Biodiversity of museum and bulk field samples compared: The Chiampo sponge fauna (Eocene, Lessini Mountains, Italy)

The sponge body fossils from the Lutetian (Eocene) of Chiampo Valley in north-eastern Italy, Lessini Mountains, ex-hibit a high diversity. The fauna, comprising 32 species, was recently described in a systematic study based on museum material. Here we compare diversity measures and rank-abundance distributions between the museum material and new material from random surface collection at the original sampling site. Not surprisingly, we find that selectively col-lected museum material tends to have greater diversity and evenness than bulk field samples. Nevertheless, abundance rank- orders are maintained between samples. Bulk field sampling revealed hexactinellids to be strongly dominant over lithistids, which suggests a deep-water setting of greater than 200 m water depth