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Chitons are molluscs with scarce world records in estuaries. In the present study, we provide the first records of two species of Polyplacophora in the Coreaú River estuary, Camocim, Ceará, Brazil: Ischnochiton striolatus and Ischnoplax pectinata. The data shows these animals thrive in estuary coastal regions. The taxonomic data together with the ecological data presented in this study, it is possible to conclude that this research represents a significant milestone in understanding the biodiversity of Brazilian estuarine areas. [ABSTRACT FROM AUTHOR]

Tehran province as a diverse habitat for different animal species, has the potential to support many land molluscs species. However, a little glimpse of the research on malacology shows that Tehran province is probably the least well-studied area for land snails in Iran. Herein, the very first comprehensive study about the land snails collected from Tehran province in addition to the previous scientific document is presented. The data included here are based on the field investigations and the published records by different authors from 2008 to 2023 This checklist is collectively composed of 22 species belonging to 16 genera under nine families from different parts of Tehran province. However, some areas of Tehran province have not been investigated in terms of the diversity of snail species. The outcome of this report shows that more research is needed on the species diversity of terrestrial snails in Tehran province. [ABSTRACT FROM AUTHOR]

Meretrix meretrix is one of the economical shellfish that has been exploited in Kendari Bay, Indonesia. Several studies have been done, but its growth pattern and condition index are not fully known. This study aims to determine its growth pattern and condition index at the Kambu River estuary, Kendari Bay. This research was conducted for 6 months from August 2021 to January 2022. Clams were collected using a rake, cleaned, and brought to the laboratory to be measured for length and weight using calipers and scales with an accuracy of 0.1 mm and 0.01g, respectively. Furthermore, the clam meat was dried using an oven and weighed. Data on growth and condition index were analyzed using simple regression and the Mann-Whitney test, respectively. The results showed that the growth of M. meretrix was in negative allometric conditions, with b values in males and females in the range of 2.20-3.00 and 1.86-2.73, respectively. The condition index of male and female clam ranged from 1.86-2.62 and 1.66-2.41, respectively, and differed significantly by month. The results of the Mann-Whitney test on clam showed that there was no significant difference between August-November and December-January. In conclusion, male and female clam had relatively different patterns based on the observation period, while the condition index was in the skinny and medium category. [ABSTRACT FROM AUTHOR]

The platycerate gastropods Orthonychia yutaroi Ebbestad, sp. nov. (Ordovician, Boda Limestone, Sweden), O. enorme (Silurian, Sweden, Gotland), O. parva (Pennsylvanian, Finis Shale Member, USA), and Orthonychia sp. (Mississippian, Imo Formation, USA) are studied including their protoconch morphology. Orthonychia yutaroi is the oldest known species in Orthonychia. Platycerates contain species with both, openly and tightly coiled protoconchs. This is the first report that tightly coiled protoconchs occur in Orthonychia. This and previously published observations blur the diagnostic difference between orders Cyrtoneritimorpha (openly coiled protoconch) and Cycloneritimorpha (tightly coiled protoconch). We suggest to treat Cyrtoneritimorpha and Cycloneritimorpha as synonyms of Neritimorpha. The monotypic Devonian genus Pragoserpulina is morphological so close to the Orthonychia species reported herein that synonymy of both genera seems to be possible (and thus of the families Pragoserpulinidae and Orthonychiidae). Protoconch morphology and dimensions suggest that the studied platycerate species had planktotrophic larval development. By contrast, two studied Carboniferous euomphaloid species (one with an openly and the other with tightly coiled protoconch) have paucispiral, large protoconchs indicating non-planktotrophic larval development. We assume that openly and tightly coiled protoconchs were present in various Paleozoic gastropod clades and that selection acted against the openly coiled protoconch morphology. It has previously been proposed that increasing predation pressure in the plankton was the reason for the demise of openly coiled protoconchs (Paleozoic plankton revolution). The presence of larval planktotrophy in platycerates excludes the possibility that they belong to extant basal gastropod clades such as Patellogastropoda, Cocculiniformia, and Vetigastropoda. However, a previously proposed close relationship to Neritimorpha is corroborated. [ABSTRACT FROM AUTHOR]

This study was designed to investigate about species diversity of soil mollusks in Shemiranat county. The country was divided into 10 sampling stations and the collected samples were identified morphologically and systematically according to the certified identification keys. Results showed the significant effect of temperature and relative humidity on the abundance of the soil mollusks. There were no samples collected in cold months, but in warm seasons, August had the most numerous samples, and March showed the lowest abundance. In this study, a total of 94 samples belonging to 10 species under 9 genera and 8 families were identified as follows: Helix lucorum (Helicidae), Cernuella neglecta, Monacha cantiana and M. parumcincta (Hygromidae), Succinea putris (Succineidae), Chondrula tridens (Enidae), Planorbis intermixtus (Planorbidae), Deroceras tritulatum (Agriolimacidae), Ambigolimax valentianus (Limacidae) and Arion fuscus (Arionidae). P. intermixtus was the most abundant species among the collected samples and S. putris had the lowest density. [ABSTRACT FROM AUTHOR]

Newly collected Early Badenian (Middle Miocene) Conorbidae and Conidae assemblages are presented from three localities in the Hungarian part of the Pannonian Basin. Ten species - among others Pseudonoduloconus wagneri (Boettger) - are recorded for the first time in the region, others show extended geographical distribution. A new species, Monteiroconus strauszi n. sp. is designated. With 67 figures and 1 table. [ABSTRACT FROM AUTHOR]

The cosmopolitan terrestrial slug, Deroceras laeve (O. F. Müller, 1774), is reported in the Philippines for the first time and characterized through morphology, morphometrics, and cytochrome oxidase subunit I (COI) gene analysis. Slug samples were recovered from two administrative regions in Mindanao, Philippines. In Region X, there were two sites: Misamis Oriental (Gingoog, 664 m a.s.l.; Claveria, 937 m a.s.l.) with farms planted with cabbage (Brassica oleracea), radish (Raphanus sativus), and eggplant (Solanum melongena); and Bukidnon (Talakag, 1410 m a.s.l.) planted with cabbage. In Region XI, specimens were collected from potted ornamentals in five nurseries along the Kapatagan road, Davao del Sur, 1000-1200 m a.s.l. The external morphology of the specimens matched the published descriptions, and their identity was further confirmed by their partial COI sequences. The obtained COI sequence of the specimen in Region X showed 99-100% similarity with the voucher specimens from Mexico (, , , , and ); while that of the specimen from Region XI is 100% identical to specimens collected from Japan (), Canada ( and ), UK (), and Vietnam ( and ). Moreover, D. laeve from Region X and Region XI shared 98% similarity with each other. Preliminary surveys show that slug occurrence is prevalent mainly in highland regions of the southern Philippines where specialty crops/high value crops like vegetables and ornamentals are cultivated. Further surveys are essential to confirm any damage that they may cause, their distribution, associated parasites, and pest status in the Philippines. [ABSTRACT FROM AUTHOR]

