Sexual Reproduction of the Black Sea Diatom Climaconeis scalaris (Brébisson) E.J. Cox

Abstract

The paper reports a process of sexual reproduction in the Black Sea diatom Climaconeis scalaris (Brebisson) E.J. Cox, 1982, initiated in laboratory conditions. A crossing system of this species allows both homo- and heterothallic reproduction. The fertilization is allogamous. Diploid mother gametangial cells secreted mucilage, forming a mucilage track, while actively gliding relative to each other. Each gametangium in a pair produced two elongated, cylindrical round-ended haploid gametes, which were largely morphologically and behaviorally isogamous. The division of the protoplast of the gametangial cell occurred in the transapical plane without the rearrangement of gametes. Growing auxospores were located parallel to the parent frustules. The research produced data on changes in the cell size, number of chloroplasts, and the position of cardinal points in the life cycle of the examined species.