The Philippine sailfin lizard (Hydrosaurus pustulatus), also known as crested lizard, sail-fin lizard, sailfin water lizard, soa-soa water lizard or its native name ibid, is an oviparous lizard found in several of the islands that make up the Philippines, in New Guinea, and some parts of eastern Indonesia. The Philippine Sailfin Lizard is a protected species in its native country of the Philippines as it is a target for exotic pet collectors and sought after in the international pet trade. This is largely because these lizards have unique dorsal crests (otherwise known as sailfins) that give the organism a structure similar to a sail, and the Philippine sailfin lizard also has very bright coloration patterns that make them attractive to the eye. The pustulatus species is unique within the Hydrosaurus genus because of the confusion for the past several decades of classifying these organisms amongst other lizards within their same genus in their habitat. They are also very talented swimmers, and smaller juvenile lizards can run on top of water due to their bodily structure. The genus Hydrosaurus means water lizard, which reflects the aforementioned abilities lizards have in water. The Philippine sailfin lizard usually lies close to bodies of water, stays in tree branches, and runs across the ground to get around their habitat. They utilize their sailfins/scales to do territorial displays in the presence of a competitor or a predator. In terms of their reproduction, they utilize sexual reproduction and breed one time each year, but they can produce multiple clutches of eggs with between 2 and 8 eggs. These eggs are buried into the soil for a period of two months before hatchlings are produced. Philippine sailfin lizards are heavily studied by herpetologists and other scientists, as they are unique amongst other reptile lizards with regard to their coloration and form.
History and taxonomy
In 1829, Johann Friedrich von Eschscholtz discovered a new sailfin lizard species in the Philippines and designated it as Hydrosaurus pustulatus. The genus Hydrosaurus is specific to Southeast Asia, and it only contains three major species (with two additional species falling under H. amboinensis): H. amboinensis, H. pulsatus, and H. weberi. The Philippine sailfin lizard and the genus Hydrosaurus is also commonly referred to as a water dragon due to their excellent ability to swim in and sometimes run across water. There have been issues with the taxonomic identification of Hydrosaurus pustulatus because the original descriptions were of immature members of the species in the 1800's and were not descriptive enough for diagnostic procedures in environmental studies. As a result, efforts for understanding the spread of different taxonomic groupings have been a challenge.
Habitat and distribution
The Philippine sailfin lizard is found across several of the islands that comprise the Philippines, including Guimaras, Romblon, Negros, and Cebu, but the lizard is not found in Palawan Island. The lizard is also found in New Guinea and some of eastern Indonesia. The Philippine sailfin lizard lives in tropical wooded habitats near water, like rivers, riverbanks, rice-fields and mangrove. The Philippine sailfin lizard also lives in moderately high densities in these habitats. The Philippine sailfin lizard also prefers the bodies of water that they reside nearby being freshwater. Due to confusion with H. amboinensis, the exact distribution in the Philippines has been labelled with some uncertainty. However, a genetic study that sampled individuals throughout the Philippine archipelago (from Mindanao in south to Luzon in north) found that all were H. pustulatus, which is divided into six clades. Additionally, the Philippine sailfin lizard is often found near rocky areas close to a stream.