This work aims to study the biodiversity of the mollusks that colonize the mediolittoral stage at the level of the Algerian East coasts (south-west of the Mediterranean) during summer 2021. The qualitative study reveals the existence of nine species: Patella nigra, Patella vulgata, Patella rustica, Patella ulyssiponensis, Patella caerulea, Phorcus lineatus, Mytilus galloprovincialis, Stramonita haemastoma, Acanthopleura granulata. The station 2 (la montagne) has the highest value with a maximum density of 54 ± 9.53 ind/m² while the lowest density has been found in the station 4 (Boufkirine) 9.33 ± 0.57 ind/m². The most important values of index of the diversity and evenness index (E) were recorded in station 2 (H'=2.16; E=0.77) respectively. The leading mollusk in the studied area is the patelidae Patella rustica (74.83%) followed by the gastropod Stramonita haemastoma (26.57%) and the bivalve Mytilus galloprovincialis (23.78%). [ABSTRACT FROM AUTHOR]

Eight marine gastropod records were recorded from the north west of the Arabian Gulf, Iraqi coast during March 2020. The species are Turritella cochlea Reeve, 1849 (family Turritellidae), Rhinoclavis fasciata (Bruguière, 1792) (family Cerithiidae), Semiricinula tissoti (Petit de la Saussaye, 1852) (family Muricidae), Ancilla castanea (G. B. Sowerby I, 1830) (family Ancillariidae), Bulla ampulla Linnaeus, 1758 (family Bullidae), Oliva bulbosa (Röding, 1798) (family Olividae), Naria turdus (Lamarck, 1810) and Erronea caurica quinquefasciata (Röding, 1798) (family Cypraeidae). These records raise the number of marine gastropods from the Iraqi coast to 40 species. [ABSTRACT FROM AUTHOR]

Background: Despite their large size, striking colouration and genital extravagance, the taxonomy of the European giant keelback slugs of the genus Limax is still poorly understood. Preliminary morphological and molecular data suggest that many unnamed or unrecognised species exist, especially in the Alps, the Mediterranean and the Balkans. We organised a citizen science expedition to Durmitor National Park in Montenegro and discovered a new species, genetically distinct, but morphologically similar to the sympatric L. cinereoniger Wolf 1803 and describe it as L. pseudocinereoniger. [ABSTRACT FROM AUTHOR]

Background In Morocco, many uncertainties surround the current diversity and distribution of the bivalve family Sphaeriidae. Such information, including taxonomy and conservation status, are vital for further studies to improve the knowledge of this family in Morocco and represents the first step towards the development of a national conservation plan for all freshwater bivalves. Between 2016 and 2019, several investigations were carried out to assess the diversity and distribution of Sphaeriidae in the different basins of Morocco, covering different types of habitat (lakes, springs, rivers and small ponds). The identification of specimens and their morpho-ecological features was based on morphological and morphometric analyses. The data on the general distribution of the collected species allowed the evaluation of their conservation status as well. The shell morphology and morphometric analyses revealed the existence of five species belonging to the genus Pisidium [P. casertanum (Poli, 1791), P. (cf.) personatum Malm, 1855, P. subtruncatum Malm, 1855, P. amnicum (O. F. Müller, 1774) and Pisidium sp.] and one species to the genus of Musculium [M. lacustre (O. F. Müller, 1774)]. Sphaeriidae were found in all Moroccan basins, except Bouregreg and Sakia El Hamra-Oued Eddahab Basins. The results showed that Sebou Basin was the species richest with the occurrence of the five species, while Loukkos and Sous-Massa Basins had the lowest-species richness with one species only. The conservation status of sphaeriids in Morocco was evaluated for the first time and resulted in P. (cf.) personatum and P. subtruncatum being proposed as Least Concern and Vulnerable, respectively, while the status of Regionally Extinct is suggested for both species P. amnicum and M. lacustre. New information First evaluation of the diversity and species richness of the family Sphaeriidae in Morocco with an assignment of an updated conservation status of the recorded species. [ABSTRACT FROM AUTHOR]

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. The 3D model dataset can be also further processed through volume rendering and morphometric analysis. The success of micro-CT as a visualisation technique depends on several methodological manipulations, including the use of contrast enhancing staining agents, filters, scanning mediums, containers, exposure time and frame averaging. The aim of this study was to standardise a series of micro-CT scanning and 3D analysis protocols for a marine gastropod species, Hexaplex trunculus. The analytical protocols have followed all the developmental stages of this gastropod, from egg capsules and embryos to juveniles and adults. [ABSTRACT FROM AUTHOR]

The Mekong and Chao Phraya rivers harbor a species-rich freshwater mussel assemblage containing a large radiation of the Pseudodontini species. Members of the genera Bineurus Simpson 1900 and Thaiconcha Bolotov et al., 2020 primarily inhabit small and medium-sized tributaries of these rivers. Here, we present an integrative taxonomic review of these genus-level clades. We show that Bineurus contains four species: B. mouhotii (Lea, 1863), B. exilis (Morelet, 1866) stat. rev., B. anodontinum (Rochebrune, 1882) stat. rev., and B. loeiensis sp. nov. In its turn, Thaiconcha comprises three species: T. callifera (Martens, 1860), T. munelliptica sp. nov., and T. thaiensis sp. nov. Two species, Pseudodon ovalis Morlet, 1889 and P. thomsoni Morlet, 1884, are considered here as questionable taxa. These findings further highlight that Southeast Asia represents a significant evolutionary hotspot of freshwater mussels, which requires further international collaborative research and conservation efforts. [ABSTRACT FROM AUTHOR]

