Rhachisaurus brachylepis (DIXON, 1974)
Can you confirm these amateur observations of Rhachisaurus brachylepis?
|Higher Taxa||Gymnophthalmidae (Rhachisaurinae), Sauria, Gymnophthalmoidea, Squamata (lizards)|
|Common Names||E: Dixon's Anotosaura|
Portuguese: Lagartinho, Lagarto-do-Folhiço
|Synonym||Anotosaura brachylepis DIXON 1974: 17|
Rhachisaurus brachylepis — PELLEGRINO et al. 2001
Rhachisaurus brachylepis — CASTOE et al. 2004
Rhachisaurus brachylepis — GOMIDES et al. 2020
|Distribution||Brazil (Minas Gerais)|
Type locality: Brazil, Minas Gerais, Serra do Cipo
|Types||Holotype: MCZ 133174, adult female|
|Diagnosis||Diagnosis (genus): The genus Rhachisaurus is characterized by the absence of an external ear opening, the presence of four digits on the front and hind limbs, a high number of short, narrow and smooth dorsal scales (57–60), absence of collar, a tail that is more than twice body length, a large number of temporals, ten rows of gulars, three pairs of chinshields, four supraoculars, six superciliaries, squared ventrals and rounded scales in the lateral sides of the neck.|
Diagnosis (genus): Rhachisaurus brachylepis is the only species of Rhachisaurus and was included in the monotypic subfamily Rhachisaurinae Pellegrino et al., 2001 to resolve the nonmonophyly of Anotosaura. Here, we compare Rhachisau‐ rus with other genera of gymnophthalmids following the taxonomic arrangement proposed by Goicoechea et al. (2016).
Among the genera of Gymnophthalminae Fitzinger, 1826, Rhachisaurus differs from all species of Gymnophthalmini Fitzinger, 1826 (Calyptommatus Rodrigues, 1991a, Gymnophthalmus Merrem, 1820, Micrablepharus Dunn, 1932, Nothobachia Rodrigues, 1984, Procellosaurinus Rodrigues, 1991b, Psilops Rodrigues et al., 2017, Scriptosaura Rodrigues and Santos, 2008, and Vanzosaura Rodrigues, 1991b) except Tretioscincus Cope, 1862 by having eyelids present. The only genus of the tribe with eyelids is Tretioscincus which differs from Rhachisaurus by having large, scincoid scales on the body and an external ear openning, among other characters.
Among the taxa of the tribe Heterodactylini Goicoechea et al., 2016, Rhachisaurus differs from Caparaonia Rodrigues et al., 2009 and Colobodactylus Amaral, 1933 by the absence of ear openings (present in both genera) and can be distinguished from Heterodactylus Spix, 1824 by the dorsally partly divided nasal scale, three pairs of enlarged chinshields, no enlarged nuchals, and absence of a well-developed collar fold (nasal scales not divided, two pairs of chinshields, enlarged nuchals present, and weakly developed collar fold present in Heterodactylus).
Analyzing the genera of Iphisini Gray, 1851, Rhachisaurus differs from Acratosaura Rodrigues et al., 2007, Alexandresaurus Rodrigues et al., 2007, Colobosaura Boulenger, 1887, Iphisa Gray, 1851, Rondonops Colli et al., 2015, and Stenolepis Boulenger, 1888 by the absence of ear openings (present in all six genera).
Among the genera of Cercosaurinae Gray, 1838, Ecpleopodini Fitzinger, 1843, Rhachisaurus differs from Anotosaura by the presence of three pairs of chinshields with two in medial contact and by the dorsally partly divided nasal (three pairs of chinshields—all in medial contact— and nasal not divided in Anotosaura). Rhachisaurus can be distinguished from Amapasaurus Cunha, 1970, Arthrosaura Boulenger, 1885, Colobosauroides Cunha et al., 1991, Ecpleo‐ pus Duméril and Bibron, 1839, Loxopholis Cope, 1869, Lepo‐ soma Spix, 1824, and Yanomamia Pellegrino et al. 2018 by the absence of frontoparietals (present in all seven genera). It can also be distinguished from Dryadosaura Rodrigues et al., 2005, Marinussaurus Peloso et al., 2011, and other additional Ecpleopodini genera by the absence of ear openings (present in other genera). In Bachiini Colli et al., 2015, Rhachisaurus differs from Bachia Gray, 1845 by the presence of three pairs of enlarged chinshields (two pairs in Bachia).
Finally, Rhachisaurus differs from all genera of Cercosaurini Gray, 1838 and Riolama Uzzell, 1973, the only known genus of Riolaminae Kok, 2015 (Recoder et al., 2020), by lacking external ear openings (present in all other genera). (Gomides et al. 2020).
|Comment||Type species: Anotosaura brachylepis DIXON 1974 is the type species of the genus Rhachisaurus PELLEGRINO et al. 2001. The species is also the type (and only) species of the subfamily Rhachisaurinae.|
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