GEISEN, Markus, Chantal BILLARD, Alexandra T.C. BROERSE, Lluisa CROS, Ian PROBERT, & Jeremy R. YOUNG 2002 (Nov. 29) Life-cycle associations involving pairs of holococcolithophorid species: intraspecific variation or cryptic speciation? Eur. J. Phycol. 37(4): 531-550, 44 figs., 2 tables [Daktylethra pirus a life-cycle stage of Syracosphaera pulchra, Syracolithus quadriperforatus a life-cycle stage of Calcidiscus leptoporus]