For more than 10 years (2007-2018), the benthic macroinvertebrates of Bahía de Chamela (Mexican Pacific) were sampled at 31 sites (0-25 m depth). A total of 308 species of the five main classes of benthic molluscs were obtained (106 bivalves, 185 gastropods, 13 polyplacophorans, two scaphopods and two cephalopods). This is a significant increase in the number of species (246 new records) compared to the 62 species previously recorded more than 10 years ago. The distribution in the 31 localities of the bay is given for the first time for most of the species, together with information on its ecological rarity (incidence in the samples). Two families of bivalves (Veneridae and Mytilidae) and three families of gastropods (Calyptraeidae, Muricidae and Collumbellidae) comprised ~ 30% of all species. Ecological rarity was evident with 45 families (45.0%) with only one species and 178 species (57.8%) collected in one site and 67 (21.8%) in two sites. The molluscs of Bahía de Chamela represent 12.2% of all species recorded in the Mexican Pacific. Their biogeographic affinities are mostly related to the Tropical Eastern Pacific (TEP) including the oceanic islands and a few are restricted to the Tropical Mexican Pacific (TMP). Some have broader distributions to adjacent northern and southern temperate regions of the American Pacific, one to the western Atlantic, two pantropical (PAN) and two cosmopolitans (COS). The range distribution of each species was reviewed and updated, thus finding that seven species have extended their ranges of geographic distribution. [ABSTRACT FROM AUTHOR]

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Type specimens and (or) photographs of the 21 named taxa used for California Holocene olivellids were examined to recognize four modern species now assigned to the genus Callianax and one species presumed extinct. The California Holocene species include C. alectona, C. biplicata, C. diegensis, and C. strigata, while the extinct species is Olivella pedroana. Other olivellid names previously used in California are also discussed and these include O. baetica, O. biplicata alba, O. biplicata angelana, O. biplicata brunnea, O. biplicata fucana, O. biplicata lapillus, O. biplicata parva, O. boetica, O. b. diegensis, O. b. mexicana, O. dama, O. glandinaria, O. intorta, O. minuta, O. nota, O. porteri, and O. pycna. Olivella dama and O. intorta are valid species that occur further south in Mexico and are not present in California today despite reports. Olivella nota is also a valid name but for a west Pacific species. [ABSTRACT FROM AUTHOR]

Following the disappearance of the seven Buckingham Member (Unit 10) Cypraeidae from the Myakka Lagoon System (Myakka), there was a hiatus represented by two strata at Sarasota (Pinecrest Members 9 & 8) in the early Piacenzian Pliocene, 3.6 million years ago (“mya"), from which no Cypraeidae have been recorded. This was followed by the warmest and most tropical conditions of the entire Pliocene. The sea grass beds and mud flats, which were the preferred habitats of the Pinecrest Cypraeidae, returned in force. The depositional strata which resulted, Pinecrest (Unit 7) and its Kissimmee River Valley Equivalent, were very thick and probably represent a long period of uninterrupted deposition. Eight new species in six genera emerged in Myakka. In the Kissimmee River Valley (Kissimmee), six new species in three genera (one new) emerged as the first and earliest known Cypraeidae species from that area. This represented geographically separate, but parallel, evolutionary tracks. Pinecrest Members 6 & 5 represented a repeat of the conditions experienced during Pinecrest Members 9 & 8, resulting in the disappearance of all Pinecrest (Unit 7) Cypraeidae from Myakka and Kissimmee. [ABSTRACT FROM AUTHOR]

This study reports fifteen species of nudibranchs from the coast of Pakistan (Northern Arabian Sea) except Jorunna funebris reported here, all are new records. [ABSTRACT FROM AUTHOR]

Two new species of genus Amphidromus Albers, 1850 are described from Vietnam and compared to five other species of this genus: Amphidromus koenigi Thach & Huber, 2018, Amphidromus laii Thach, 2019, Amphidromus inconstans Fulton, 1898, Amphidromus kaloensis Fulton, 1896 and Amphidromus bernardfamyi Thach, 2017. [ABSTRACT FROM AUTHOR]

Abstract Native to the Indo-Pacific, the Manila clam has been introduced to North America and Europe, becoming the most economically-important cultured bivalve species worldwide. Research on this species is inconvenienced by the co-existence of several scientific synonyms; non-taxonomists do not necessarily understand why this is so, what names are valid, and how they should justify using a particular name. In order to clarify all of these points, the historic and current taxonomic situation is summarized and explained, and a practical recommendation is proposed. Beyond the sole case of the Manila clam, the problems and issues raised here are experienced by researchers working on many taxa; the present work seeks to clarify the general taxonomic landscape for non-taxonomists. Highlights • Manila clam, the most important cultured bivalve species worldwide, is known under many taxonomic synonyms. • This taxonomic and nomenclatural uncertainty is confusing and vexatious to non-taxonomist researchers and journal editors. • We explain why this situation exists, and make a recommendation to reduce this instability in the non-taxonomic literature. [ABSTRACT FROM AUTHOR]

Abstract The wedge clam (Donax trunculus) is widely distributed along exposed Atlantic coasts, from France to Senegal. This species has high commercial importance, with the mean capture production on the last ten years of approx. 850 tonnes (50% represented by Portugal captures). D. trunculus populations are modulated by several drivers such as tidal range, temperature, sediment grain size, fishing pressure, predation and parasitism. Regarding parasitism, D. trunculus is the first intermediate host of Bacciger bacciger (trematode parasite) where the sporocysts develop. The sporocyst is the most damaging stage, reported as being responsible for bivalve castration and flesh mass depletion. In order to test the hypothesis that B. bacciger infection modified wedge clam health status, including its biochemical performance and gene expression, clams were sampled every other month during one year in the Faro beach (south coast of Portugal). The results obtained revealed that B. bacciger total prevalence ranged between 0 and 33% in May and July, respectively. Overall, transcriptomic and biochemical results showed that B. bacciger induced in D. trunculus defense mechanisms against oxidative stress and increased the host metabolism and energy demand, especially in spawning and spent periods. The present work concluded that the markers used can provide additional and ecologically relevant information not only about the environmental conditions that animals experience but also the invasion effects of pathogens. These findings can contribute to predicting organism chance of reproduction and survival in their natural context, which can be applied in bivalve conservation and disease episodes management. Graphical abstract Image 1 Highlights • First record of Bacciger bacciger infecting Donax trunculus in Portugal. • Bacciger bacciger prevalence followed a seasonal pattern. • Bacciger bacciger activated clams defense mechanism against oxidative stress. • Bacciger bacciger increased clams metabolism and energy demand. • Trematode parasites can interfere with host population performance. [ABSTRACT FROM AUTHOR]

