The origins of the large form of the land snail Cornu aspersum known in the snail breeding industry as 'Helix aspersa maxima' remain enigmatic. Here, we tested the hypothesis that it is a distinct subspecies of C. aspersum, which represents a mitochondrial lineage sister of all remaining haplotypes in this species. We analysed 2-gene and mitogenomic alignments of a representative set of C. aspersum lineages. We show that there is no evidence for a split between 'maxima' and the typical C. aspersum in the mitochondrial data. Instead, the sister relationship recovered in an earlier study was a phylogenetic artifact caused by an extremely elevated mitochondrial substitution rate of 'maxima'. The sequences of 'maxima' are in fact nested among those of typical C. aspersum. Based on the origin of the sequences most similar to that of 'maxima', and considering available information on the origins of its heliciculture stock, we suggest that 'maxima' in the sense of a large-bodied C. aspersum with black mantle margins has originated from the northeast of Morocco.
A new species of Hua, Hua chishuiensis sp. nov., is described from the upper Yangtze River Basin in Yunnan Province, China, based on morphological and molecular evidence. The new species is distinguished from its congeners by a combination of characters, including a smooth shell with 4-6 whorls, central teeth with a triangular pointed major cusp and 3-4 smaller cusps on each side, inner marginal teeth with five denticles and outer marginal teeth with eight flattened denticles, a body width of about 57.1-71.8% of shell height and a large body whorl comprising about 77.8-88.0% of shell height. Molecular analysis based on partial mitochondrial COI and 16S rDNA also supports the systematic position of the new taxon. Furthermore, the article documents the first record of Hua wujiangensis in the Chishui River, where its shell morphology deviates markedly from the type material, a pattern likely reflecting phenotypic responses to the localised environmental conditions prevailing in these isolated habitats. These findings expand our understanding of freshwater molluscan diversity in southwestern China and underscore the karst landscapes as a pivotal centre of endemism and cryptic diversity for freshwater gastropods.
We report the first record of the camaenid snail Amphidromus leucoxanthus (Martens, ) from Malaysia, significantly expanding its known distributional range. This finding represents the first documented occurrence of the species outside the eastern Gulf of Thailand. This range extension may indicate historical dispersal across adjacent biogeographical regions or the persistence of a relict population from past climatic periods.
Aspects of the reproduction and early development of the crimson foot semislug, Stanisicarion freycineti (F & eacute;russac, 1821), were investigated. Animals laid clutches of 15-28 sulcated eggs each from which juveniles hatched 21-31 days later. The mean egg length and width was 0.39 and 0.31 mm, respectively. Growth was linear for the first 25 days, with an increase of shell size of 0.04 mm d-1 and an increase in body mass (whole animal wet weight) of 1.8 mg d-1. When offered a choice of food items, S. freycineti preferred flesh (chopped parts of Cornu aspersum) over native grasses, a lichen or a fungus. Interestingly, the pedal mucus produced by the semislugs was yellow-orange on collection, which then turned clear, rather than the reported red. These observations add to the scant knowledge we currently have about this species.
The New Zealand black-footed abalone, Haliotis iris, holds significant ecological, economic, and cultural value. Abalone from the Chatham Islands fisheries contribute substantially to the national catch, yet populations show marked variability in growth rates. To investigate whether this variability relates to the gut microbiome, sub-adult and adult abalone from four sites were assessed using morphometrics and 16S rRNA gene Illumina MiSeq sequencing. Adult abalone collected from Ascots Beach and Wharekauri were heavier, longer and had larger tissue areas than those from Owenga Harbour and Point Durham, whereas sub-adults showed no size differences. Gut content analysis revealed that fast-growing populations consumed more red algae and less green algae, while brown algae dominated digestion across all sites. Although alpha-diversity did not differ significantly among sites or ages (except at Point Durham), microbial beta-diversity varied significantly by both factors. Core taxa included Psychrilyobacter, Mycoplasma, Vibrio, Propionigenium, unassigned Bacilli, and Blastopirellula. Site- and age-associated microbiome differences may reflect seaweed availability and nutritional quality, warranting further investigation through targeted feeding trials. This study provides a reference baseline for future gut microbiota research on wild H. iris and highlights how algal nutrients and gut-bacteria-mediated digestion may contribute to population-level growth patterns, supporting sustainable fishery management.
