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While most Cerithioidea are marine, some occur in brackish and freshwater habitats. Many members are systematically problematic due to variability or homoplasy in conchological characters, which has led to taxonomic redundancy, but also because of discrepancies between phylogenetic trees and morphologically distinguishable units as revealed in recent molecular genetic studies. We have chosen an evolutionary systematic approach and combine analyses of shell biometry and geometric morphometrics with the analyses of reproductive traits and molecular genetics based on mtDNA and AFLP markers in order to resolve the relationships among species of the genus Sermyla. We describe a new species from Sulawesi, Sermyla kupaensis sp. nov., which is characterized by a distinct reproductive strategy. This unique reproductive strategy corresponds with its distinct molecular genetic signal. However, it is not possible to distinguish S. kupaensis from S. riquetii based on shell morphology alone. We also provide data on the population structure of the endemic Australian species Sermyla carbonata, for which we found a drainage-based population structure. Overall, we present a new concept of the relationships among the species within the genus Sermyla based on morphological and genetic data.

Abundant species are typically also viewed as ecologically dominant, and are frequently used to characterize the communities in which they live. Such characteristic assemblages may also be used as indicators of environmental conditions, such as relative stability. Fossil and modern turritelline gastropods are often the most abundant species in the marine assemblages and communities in which they occur, forming ‘turritelline-dominated assemblages’ (TDAs). We use data on modern Turritella bacillum from waters around Hong Kong as a case study to analyse fluctuations in abundance over 25 years. While turritellines were not always dominant in the area surveyed (~1650 km2), populations were notably persistent, and rebound after decline of abundances occurred within ~5 years at some sites. δ18O sclerochronology suggests that individuals were ~1–2 years old. It is also notable that T. bacillum was found to be abundant at salinities as low as 10–15 psu, despite the general characterization of turritellines as fully marine. Comparison with data on modern T. communis in the western English Channel corroborates this pattern, as localized sites of high abundance also appear transient. These results have implications for the interpretation of TDAs in the fossil record: they may signify the cumulative result of short-lived, spatially restricted populations, possibly resulting from essentially stochastic larval settlement. This suggests that the palaeoenvironmental setting of fossil TDAs does not always control their occurrence on short temporal scales.

The taxonomic history of Chinese semisulcospirids is confusing. Originally placed in Melania by late 19th century authors, species have subsequently been dispersed into four different genera, i.e. Semisulcospira Böttger, 1886, Senckenbergia Yen, 1939, Hua Chen, 1943, and Namrutua Abbott, 1948; however, these placements were not conducted within a phylogenetic context. Based on examination of newly collected samples from the Chinese provinces Yunnan, Guizhou, Jiangxi, Anhui and Chongqing, we revised the systematics of the Chinese Semisulcospiridae based on comparative anatomy and mitochondrial phylogenetics. We have examined shell, radular, and reproductive features and employed Bayesian and Maximum Likelihood analyses of partial sequences of mitochondrial genes cytochrome c oxidase I and 16S rRNA to resolve the phylogenetic relationships. The results revealed that Semisulcospiridae is represented by three genera in China, which differ in their reproductive strategy, including Semisulcospira, which is viviparous and contains three species (S. ningpoensis, S. gredleri, and S. pleuroceroides); Hua, which is oviparous and contains 11 species; and Koreoleptoxis, which is oviparous and contains one species. Namrutua and Senckenbergia are identified here as junior subjective synonyms of Semisulcospira. All taxa recognised herein formed well differentiated clades in three mitochondrial phylogeny, and could be reliably distinguished by differences in shell shape and sculpture. Four new species of Hua are described from Yunnan Province. This is the first comprehensive study to review the taxonomy of semisulcospirids in China. These species are sensitive to water quality, and economic development and infrastructure expansion have negatively impacted many populations. We fear that some species may have disappeared before being investigated or described scientifically. Therefore, this research will hopefully inspire further studies and surveys to foster our understanding of freshwater gastropod diversity in China. http://zoobank.org/urn:lsid:zoobank.org:pub:EF2147FD-9EEE-4922-90DC-76651EF9E6AE

