Hermannella tivelae (Crustacea: Copepoda) asociada a la almeja Pismo, Tivela Stultorum (Mollusca: Bivalvia) en Baja California, México

Abstract

THE PISMO CLAM, TWELLA STULTORUM IS EXPLOITED IN THE PACIFIC COAST OF BAJA CALIFORNIA, NEW MEXICO. IN SPITE OF ITS COMMERCIAL IMPORTANCE THERE ARE NO SURVEYS ON THE PARASITES OR COMMENSALS ASSOCIATED TO LOCAL POPULATIONS OF THIS MOLLUSC. DURING A STUDY CARRIED OUT BETWEEN JUNE 1996 AND JUNA 1997, THE COPEPOD HERRMANNELLA TIVELAE WAS FOUND IN THE MANTLE AND GILLS OF THE CLAM. THIS IS THE FIRST RECORD OF H. TIVELAE IN MEXICO. ITS OCCURRENCE RANGED FROM 1 TO 128 COPEPODS PER CLAM AND THE PREVALENCE WAS FROM 96 TO 100 %. NO HISTOLOGICAL DAMAGES WERE ASSOCIATED TO THE PRESENCE OF THIS COPEPOD IN MANTLE AND GILLS, OR EVEN IN TH DIGESTIVE TRACT (GUT, STOMACH AND DIGESTIVE DIVERTICULA). THERE WAS NOT RELATION BETWEEN THE CONDITION INDEX (CI) OF THE HOST AND THE NUMBER OF COPEPODS. THESE TWO FACTS SUGGEST THAT H. TIVELAE IS A COMMENSAL IN T. STULTORUM, HOWEVER, FURTHER STUDIES ARE NEEDED TO CONFIRM THE ASSOCIATION TYPE. LIVING COPEPODS HAVE A TRANSPARENT BODY WITH A WIDE BROWN BAND FROM THE PROSOME TO THE UROSOME; THIS IS THE FIRST DESCRIPTION OF H. TIVELAE COLOR.