A revision of the Bajocian Lissoceratinae is presented. The study of more than 500 lissoceratins from different sites of the Western Tethys (Northwest European, Sub-Mediterranean and Mediterranean bioprovinces) within the Tethys-Panthalassa Realm provided data useful to implement the systematics of these almost neglected, never deeply analysed ammonites. Two genera, Lissoceras Bayle and Semilissoceras n. gen., are described with 16 species, among which eight new species (four dimorphic, three macroconchiate and one microconchiate): L. submediterraneum, L. maizetense, L. ovale, L. sturanii, L. maerteni, S. ellipticum, S. turgidulum and S. costellatum. The neotype of L. oolithicum is established. The microconchiate genus Microlissoceras is regarded as the junior synonym of the macroconchiate Lissoceras. Taxa are discussed according to four groups that gather taxa sharing common morpho-structural features. They roughly relate to successive biochronostratigraphical intervals within the Bajocian Stage and are headed by species largely known in literature: S. semicostulatum (Buckman) with suboval to compressed whorl section and rectiradiate ribs on the outer half flank; L. oolithicum (d'Orbigny) with subtriangular to ovate whorl section, large and depressed ventral saddle, large suspensive lobe; L. haugi Sturani with ovate to globular whorl section, narrow lobe E and suspensive lobe; and L. psilodiscus (Schloenbach) with highly compressed whorl section, high ventral saddle and narrow lobe E. The phyletic relation of Lissoceras and Semilissoceras to the Aalenian-Bajocian Bradfordia-group is discussed, regarding Semilissoceras as the known stem-taxon of the subfamily Lissoceratinae. [ABSTRACT FROM AUTHOR]

Evolutionary and ecological hypotheses of the freshwater mussel subfamily Ambleminae are intensely geographically biased—a consequence of the complete exclusion of Mesoamerican taxa in phylogenetic reconstructions of the clade. We set out to integrate a portion of the Mesoamerican freshwater mussel assemblage into existing hypotheses of amblemine classification and evolution by generating a molecular phylogeny that includes four previously unsampled Mesoamerican genera and nine species endemic to that region. Given the traditionally hypothesized affinity to Nearctic mussels and the understanding that classification should reflect common ancestry, we predicted that (a) Mesoamerican genera would be recovered as members of the recognized tribes of the Ambleminae, and (b) genera would be supported as monophyletic. The mutilocus phylogeny (COI + 28S + 16S) reported herein does not fully support either of those hypotheses. Neither Cyrtonaias nor Psorula were supported as monophyletic and we predict several other Mesoamerica genera are also non‐monophyletic. The reconstructed phylogeny recovered four independent lineages of Mesoamerican freshwater mussels and these clades are distributed across the phylogeny of the Ambleminae, including the tribe Quadrulini (Megalonaias), Lampsilini (two lineages: Cyrtonaias explicata/Sphenonaias microdon, and Pachynaias), and a previously unrecognized, exclusively Mesoamerican and Rio Grande clade consisting of the genera Psoronaias, Psorula and Popenaias. The latter clade possesses several morphological characteristics that distinguish it from its sister taxon, tribe Lampsilini, and we recognize this newly identified Mesoamerican clade as a fifth tribe of the Ambleminae attributable to the Popenaiadini Heard & Guckert, 1970. This revised classification more completely recognizes the suprageneric diversity of the Ambleminae. [ABSTRACT FROM AUTHOR]

Deep-sea clams (Bivalvia: Vesicomyidae) have been found in reduced environments over the world oceans, but taxonomy of this group remains confusing at species and supraspecific levels due to their high-morphological similarity and plasticity. In the present study, we collected mitochondrial COI sequences to evaluate the utility of DNA barcoding on identifying vesicomyid species. COI dataset identified 56 well-supported putative species/operational taxonomic units (OTUs), approximately covering half of the extant vesicomyid species. One species (OTU2) was first detected, and may represent a new species. Average distances between species ranged from 1.65 to 29.64%, generally higher than average intraspecific distances (0-1.41%) when excluding Pliocardia sp.10 cf. venusta (average intraspecific distance 1.91%). Local barcoding gap existed in 33 of the 35 species when comparing distances of maximum interspecific and minimum interspecific distances with two exceptions (Abyssogena southwardae and Calyptogena rectimargo-starobogatovi). The barcode index number (BIN) system determined 41 of the 56 species/OTUs, each with a unique BIN, indicating their validity. Three species were found to have two BINs, together with their high level of intraspecific variation, implying cryptic diversity within them. Although fewer 16 S sequences were collected, similar results were obtained. Nineteen putative species were determined and no overlap observed between intra- and inter-specific variation. Implications of DNA barcoding for the Vesicomyidae taxonomy were then discussed. Findings of this study will provide important evidence for taxonomic revision in this problematic clam group, and accelerate the discovery of new vesicomyid species in the future. [ABSTRACT FROM AUTHOR]

The Spanish slug, a species that is considered to be the most destructive pest among molluscs of Europe, is reported to spread widely across Ukraine during last 5–7 years. In addition to its 5 known colonies in Western Ukraine, over 60 new localities from Western, Central, Northern, Southern and Eastern Ukraine are reported for the first time using own materials and reports with photo from the general public. Newly reported localities include such major cities as Kyiv, Kharkiv, Donetsk, Khmelnitsky, Vinnytsia, Ternopil, Zhytomyr, Lutsk, Chernivtsi and Ivano-Frankivsk, and also the settlements in Odesa and Mykolaiv Regions. Species is also reported for the first time from Grodno City in Belarus and from Moscow City in Russia. Much wider future expansion of the Spanish slug in Eastern Europe is expected in near time. [ABSTRACT FROM AUTHOR]

