First occurrence of the interstitial polychaete Saccocirrus pussicus (Saccocirridae, Polychaeta) in exposed beaches of Uruguay.

This paper reports the first occurrence of the family Saccocirridae, (Saccocirrus pussicus), in exposed sandy beaches of Uruguay. 981 individuals, with densities between 20 and 18,080 ind/m2 and mean density of 163.5[plus or minus]362.9 ind/m2 were found, mainly in the swash zone, with a clearly patchy distribution.