“ OPISTHOBRANCHIA ” The taxon Opisthobranchia P. Fischer, 1883, has been undergoing a constant critical revision during its history. In recent years there is increasing evidence that it will not survive the molecular revolution in molluscan systematics (Wägele et al., 2014), so that informal names as “sea slugs” may be provisionally adopted to refer to most “opisthobranch” taxa (e.g. Crocetta et al., 2015). Here, however, listing the material under “ Opisthobranchia ” is also convenient to follow the survey on the Monterosato material already provided by Oliverio & Tringali (2001).

Published as part of Appolloni, Massimo, Smriglio, Carlo, Amati, Bruno, Lugliè, Lorenzo, Nofroni, Italo, Tringali, Lionello P., Mariottini, Paolo & Oliverio, Marco, 2018, Catalogue of the primary types of marine molluscan taxa described by Tommaso Allery Di Maria, Marquis of Monterosato, deposited in the Museo Civico di Zoologia, Roma, pp. 1-138 in Zootaxa 4477 (1) on page 72, DOI: 10.11646/zootaxa.4477.1.1, http://zenodo.org/record/1454652