ИСТИНА

Since June 2012, samples of wild caught white shrimp Litopenaeus setiferus from Plaquemines Parish (Louisiana) fisheries with clinical signs of microsporidiosis have been repeatedly delivered to the Louisiana Aquatic Diagnostic Laboratory for identification. Infection was limited predominantly to female gonads and was caused by a microsporidium producing roundish pansporoblasts with 8 spores (3.6 x 2.1um) and anisofilar (2-3+4-6) polar filament. These features allowed identification of the microsporidium as Agmasoma penaei Sprague, 1950. A. penaei is known as a microsporidium with world-wide distribution, causing devastating epizootics among wild and cultured shrimps. This paper provides molecular and morphological characterization of Agmasoma penaei from the type host and type locality. Comparison of the novel SSUrDNA sequence of A. penaei from LA (GenBank Acc#1654619) to the one of A. penaei from Thailand revealed 95% similarity, which suggests these geographical isolates are two different species. The A. penaei sequences did not show significant homology to any other examined taxon. Phylogenetic reconstructions using the SSU rDNA and alpha and beta-tubulin sequences supported its affiliation with the Clade IV Terresporidia sensu Vossbrink 2005, and its association with parasites of fresh and salt water crustaceans of the genera Artemia, Daphnia, and Cyclops.