Calothrix rhizosoleniae

Photic zone I Cyanobacteria E Endosymbiont/ diatom Calothrix rhizosoleniae Janson et al., 1999a,b Foster and Zehr, 2006... 

Lemmerman (1905) was one of the first to depict the unique association of another heterocystous cyanobacterium, Calothrix rhizosoleniae, attached to the spines of a Chaetocoeros compressus diatom. Norris (1961) noted that the cyanobionts only attach transversely to the intercellular spaces of the diatom with the heterocyst closest to the host diatom. Others report the same symbiont as R. intracellularis (G6mez et al., 2005 Janson et ai, 1999 Karsten, 1907 Norris, 1961), thus there is... 

Although the Calothrix cyanobionts of Chaetoceros are attached to the diatom spines, the cyanobionts are only located at the interceUular spaces and attached transversely at the heterocyst (Norris, 1961), which could be seen as a morphological adaptation for nitrogen transfer. Others (e.g., ViUareal, 1990) have suggested that the extraceUular location of the Richelia symbionts with Rhizosolenia clevei is mechanistic for nitrogen transfer. 

Fig. 4.8. Characteristic cyanobacteria 1 — Chroococcus, 2 — Aphanothece, 3 — Chamaeaiphon, 4 — Oscillatoria, 5 — Spirulina, 6 — Lyngbya, 7 — Anabaena, 8 — Cylindrospermum, 9 — Calothrix, 10 — Tolypothrix, 11 — Richelia inside a cell of the diatom Rhizosolenia (modified from ref. [13])...

---