Sporadic records of stranded specimens in the Strait of Messina represented the only source of information about Microichthys coccoi R & uuml;ppell, 1852 until the beginning of the 21st century, when some occasional reports by trawl surveys occurred in eastern Aegean, north Tyrrhenian, north-eastern Ionian, and Balearic seas. Until now, some uncertain exists about the areal, ecology and biology of this rarely collected species, and its morphological features have not been exhaustively described. In this paper, the stranding of two further specimens is reported, together with the first description of the sagitta and the palatal teeth. Some insights into its biology and ecology have also been suggested.

Several marginelliform species from the South Pacific collected in Fiji, Western Samoa and Pitcairn Islands are revised on the basis of their shell morphology. The species Volvaria (Volvarina) pygmaea Garrett, 1873 described from Fiji is re-assigned to the genus Gibberula Swainson, 1840, and a lectotype is designated. The species Gibberula vomoensis Wakefield et McCleery, 2004 described from Vomo Island (Western Fiji) is illustrated by a specimen from the same area (Beqa Island, Western Fiji) as a complement to the original description of the species. The species Crithe cossinea Cossignani, 1997, described from the Philippines, is reported from Western Fiji and its biogeographical status is discussed herein. Six species are described as new: Gibberula aureola n. sp. from Western Samoa and G. dixoni n. sp. from Pitcairn, Cystiscus turbinatus n. sp. from Pitcairn, Volvarina storea n. sp. from Western Samoa, Granulina vitiensis n. sp. from Western Fiji, and G. biplicata n. sp. from Pitcairn.

We review the Conoidea (excluding Conidae and Terebridae) belonging to Families Borsoniidae, Clathurellidae, Drilliidae, Horaiclavidae, Mangeliidae, Mitromorphidae, Pseudomelatomidae and Raphitomidae recorded from Masirah Island, Oman, with data on their morphology, systematics, nomenclature and distribution. The genus Masirahia and 25 species are described as new (Etrema lineoangulosa, Clavus familiaris, Clavus improprius, Clavus minutoventrosus, Clavus mursaysensis, Clavus translucidus, Anacithara boyeri, Masirahia rotundigranulata, Masirahia rosadoi, Pseudexomilus robini, Eucithara aureolineata, Eucithara masirahensis, Gingicithara seroseparata, Pseudorhaphitoma mollisculpta, Crassispira hervillardi, Crassispira porphirioi, Crassispira simbillei, Funa incisospirata, Funa pseudotheoreta, Funa zahariasi, Ptychobela boschi, Ptychobela pelorcei, Daphnella trincadoi, Glyphostomoides alyaensis, Pseudodaphnella cyrillliformis). We also present one Pseudodaphnella sp. without describing it as new species. The lectotype of Drillia theoreta (Melvill, 1899) is here designated.

The Pyramidellidae of the Red Sea remain poorly known, despite the high interest in the biodiversity and biogeographic history of this region. A new odostomiine gastropod species, Odostomia (s.l.) ritae n. sp., from the northern Red Sea, is described and compared with similar species occurring in the Indo-West Pacific. The type specimens of several related species-Zua thalassina Jousseaume, 1890, Odostomia sperabilis Hedley, 1909, Odontostomia dalli Hornung & Mermod, 1925, and Odostomia decouxi Saurin, 1959-are illustrated for comparison. The new species is provisionally placed in the genus Odostomia Fleming, 1813, sensu lato, on the basis that this is the oldest valid name for odostomiines, pending a comprehensive study at a supraspecific level of the Pyramidellidae. Zua thalassina Jousseaume, 1890 (Cochlicopidae) is transferred to the family Pyramidellidae as Odostomia (s.l.) thalassina (Jousseaume, 1890) n. comb. The discovery of such a minute and morphologically distinctive species underscores the taxonomic gaps in this regional fauna and highlights the Red Sea as a complex area with high potential for ongoing future discoveries.

Granulina gujaratensis n. sp. is described from Western Gujarat (India) on the basis of its shell morphology and of its soft parts chromatism. Granulina gujaratensis is compared with the most closely resembling species G. nebulosa Boyer, 2018, described from Masirah Island (Oman).

A non-indigenous pyramidellid is newly reported in Capo Peloro lagoon, north-eastern Sicily, Italy. Its introduction is likely due to mussel or oyster farming activities carried out over several decades in the lagoon. Due to its peculiar shell morphology, it is most like species described from the west coast of North America by Dall and Bartsch in the early 20th century, and type specimens of the most similar species are illustrated for comparison. Based on comparisons with native Mediterranean species and the global fauna, we tentatively attribute the newly recorded species from Capo Peloro lagoon to Menestho (s.l.) cf. enora (Dall & Bartsch, 1909) comb. nov. The systematic placement is tentative pending additional information on this species and a revision of the genus.

