DALLAS -- A new species of miniature gecko, not much longer than a match stick, has been discovered by biologists at the University of Texas at Arlington.
The tiny lizards are among several species of geckos found in Venezuela. They were first discovered in 2002 scurrying along the lush forest floor of the Paria Peninsula in the northeast of the country. At the time, scientists believed the brown geckos with their pale markings and curious cone-shaped heads were an already known species. But that turned out not to be the case when more of these geckos were collected years later.
"It's a pretty cool discovery," said Walter Schargel, a professor of biology at the University of Texas at Arlington, who led the new study about the lizards that was published in the Zoological Journal of the Linnean Society. He added that his team named the species the fuscofortunatus, or the lucky brown, because of "how lucky it was for us to find this tiny brown lizard in the middle of the leaf litter in this area."
There are more than 1,500 species of geckos worldwide. The smallest, at less than an inch long, is the dwarf gecko; the largest, at 14 to 17 inches long, is the New Caledonian giant gecko. In Texas, the two main species of gecko -- the Mediterranean house gecko and common house gecko -- can reach lengths of up to five inches and six inches, respectively.
Pseudogonatodes fuscofortunatus, the full name of the species discovered by Schargel and his colleagues, is on the smaller side, measuring 1.5 inches from its snout to the base of its tail as an adult. With the tail included, it's nearly 2.6 inches long. (Schargel said geckos often lose and regenerate their tails, so including its measurement in the total length is not always ideal for biologists.)
It was in June 2002 that the gecko first caught Schargel's attention. He and Gilson Rivas, a co-author on the study, were trekking through the Paria Peninsula when they spotted it. But given its size and propensity to hide in the dense forest floor, it was hard to catch. Rivas, who is based at the University of Zulia in Venezuela, managed to snag one when he returned a month later.
"At the time, Rivas gave it a tentative identification," Schargel said. "He said, 'OK, well it might be another specimen of another species in the same genus that's found in the central coastal range of Venezuela called Pseudogonatodes manessi.'"
But because of how plentiful geckos were in the peninsula, the thought the lizard could be a new species remained in the back of Schargel's mind.
In 2014, Rivas and Mayke De Freitas, then at the University of Cambridge and another co-author of the study, revisited the same patch of forest in the Paria Peninsula and collected three more geckos.
Those geckos, along with the one collected in 2002, had their scaly bodies measured in various ways and underwent a CT scan to compare their bone shape to other gecko species endemic to Venezuela. The researchers also did genetic analysis to parse out the relationship between these geckos and others in the peninsula.
While some features of the Pseudogonatodes fuscofortunatus, such as its scale count and color pattern, bore a resemblance to those of other geckos in Venezuela's coastal mountain range, that's where the similarities ended.
For one, its DNA sequence demonstrated significant genetic divergence, meaning its genome was unique compared to other known geckos.
Another clue pointing to a new gecko species was the lizard's skeletal structure. The nasal bones leading from the snout to the back of the gecko's head were completely separate -- something that's been observed only in one other unrelated gecko species, Schargel said.
"In the paper, we describe this condition as a 'telescope skull,' basically spy glasses," he said, because of how the bones appear like they could retract and overlap.
The parietal bones, which form the sides of the head, were completely fused, which Schargel said is very uncommon, not just for geckos but for reptiles in general.
Why Pseudogonatodes fuscofortunatus developed this rare skull shape is a mystery for evolutionary biologists to unravel with future research, Schargel said. An answer may provide insights not only into the gecko's evolution but our own as well, said Peter Uetz, an associate professor of biology at Virginia Commonwealth University's Center for Biological Data Science who was not involved in the study.
"We could learn something about the human brain or skull development," Uetz said. "These kinds of things are often determined by very few genes ... When our ancestors were evolving and their skulls grew bigger and bigger, it's one of those things you have to accommodate. How do you explain that?"
For Jonathan Losos, a professor of biology at Washington University in St. Louis who was not involved in the study, the discovery exemplifies the importance of conservation and the need for scientists to search for undiscovered creatures before they go extinct. According to a 2022 World Wildlife Fund report, there's been a 94% decline in biodiversity in Latin America and the Caribbean due to the impact of human activities on the environment.
"It is remarkable how much we don't know about common species and there's so many species we know almost nothing about," Losos said. "Probably the majority of the world's species have yet to be discovered. We need to know what's out there before it's lost."