Hoosier Cavefish: Eyeless Fish Species Discovered in Indiana

May 30, 2014 by Sci-News.com

Ichthyologists from Louisiana State University in Baton Rouge and the University of Kentucky have announced the discovery of a new eyeless cavefish in the caves of southern Indiana – it is the first new cavefish species described from the United States in 40 years.

Amblyopsis hoosieri in life, 6.1 cm long. Image credit: M.L. Niemiller.

Amblyopsis hoosieri in life, 6.1 cm long. Image credit: M.L. Niemiller.

The new species has been named Amblyopsis hoosieri. The common name of the fish is the Hoosier Cavefish.

“The specific epithet hoosieri is in reference to this species being from the state of Indiana,” the scientists explained in a paper published in the open-access journal ZooKeys.

“It is also a reference to Indiana University, where biologist Carl H. Eigenmann (1863–1927) was a Professor of Zoology and studied blind cave vertebrates. Notably, Eigenmann’s wife Rosa (1858–1947) is considered by many to be the first female ichthyologist. She and her husband described more than 100 species together.”

“Indiana University was also home to the Father of American Ichthyology, David Starr Jordan (1851–1931), for most of his illustrious career.”

“We derive the specific epithet from the proper noun ‘Hoosier.’ Notably, the senior author of the manuscript is a fervent fan of Indiana Hoosier basketball while the first author is an alumni of the University of Michigan and is not.”

The new fish is the closest relative of Amblyopsis spelaea, a previously known cavefish from the longest cave system in the world, Mammoth Cave in Kentucky.

These two species are separated by the Ohio River, which also separates the states of Indiana and Kentucky.

Amblyopsis spelaea has a knockout mutation in the genetic sequence of rhodopsin, a gene important in vision. Amblyopsis hoosieri, on the other hand, lacks this mutation and maintains a functional rhodopsin gene, despite lacking eyes and vision.

Amblyopsis hoosieri is a robust, blind (eyes not developed) cavefish typically reaching between 6–8 cm. The head is large, flat dorsally, but broad. Scales are inconspicuous and cycloid.

The body is uniformly depigmented, including inside mouth, pinkish-white, reddish near gills; fins are transparent.

Notably, Amblyopsis hoosieri has an anus right behind its head, and the females brood their young in their gill chamber.

The fish occurs in caves developed in carbonate rock of the Crawford-Mammoth Cave Uplands and Mitchell Plain in the South-Central karst region of Indiana within the area that remained ice free throughout the Pleistocene Epoch. It is found primarily in larger cave streams at or near the water table where it has been observed in pools with low flow at depths as shallow as 0.1 m to more than 2 m deep.

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Chakrabarty P et al. 2014. The Hoosier cavefish, a new and endangered species (Amblyopsidae, Amblyopsis) from the caves of southern Indiana. ZooKeys 412: 41–57; doi: 10.3897/zookeys.412.7245