Siamese twinning has occurred in the quince monitor lizard, according to a paper published in Herpetological Notes. According to the authors of the pa
Siamese twinning has occurred in the quince monitor lizard, according to a paper published in Herpetological Notes. According to the authors of the paper, Mona van Schingen and Thomas Ziegler, the twins were born in 2009 to siblings in a clutch that also included a malformed hatchling in addition to the twins. The twins were conjoined at the cranium and abdomen and their extremities, including their tails were fairly well developed. Their vertebral columns were severely distorted, and they both had fewer ventral scales between the snout and hind limbs than normally developed quince monitors. In fact, one of the twins had more ventrolateral scales that the other twin, but both had less scales than a normally developed quince monitor lizard. The twins were smaller than their siblings in the clutch.
Two-headed reptiles are rare but not uncommon in snakes and turtles, but Siamese twins in lizards is reportedly even more rare. It is not known why the Siamese twins occurred in the clutch, but scientists believe that there may be genetics at play as the parents were siblings, or perhaps environmental causes such as pesticide or other chemical use in their natural range may have caused the twinning and malformation of the sibling lizard.
Quince monitors are native to the Sula Islands of Indonesia and other islands in the chain. They are a mangrove monitor that apparently spends more time away from mangrove forests. It grows to about four feet in length and sports a bright yellow head, legs, and tail. The tail has bands of yellow and black and pales toward the last third of the tail. The lizard has suffered serious population declines that some attribute to the animal trade and habitat loss.
The full paper can be downloaded in PDF format on the Herpetological Notes website.
John B. Virata keeps a western hognose snake, a ball python, two corn snakes, a king snake, and two leopard geckos. His first snake, a California kingsnake, was purchased at the Pet Place in Westminster, CA for $5. His first pet reptile was a green anole that arrived in a small box via mail order. Follow him on Twitter @johnvirata