Sentence:  Characteristic traits, all apomorphies, are perichaetine setae, tubulo-racemose prostates, avesiculate <WSD>meroic</WSD> nephridia and opisthogastry (the development of intestinal gizzards, which in this genus are multiple in the region of segments 20–26). 
Meaning of the word marked with <WSD> tags:  (biology) Pertaining to nephridia that are formed by longitudinal or traverse fragmentation of a single original pair of embryonic rudiments in each segment.