Mixonephridia or nephromixia in terebellid polychaetes? a clarification

Abstract

Abstract 1. In recent texts confusion exists in the usage of E.S. Goodrich's terms “mixonephridia” and “nephromixia”, in reference to the segmental organs of polychaete annelids. 2. Goodrich (1945) himself applied the term mixonephridia to the segmental organs that had been described in several families of sedentary polychaetes by Meyer (1887). 3. However, it is shown that the ciliated funnels of these organs in the terebellids Lanice conchilega and Eupolymnia nebulosa in fact contain two distinctly different tissues corresponding to the nephrostomial and coelomostomial components of a nephromixium as defined by Goodrich. 4. Examination of Meyer's text and figures shows that this author had in 1887 already presented clear evidence, apparently overlooked by Goodrich, that in terebellids the ciliated funnels of the segmental organs have the dual composition typical of nephromixia in the sense of the terminology introduced by Goodrich and widely, if at times inaccurately, used today.