[The genus Montenegrina O. Boettger, 1877 (Gastropoda: Stylommatophora: Clausiliidae) in Greece] Montenegrina O. Boettger, 1877 (Gastropoda: Stylommatophora: Clausiliidae) is a genus of door snails that lives on limestone rocks, widespread from the southernmost regions of the Dinaric Mountains to the northern part of the Pindus Mountains in Greece. In this paper, based on the most recent bibliography, an updated and annotated list of Montenegrina species reported for Greece is provided.

Two new species of Gibberula are described from Cameroon as G. knudseni sp. nov. and G. browningleeae sp. nov. based on their shell features. The shell of G. knudseni suggests distant affinities with the complex G. oryza (Lamarck, 1822)/G. miliaria (Linnaeus, 1758) from the Mediterranean and North-West Africa, and with G. cristata Gofas, 1989 described from the Luanda Province, in North Angola. The shell of G. browningleeae shows some affinities with G. punctillum Gofas & Fernandes, 1988 from Sao Tome, differing by a lower spire, a rounded top, smaller and less numerous labial teeth, and a noticeably less indented siphonal notch. The bathymetrical and geographical distribution of these two new species remains to be refined.

The elusive species Volvarina cernita (Locard, 1897) is rediscovered from the lower infralittoral and the upper circalittoral of the Cape Verde archipelago, and compared with the closest forms. A lectotype is designated for this species. Volvarina antoniogonzalezi (Ortea, Moro & Espinosa, 2019), syn. nov., described from the lower infralittoral of Sal, is placed in synonymy with V. cernita. The species V. joubini (Dautzenberg & Fischer, 1906) is rediscovered from Boa Vista and considered a sibling species of V. cernita. Boa Vista Island is proposed as the type locality of V. joubini. A new species of tiny size and showing lesser affinities with V. cernita is described from the circalittoral of Santiago as V. santiagoensis sp. nov. A species group "V. cernita" is defined as being composed of a subgroup "V. cernita" resulting from a radiation at the lower infralittoral and upper circalittoral levels, and of a subgroup "V. blezai" (Ortea, 2019) resulting from a radiation at the upper infralittoral level.

The Caecidae J. E. Gray, 1850 collected from several deep-water stations of the BIOPAPUA, PAPUA NIUGINI and KAVIENG expeditions carried out by the Museum national d'Histoire naturelle, Paris, are revised. About 200 specimens of this family were collected, belonging to three genera and 20 species, i.e., Caecum Fleming, 1813 (15 species), Mauroceras Vannozzi, 2019 (three species) and Parastrophia de Folin, 1869 (two species). Five species are described as new: Caecum restrictum n. sp., C. miliarium n. sp., C. microannulatum n. sp., C. lozoueti n. sp. and C. temporale n. sp. All recorded species are illustrated. Except for C. miliarium n. sp., occurring in large number in the type locality and showing the complete growth sequence, all species are represented by few specimens, often in poor condition. With the addition of the five new species and the new record of Caecum dakuwaqa Pizzini, Raines & Vannozzi, 2013, the inventory of the Caecidae known from northeastern Papua New Guinea reached 43 species. Furthermore, an indeterminate specimen, possibly belonging to an undescribed species, is illustrated.

The cystiscid fauna from Ascension and St. Helena is studied on the ground of semi-intensive samplings worked during the years 2014–2019 by the Shallow Marine Surveys Group (Falklands, United Kingdom). The study of the shell morphology and of its variability allows to describe as new three Gibberula species in Ascension Island: G. monticola n. sp., G. oceanica n. sp. and G. gemella n. sp. The three Volvarina species reported from Ascension by E.A. Smith (1890b) look to result from wrong records in the literature. Marginella (Volvaria) consanguinea E.A. Smith, 1890 is recognized in the fauna from St. Helena and provisionally replaced in the genus Plesiocystiscus, together with a new species described as P. meridionalis n. sp. and wrongly recognized by E.A. Smith (1890a) as corresponding to Granula cinerea Jousseaume, 1875. A lectotype is appointed among the syntypes of Marginella consanguinea. The species Marginella (Volvaria) atomus E.A.Smith, 1890 described from St. Helena was not found in the samplings under study. Due to the similarities observed between the cystiscid fauna from St. Helena and that from South Africa, the occurrence of transportation of live specimens or of empty shells in seaweeds from South Africa to St. Helena deserves to be verified. The documentation of live animals of cystiscid species of St. Helena is required for a verification of the generic status of the considered species, of the possible occurrence of sibling species, and for possible comparison with the fauna of South Africa.

