A An international team of researchers announced on Friday that they had discovered a nanochameleon, a new species of chameleon that, with a 13.5 mm body length, has become the smallest reptile of the nearly 11,500 known species.
"With a body length of only 13.5 millimeters and a total length of almost 22 millimeters, the male of the nanochameleon is the smallest known among all higher vertebrates," explains the researcher from the Munich State Zoological Collection in a statement ( ZSM) and first author of the study, Frank Glaw.
This new species of chameleon (Brookesia nana) was discovered in the north of the island of Madagascar (East Africa) by a team of German-Malagasy researchers led by the ZSM. "The island effect, according to which species are smaller on small islands, is not a convincing explanation for these mountain dwellers," explains Fano-mezana Ratsoavina, researcher at the University of Antananarivo in Madagascar.
The female is significantly larger, with a body length of 19 millimeters and a total length of 29.
According to the scientists, for the moment they could not find more copies of the new species, whose habitat is, according to their research, a few square kilometers. "Unfortunately, the habitat of the nanochameleon is badly affected by deforestation, but the area was recently put under protection for the species to survive," says Oliver Hawlitschek, scientist at the Hamburg Center for Natural History, who is involved in the research.
To determine the age of the specimens, the researchers analyzed their genitalia, after which they discovered two eggs inside the female's body. To find out if the male is also sexually mature, the team examined the animal's genitalia, known as hemipenes, which are duplicated in all lizards and snakes and, according to scientists, are often important characteristics for distinguishing related species.
The researchers also compared the length of their genitalia with 51 other species of chameleons from Madagascar and discovered a tendency for smaller chameleon species to have larger male genitalia in relation to body size. In the case of the nanochameleon, its length was 18.5 percent of the body length, the fifth highest value of all the chameleon species studied, and in the B. tuberculata species, which is also very small, the genitalia they came to represent almost a third of the length of the body.
According to the researchers, this may be due to size difference between the sexes -the so-called sexual dimorphism- that, in the case of the larger chameleon species, the males are usually much larger than the females, while in the smaller species, the opposite is the case. "As a result, extremely miniaturized males would need relatively larger genitalia to be able to successfully mate with their females, which are much larger," explains Miguel Vences from the Technical University of Braunschweig.