Deroceras laeve is a recognised pest of agriculture and horticulture in Darjeeling Himalayas and other parts of India due to its unchecked feeding and high adaptability. To identify a biocontrol agent against D. laeve, this study aims to assess the efficiency of Bipalium sp. (land planaria) by observing predation under varying prey and predator sizes and habitats, temperature-dependent functional response, prey preferences and non-consumptive effect upon D. laeve. The land planaria consumed a higher number of small-sized (3 +/- 0.24) D. laeve, followed by the medium-sized (2.1 +/- 0.38) D. laeve individuals per day, than larger slugs. No substantial difference in consumption rate was observed between large- and small-sized predators, nor was there a difference due to habitat complexity. The type II functional response curve indicated lower handling time at 20 degrees C than at 15 degrees C. Moreover, Bipalium sp. exhibited no prey preference towards D. laeve and Tanychlamys sp. (a native land snail). As a non-consumptive effect of the predator, D. laeve exhibited lower leaf consumption rates in the presence of the predator and its cues than in the control group. Therefore, the results suggest that Bipalium sp. may contribute to the suppression of the pestiferous slug population through combined consumptive and non-consumptive effects.
The arcid clam Anadara trapezia has an extensive Pleistocene range in Western Australia, but it is currently found in that state only at King George Sound, near Albany. This is thousands of kilometres west of other known populations of the species, which is widely distributed in eastern Australia. Whether the King George Sound population is a recent introduction or relictual is uncertain, so sequences of adenosine triphosphate synthase subunit alpha intron (ATPS alpha), a nuclear gene, and the mitochondrial cytochrome c oxidase subunit I (COI) were collected. Sequences were obtained from Oyster Harbour in King George Sound and Burrill Lake, New South Wales and compared to GenBank data. There was a low level of localised variation in both ATPS alpha and COI in Oyster Harbour, suggesting either recent establishment or ongoing gene flow. Indeed, no differences were observed between any COI sequences, suggesting the possibility of a selective sweep in A. trapezia mitochondrial DNA that has occurred so recently that variation has not been regenerated. Such a situation is rarely observed and is not previously recorded from Mollusca. Tracking variants as they arise could be highly useful for investigating their spread in this important bivalve species' natural populations.
The whelk Dicathais orbita (Gmelin, 1791) is a dominant predatory gastropod on rocky shores from southern Queensland across southern Australia to North West Cape, Western Australia (WA). Most of the limited studies of D. orbita feeding were made on intertidal rock platforms at Rottnest Island, off Perth WA. We provide D. orbita feeding observations on Perth metropolitan platforms at Waterman and Cottesloe. The feeding rate was 8.2% at Waterman and 6.0% at Cottesloe. Seven taxa were consumed. Feeding on dead abalone Haliotis roei Gray, 1826 in tidepools (20 occurrences) and attacks on the gastropod Lunella torquata (Gmelin, 1791) (17 occurrences) were the most common observations. Combined with previous studies, D. orbita is shown to be a generalist feeder that consumes a wide variety of prey.
