Villalobosius is a genus of crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s in the family Pseudothelphusidae

Pseudothelphusidae

Pseudothelphusidae is a family of freshwater crabs found chiefly in mountain streams in the Neotropics. They are believed to have originated in the Greater Antilles and then crossed to Central America via a Pliocene land bridge.-Parasitology:...

, containing a single species, Villalobosius lopezformenti. It lives in the northern part of the state of Oaxaca

Oaxaca

Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...

, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, on the Isthmus of Tehuantepec

Isthmus of Tehuantepec

The Isthmus of Tehuantepec is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean, and prior to the opening of the Panama Canal was a major shipping route known simply as the Tehuantepec Route...

, and is adapted to a troglobitic

Troglobite

Troglobites are small cave-dwelling animals that have adapted to their dark surroundings. Troglobite species include spiders, insects, fish and others. They live permanently underground and cannot survive outside the cave environment. Troglobite adaptations and characteristics include a heightened...

 lifestyle.

Nomenclature

The species was originally described as Stygothelphusa lopezformenti in 1991, but the genus name Stygothelphusa was discovered to be a junior homonym of Stygothelphusa Ng, 1989, and a replacement name

Nomen novum

In biological nomenclature, a nomen novum , new replacement name is a technical term...

, Villalobosus, was created in 2000. This was also found to be a junior homonym, of the subgenus Villalobosus Holthuis, 1972 in the crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 genus Procambarus

Procambarus

Procambarus is a genus of crayfish in the family Cambaridae, all native to North and Central America. It includes a number of troglobitic species, and the parthenogenetic Marmorkrebs...

, and so it, too, was replaced. The genus is therefore currently known as Villalobosius.