Elphidium excavatum (Terquem); ecophenotypic versus subspecific variation

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Abstract
Large sympatric populations and assemblages of the highly variable foraminiferal species E. excavatum (Terquem) from 7 widely spaced locations indicate that various morphotypes of Elphidium within these populations can be linked to one another in a number of interlocking intergradational series. These morphotypes are grouped into 5 formae (ecophenotypes): E. excavatum f. excavata (Terquem), E. excavatum f. selseyensis (Heron-Allen and Earland), E. excavatum f. clavata Cushman, E. excavatum f. lidoensis Cushman and E. excavatum f. magna f. nov. These formae are equivalent to those of Feyling-Hanssen except for E. excavatum f. selseyensis sensu Feyling-Hanssen (= E. excavatum f. excavata, this work) and E. excavatum f. alba Feyling-Hanssen, which is regarded here as a diagenetically produced E. excavatum f. clavata. Five morphotypes previously considered as species, subspecies or ecophenotypes by various workers occur in an uninterrupted intergradational series at 1 location; they are (conspecific) ecophenotypes. Although all of these formae are taxonomically identical, the distinction between them should be retained, because it appears that the diversity of formae and individual formae are indicative of environmental conditions. The recognition of ecophenotypes of E. excavatum has provided the potential for this species to become a valuable interpretive tool in paleoecological and biostratigraphic studies of Pleistocene and Holocene sediments.