Temperature strongly influences embryonic survival and development in marine gastropods, yet thermal adaptation remains poorly understood in cone snails of the genus Conus. We examined the effects of incubation temperature on embryonic survival and developmental rate in four Conus species with different geographic distributions using laboratory experiments. The northern distribution limit is highest in C. fulmen, followed by C. lividus and C. ebraeus, and lowest in C. pulicarius. Embryonic survival exhibited clear convex relationships with temperature in all species. Logistic regression indicated that the temperatures supporting 50% survival to the veliger stage were 20.0-28.7 degrees C (C. fulmen), 20.3-30.8 degrees C (C. lividus), 19.5-30.3 degrees C (C. ebraeus), and 22.9-31.1 degrees C (C. pulicarius). The prehatching period decreased with increasing temperature and was well described by heat summation theory. Lower threshold temperatures for development ranged from 12.3-14.7 degrees C and tended to be higher in C. pulicarius. Interspecific differences in prehatching period were small, whereas veliger shell size differed markedly among species and was independent of temperature. These results demonstrate species-specific thermal adaptation consistent with geographic distributions. Estimated lower and upper thermal limits provide useful indices for assessing the spatial and temporal conditions necessary to sustain high embryonic survival in these species.
Members of the genus Thyasira host chemoautotrophic bacteria in their gills and are commonly found in hydrocarbon seeps and hydrothermal vents. Here, we report two new species of Thyasira from serpentinite seeps on Mariana Forearc mud volcanoes. One new species, Thyasira chamorroensis n. sp., is described from three articulated specimens recovered from the Summit Site of the South Chamorro Seamount (2915 m). The other new species, Thyasira tesoru n. sp., was collected from the Big Blue seep on the As & ugrave;t Tesoru Seamount (1240 m); it is described based on one articulated specimen and 15 disarticulated valves. The finding of two new Thyasira species from serpentinite seeps highlight the uniqueness of the biological community at this previously much-overlooked type of chemosynthetic habitat. These represent the first records of the genus Thyasira from the Mariana region, despite previous surveys of many hydrothermal vent systems there.
The Late Pleistocene deposits of Taiwan are known for their diverse fossil molluscan assemblages, yet much of the taxonomic work on this fauna remains outdated, in particular on the family Veneridae. In this study, we examine newly collected fossil venerids from the Szekou Formation, together with a re-evaluation of previous collections. Our revision resulted in several taxonomic updates, including the reassignment of previously reported taxa and the recognition of additional species not previously recorded from the formation. In total, 23 venerid taxa across 17 genera were documented, most of which correspond to species still present in modern Taiwanese waters. Changes in species diversity across stratigraphic levels correspond with previously proposed palaeoenvironmental stages of lagoonal development and increasing restriction of the basin. The strong overlap between fossil and modern species suggests ecological continuity in the subtropical West Pacific and supports interpretations of a warm-water palaeoenvironment during deposition of the Szekou Formation.
Assiminea ganghwensis Fukuda, S. Kim, Sawada and J.-S. Hong, n. sp. is described from salt marsh habitats in inner bays along the western and southern parts of the Korean Peninsula. According to a molecular phylogenetic analysis it is a member of Assiminea Fleming, 1828. The species is unique in the genus in having distinct spiral cords on the teleoconch surface, but the black seminal receptacle is also known in A. grayana (Fleming, 1828) and A. parasitologica Kuroda, 1958. In the new species, the protoconch is large with distinct spiral cords and therefore assumed to represent direct development. The central teeth of the radula have two pairs of basal cusps. The ganglia in the circumoesophageal nerve ring are very concentrated. Other anatomical characters including the digestive and reproductive systems are generally similar to those of Assiminea species hitherto known. Ecologically, within the Assimineidae the new species exhibits a previously unreported stem-climbing behaviour on salt marsh plants.ZooBank registration: https://www.zoobank.org/NomenclaturalActs/94016243-A4F7-470F-BB17-4A1FAFBC39B8
Three new genera are introduced for some New Zealand land snail taxa previously referred to the endemic charopid genus Allodisus Pilsbry, 1892. Australlodiscus n. gen. includes seven species from Te Waipounamu / South Island, four of which are described here as new; Allodiscus turbotti Powell, 1948 from Manawat & amacr;whi / Three Kings Islands is assigned to the new monotypic genus Axiallodiscus n. gen.; and Kurehea n. gen. is introduced for three species from southern Te Waipounamu / South Island, one of which is new. A new species name, Allodiscus capax n. sp., is introduced for A. cassandra of authors not Hutton, 1883, from Manawat & amacr;whi / Three Kings Islands.
