Taxonomy of the family Siliquariidae (Mollusca, Caenogastropoda) in Eastern Atlantic Ocean and Mediterranean Sea: Description of a new genus and a new species

Abstract

The caenogastropod family Siliquariidae comprises genera with a ‘vermetid‐like’ habitus (Caporbis and Stephopoma), belonging to the subfamily Stephopominae, and genera with a longitudinal shell‐slit (Tenagodus and Pyxipoma), obligatorily associated with demosponges (subfamily Siliquariinae). Only one species of siliquariid is known from the Mediterranean (Tenagodus obtusus) and two from the Eastern Atlantic Ocean (T. senegalensis and Stephopoma mamillatum). The study of recently collected specimens and historical collections led to a reassessment of the status of extant Siliquariidae species present in the area. In particular, the Atlantic T. senegalensis is herein considered as a junior synonym of the Mediterranean T. obtusus, due to morphological and ecological features. A new siliquariinid, Petalopoma elisabet‐tae n. gen. n. sp., was found in the coralligenous biocoenosis along the Portofino Promontory (Ligurian Sea, NW Mediterranean). The new genus, characterised by a flattened operculum which is present only in related, unspecialised filter‐feeders such as turritellids, might have a basal position in siliquariid phyloge‐netic trees.

Key words:

• Siliquariidae
• Mollusca
• Mediterranean Sea
• Eastern Atlantic Ocean
• Tenagodus
• Petalopoma elisabettae