Image © Alfred van Geest
Cell of Xanthidium bifidum. Notice open sinus and two superimposed sines at each of its apical angles.
Cell dimensions (L x B): 15 x 15 µm
Xanthidium bifidum is one of the smallest Xanthidium species. Cells are characterized by an open sinus and cup- to bowl-shaped semicells, the apical angles of which are provided with two superimposed spines*. Zygospores are compressed-spherical, in frontal view with undulate margins (about pumpkin-shaped). In the Netherlands, X. bifidum is incidentally encountered in moorland pools but it could easily be overlooked. Zygospores are only found once.
* Like Xanthidium octocorne this species maybe is better to be accounted the genus Octacanthium. For that matter, based on molecular data, Šťastný et al. (2013) transferred X. octocorne to the genus Staurodesmus.
SEM image © Jan Šťastný
SEM image of Xanthidium bifidum
Šťastný, J., Skaloud, P., Langenbach, D., Nemjova, K. & Neustupa, J. (2013): Polyphasic evaluation of Xanthidium antilopaeum and Xanthidium cristatum species complex. — Journal of Phycology 49: 401-416.
Mouse over images Ton Joosten © Waterdienst Lelystad
Zygospore of Xanthidium bifidum. Notice undulate margins.