The systematic classification of Australian pupilloideans is revised based on molecular phylogenetic analyses of sequences of the nuclear ribosomal loci ITS1, 5.8 S rRNA, ITS2, and 28S. Based on the phylogenetic trees produced herein, we synonymise the two monotypic genera Omegapilla Iredale, 1937 with Pupilla Fleming, 1828 and Nesopuparia Pilsbry, 1926 with Nesopupa Pilsbry, 1900. The Australian species Cylindrovertilla kingi (Cox, 1864) and C. hedleyi (Pilsbry, 1920) as well as Insulipupa malayana (Issel, 1874) from the Sunda Islands are transferred to the genus Vertigo M & uuml;ller, 1773. As these three species form a separate clade in the Vertigo tree, we propose treating Cylindrovertilla as a subgenus of Vertigo. This tentative decision requires confirmation from studying the type species. We remove the name Themapupa Iredale, 1930, from the synonymy of Pupoides Pfeiffer, 1854, recognising it as a distinct genus containing eight Australian species. The familial placement of Themapupa remains unresolved, however. The family Valloniidae appears as non-monophyletic, as Vallonia and Pupisoma represent two unrelated clades. Molecular studies including additional taxa and markers are required to resolve pupilloidean relationships more reliably.
Research over the last decade has substantially increased the knowledge of the cirrate octopod (Octopoda: Cirrata) fauna from waters around Australia, but this has relied upon historically collected specimens. In recent years footage of cirrate octopods from Australian waters has become increasingly available, with the increased taxonomic resolution of the group allowing such footage to be better assessed. Herein, a total of ten observations of live cirrates collected using remotely operated vehicles and towed cameras from around Australia over 2016-2022 are examined and allocated to species, genus or family level, including two species of Inopinoteuthis (Cirroteuthidae), three Grimpoteuthis species (Grimpoteuthidae) and one Insigniteuthis species (Opisthoteuthidae). Behaviours and morphology are remarked on for each individual and novel behaviours and morphological features are also reported, including a pelagic cirroteuthid tightly coiling and contracting its arms within its webbing while fin swimming, and pigmented rows of spot-like markings in Grimpoteuthis spp. distinct from the 'areolar spots' recorded in Opisthoteuthidae.
Bangladesh's climate is favourable for giant freshwater prawn (Macrobrachium rosenbergii) farming, but conventional practices contribute to high greenhouse gas (GHG) emissions, threatening aquaculture sustainability. Integrated multi-trophic aquaculture (IMTA) offers a promising approach to mitigate GHG by incorporating species that extract excess organic matter from farms. Molluscs, particularly snails, have been suggested as potential extractive species. This study aimed to identify suitable local snail species for IMTA in the southwestern Khulna district across three salinity zones (low, medium, moderately high) during the monsoon (July-October). Sampling covered three waterbody types: aquaculture, non-aquaculture and open waterbodies. Year-round perceptions-based data were obtained through focus group discussions (FGDs), while direct quadrat sampling provided monsoon-season field observations data, identifying nine and seven mollusc species, respectively. Bellamya bengalensis was most abundant in late monsoon within non-aquaculture waterbodies (39.56 +/- 12.74 individuals/m(2)), whereas Pila globosa peaked in mid-monsoon (10.22 +/- 3.41 individuals/m(2)). Snail abundance was highest in undisturbed, vegetated non-aquaculture waterbodies. Distribution patterns were influenced by salinity and water quality parameters. Both B. bengalensis and P. globosa show potential for IMTA for their availability and potential use in feed, with B. bengalensis particularly suited because of its filter-feeding behaviour, adaptability and rapid reproduction.
