Secondary-tail formation during stolonization in the Japanese green syllid,Megasyllis nipponica |
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Authors: | Daisuke S. Sato Mayuko Nakamura María Teresa Aguado Toru Miura |
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Affiliation: | 1. Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa, Japan;2. Animal Evolution & Biodiversity, Georg-August-Universität Göttingen, Göttingen, Germany |
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Abstract: | Benthic annelids belonging to the family Syllidae show a distinctive sexual reproduction mode called “stolonization,” in which posterior segments are transformed into a reproductive individual-like unit called a “stolon.” Megasyllis nipponica forms a stolon head and a secondary tail in the middle of the trunk before a stolon detaches, while, in the case of posterior amputation, posterior regeneration initiates at the wound after amputation. To understand the difference between posterior regeneration and secondary-tail formation during stolonization, detailed comparisons between the developmental processes of these two tail-formation types were performed in this study. Morphological and inner structural observations (i.e., cell proliferation and muscular/nervous development) showed that some processes of posterior regeneration, such as blastema formation and muscular/nervous regeneration at the amputation site, are missing during secondary-tail formation. In contrast, the secondary tail showed some unique features, such as the formation of ventrolateral half-tail buds that later fused in the middle and muscle/nerve branches formed before the detachment of the stolon. These novel features in the process of stolonization are suggested to be adaptive since the animals need to recover a posterior end quickly to stolonize again. |
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Keywords: | half-tail buds regeneration secondary tail stolonization Syllidae |
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