The systematics of Semisulcospiridae in China is revised here based on morphological characters and mitochondrial phylogenetics. Phylogenetic relationships within the Chinese semisulcospirids were assessed via DNA sequences from mitochondrial analysis (cytochrome c oxidase I and 16S rRNA). This research contains most morphospecies of semisulcospirids previously recorded in China. Based on these results, the family of Chinese Semisulcospiridae is represented by three genera: i.e., viviparous Semisulcospira B?ttger, 1886, oviparous Hua Chen, 1943 and Koreoleptoxis Burch and Jung, 1988. These genera can be distinguished from each other by reproductive anatomy, reproductive mode, and radula features. Species of Hua are mainly distributed in southwest China and Guangxi, whereas Koreoleptoxis and Semisulcospira are mainly distributed in south and northeast China.

Thiaridae are a speciose group of freshwater snails in tropical areas including a high number of described nominal taxa for which modern revisions are mostly lacking. Using an integrative approach, the systematic status of a group of thiarids from the Oriental region, including the nominal speciesMelaniaasperaandM.rudis, is reassessed on the basis of shell morphology and biometry, radula dentition patterns, and reproductive biology along with molecular genetic methods. Our results suggest that populations from the Oriental region cannot be distinguished on the basis of shell morphology, radula characters and their reproductive mode and are monophyletic based on mitochondrial sequences. Hence,M.rudiswithM.asperaare regarded as belonging to the same species along with several other nominal taxa that were previously included inM.rudis. Moreover, populations from Thailand and Australia, from where the species was not previously recorded, could be shown to form a monophyletic group together with samples from Indonesia. However, a generic affiliation withThiara, in which the investigated taxa were often included in the past, was not supported in our phylogenetic analyses, highlighting the need for a comprehensive revision of the genus-group systematics of Thiaridae as a whole.

This nomenclator provides bibliographic details on all names in the family-, genus-, and species-group of the the family Paludomidae. All nomenclaturally available names are discussed including junior homonyms and objective junior synonyms as well as unavailable names such as nomina nuda, infrasubspecific names and, to some extent, also incorrect subsequent spellings. In the family-group a total of 28 names are included in the nomenclator, of which 21 are available and seven unavailable names. Of the available names in the family-group, six are invalid for nomenclatural reasons. In the genus-group a total of 57 names are included in the catalogue. Of the available names in the genus-group, 11 are invalid for nomenclatural reasons. In the species-group a total of 499 names are included, of which 463 are available, but 21 are invalid for nomenclatural reasons. All names are given in their original combination and spelling (mandatory changes are discussed and corrected spellings are provided), along with the reference to the original publication. For each family- and genus-group name, the original classification and the type genus or type species, respectively, are given. For species-group taxa the type locality and type horizon (for fossil taxa) are provided, usually as given in the original publication. A new name,Cleopatraadaminom. nov., is proposed for the fossilCleopatracylindrica(Adam, 1957), which is a homonym ofCleopatracridlandicylindricaMandahl-Barth, 1954, and a lectotype forCleopatradubiaAdam, 1959 is designated. A new replacement nameLeloupiellanom. nov. is proposed forStormsiaLeloup, 1953 which is a homonym ofStormsiaBourguignat, 1891.