Oncomelania hupensis, the sole intermediate host for Schistosoma japonicum, is a barrier to schistosomiasis elimination. Currently, chemical molluscicides are widely used; however, they can lead to environmental residues and toxicity problems. Molluscicides derived from microorganisms offer the advantages of mass production and environmental compatibility. Building on the molluscicidal activity of Penicillium aurantiocandidum Z12, we fractionated its fermentation broth via centrifugation and solvent extraction to identify active components. Ethyl acetate extract (EAE) and n-butanol extract (BE) demonstrated molluscicidal effects in toxicity tests. EAE (LC50 = 1.40 g/L, 95% Cl = 1.21-1.60; LC90 = 2.92 g/L, 95% Cl = 2.44-3.78) was significantly more potent than BE (LC50 = 2.17 g/L, 95% Cl = 1.96-2.39; LC90 = 3.31 g/L, 95% Cl = 2.93-4.07). ANOVA/Kruskal-Wallis analysis showed specific concentrations of EAE (0.4, 0.7 g/L) and BE (3.2 g/L) significantly reduced snails' total hepatic protein content after 72 h. Treatment with EAE and BE at LC50 values also significantly suppressed superoxide dismutase (SOD) and peroxidase (POD) activities in head-foot tissue after 72 h. In conclusion, molluscicidal components concentrate in EAE and BE. Their mechanism involves inhibiting hepatic protein synthesis and suppressing SOD/POD activity, leading to snail death. More research is needed to further explore the specific effective constituents and their mechanisms.
Palisadia Laseron, 1956 is a little-known gastropod genus in the echinoderm-parasitic family Eulimidae (Caenogastropoda: Vanikoroidea). This genus has so far been reported from empty shells only, which are characterised by (1) small size, around 3 mm in length; (2) enlarged, strong varices on either side which protrude above the sutures; (3) a distorted subtriangular aperture; and (4) a columella with a shallow sinus. Recently, two live and two fresh empty shell specimens were collected in the Okinawa Islands, south-western Japan. The live specimens allowed us to observe their soft part morphology and investigate phylogenetic relationships using molecular approaches, which confirmed the familial assignment of the genus to Eulimidae. The present molecular phylogeny based on six gene sequences recovered Palisadia to form a monophylum together with the ophiuroid-parasitic genera Pyramidelloides, Eulima, Hemiliostraca, and Introphiuricola. Although the live specimens were collected as free-living form without host information, the present study suggests that species of Palisadia are temporary parasites of ophiuroids. In addition, Palisadia species may prefer cryptic habitats, because many specimens were collected from a submarine cave, the bottom sediment of reef crevices, and under corals.
Freshwater snails are significant vectors for schistosomiasis, a disease caused by parasitic worms, and they also hold veterinary importance as hosts for various diseases. Climate change significantly influences the transmission of schistosomiasis by affecting these snails. Changes in temperature impact their growth, reproduction, and survival, with each species exhibiting distinct optimal temperature ranges. This can result in shifts in snail populations and the distribution of the disease. Rising temperatures and altered precipitation patterns expand the geographic range of snails, increasing infection risk in regions such as eastern Africa, China, and Brazil. Temperature plays a critical role in parasite development and snail survival, with varying temperature tolerances among snail species affecting disease transmission dynamics. Rather than merely expanding transmission areas, climate change may shift them, potentially pushing African snail species out of their thermal comfort zones. To effectively manage climate-sensitive diseases like schistosomiasis, comprehensive public health strategies are essential. This includes developing adaptive plans, prioritising research, and fostering collaboration. Understanding the intricate relationship between climate change and disease transmission is crucial for designing targeted interventions. Enhanced surveillance and control measures are necessary to protect vulnerable populations and mitigate the impacts of climate change on schistosomiasis transmission.