Lavajatus moroi is a new genus and species found in cave environment from Santa Quiteria region, Ceara, Brazil. It is mainly characterized by the very elongated shell measuring about 30 mm, the growth is uniform, adult shell of ~28 whorls, and the shell profile is rather straight. The species has an extraordinary capacity of retraction inside the shell, keeping empty from 'A to'/j of the shell length when retracted. Anatomically, lung lacking developed vessels; ureter entirely tubular; kidney wide, with narrow anterior projection; genital structures mostly located inside anterior half of the haemocoel; lack of jaw, esophagus very narrow; large pair of retractor muscles of buccal mass (m2), with a branch passing through the nerve ring; odontophore lacking horizontal muscle (m6), with cartilages ~3/5 fused with each other; spermoviduct having two regions, being the anterior one normally bearing young specimens; and nerve ring having a large visceral/ subesophageal ganglion. The dissection of the intrauterine young specimens, which normally have a swollen head and a posterior pedal flap, revels some interesting ontogenetic features, such as the extreme elongation of some structures, e. g., the lung and digestive tubes, the repositioning of some haemocoel structures, and the modification of the nerve ring (appearance of the pleural ganglia, fusion and migration towards anterior of the subesophageal ganglia) during the development. Comparison with known subulinines is performed, including accounts on the youth intrauterine development. The new species is almost troglobian, except for the presence of eyes. [ABSTRACT FROM AUTHOR]

A new subspecies of genus Leptopoma Pfeiffer, 1847 is described from Selawati Island, West New Guinea, Indonesia and compared to six other species and forms of this genus: Leptopoma melanostoma (Petit, 1841), Leptopoma niasense Fulton, 1907, Leptopoma perlucidum f. subalatum Quadras & Möllendorff, 1893, Leptopoma helicoides (Grateloup 1840), Leptopoma vitreum (Lesson, 1830) and Leptopoma stainforthi (Sowerby, 1842). It is characterized by a translucent shell, dark brown umbilicus, black outer lip and columella, narrow but raised peripheral rib, and wide dark brown umbilicus. [ABSTRACT FROM AUTHOR]

The Volutid genus Arctomelon Dall, 1915 in Alaskan waters is examined, four species are recognized. A new species, Arctomelon borealis sp. nov. is described from bathyal depths of the central Aleutian Islands. A. stearnsii ryosukei (Habe & Ito, 1965) is recognized as a distinct species. [ABSTRACT FROM AUTHOR]

This paper seeks to correct the erroneous taxonomy associated with the current understanding of the Altivasum flindersi (Verco, 1914) complex based on type revision, morphological differences and geographic separation. Structurally, there are three distinct species that can be differentiated, Altivasum flindersi (Verco, 1914), A. typicum Hedley, 1916 and A. profundum sp. nov. Geographically, these species are not all sympatric, with A. typicum restricted to shallower waters, at depths around 20-180 m off the south Western Australian coast, whereas A. profundum is located at the edge of the South Western Australian continental shelf, and A. flindersi is found off the coast of the Great Australian Bight at similar depths to A. typicum. There is an overlap in distribution between A. typicum Hedley, 1916 and A. flindersi (Verco, 1914) on the western side of the Great Australian Bight where they are often associated with similar habitats. [ABSTRACT FROM AUTHOR]

Two new fossil Helmet Shells of the genus Cassis Scopoli, 1777, are described from the Early Pleistocene (Gelasian Age) Caloosahatchee Formation of southern Florida. The two new species include Cassis calusa n. sp. (restricted to the Fort Denaud Member, early Gelasian Age) and Cassis powelli n. sp. (restricted to the Ayers Landing Member, late Gelasian Age) and these are ancestral to both the Calabrian Pleistocene Cassis schnireli Petuch, 1994 (Holey Land Member, Bermont Formation) and the living Carolinian Province Cassis spinella Clench, 1944. The two new Helmet Shells represent the seventh and eighth species of Cassis known from the Florida fossil record. [ABSTRACT FROM AUTHOR]

Pyrulofusus harpa (Mörch, 1857) and Volutopsius castaneus (Mörch, 1857) were described from Sitka, Alaska, however no specimens of either species have been found at Sitka, nor indeed anywhere in the eastern Gulf of Alaska. It seems more likely that the types of both species came from Kodiak, where both species are frequently found. The type localities for both species are herein corrected. [ABSTRACT FROM AUTHOR]

Cephalopods are an important, abundant and taxonomically diverse component of the bathypelagic realm. However, their biology, ecology and distribution are poorly known. Specimens of Mastigoteuthis agassizii (Mastigoteuthidae) have been captured in the southern part of the Denmark Strait, which is at approximately 65°N. This site is approximately 550 km north of the previously most northern known border of the Mastigoteuthidae range. The main goal of this paper is to provide an extended morphological description and biological analysis of M. agassizii, the first species of the Mastigoteuthidae caught in the Subarctic Atlantic. Despite sample collection at 534 deep-water stations in the area, only two specimens were captured, indicating the rarity of this species in the northern part of its range. We suggest that the typical range of this species is bathyal depths throughout the North Atlantic to the Subarctic, but not through the Denmark and Davis Straits to the Arctic. These findings coincide with the geographic border of the Northern Atlantic boreal bathyal province, which is warmer and more saline compared to the Arctic province further to the north. We also provide the first descriptions of the radula and reproductive system of M. agassizii. The female had synchronous ovulation, fecundity of approximately 23,000 oocytes, oocyte resorption having not been found, most likely due to the early maturity stage of the female. The males, as proven by our sample and additional photo in other source, were found to have the distal part of the penis enlarged, divided into two valves and pigmented, possibly indicating they can protrude outside the mantle cavity. This enlarged valved part, as it is supposed in the literature for other deep-water squid families having it, may be used as an analogue to the lacking hectocotylus. [ABSTRACT FROM AUTHOR]

The shells of some freshwater and brackish-water gastropods, including species of Pleuroceridae, Vivipalidae, and Neritidae, show considerable deterioration while their inhabitants are still alive and reproductively active, giving them the appearance of dead or empty shells. Although the worn-out appearance of these shells may be an inevitable outcome of their tendency to dissolve in calcium-poor water, it is possible that the gastropods adjust their investment in shell calcification to allow for moderate shell corrosion. The habitats where gastropods live retain many old, empty shells, and, by mimicking these disused shelters in appearance and texture, gastropods with corroded shells may avoid detection by predators using visual and tactile cues to locate prey. A similar behaviour, whereby animals use niche construction by conspecific antecedents to masquerade as old deserted dwellings, may also be found in other animal groups, such as leaf-rolling caterpillars, leaf beetles and land snails on limestone habitats. [ABSTRACT FROM AUTHOR]

The colonization of foreign species into the Mediterranean Sea has increased in number and geographic coverage over the past decades. For instance, the marine mollusc Haminoea cyanomarginata has scattered across the Central and Eastern Mediterranean since its description in the Red Sea by Heller and Thompson in 1983. In this study, we add the first records of the species in the Western Mediterranean basin and review the progression of its colonization from the Red Sea. The new records were obtained through the online database of the NGO called Catalan Opisthobranch Research Group (Spain), thus highlighting how citizen science platforms can provide an early warning for marine scientists and managers in relation to exogenous species. [ABSTRACT FROM AUTHOR]