The molluscan radula, a thin membrane with embedded rows of teeth, is the structure for food processing and gathering. For proper functioning, radular failures must be either avoided or reduced when interacting with the preferred food, as this might be of high significance for the individual fitness. Thus, the analysis of structural failure in radular teeth could be included in studies on trophic specializations. Here, we tested the failure of non-mineralized, chitinous radular teeth from taxa, belonging to an African paludomid species flock from Lake Tanganyika and surrounding river systems. These species are of high interest for evolutionary biologists since they represent a potential result of an adaptive radiation including trophic specialisations to distinct substrates, the food is attached to. In a biomechanical experiment a shear load was applied to tooth cusps with a force transducer connected to a motorized stage until structural failure occurred. Subsequently broken areas were measured and breaking stress was calculated. As the experiments were carried out under dry and wet conditions, the high influence of the water content on the forces, teeth were capable to resist, could be documented. Wet teeth were able to resist higher forces, because of their increased flexibility and the flexibility of the embedding membrane, which enabled them either to slip away or to gain support from adjacent teeth. This mechanism can be understood as collective effect reducing structural failure without the mineralisation with wear-minimizing elements, as described for Polyplacophora and Patellogastropoda. Since the documented mechanical behaviour of radular teeth and the maximal forces, teeth resist, can directly be related to the gastropod ecological niche, both are here identified as an adaptation to preferred feeding substrates. Statement of significance The radula, a chitinous membrane with teeth, is the molluscan feeding structure. Here we add onto existing knowledge about the relationship between tooth's mechanical properties and species’ ecology by determining the tooth failure resistance. Six paludomid species (Gastropoda) of a prominent species flock from Lake Tanganyika, foraging on distinct feeding substrates, were tested. With a force transducer wet and dry teeth were broken, revealing the high influence of water content on mechanical behaviour and force resistance of teeth. Higher forces were needed to break wet radulae due to an increased flexibility of teeth and membrane, which resulted in an interlocking or twisting of teeth. Mechanical behaviour and force resistance were both identified as trophic adaptations to feeding substrate.

Stenomelania snails (Fisher 1885) have been reported from the coastal regions of the Indian Ocean and the Pacific Ocean, spanning India to Australia. Here, the species diversity and distribution of these snails in the south of Thailand are recorded. The snails were also examined for trematode infections in 13 locations in three Provinces, viz. Krabi, Trang and Satun, along the coast of the Andaman Sea. A total of 1,551 snails were in five morphs tentatively identified as Stenomelania aspirans, S. crenulata, S. punctata, S. torulosa and the closely-related Neoradina prasongi. With 10 infected snails, the trematode infection rate was 0.64%. The cercariae were categorised into three species from two morphologically-distinguishable types, viz. parapleurolophocercous cercariae (Haplorchis taichui and Procerovum cheni) and xiphidiocercariae (Loxogenoides bicolor), through the morphological characterisation of the larval stage. These trematodes were also analysed using the internal transcribed spacer subunit II region to confirm the species identity at generic and infrageneric levels.

The cerithioidSupplanaxis nucleus(Bruguière, 1789) is widespread in the Caribbean, where it lives in often dense aggregates on hard surfaces in the middle-high intertidal. Molecular evidence shows that it comprises two species that are in fact morphologically diagnosable. We fix the nomenclature ofSupplanaxis nucleusby designating a sequenced neotype from Bruguière’s historical locality of Barbados, and identify the second, cryptic species asS. nancyae(Petuch, 2013). The two live syntopically across the Caribbean and form a closely related species group with the PanamicS. planicostatus(G.B. Sowerby I, 1825).Planaxis nucleolaMörch, 1876, described from St Croix, in the Virgin Islands, never again recorded in the literature but listed as a synonym ofS. nucleusin taxonomic authority lists, is recognized as a valid species ofHineaGray, 1847.ProplanaxisThiele, 1929 andSupplanaxisThiele, 1929, are synonyms and the latter is given precedence over the former.

