| Catenula lemnae Duges, 1832 | Feb 1989-Jan 1990 | | | many individuals reproducing asexually (chains of zooids). |
| Weldonia paraguayensis Martin, 1908 | Feb-Mar 1989 | | | many individuals. |
| Stenostomum leucops (Duges, 1828) | Feb 1989 | | | many individuals. |
| Stenostomum uronephrium Nuttycombe, 1931 | Feb, Jun, Aug, Nov 1989 | | | five individuals. |
| Microstomum lineare (Müller, 1773) | Feb 1989-Jan 1990 | | | many immature individuals. |
| Dalyellia obscura Norena-Janssen, 1995 | May, Oct 1989 | | | five specimens. |
| Gieysztoria santafeensis Norena-Janssen, 1995 | Feb 1989-Jan 1990 | | | many specimens. |
| Gieysztoria quadrata Norena-Janssen, 1995 | Feb 1989 | | | many specimens. |
| Gieysztoria coronae Norena-Janssen, 1995 | Aug 1989 | | | three specimens. |
| Gieysztoria tigrensis Norena-Janssen, 1995 | Nov 1989 | | | many specimens. |
| Gieysztoria pseudodiadema Norena-Janssen, 1995 | Feb 1989 | | | one specimen. |
| Gieysztoria variata Norena-Janssen, 1995 | Sep 1989 | | | many specimens. |
| Rhynchomesostoma inaliensis Norena-Janssen, 1995 | Aug-Oct 1989 | | | one specimen. |
| Mesostoma ehrenbergii (Focke, 1836) | Mar-Oct 1989 | | | several specimens. |
| Mesostoma productum (Schmidt, 1848) | Aug-Oct 1989 | | | four specimens. |
| Bothromesostoma evelinae Marcus, 1946 | Jun 1989 | | | nine specimens. |
| Gyratrix hermaphroditus Ehrenberg, 1831 | Jul 1988 | | | many specimens. |
| Gyratrix hermaphroditus Ehrenberg, 1831 | Oct, Dec 1989 | | | many specimens. |