Poecilogony is the intraspecific variation in developmental mode, with larvae of different types produced by the same individual, population or species. It is very rare among marine invertebrates, and in gastropods has long been described only in a few opisthobranchs. The physiological and regulatory mechanisms underlying larval evolutionary transitions, such as loss of planktotrophy that occurred repeatedly in many caenogastropod lineages, are still largely unknown. We have studied the inter- v. intraspecific variation in larval development in the north-east Atlantic neogastropod genus Raphitoma Bellardi, 1847, starting with an iterative taxonomy approach: 17 morphology-based Preliminary Species Hypotheses were tested against a COI molecular-distance-based method (ABGD), and the retained species hypotheses were eventually inspected for reciprocal monophyly on a multilocus dataset. We subsequently performed an ancestral state reconstruction on an ultrametric tree of the 10 Final Species Hypotheses, time-calibrated by fossils, revealing that the interspecific changes were planktotrophy > lecithotrophy, and all have occurred in the Pleistocene, after 2.5 million years ago. This is suggestive of a major role played by Pleistocene Mediterranean oceanographic conditions – enhanced oligotrophy, unpredictable availability of water column resources – likely to favour loss of planktotrophy. Within this group of species, which has diversified after the Miocene, we identified one pair of sibling species differing in their larval development, Raphitoma cordieri (Payraudeau, 1826) and R. horrida (Monterosato, 1884). However, we also identified two Final Species Hypotheses, each comprising individuals with both larval developmental types. Our working hypothesis is that they correspond to one or two poecilogonous species. If confirmed by other nuclear markers, this would be the first documentation of poecilogony in the Neogastropoda, and the second in the whole Caenogastropoda. Although sibling species with different developmental strategies may offer good models to study some evolutionary aspects, poecilogonous taxa are optimally suited for identifying regulatory and developmental mechanisms underlying evolutionary transitions.

Two poorly known species of genus Raphitoma Bellardi, 1847 (Gastropoda Conoidea) are revised. Raphitoma pumila (Monterosato, 1890) is redescribed and Cordieria cordieri var. hispida, Monterosato, 1890 is raised to species level and transferred to the genus Raphitoma, hence requiring the creation of a replacement name (R. hispidella nomen novum) due to secondary homonymy with R. hispida Bellardi, 1877.

The Mediterranean mangeliid species commonly ascribed to the genus Mangelia Risso, 1826 are here reviewed with the description of three new species: Mangelia algarvensis Spada n. sp., M. striolatoides Sabelli & Spada n. sp. and Mangelia tenuisculpta Spada n. sp. One new genus, Pseudomangelia n. gen. Sabelli & Spada (type species Pleurotoma vauquelini Payraudeau, 1827) is described and the genera Lyromangelia Monterosato, 1917, Pyrgocythara Woodring, 1928, Smithiella Monterosato, 1880 and Villersiella Monterosato, 1890 are resurrected on the basis of different morphology of the shell, of the living animal and of the radula.

A new raphitomid toxoglossa, Raphitoma griseomaculata n. sp. (Gastropoda Conoidea), is described from the Ionian Sea. It is the sister species to R. densa (Monterosato, 1884) from which it differs in the different protoconch (paucispiral vs. multispiral), adding to a long list of pairs of the cenogastropod species that differ in their larval development.

In this paper, the authors deal with Raphitoma corbis (Potiez et Michaud, 1838) (Gastropoda Conoidea), a poorly-known taxon differently interpreted over time, by fixing a neotype in order to stabilize the nomenclature because the type material has been lost.