Madagascar is home to more than 40 percent of the 193 or so documented chameleon species. Frank Glaw of the Zoological State Collection of Munich, Germany, and his colleagues conducted intensive fieldwork in the forests of the island’s northern tip, seeking the tiny reptiles where they roost—on limestone boulders and in low vegetation above the leaf litter.
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The smallest of the four newfound dwarf chameleons, Brookesia micra, caught alongside a small creek, measures less than one and one-eighth inches from nose to tail. A B. micra juvenile can perch comfortably upon the head of a wooden match. The chameleons all possess conical, bulging eyes, and share skin tones of various beiges, browns, and grays. When stressed, some display a whitish stripe down their spines. The research team conducted genetic analyses and confirmed that the four types of chameleons represent new and very distinct species. A comparison of the mini-reptiles’ hemipenes (the pair of penis-like organs in the male) and other morphologies revealed phenotypic differences as dramatic as the genetic ones.
The chameleons’ diminutiveness could stem from “island dwarfism,” in which isolated species evolve smaller size as an adaptation to limited range and resources. In the case of B. micra, which turned up on a very small islet called Nosy Hara, a “double” island dwarf effect might have occurred. Despite their modest need for real estate, the newly described chameleons are vulnerable to habitat loss. The scientists’ names for two of the species—B. tristis and B. desperata—derive from the Latin words for “doleful” and “desperate,” respectively, and refer to the severe deforestation taking place around the lizards. (PLoS ONE)