Pollutants May Have Caused Morphological Abnormalities in Some Polychaete Species (Annelida) Collected from Cilacap, Central Java, Indonesia

Morphological abnormalities in <i>Perinereis aibuhitensis</i> (Grube 1878) (Nereididae) and <i>Diopatra claparedii</i> Grube 1878 (Onuphidae) were observed in the specimens collected from the intertidal habitat around Donan Creek in Cilacap City, Central Java Province, Indonesia. The <i>P. aibuhitensis</i>, which is not supposed to have branchiae, possesses digitate branchiae on its dorsum, and lacks eyes. To our knowledge, the presence of branchiae in the genus <i>Perinereis</i> and the shape of the feature has never been reported anywhere else. Furthermore, the <i>D. claparedii</i>, which is supposed to have the most developed branchiae on its dorsal anterior region, lacks the feature. The species also lacks both prostomial and peristomial appendages, and has various anomalous cirri. While the abnormalities in the <i>P. aibuhitensis</i> are likely to be associated with the hypoxic condition of the animal's habitat, the anomalies in the <i>D. claparedii</i> appear to be more related to the exposure to pollutants, particularly heavy metals. Taxonomic investigations are required to reveal the polychaete species richness in this area, and may identify species that have the potential to be used as biological indicators of coastal water pollution in southern Java.