Ristella

Ristella is a genus of skinks, lizards in the familyScincidae. The genus is endemic to the Western Ghats of southwestern India. Member species are commonly known as cat skinks because of their retractile claws. This genus can be instantly identified by the presence of only four fingers in forelimbs in all the species (instead of the usual five). All the members look more or less similar, and are drab dark brown to blackish in colouration, with paler undersides. This poorly known group of lizards is diurnal, insectivorous, terrestrial to semi-fossorial in habits. They inhabit deep leaf-litter and grasslands in montane forests and rainforests.

Lizards of the genus Ristella share the following characters. The palatine and pterygoid bones are in contact on the median line of the palate, which is toothless. The palatine notch is small, far behind, corresponding to the posterior notch of the tongue. The teeth are conical. The eyelids are well developed, and are scaly. The ear-opening is distinct. The nostril is pierced in a single nasal scale. There are no supranasals. The prefrontals are small or coalesced. The frontoparietals and the interparietal are distinct. The limbs are well developed. The anterior limbs have four digits, and the posterior have five. The claws are completely retractile, each into a large compressed sheath formed of one large scale cleft beneath.^[2]

All species in the genus Ristella are endemic to the Western Ghats hill-tracts of southwestern India. Currently these skinks have been recorded from the southern and central Western Ghats of Tamil Nadu, Kerala and Karnataka states. Hill ranges such as Travancore hills, High Ranges, Anaimalai, Nilgiris, Palni Hills, Coorg, Canara and Goa Ghats have been known to harbour these lizards.^[2]

• A. A pair of small prefrontals; frontonasal forming a suture with frontal.
  • a. Ear-opening much larger than nostril; dorsal scales feebly bi- or tricarinate.
    • R. rurkii
  • b. La abertura del oído no es, o es ligeramente, más grande que la fosa nasal; las escamas dorsales son marcadamente bicarinadas.
    • R. travancorica
• B. Dos escudos ácigos entre rostral y frontal.
  • a. De 22 a 24 escamas alrededor de la parte media del cuerpo; extremidades adpresas que no se tocan.
    • R. guentheri
  • b 26 escamas alrededor del cuerpo; extremidades adpresas que se encuentran o se superponen.
    • R. beddomii ^{[ 2 ]}

Se reconocen como válidas las siguientes cuatro especies : ^{[ 3 ]}

• Ristella beddomii Boulenger , 1887 - Eslizón gato de Beddome
• Ristella guentheri Boulenger, 1887 - Ristella de Günther
• Ristella rurkii Gray , 1839 - Ristella de Rurk
• Ristella travancorica ( Beddome , 1870) - Eslizón gato de Travancore, Travancore ristella

Nota bene : Una autoridad binomial entre paréntesis indica que la especie fue descrita originalmente en un género distinto de Ristella .

• Gray JE (1839). "Catálogo de los saurios de lengua delgada, con descripciones de muchos géneros y especies nuevos". Annals and Magazine of Natural History , [ Primera serie ] 2 : 331-337. ( Ristella , género nuevo, pág.  333).

• Ganesh SR (2018). "El redescubrimiento del eslizón gato de Rurk, Ristella rurkii Gray, 1839 (Reptilia: Ristellidae), con observaciones sobre su distribución e historia natural". Journal of Threatened Taxa 10 (10): 12376-12381. https://doi.org/10.11609/jott.3946.10.10.12376-12381