Alongside confirmation of the monophyly of the gastropod family Mitridae, a recent molecular phylogenetic analysis disclosed multiple inconsistencies with the existing taxonomic framework. In the present study, we expanded the molecular sampling to 103 species, representing 26% of the 402 extant species currently accepted in the family and 16 of the 19 currently accepted extant genera; 83 species were sequenced for four molecular markers [cytochrome c oxidase subunit I (COI), 16S and 12S rRNA, and H3 (Histone 3)]. Molecular analyses were supplemented by morphological studies, focused on characters of the radula and, in a more restricted data set, proboscis anatomy. These data form the basis for a revised classification of the Mitridae. A first dichotomy divides mitrids into two unequal clades, Charitodoron and the Mitridae s.s. Species of Charitodoron show profound differences to all other Mitridae in foregut anatomy (lacking an epiproboscis) and shell morphology (smooth columella, bulbous protoconch of non-planktotrophic type), which leads to the erection of the separate family Charitodoronidae fam. nov. Three traditional subfamilies (Mitrinae, Cylindromitrinae and Imbricariinae) correspond to three of the inferred phylogenetic lineages of Mitridae s.s.; we redefine their contents, reinstate Strigatellinae Troschel, 1869 as valid and establish the new subfamily Isarinae. In the absence of molecular material, a sixth subfamily, Pleioptygmatinae, is included in Mitridae based on morphological considerations only. To resolve the polyphyly of Mitra and Cancilla in their current taxonomic extension, we reinstate the genera Episcomitra Monterosato, 1917, Isara H. & A. Adams, 1853 and Probata Sarasúa, 1989 and establish 11 new genera: Quasimitra, Roseomitra, Fusidomiporta, Profundimitra, Cancillopsis, Pseudonebularia, Gemmulimitra and Neotiara in Mitrinae; Imbricariopsis in Imbricariinae; Carinomitra and Condylomitra are left unassigned to a subfamily. Altogether 32 genera are recognized within the family. Their diversity and distribution are discussed, along with general trends in morphological evolution of the family. [ABSTRACT FROM AUTHOR]

The study of morphology is a common means of biological grouping and classification. In recent years, morphometric studies have been dominated by quantitative geometric-morphometric methods of data extraction such as outline or landmark-based analysis. These methods are often used in conjunction with various classification methods such as linear discriminant analysis (LDA) and random forests (RF) in order to achieve inter- and intraspecific grouping based on environmental factors. Despite numerous studies incorporating these data-extraction and classification methods, comparisons of the effectiveness of these methods are largely lacking, especially for species which display low morphological variation. The aim of this study was to compare the effectiveness of two data-extraction methods, elliptic Fourier analysis (EFA) and generalized Procrustes analysis, and two classification methods, LDA and RF, using Littorina littorea as the study organism. The results show that the principal component scores derived from EFA, provided the optimal data input for classification while the greatest percentage of successfully classified individuals was achieved using LDA. However, based on this study RF is the recommended classification method as it is resistant to overfitting, makes no assumptions about the data, is well suited to morphometric data and produces similar rates of classification to LDA. The results are discussed in a biological context for L. littorea, based on the environmental factors of zonation and shore exposure. [ABSTRACT FROM AUTHOR]

Chaetoderma nitidulum Lovén, 1844 is a common species of caudofoveate (chaetodermomorph) with a wide distribution range in the northeastern Atlantic Ocean. It was the first species of aplacophoran mollusc to be described, but its species identity has been debated. Here, we investigate the molecular and morphological diversity of specimens from a large geographical area and size range, which had been preliminarily identified, based on morphology, as C. nitidulum. Analyses of molecular data revealed two distinct genetic sister lineages in the Eastern Atlantic and one clade sister to these in the Western Atlantic. Morphological analyses showed significant variation that does not reflect the genetic linages. In addition, molecular phylogenetics combined with comparative morphological analyses showed that radula characters used to distinguish the genera Chaetoderma and Falcidens within Chaetodermatidae do not represent apomorphies, but are a result of ontogenetic changes in C. nitidulum. The emerging phylogenetic patterns were surprising, bringing us one step closer to understanding chaetodermatid ontogeny and evolution, but they also emphasize that the systematic relationships of chaetodermatid caudofoveates are still far from understood. [ABSTRACT FROM AUTHOR]

Confirming the extinction of species with only old occurrence records is often difficult, due to the scarcity of biological information. Phylogenetic position and taxonomic status of the potentially extinct species are unclear in most such cases. In the present study, we document that a species of the endemic genus Hirasea of the oceanic Ogasawara Islands, which was formerly believed to have become extinct, still survives, on the basis of combined surveys involving molecular phylogenetics and morphometrics. Hirasea is notorious for its highly diversified shell morphologies and a number of species and subspecies have already become extinct because of environmental changes and impacts of alien predators. In this study, we first reconstruct phylogenetic relationships among extant Hirasea populations. Next, on the basis of quantitative shell morphological analysis of extant populations and type specimens, we identify morphological traits that reflect phylogenetic relationships among the species. By using these morphological traits and molecular phylogenies, we demonstrate that H. nesiotica liobasis, previously considered extinct, is still extant on Chichijima. Although classifications by means of morphology and molecular phylogeny often show incongruences, judgement of the conspecific status of living and extinct populations is still possible by considering ranges of variation and phylogenetic constraints on morphological traits. [ABSTRACT FROM AUTHOR]

Aglajidae is a family of predominantly colourful shallow water marine slugs widely distributed in coral, rocky and sandy habitats of tropical and temperate waters worldwide. The monophyly of the group is supported by morphological traits, but recent molecular phylogenetic studies questioned not only the monophyletic status of the family but also the definition of its traditional genera and relationships. Therefore, in order to test the monophyly of the family and of its genera and to elucidate internal sister relationships, we here present a new multilocus phylogenetic study based on Bayesian inference and maximum likelihood analyses of the largest ever assembled taxon and gene data sets of Aglajidae including 412 specimens from 63 species (74% of the global diversity) with representatives of type species of all genera and 835 DNA sequences of the gene markers COI, 16S rRNA, 28S rRNA and Histone-3. The genera Aglaja, Chelidonura, Odontoglaja and Philinopsis were confirmed as not monophyletic. Fifteen evolutionary lineages of generic status were recovered and seven are here described as new, namely Biuve, Camachoaglaja, Mannesia, Mariaglaja, Niparaya, Spinophallus and Tubulophilinopsis. The valid taxonomic status of Spinoaglaja is confirmed and Migaya is considered to be a junior synonym of Nakamigawaia. Our results support the hypothesis that events of radula loss or gain have happened independently at least twice in the evolutionary history of Aglajidae, but lack of node support in the deeper parts of our tree obscured inference on the sister relationships of genera. A new classification for Aglajidae is proposed and diagnostic features for all 15 genera are given. [ABSTRACT FROM AUTHOR]