Melanopsidae are an important component of the freshwater fauna of the subtropical to temperate regions of the Western Palaearctic and also are reported from Zealandia, representing an unparalleled disjunction among a group of freshwater animals. We sequenced markers for species of all constituent genera covering the entire range of the group. Our phylogenetic analyses indicate that Melanopsidae are only monophyletic when excluding Holandriana from the Balkans, which was found to be more closely related to Pleuroceridae (eastern North America) and Semisuclospiridae (western North America and eastern Asia) than to the remaining melanopsids. It is, therefore, placed in the previously proposed family Amphimelaniidae. Zemelanopsis from New Zealand and Caledomelanella gen.n. from New Caledonia were recovered as a deeply divergent clade, here suggested to represent Zemelanopsidae fam.n. as the sister group of Melanopsidae s.s. The genus Microcolpia, including M. daudebartii and the extinct M. parreyssii, was recovered as a moderately well-supported sister group of Melanopsis s.s., which comprises three distinct lineages: one from the western Mediterranean region, a second from the eastern Mediterranean region and the Near to Middle East, and a third from thermal springs in Tuscany. Although the Italian populations show little variability, both the eastern and western Melanopsis clades exhibit a high degree of variation in shell form and/or sculpture. Whether this is indicative of more than a species pair each (M. praemorsa/cariosa and M. buccinoidea/costata) within the eastern and western clade, respectively, or the result of parallel evolution currently cannot be answered with certainty. Distinct populations were not recovered as monophyletic clades in some cases, which may indicate incomplete reproductive isolation. We compare the timeframe for the evolution of major "melanopsid" lineages with geological events, and elucidate scenarios that may have shaped the distribution patterns observed today.

Minute intestinal flukes from several distinct families of endoparasitic platyhelminths are a medically important group of foodborne trematodes prevalent throughout Southeast Asia and Australasia. Their lifecycle is complex, with freshwater snails as primary intermediate hosts, with infecting multiple species of arthropods and fish as second intermediate hosts, and with birds and mammals including humans as definitive hosts. In Southeast Asian countries, the diversity of snail species of the Thiaridae which are frequently parasitized by trematode species is extremely high. Here, the thiarid Tarebiagranifera in Thailand was studied for variation of trematode infections, by collecting the snails every two months for one year from each locality during the years 2004–2009, and during 2014–2016 when snails from the same localities were collected and new localities found. From ninety locations a total of 15,076 T.granifera were collected and examined for trematode infections. With 1,577 infected snails the infection rate was found to be 10.46 %. The cercariae were categorized into fifteen species from eight morphologically distinguishable types representing several distinct families, viz. (i) virgulate xiphidiocercariae (Loxogenoidesbicolor, Loxogenesliberum and Acanthatriumhistaense), (ii) armatae xiphidiocercariae cercariae (Maritreminoidescaridinae and M.obstipus); (iii) parapleurophocercous cercariae (Haplorchispumilio, H.taichui and Stictodoratridactyla); (iv) pleurophocercous cercariae (Centrocestusformosanus); (v) megarulous cercariae (Philophthalmusgralli); (vi) furcocercous cercariae (Cardicolaalseae, Alariamustelae and Transversotremalaruei); as well as (vii) echinostome-type cercariae, and (viii) gymnocephalous-type cercariae. In addition, a phylogenetic marker (internal transcribed spacers 2, ITS2) was employed in generic and infrageneric level classifications of these trematodes, using sequences obtained from shed cercariae isolated from T.granifera specimens of the second study period collected in various regions in Thailand. We obtained ITS2 sequences of cercariae from nine species (of seven types): Loxogenoidesbicolor, Loxogenesliberum, Maritreminoidesobstipus, Haplorchistaichui, Stictodoratridactyla, Centrocestusformosanus, Philophthalmusgralli, as well as from one species each of echinostome cercariae and gymnocephalous cercariae. Thus, this analysis combines the parasites’ data on morphology and geographical occurrence with molecular phylogeny, aiming to provide the groundwork for future studies looking into more details of the parasite-snail evolutionary relationships.

