Darwin's Frogs Croaking Thanks to Deadly Fungus
Stuart V. Nielsen
The cocoa frog is one of six new frog species that were recently found in a rainforest-dominated mountainous region of southeastern Suriname. “At a time when so many frog species are declining and undergoing extinctions worldwide, it is particularly uplifting to discover so many new frogs in a single area,” Trond Larsen, a tropical ecologist and director of the Rapid Assessment Program at Conservation International, told Discovery News. He and his team found about 60 new species in the South American country.
The tiny Lilliputian beetle measures just 2.3 mm long and could be the smallest dung beetle in the entire Guiana Shield and among the smallest in the world. “Dung beetles act as a cleanup crew in the forest,” Larsen said. “By burying dung, they not only control parasites and disease, including those that affect people, but also disperse seeds and recycle nutrients that enable forest regeneration.”
Leeanne Alonso, director of Global Biodiversity Exploration for Global Wildlife Conservation, went on the expedition with Larsen. She thinks this beetle might be small and red to look like a seed stuck in poo, thereby fooling predators. “Dung beetles in forest areas are a good indicator of mammal diversity,” she added. Without mammals providing their food source, there would be few such insects.
Stuart V. Nielsen
The collection of new animals includes 11 species of fish that are probably new to science. “Small, brightly-colored tetras similar to this one are popular in the aquarium trade, and sustainable exports of wild species could provide financial support to local communities and incentives to conserve the species’ natural habitat,” Larsen said.
Alonso added that, as new species go, fish are relatively rare. “It’s amazing that so many were found in this region, which I believe has the world’s best and most beautiful and pristine forests in the world.” She loved it so much that she took her family there on a vacation after the research work ended.
Bats are another “good indicator of habitat quality,” Alonso said. She explained that, in this case, the bat thrives on fruit, so the region must support plenty of healthy fruit-producing trees.
Genuine coral snakes are highly venomous, but this false coral snake’s name is itself somewhat misleading, as the researchers found out the hard way. Alonso said that a helicopter pilot transporting the scientists was bitten by one. “His arm really swelled up,” she said, explaining that all such snakes have sharp teeth and venom, just not as poisonous as the “real” coral snake this species resembles.
This extraordinary new insect displays waxy fronds at the end of its body that was built for jumping among plants. “Maybe the fronds are meant to resemble anthers of a flower, helping with camouflage?” Alonso said, admitting that nature sometimes works in still-mysterious ways. She continued, “So little is known about insects from this region, so this was a real find.”
Top-level predatory big cats, such as this margay, are yet another sign of healthy habitat. More of them generally means there are more prey animals to feast upon. “Margays love to sleep and hide in caves at the site,” Alonso added.
Six new katydids, including this one, were discovered. Larsen described it as a “gangly species with oversized, spiny hind legs.” The newly discovered katydids "are indicative of the pristine, healthy forests of the Upper Palumeu Watershed," Larsen said, "and the forests in turn help to ensure continued flows of clean, plentiful water used by people throughout the rest of the country.”
“Despite their generally diminutive size, water beetles can be useful indicators of water quality, and also help to filter and keep water clean,” Larsen said. “Many of the 26 new water beetle species discovered on this survey are probably restricted to isolated habitats, especially in the mountains of southeastern Suriname, and may occur nowhere else.”
Sandra J. Raredon
Eleven new fish species were found in the region, dubbed a "tropical Eden" by the researchers. Larsen said, “This new sucker-mouthed armored catfish was rare, and only encountered in the narrow, upper reaches of the Palumeu River.
“This delicate slender opossum is really cute,” Alonso said. “It’s hard to find small mammals like this, which are indicative of primary forest.”
is the largest of all South American dung beetles, Larsen shares. Despite its name, this species feeds more frequently on dead animals than on dung. A highly unusual case in the Animal Kingdom, both males and females of this species possess a long horn on their head, which they use during intense battles with other individuals of the same sex. The vast difference in adult body size seen here is primarily determined by how much food was available to the developing larva. This species is capable of rapidly burying large animal carcasses, providing an important ecological service that sustains rain forest health.
“Given the beautiful coloration, high visibility and popularity of frogs in the poison dart frog family (Dendrobatidae), most species in this group are relatively well known,” Larsen said. “Therefore, the discovery of this species potentially new to science is particularly exciting. The toxic secretions of poison dart frogs hold great potential to yield new medicines that could greatly benefit the world -- yet with frogs declining globally, their protection in the wild is essential.”
The researchers could have just scratched the new species surface in southeastern Suriname, given that other animals, fish, insects and more unknown to science could be found there. The region’s human population is currently small -- only about 500,000 -- but it’s growing and there is a threat of future habitat-destroying activities, such as mining and logging. Alonso hopes that the wilderness can be protected, with money-generating activities such as ecotourism allowing both humans and amimals to thrive there.
Male Darwin's frogs raise young in their mouths, protecting them from predators until they have matured for weeks, when the fathers regurgitate them into the world. But nothing can protect them from a deadly fungus, which has helped push one of the two species of these frogs to probable extinction, and driven a decline in the second variety, new research shows.
The fungus, known as Batrachochytrium dendrobatidis, or chytrid fungus, has spread throughout the world and devastated many amphibian populations. But this is one of the first instances in which the fungus has been directly implicated in the disappearance of such a widely known species, researchers said.
Researchers looked at museum specimens of both species and found that the fungus started showing up in these and other frogs in the 1970s, about when populations of both began to decline, according to a study published today (Nov. 20) in the journal PLOS ONE. [40 Freaky Frog Photos]
One of the species, the northern Darwin's frog (Rhinoderma rufum), hasn't been seen since 1980 and is likely extinct. The fungus is "probably the main reason" for the frog's disappearance, said Marcus Rowcliffe, a researcher at the Zoological Society of London who wasn't involved in the present study.
The southern Darwin's frog (Rhinoderma darwinii) is still around, but has declined faster than previously thought in recent years, said Claudio Soto-Azat, a study co-author and researcher at Andrés Bello University in Santiago, Chile, who did research for the study while a student at the Zoological Society of London.
The researchers found that a small percentage of southern Darwin's frogs were infected with the fungus, although at lower rates than other species. This could mean that the fungus more easily kills them, compared to other frogs, the study noted (whereas other species can live longer with the disease, and thus more of them are found alive suffering from the infection). They also found that populations of Darwin's frogs were lower in areas with higher rates of fungal infection. In one instance in 2007, 30 wild-caught southern Darwin's frogs were sent to be captive-bred in Germany, but all 30 died from the fungus.
The fungus may have been spread to Chile by African clawed frogs, brought to the region in part to be used for pregnancy tests, in the mid-20th century. These frogs laid eggs when injected with pregnant women's urine.
Darwin's frogs are the only known species of frogs where males can get "pregnant" and hold the young within a compartment of their mouth as the tadpoles mature. They are named for Charles Darwin, who happened upon one of the two species in 1834.
Another PLOS ONE study published in June by Soto-Azat and colleagues estimated that the northern Darwin's frog bit the dust in 1982.
The International Union for Conservation of Nature, an environmental group, called chytrid fungus "the worst infectious disease ever recorded among vertebrates [animals with backbones] in terms of the number of species impacted and its propensity to drive them to extinction."
Habitat loss is also a major reason for the decline of both species, Soto-Azat said.
More From LiveScience:
Album: Bizarre Frogs, Lizards, and Salamanders
In Photos: Endangered and Threatened Wildlife
7 Devastating Infectious Diseases
Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
This story originally appeared on LiveScience.com.