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
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