64.1 Friday, Jan. 6 Large, common and variable: re-assessing the monophyly and diversity of Cerithiidae (Cerithioidea, Caenogastropoda) STRONG, E.E.; Smithsonian Institution, Washington D.C. email@example.com
The gastropod family Cerithiidae is a primarily shallow-water, marine group, comprising one of 17 families in the superfamily Cerithioidea. The family contains ~185 species currently recognized as valid and accounts for ~15% of known cerithioidean diversity. They are typically abundant and gregarious grazers in intertidal to subtidal habitats around the world, with a center of diversity in the tropical and sub-tropical Indo Pacific. Several species are known to inhabit bathyal depths to ~1200 m. The family is essentially subdivided into two subfamilies: the generally small-sized Bittiinae, and the Cerithiinae with large, solid shells. High levels of conchological variability within and between species have confounded efforts to understand the biodiversity of the family and its evolution. The ruling paradigm has been of common, highly-variable, broadly-distributed species. Intensive sampling programs targeting under-explored offshore hard bottoms in coral reef environments, coupled with new morphological and molecular data (partial COI, 12S, 16S sequences), are challenging this paradigm, revealing species complexes of small, rare and geographically circumscribed species complexes, species pairs differing in mode of larval development, and unsuspected relationships among recognized genera. Monophyly of the family as currently circumscribed is not supported. Actual diversity of the family is likely two to three times higher than currently recognized, requiring the description of many new species, and rescue of some of the roughly 1000 available names that have been sunk in synonymy or have fallen from use.