Saving the world’s oldest butterfly

In 1885 a German amateur entomologist and avid collector of butterflies, moths, beetles and hummingbirds traveled from Mexico City to Chilpancingo, swinging his net the whole way. He collected more than 6,000 specimens on that journey. It turns out that one of the species of butterflies he caught had fluttered its wings with dinosaurs.

When Oscar Theodore Baron (1847-1926) returned to Europe, he sold most of his collection. It ended up in the hands of Osbert Salvin, co-editor of the magnificent “Biologia Centrali-Americana,” a 63-volume encyclopedia of the natural history of Mexico and Central America. (The Smithsonian Institution has digitized the full set and you can access it online at www.sil.si.edu/DigitalCollections/bca/).

One of the specimens Baron trapped in his net in southern Morelos had not been identified by modern science. Osbert Salvin christened it Baronia brevicornis, “Baronia with a short horn.” In Latin, “brevis” is short, “corneus” is horn, so brevicornis.

Baronia brevicornis is endemic to the upper Balsas River valley in southern Morelos and northern Guerrero — the only place in the world that it lives. Its caterpillars feed only on a particular variety of acacia tree that grows in the low deciduous forests of Morelos.

A living entomologist with his eye on Baronia brevicornis is Dr. Luc Legal, an associate professor at the Paul Sabatier University in Toulouse, France. He has been working in Morelos in association with the Autonomous University of the State of Morelos (UAEM) since 2005.

From Dr. Legal I’ve learned something grand. Southern Morelos is one of just two places on earth that has had a stable climate since the late Cretaceous Period. That was 65 million years ago! (The other place is the Sichuan valley in China.)

He explains that though Morelos is the second smallest state in Mexico, it is one of the most biologically diverse. It hosts seven of Mexico’s nine great ecosystems, lacking only mangroves and rainforests. Dr. Legal was understandably drawn here by the variety of butterflies. Of Mexico’s 1,900 species, 500 live in the 600-square-kilometer Sierra de Huautla ecological reserve set up by the UAEM.

Dr. Legal has demonstrated convincingly through DNA analysis and molecular referencing that Beronia brevicornis has been living for 70 million years — making it the world’s oldest butterfly species. With a big smile and his hands mimicking butterflies in flight, Dr. Legal said, “We have to imagine what it was like in the Balsas River watershed with tyrannosaurus here and Baronia butterflies fluttering all around him. Truly extraordinary!”

For the first time Baronia brevicornis’s existence is in danger. Its life cycle is dependent on its caterpillars feeding on an acacia tree that flourishes on flat land — also farmers’ favorite. Thankfully the acacia is a tree considered a pioneer — meaning when there is a clearing, the acacia is one of the first trees to take root, and in doing so restores degraded soil. In fact, it is the most common tree in the low deciduous forest.

Dr. Legal has discovered that Baronia brevicornis caterpillars are found on only 2 percent of the acacia trees. Hence it would seem to be occupying only 2 percent of its potential habitat. The butterflies are particular in their choice of acacia trees, requiring a certain age, health, and density.

Dr. Legal is concerned that the Baronia brevicornis population has broken into dispersed “patches.” There may be five kilometers between patches of Baronia butterflies with no individuals in between and no connectivity between patches. This dispersion leads to a reduction in the gene pool.

Not only does Dr. Legal lobby for establishing connectivity between genetic groups, he also lobbies for establishing protected corridors between the three ecological reserves in the state of Morelos. This would allow animals to move freely between them. The Sierra de Huautla Ecological Reserve is in southern Morelos, the Sierra de Montenegro Reserve is in the center of the state, and the Chichinautzin Reserve lies at the northernmost part of the state, running along the volcanic ridge we drive over when traveling from Cuernavaca to Mexico City.

Although the reserves are protected they do have villages and farms within their boundaries. Dr. Legal praised the way the Sierra de Huautla reserve is being administered. He did not say the same about the Sierra de Montenegro. In Charlie’s Digs dated Jan. 14, 2011, I wrote about the dangers facing the Sierra de Montenegro Reserve and relayed Biologist Fernando Jaramillo’s warning about the need of a corridor between it and the Chichinautzin Reserve.

Baronia brevicornis may be the catalyst we need to establish these corridors. She isn’t a threat to anyone, she’s sure been around for a long time, and she has a sweet sounding name reflecting her demeanor. In fact Dr. Legal usually refers to her by her first name, Baronia.

Last month each of the keynote speakers at the Morelos Unico Encounter were given a desktop sculpture of Baronia as a gift of appreciation. Perhaps her champion will arise from this group.