Zoological Studies

Vol. 49 No. 2, 2010

Ultrastructure of Spermatozoa of Prionospio japonica (Annelida: Spionidae) from Taiwan

Vasily I. Radashevsky1,*, Arkadiy A. Reunov1, Olga V. Yurchenko1, Yana N. Alexandrova1, and Hwey-Lian Hsieh2

1A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
2
Biodiversity Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan

Vasily I. Radashevsky, Arkadiy A. Reunov, Olga V. Yurchenko, Yana N. Alexandrova, and Hwey-Lian Hsieh (2010) Prionospio japonica, a common inhabitant of estuaries in the northwestern Pacific Ocean, releases gametes into the water, where fertilization and planktotrophic larval development occur.  Each spermatozoon has a biradially symmetrical acrosome 0.3 0.1 μm long, a spherical nucleus 1.7 0.2 μm in diameter, 4 spherical mitochondria 0.8 0.1 μm in diameter, 2 centrioles situated perpendicular to each other, and a flagellum with a 9 2 + 2 organization of microtubules.  The biradially symmetrical acrosome, which is also present in P. cf. queenslandica, is unique among polychaetes examined to date and possibly an apomorphy shared by a group of closely related Prionospio species.

Key words: Sperm, Morphology, Polychaeta.

*Correspondence: E-mail:radashevsky@mail.ru