Several molecular studies have been conducted on northeastern Atlantic and Mediterranean patellid limpets, but Algerian specimens have never been included in these studies. This work intends to fill this gap and characterize populations of different Patella species inhabiting the Algerian coasts of Oran, clarifying the presence of Patella ferruginea that is considered as endangered. Moreover, comparison of their intraspecific variation with that of other areas might enlighten about populations connectivity and the conservation status of the analysed species. The molecular analyses performed on the samples from Oran's coasts, confirmed the presence of Patella ferruginea, P. rustica and P. caerulea, all of which shared haplotypes with other Mediterranean localities previously analysed. The intraspecific differentiation was limited, with the exception of P. rustica, which showed the greatest diversity, while P. ferruginea, the most endangered species, showed the lowest. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are well-known emerging contaminants in the marine environment. A key route by which MPs can directly affect marine life is through ingestion. The objective of the present study was to evaluate the occurrence of MPs in marine life and seafood for human consumption in the Persian Gulf. We conducted a whole body analysis of MP (between 10 and 5000 μm in diameter) abundance in five species of molluscs with different feeding strategies, including both gastropods and bivalves from the littoral zone of the Iranian coast of the Persian Gulf. The mean number of total encountered MPs in all species ranged from 0.2 to 21.0 particles per g of soft tissue (wet weight) and from 3.7 to 17.7 particles per individual. Overall, microfibres followed by fragments were the most common type of MP isolated in each species (respectively > 50% and ≈26%). Film (≈14%) and pellets (≈2%) were less commonly observed. The observed MPs were classified into three size groups (ca. 10–25 μm, 25–250 μm and 250–5000 μm), and 37–58% of MPs fell into the smallest size group. Fourier transform infrared (FT-IR) analysis confirmed the presence of polyethylene (PE), polyethylene terephthalate (PET), and nylon (PA). Our results indicated that molluscan shellfish from the Persian Gulf contain MPs, with higher concentrations in a predatory species, suggesting trophic transfer of MPs in the food web. The consumption of edible species may be a source of human microplastic intake. We compared our results with those previously reported for other regions of the world and identified the need for further studies in the Persian Gulf. [ABSTRACT FROM AUTHOR]

Planktonic larval stages of bivalves are notoriously difficult to identify due to their similar morphology. To evaluate changed patterns in the presented planktonic bivalve larvae within Gomso Bay (Yellow Sea, South Korea), three sites were sampled twice a month from June to October 2015 and were analysed using next-generation sequencing (NGS) and light microscopy. Bivalve larvae revealed different patterns, and at least five bivalve taxa were only detected by the NGS. According to the NGS results, most bivalve larvae were Crassostrea gigas (37%), followed by Ruditapes philippinarum (26%), and Solen strictus (23%); Mactra chinensis and M. veneriformis accounted for <1% of the bivalve larvae. C. gigas and S. strictus were most abundant in late June, but rare in the other investigated periods, while R. philippinarum was more abundant in June and late September. Microscopic observations showed a similar trend to the NGS in terms of bivalve larvae presence, although they were difficult to identify the exact species. Thus, morphological and molecular approaches should be combined in future studies to provide accurate sequences of correctly identified specimens to develop NGS libraries. [ABSTRACT FROM AUTHOR]

Abstract: Gaining new knowledge of the native distributions of species (phylogeography) is more and more difficult in a world affected by anthropogenic disturbance, in particular by species translocations. Increasingly, molecular markers are required to support decisions about the taxonomy of native vs. introduced species, and the existence of their hybrids, to answer phylogeographic questions. In many fields, including aquaculture, traceability and food security, taxonomic and phylogeographic knowledge is key to the successful management and conservation of biodiversity. The Pacific coast of Chile is one of the last regions without a clear and agreed understanding of the taxonomy and systematics of smooth‐shelled blue mussels of the genus Mytilus. A panel of 49 bi‐allelic single nucleotide polymorphisms (SNPs) was genotyped in 338 Mytilus individuals collected from nine Chilean and five reference populations. All analyses confirmed the hypothesis that the native Chilean blue mussel is genetically distinct from the reference species M. edulis, M. galloprovincialis and M. trossulus. These results support the hypothesis of a unique evolutionary history of the native Chilean blue mussel on the Pacific coast of South America. It is therefore concluded that the native blue mussel from Chile should be recognized as M. chilensis Hupé 1854. We confirmed a recent Mediterranean origin of introduced M. galloprovincialis on the coast of Chile. This knowledge advances the understanding of global phylogeography of blue mussels and their bioinvasions and harmonizes taxonomy in the context of aquaculture production, seafood traceability, labelling and trade. [ABSTRACT FROM AUTHOR]

The family Cardiliidae has been scarcely studied. It was historically placed in the superfamily Mactroidea. Members of this family are characterized by a cordiform shell with a typical mactrid hinge, posterior adductor muscle placed into a myophore and three ornamental areas on the external surface of the shell. Six extant and 14 exclusively fossil species have been previously mentioned in the literature as belonging to the genus Cardilia. The geographical distribution, stratigraphic range, type material and type locality of each extant and fossil species are provided. In this work, four extant species and 11 exclusively fossil species belonging to the genus Cardilia are recognized. Extant species are from the western Pacific Ocean, Indian Ocean and eastern Atlantic Ocean, while fossil taxa are recorded from deposits of middle Eocene to late Pliocene in Europe and Asia,. One of them is formally described herein as Cardilia edwardsi new species. [ABSTRACT FROM PUBLISHER]

