Showing posts with label Acrodont Lizards. Show all posts
Showing posts with label Acrodont Lizards. Show all posts

Saturday, 2 February 2019

Calumma roaloko: A new species of Chameleon from Madagascar.

The island of Madagascar has long been seen as a biodiversity hotspot, with a high number of endemic species (species found nowhere else). However, studies over the past two decades have shown that this biodiversity has been considerably underestimated for many groups, as better biological surveying has revealed both a large number of cryptic species (species which resemble other species so closely that they cannot be told apart by simple physical examination) and species with limited ranges or secretive habits that had been overlooked by earlier surveys. Among Vertebrates this newly discovered biodiversity has been particularly notable in three groups, the Primates (Lemurs), Anurans (Frogs), and Squamates (Snakes and Lizards).

In a paper published in the journal Zoosystematics and Evolution on 19 October 2018, David Prötzel of the Zoologische Staatssammlung München, Shea Lambert of the Department of Ecology and Evolutionary Biology at the University of Arizona, Tucson, Ginah Tsiorisoa Andrianasolo of the Mention Zoologie et Biodiversité Animale at the Université d’Antananarivo, Carl Hutter of the Biodiversity Institute and Department of Ecology and Evolutionary Biology at the University of Kansas, Kerry Cobb of the Department of Biological Sciences at Auburn University, Mark Scherz, also of the Zoologische Staatssammlung München, and of the Zoologisches Institut at the Technische Universität Braunschweig, and Frank Glaw, again of the Zoologische Staatssammlung München, describe a new species of Chameleon from Madagascar.

Chameleons are an exclusively Old World group of Iguanid Lizards closely related to the Agamids (or Dragon Lizards) which are also found only in the Old World, the two groups together being referred to as the Acrodonta. They are noted for their ability to change colour, though this ability is not found in all species. Chameleons also have highly specialised feet, with five toes arranged into two opposing groups, to aid movement in trees (where most species are found), highly modified eyes, which can be pivoted seperately, and a sticky tongue that can be launched as a projectile at prey items (usually Insects), which are then drawn back into the mouth.

The new species is placed in the endemic Malagasy genus Calumma, and given the specific name roaloko, which means 'two colours' in Malagasy, in reference to the patterning of the males of the species, which have a bright green upper side and a white underside (females are a drab brown all over). The species is described from five specimens, an adult male and an adult female, plus two subadult males and a subadult female. The adult male is 93.7 mm in length, the female 85.5 mm. Both sexes have a soft appendage on their snout, with the males having an indigo stripe that runs from this through the eye to the back of the head.

In-life photos of four specimens of Calumma roaloko; (a) subadult male; (b) adult male; (c) subadult male; (d) adult female. Prötzel et al. (2018).

All of the specimens were collected at an altitude of 1100 m above sea level in a fragment of rainforest close to the Analamazaotra Special Reserve and Andasibe-Mantadia National Park, and within an area called the Réserve de Ressources Naturelles du Corridor Ankeniheny-Zahamena, one of a series of newly protected area of rainforest fragments, currently administered by several local councils, but which it is planned to add to the country's national parks system. The fragment of rainforest in which the Chameleons was found currently measures less than 300 km³ and is considered to be shrinking. Calumma roaloko could potentially be found in neighbouring forest fragments, including those within the longer standing Analamazaotra and Andasibe-Mantadia national parks, or the privately run  Réserve de Vohimana, all of which contain larger areas of forest. However, since the species has not yet been located outside its original forest fragment, Prötzel et al. suggest that it should be classified as Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

 Posed photos of a subadult male specimen of Calumma roaloko; (a) Indigo coloration on the rostral appendage and head scalation is apparent; (b) portrait of the same specimen.

See also...

https://sciencythoughts.blogspot.com/2018/11/anolis-dracula-new-cryptic-species-of.htmlhttps://sciencythoughts.blogspot.com/2017/06/brachylophus-gau-new-species-of-south.html
https://sciencythoughts.blogspot.com/2016/12/sceloporus-goldmani-new-populations-of.htmlhttps://sciencythoughts.blogspot.com/2016/10/jeddaherdan-aleadonta-agamid-lizard.html
https://sciencythoughts.blogspot.com/2016/08/anolis-landestoyi-chameleon-like-anole.htmlhttps://sciencythoughts.blogspot.com/2016/04/tropidurus-sertanejo-new-species-of.html
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Monday, 3 October 2016

Jeddaherdan aleadonta: An Agamid Lizard from the Late Cretaceous of Morocco.

