Appendicularians (Urochordata)

Abstract

This revision updates the knowledge about the taxonomic composition and distribution of the species of appendicularians found in both the Pacific and Atlantic coasts of Costa Rica. Comments are provided also on the methodological problems involved in the taxonomic study of these organisms. In general, it was found that investigations on the Costa Rican appendicularians have been scarce. These organisms are widely distributed in the oceanic and neritic realms and although they have not been studied in detail, they are actually frequent in coastal and lagoonal zooplankton communities of Costa Rica. They have been mentioned from different areas of the Costa Rican Pacific such as the Golfo de Nicoya and Golfo Dulce and in the coastal embayments Murciélago and Culebra. On the Caribbean coasts, they have been known to occur off the urban area of Limón and in the reef zone of Cahuita. The regional studies on this group are also quite scarce; there is only one general reference in the Eastern Pacific. Up to six species of appendicularians have been known to occur in the Pacific coast of Costa Rica; this figure represents only about 14% of the total species number (43) recorded in the Pacific Ocean. The current status of knowledge is not better in the Caribbean coast; there are no species records of appendicularians in this zone.