The limited record of the bactritoid-like coleoid cephalopods is here expanded due to discovery of a late Carboniferous (Moscovian) orthocone comprising a phragmocone and a body chamber with a proostracum-like structure, a sheath-like rostrum, an ink sac, and a muscular mantle preserved on top of the conch. The specimen comes from the Wewoka Formation in the vicinity of the city of Okmulgee, Oklahoma, which previously yielded an orthocone indicative of an evolutionary branch of the Carboniferous cephalopods described as the order Donovaniconida Doguzhaeva, Mapes, and Mutvei, 2007a within the subclass Coleoidea Bather, 1888. Here, we describe from that site a bactritoid-like coleoid, Oklaconus okmulgeensis n. gen. n. sp. in Oklaconidae n. fam. A broad lateral lobe of the suture line and a compressed conch with a narrowed dorsal side and a broadly rounded ventral side distinguish this genus from Donovaniconus Doguzhaeva, Mapes, and Mutvei, 2002b. The muscular mantle is preserved as a dense sheet-like structure, with a crisscross pattern and a globular-lamellar ultrastructure. Recent knowledge on the early to late Carboniferous coleoids is discussed. Carboniferous coleoids show a high morphological plasticity with a capacity for being altered to create the diverse combinations of ‘bactritoid’ and ‘coleoid’ structures. This could be the principle evolutionary driver of their radiation in the late Carboniferous. [ABSTRACT FROM PUBLISHER]

Four rare Pennsylvanian (Stark Shale: Pennsylvanian, Missourian [=Kasimovian]) coleoids from Nebraska and Iowa, which are preserved as flattened partial phragmocones and body chambers associated with three-dimensionally fossilized ink sacs, are herein described as Pabianiconus starkensis new genus new species, Nebraskaconus whitei new genus new species, and Starkites compressus new genus new species. One specimen that is missing most of the phragmocone, is provisionally assigned to Donovaniconus. The fossils are assigned to the Coleoidea because of the presence of ink-filled sacs in the body chamber region of the conch. Additionally, eight fragmented and flattened phragmocones and body-chamber clusters with similar morphologies, including some with ink fragments and arm hooks, are assigned to the Coleoidea, but are not named because of their fragmentary condition. On most of the eight specimens, the shell material is associated with other unidentified finely macerated material, which suggests these fossils are probably either ejectoid masses or coprolites from coleoid predators and/or scavengers. However, the new genera named above appear to have been deposited as complete animals, based on the presence of the ink-filled sacs that are in the body chambers. With their body chamber and phragmocone morphologies, these rare coleoid taxa provide valuable information about conch variability within the Carboniferous evolutionary radiation of coleoids. [ABSTRACT FROM PUBLISHER]

Several hydroids, corresponding to various morphotypes included earlier in the synonymy of Halopteris polymorpha (Billard, 1913), occur in materials obtained recently from Indonesia and the Maldives, or are housed in the collection of the Muséum d'histoire naturelle of Geneva, Switzerland. Among them, new specimens, indistinguishable morphologically from the lectotype, are fully redescribed, together with the so-called variety sibogae Billard, 1913. While the latter displays in life an original, not yet documented coloration (bright yellow cauline polyps contrasting with their pure white cladial counterparts), the former is uniformly yellow throughout. This feature, combined with a series of morphological differences, demonstrates that we are dealing with a well-characterized species, whose name should be H. sibogae (Billard, 1913). The sofar unknown gonothecae of the latter are described for the first time, together with the males of the nominal species. The taxonomy of H. polymorpha is analyzed in-depth and reassessed, where available also using 16S DNA sequences. Morphological traits can be used to split the species complex and allow the separation of three as yet undescribed species, H. australis from New Caledonia and French Polynesia, H. millardae from the Maldives and the Seychelles, and H. brasiliensis from Brazil. Additionally, new records of H. vervoorti Galea, 2008 extend its known geographical distribution to Madagascar, the Maldives and Indonesia, while some literature records suggest that it could spread as far as Australia, Japan and Fiji. All species are fully described and illustrated, and their morphology is compared to that of their related congeners. [ABSTRACT FROM AUTHOR]

The rocky intertidal gastropods of the Marine Priority Region No. 32 (MPR 32) in the State of Guerrero are one of the most studied invertebrates, however, little is known about their diversity and distribution. Here we report 16 new records of gastropods collected at six sites of the rocky coast (MPR 32) located in the State of Guerrero, Mexico. These records represent extensions of distributional range for an assemblage of species in different geographical scales, of which two are new for Mexico, five for the Mexican Transitional Pacific, four for the State of Guerrero and five for the MPR 32. These new records reveal the need for increasing taxonomic and biogeographic studies on the marine diversity in Mexico, especially in the Mexican Transitional Pacific Ecoregion. [ABSTRACT FROM AUTHOR]

The occurrence and the intensity of specific behavioural defensive reactions were investigated in freshwater snails of the family Physidae, which vigorously shake their shells when attacked by invertebrate predators. Physella acuta and Physa fontinalis were exposed to two species of leeches with different hunting strategies-- the molluscivorous Glossiphonia complanata and the opportunistic predator Erpobdella octoculata. Parameters of reaction were measured and compared between snails and leeches. Significant differences were found in the reactions of both snail species in 10 out of 11 measured parameters. Physa fontinalis reacted more intensively, with a higher number of shell movements triggered by both leech species. The study showed possible recognition by the prey of the predator species, followed by a specific defensive reaction. In general, G. complanata elicited more intensive reactions, especially in treatment with P. fontinalis. [ABSTRACT FROM AUTHOR]

There are 108 species of nematode that are known to have co-evolved with gastropods and use them as definitive, intermediate or paratenic hosts. One nematode (Phasmarhabditis hermaphrodita) is lethal to eight species of snail, but nine species are resistant for unknown reasons. This study investigated whether a previously untested snail species, Arianta arbustorum, was susceptible to P. hermaphrodita. Snails were exposed to 0, 30 and 90 P. hermaphrodita per cm2 applied to the soil surface for 40 days. Survival, feeding inhibition and differences in weight were monitored. It was found that A. arbustorum was resistant to P. hermaphrodita. The nematode did not cause mortality, induce feeding inhibition or affect weight. At the end of the experiment, surviving A. arbustorum had encapsulated and killed the invading nematodes in their shells. Inspection of shells of A. arbustorum collected on sand dunes in the north of Scotland, and in those collected by others in 1966 and 1908, revealed the presence of encapsulated nematodes. Arianta arbustorum can encapsulate and kill invading nematodes under laboratory conditions and in the wild, and the evidence of encapsulation remains for a long time. [ABSTRACT FROM AUTHOR]