Acrodontan Lizards (Chameleons, Agamas, Iguanas and New World Lizards such as Anoles) first appear in the fossil record in the Middle Jurassic of India, and have spead to China, Myanmar and Brazil by the End of rhe Cretaceous. They are a highly distinctive group, and have long been thought, on the basis of morphological evidence, to be the earliest group of Lizards to have branched off from the rest of the famiy, though more recent molecular studies suggest that they are closely related to Snakes and Anguimorph Lizards (Monitors etc.). Africa is one of the modern biodiversity hotspots for this group, and is thought likely to have hosted a major evolutionary radiation of them, but to date there has been only a very limited number of fossil Acrodontans discovered on the continent, including specimens from the Palaeocene of Morocco, Algeria and Tunisia.

In a paper published in the journal Royal Society Open Science on 21 September 2016, Sebastián Apesteguía of the Fundación de Historia Natural‘Félix de Azara’ at the Universidad Maimónides, Juan Daza of the Department of Biological Sciences at Sam Houston StateUniversity, Tiago Simões of the Department of Biological Sciences at the University of Alberta, and Jean Claude Rage of the MuséumNational d’Histoire Naturelle, describe a new species of Agamid Lizard from the Late Cretaceous Kem Kem Beds of northern Morocco.

The new species is named Jeddaherdan aleadonta, where 'Jeddaherdan' derives from the Amazigh Berber words for grandfather (Jeddi) and Spiny-tailed Lizard (Aherdan), and 'aleadonta' means 'dice-toothed' in reference to the roughly cubic shape of the teeth. The species is described from a single fragment of dentary (lower jaw) collected by the French palaeontologist René Lavocat (1909–2007) from the Kem Kem Beds of Gara Tabroumit in southern Morocco between 1948 and 1951 and stored in the collection of the Muséum National d’Histoire Naturelle, where it was mistakenly identified as the jaw of a Fish. Exact collection details for the specimen are missing, but it is likely to be between 90 and 100.5 million years old.


Jeddaherdan aleadonta (MNHN.F.MRS51.1) in (a) dorsal; (b) lateral; (c)medial; (d) ventral views. Scale bar equals 5 mm. Abbreviations: An.ft, angular facet;A.pr, alveolar process; Co.ft, coronoid facet; Co.pr, coronoid process;D.su, dentary sulcus; m.f, mental foramen; Mk.g, Meckel’s groove; pv.pr, posteroventral process; San.ft, surangular facet; sd.cr, sub-dental crest; sd.sh, sub-dental shelf; si.cr, sinusoidal crest; tt.w, tooth wear; Part.ft, prearticular facet. Apesteguía et al. (2016).
 
Most Lizards replace their teeth continuously throughout their lives, however in Acrodontans this tooth replacement is very limited, occurring only at the front of the jaw and only in growing juveniles. The teeth at the side of the mouth are replaced serially during life, with new teeth erupting behind (i.e. further back on the jaw) the old as these are worn down. In the Moroccan Agamid specimen the teeth are worn at the front of the jaw fragment, and there are no signs of further eruptions at the back of the jaw, suggesting that this was an individual appoaching the end of its natural life-span.

 The estimated silhouette of the skull of MNHN.F.MRS51.1 is based on Uromastyx aegyptia (FMNH78661). Scale bar equals 5 mm. Apesteguía et al. (2016).

See also...

http://sciencythoughts.blogspot.co.uk/2016/08/anolis-landestoyi-chameleon-like-anole.htmlAnolis landestoyi: A Chameleon-Like Anole Lizard from Hispaniola.                                 The Anole Lizards of the Greater Antilles islands are considered a classic example of island biogeography. Easch Island has its own set of Lizards, which tend to be most closely related...

http://sciencythoughts.blogspot.co.uk/2016/04/tropidurus-sertanejo-new-species-of.htmlTropidurus sertanejo: A new species of Ground Lizard from Bahia State, Brazil.   Ground Lizards of the genus Tropidurus are found across tropical and subtropical South America. They are ground dwelling Iguanas, favouring open habitats, closely related to the Marine Iguanas...

http://sciencythoughts.blogspot.co.uk/2015/12/albanerpetontids-frogs-and-lizards-from.htmlAlbanerpetontids, Frogs and Lizards from the Late Cretaceous of northeast Spain.             During the Late Cretaceous high sea levels split Europe up into a series of islands, each with its...

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