Posted on behalf of Henry Nicholls.

A species of Galapagos tortoise thought to have been extinct for more than 150 years may, in fact, be alive and well. This finding, by geneticists at Yale University in New Haven, Connecticut, is particularly surprising given that this reptile is of giant proportions, measuring more than a metre from the front to the back of its shell and weighing more than 200 kilograms. How could such a behemoth have gone unnoticed for so long?

The answer, it turns out, is simple. They’ve been hiding. When Charles Darwin visited the Galapagos Island of Floreana in 1835, he found no sign of its native tortoise and assumed that whalers, pirates and human settlers had wiped them out. Since about 1850, no tortoises have been found on the island (except for one or two introduced animals kept as pets by the locals). It makes sense, therefore, that the International Union for Conservation of Nature would classify the Floreana tortoise Chelonoidis elephantopus (sometimes called Chelonoidis nigra) as extinct.

But the Yale geneticists now have good evidence that some purebred Floreana tortoises may still be alive on a different island in the archipelago. For more than a decade, the researchers have been absorbed by the bizarre mixture of genes found in the tortoises on Wolf Volcano at the northern tip of Isabela, the largest island in the chain. They began by studying mitochondrial sequences, which suggested that tortoises from the distant islands of San Cristobal and Espanola have somehow reached Wolf. Their guess was — and still is — that whalers and pirates were responsible. “Tortoises were occasionally stashed on various islands for safe-keeping and even tossed overboard in large numbers in nearshore areas to lighten cargo during flight or battle,” they wrote in 2002.

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Cross-posted from Scientific American‘s Observations blog on behalf of Katherine Harmon.

A heap of dead bees was supposed to become food for a newly captured praying mantis. Instead, the pile ended up revealing a previously unrecognized suspect in colony collapse disorder — a mysterious condition that for several years has been causing declines in US honeybee populations, which are needed to pollinate many important crops. This new potential culprit is a bizarre — and potentially devastating — parasitic fly that has been taking over the bodies of honeybees (Apis mellifera) in Northern California.

John Hafernik, a biology professor at San Francisco State University, had collected some belly-up bees from the ground underneath lights around the university’s biology building. “But being an absent-minded professor,” he noted in a prepared statement, “I left them in a vial on my desk and forgot about them.” He soon got a shock. “The next time I looked at the vial, there were all these fly pupae surrounding the bees,” he said. A fly (Apocephalus borealis) had inserted its eggs into the bees, using their bodies as a home for its developing larvae. And the invaders had somehow led the bees from their hives to their deaths. A detailed description of the newly documented relationship was published online Tuesday in PLoS ONE.

The team performed a genetic analysis of the fly and found that it is the same species that has previously been documented to parasitize bumblebee as well as paper-wasp populations. That this parasite hasn’t previously been reported as a honeybee killer came as a surprise, given that “honeybees are among the best-studied insects of the world”, Hafernik said. “We would expect that if this has been a long-term parasite of honeybees, we would have noticed.”

The team found evidence of the fly in 77% of the hives they sampled in the Bay Area of California, as well as in some hives in the state’s agricultural Central Valley and in South Dakota. Previous research has found evidence that mites, a virus, a fungus, or a combination of these factors might be responsible for the widespread colony collapse. (Read more about colony collapse disorder in our feature Solving the Mystery of the Vanishing Bees.) And with the discovery that this parasitic fly has been quietly killing bees in at least three areas, it might join the list of possible forces behind colony collapse disorder.

Read the rest of this story on Scientific American.

Image: Parasitic fly larva emerging from a dead bee’s neck. Courtesy of John Hafernik.