Margaritifera auricularia (Unionoidea, Margaritiferidae), the giant freshwater pearl mussel rediscovered in Spain

Abstract

Margaritifera auricularia was described by Spengler in 1793. Since then specimens have been found in several localities in Western Europe and North Africa, often as fossils. However no living specimens have been scientifically recorded since 1917 (Haas, 1917). This author was the only one to study live specimens, collected in the Ebro River in Spain, publishing a short paper about its anatomy (Haas, 1924). As no more specimens were ever found, no data exist about its reproductive habits, spawning season nor is there a description of its lar- val stages. In a recent survey of Spanish Rivers to inven- tory the Habitats Directive (Directive 92/43/CEE) non-insect invertebrate species (Ramos, 1998), we found living populations of this giant pearl mussel in a very ancient channel (Imperial Canal) of the Ebro River (Araujo & Ramos, 1996) and in the Ebro (Álvarez Halcón, 1998), both in Aragón. More recently, there has been news about other M. auricularia populations living in the lower course of the Ebro river and in one of its irrigation chan- nels (Altaba, 1997), both in Catalonia.