Descriptive osteology of Corydoras aeneus (Siluriformes: Callichthyidae)
Both the cranial and postcranial osteology of Corydoras aeneus (Gill, 1858) is described based on the study of five adult specimens. The results were compared to the condition described for other loricarioid fishes. Most results corresponded with the expected pattern based on studies dealing with parts of the callichthyid osteology, although some differences were observed. One of these differences was the presence of a suprapreopercular bone, a bone that was previously unmentioned in any callichthyid species. Further, several homologies were resolved and mainly confirmed existing hypotheses. This way, for example, based on the presence of several branches of the lateral line system, the compound dorsolateral bone of the otic region was identified as the posttemporo-pterotico-supracleithrum. Further, the presence of several otoliths in the compound bone forming the neurocranial floor in the occipital region, confirmed the fact that the bone comprised out of a fusion of both basi- and exoccipital bones. This study, however failed to resolve some other questions regarding homologies (i.e., lacrymo-antorbital, suprapreopercle) pointing out the need for further ontogenetic research. In this light, this study provides the basis for this further comparative and ontogenetic research on callichthyids specifically and on loricarioids in general.