado, L. F. (2020) La muerte anunciada de dos gigantes macaronésicos: el gran escinco caboverdiano, Chioninia coctei (Duméril & Bibron, 1839) y el lagarto de Salmor, Gallotia simonyi (Steindachner, 1889). Bol. Asoc. Herpetol. Esp. Vol. 31 (2), pgs. 3-30.
↑ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN978-1-4214-0135-5. (Macroscincus coctei, p.56).
↑ Bocage, J.V.B. (1873) Sur l' habitat et les caractères zoologiques du "Macroscincus coctei" ("Euprepes coctei " Dum. et Bibr.). Jornal de Sciencias Mathemáticas, Physicas e Naturais, 4: 295–306.
↑ Karin, B. R., Metallinou, M., Weinell, J. L., Jackman, T. R., & Bauer, A. M. (2016). Resolving the higher-order phylogenetic relationships of the circumtropical Mabuya group (Squamata: Scincidae): An out-of-Asia diversification. Molecular phylogenetics and evolution, 102, 220-232.
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