Research on the genus Megastomia Monterosato, 1884 from the Mediterranean Sea led us to study in recent times the species occurring in neighbouring regions, with particular attention to the Red Sea and western Indian Ocean. Among the number of species we examined, we focussed on four of them, characterised by the presence of a fine suprasutural groove, which are presented and illustrated in detail. One of them, originally described as Odostomia, is moved to Megastomia due to the presence of spiral ridges inside the aperture, i.e., M. dorica (Melvill, 1904) n. comb., whereas the other three are described as Megastomia blattereri n. sp. from the northern Red Sea, and M. gorii n. sp. and M. omanensis n. sp. from Oman. Furthermore, the type material of similar species from the Indo-West Pacific, such as Odostomia ovoidea A. Adams, 1860, O. tenera A. Adams, 1860, O. antelia Melvill, 1896, O. eutropia Melvill, 1899, O. metcalfei Pritchard & Gatliff, 1900, O. major Melvill & Standen, 1901, O. dorica Melvill, 1904, O. zaleuca Melvill, 1910, Syrnola lorioli Hornung & Mermod, 1924 and O. (M.) nhatrangensis Saurin, 1959 is illustrated. New generic attributions for several of them are proposed. Furthermore, the lectotype of Odostomia major is designated.

We here present a checklist of marine molluscs living along the coasts of Salento Peninsula, (Apulia, Italy). In respect to past efforts, this new checklist covers a study area extended to North of Capo d’Otranto along the Adriatic coast and the study material includes now all Mollusca, irrespective of the possession of a shell. A thorough review of the available material made it possible to reject a number of species included in previous checklists, due to misidentifications or records based on fossil material, or in any case not verified and therefore unconfirmed. On the other hand, new samplings allowed to include 64 new records for the biogeographical sectors 6 (Ionian Sea) and 7 (southern Adriatic Sea) of the Italian checklist. This work highlights the rich specific biodiversity of the Salento coasts, as a result of its biocenotic complexity.

The worldwide diffused bubble snails, Haminoeidae, although characterized by an extreme morphological homogeneity, display the most diverse radiation inside the order Cephalaspidea. This hidden diversity within the family Haminoeidae was recently unraveled by molecular studies, which helped to understand the evolutionary history of this group by clarifying some aspects of its systematics. In fact, the type genus Haminoea W. Turton and Kingston (1830) was proved to be polyphyletic and, consequently, the genus Haminoea sensu stricto was restricted to the Mediterranean, Atlantic and East Pacific species, with the Mediterranean Haminoea hydatis Linnaeus (1758) as the type taxon. However, at the specie rank, many aspects need to be clarified, especially concerning the Mediterranean fauna. Due to low reliability of macro-morphological characters, the minimal quantity of molecular data currently available on Mediterranean specimen adds to the lack of molecular comparison in most reports. Based on such considerations, Haminoea species from an interesting Mediterranean study area, Faro Lake, a Sicilian coastal lake that is considered a hot spot for both alien and endemic marine Heterobranchia, have been studied using an integrative taxonomic approach. Eleven Mediterranean specimens belonging to four Haminoea bubble snails have been collected, identified and compared with samples from other localities, integrating ecological, morphological, anatomical (reproductive apparatus) and molecular data. Based on molecular investigations carried out on three different molecular markers (H3, 16S and COI), the morphological identifications of the species collected in the Faro Lake have been confirmed, and 37 new sequences are provided for future comparisons. Furthermore, results from this integrative systematic study shed light on the phylogenetic relationships occurring in this group of bubble snails that could be useful in identifying valid diagnostic morphological characters. Haminoea hydatis and H. navicula were confirmed to be close to each other, with H. orteai as sister to them and with H. orbignyana as the basal taxon. Given external morphological features are unreliable with species identification in Haminoea genus open questions on the geographical distribution of the species and on their ranges of intraspecific variability have yet to be addressed and further in-depth studies are needed. Finally, the presence of three sympatric Haminoea species, two of which are considered native or long-time naturalized, along with other occasional congeneric species, and the absence of the introduced invasive Haloa japonica, reflects both the resilience and stochastic space-temporal dynamics of Faro Lake. This confirms it as an inexhaustible source of case-studies.

Two new Marginellidae species are described from Callao, Peru, and placed into the genus Prunum Herrmannsen, 1852, as P. sigmoides n. sp. and P. lamellosum n. sp.The reliability of the locality attributed to these new species is discussed, and the two species are considered to come with high probability from Western South America, due to their original features not matching Prunum morphs known from the rest of the Panamic Province, Caribbean or West Africa.