PARAOPHIOIDINA-SCOLECOIDES N-SP, A NEW ASEPTATE GREGARINE FROM CULTURED PACIFIC WHITE SHRIMP PENAEUS-VANNAMEI

The aseptate gregarine Paraophioidina scolecoides n. sp. (Eugregarinor ida: Lecudinidae) heavily infected the midgut of cultured larval and p ostlarval specimens of Penaeus vannamei from a commercial 'seed-produc tion' facility in Texas, USA. It is morphologically similar to P korot neffi and P. vibiliae, but it can be distinguished from them and from other members of the genus by having gamonts associated exclusively by lateral syzygy. Shrimp acquired the infection at the facility; naupli i did not show any evidence of infection, but protozoea, mysis, and po stlarval shrimp had a prevalence and intensity of infection ranging fr om 56 to 80% and 10 to >50 parasites, respectively. Infected shrimp re moved from the facility to aquaria at another location lost their gamo nt infection within 7 d. When voided from the gut, the gregarine disin tegrated in seawater. Results suggest that R vannamei is an accidental host, although a survey of representative members of the invertebrate fauna from the environment associated with the facility failed to dis cover other hosts. No link was established between infection and eithe r the broodstock or the water or detritus from the nursery or broodsto ck tanks.