Monosiphonous growth and cell-death in an unusual Bostrychia (Rhodomelaceae, Rhodophyta): B. anomala sp. nov.

doi:2013.28.2.161

Algae > Volume 28(2); 2013 > Article

Algae 2013;28(2): 161-171. doi: https://doi.org/10.4490/algae.2013.28.2.161

John A. West¹^,*, Susan Loiseaux de Goër² and Giuseppe C. Zuccarello³

¹School of Botany, University of Melbourne, Parkville, VIC 3010, Australia
²11 Rue des Moguerou, 29680 Roscoff, France
³School of Biological Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand

*Corresponding Author

Email: jwest@unimelb.edu.au

ABSTRACT

A morphologically distinct lineage within the Bostrychia moritziana-B. radicans species complex is described as a new species. Bostrychia anomala has thalli with branched monosiphonous filaments with apical cell divisions. The species has terminal tetrasporangial stichidia, each subtending cell bearing tetrasporangia with 2 cover cells. Discharged spores divide transversely, the lower cell first forming a narrow rhizoid and the upper cell forming a monosiphonous shoot. Females have subterminal procarps and males have terminal spermatangial stichidia. Carposporophytes are spherical. Isolates in culture show a pattern of cell death not associated with injury, reminiscent of programmed cell death. Bostrychia anomola shows cell death at intervals along the filaments resulting in division of adjacent cells on either side of the dead cell re-joining the filament; cell division of only one adjacent cell resulting in branching at that site; or filaments fragmenting at the cell death point with adjacent cells forming new apical cells, a means of thallus propagation. The cell death pattern could be a method of filament propagation in the mangrove environment where sexual reproduction is rare.

Key words: Bostrychia anomala sp. nov.; monosiphonous; ‘non-fusion-division’; programmed-cell-death; Rhodomelaceae; sexual life history; vegetative propagation