The ultrastructure of spermatophoral sperm is investigated for the first time in a cerithioidean gastropod. Thiara amarula (Linnaeus, 1758), a widespread Indo-West Pacific species of the Thiaridae, produces uniaxonemal euspermatozoa and multiaxonemal paraspermatozoa. Euspermatozoa possess a laterally-flattened acrosomal vesicle (with eccentrically positioned invagination and subacrosomal material), a tubular, laterally-compressed nucleus, an elongate midpiece (with four, straight, equal-sized mitochondria each with parallel cristae), an elongate glycogen piece and an end piece. The eusperm nucleus exhibits or is associated with a number of unusual features including: (1) nuclear contents differentiated into two components (fibrous, highly electron-dense material, enclosing a pair of less-dense, finely granular tracts); (2) nuclear invagination with two elongate grooves aligned at 90 degrees to the axonemal central microtubules and parallel with the 1 and 5 axonemal doublets; (3) a periodically-banded rootiet associated with the centriolar complex near the nuclear apex; (4) an electron-dense structure attaching the nucleus to the axoneme at the nucleus-midpiece junction. Feature (1) has been reported elsewhere in Melanoides tuberculata (Thiaridae), but in no other examined gastropods (or other molluscs) and its purpose is unknown. Paraspermatozoa of T. amarula possess an elongate head region (up to 14 axonemes and large, irregular mitochondria enclosed by sheath of spherical, dense vesicles), a short 'glycogen' region and a posterior tuft of glycogen tails. The two sperm types do not form spermatozeugmata and observations suggest that neither type undergoes any noticeable structural change while inside the spermatophore. Sperm features suggest a close relationship between T. amurula and M. tuberculata and more broadly with other 'Group T cerithioidean families exhibiting four equal-sized eusperm mitochondria, including Potamididae, Modulidae, Scaliolidae, Melanopsidae, Semisulcospiridae and Pleuroceridae.

Although generally considered rare in gastropods, septation has long been noted in turritellids, but functional hypotheses do not survive strong scrutiny. Here we outline a methodology for testing spandrel hypotheses and apply it to the problem of turritellid septa. We follow Gould in using “spandrel” as a term for all features that are nonadaptive sequelae of adaptive features of organisms, including those that are structurally necessary, those that are developmentally correlated, and nondeterministic by-products that are correlated to features under selection.In turritellids, septa are constructed in microstructural continuity with secondary internal thickening of the shell, are highly variable features infraspecifically, and are strongly associated with degree of shell thickening. We therefore conclude that rather than being themselves adaptive, turritellid septa are spandrels of shell thickening. Turritellid septa are composed of crossed lamellar aragonite, which appears to be constructed by mantle epithelium over the visceral mass. Septation was also found in 22 of 24 gastropod families examined from a broad phylogenetic distribution. Septa thus appear to be a widespread feature of caenogastropods, in strong contrast to previous assertions that septa are less common in modern or high-spired shells.

A new genus, Limatium gen. n., and two new species, L.pagodula sp. n. and L.aureum sp. n. are described, found on outer slopes of barrier reefs and fringing reefs in the South Pacific. They are rare for cerithiids, which typically occur in large populations. The two new species are represented by 108 specimens sampled over a period of 30 years, only 16 of which were collected alive. Three subadults from the Philippines and Vanuatu likely represent a third species. In addition to their rarity, Limatium species are atypical for cerithiids in their smooth, polished, honey to golden brown shells with distinctive white fascioles extending suture to suture. The radula presents a unique morphology that does not readily suggest an affinity to any of the cerithiid subfamilies. Two live-collected specimens, one of each species and designated as holotypes, were preserved in 95% ethanol and sequenced. Bayesian analysis of partial COI and 16S rDNA sequences demonstrates a placement in the Bittiinae, further extending our morphological concept of the subfamily.

The Interior Highlands, in southern North America, possesses a distinct fauna with numerous endemic species. Many freshwater taxa from this area exhibit genetic structuring consistent with biogeography, but this notion has not been explored in freshwater snails. Using mitochondrial 16S DNA sequences and ISSRs, we aimed to examine genetic structuring in the Pyramid Elimia, Elimia potosiensis, at various geographic scales. On a broad scale, maximum likelihood and network analyses of 16S data revealed a high diversity of mitotypes lacking biogeographic patterns across the range of E. potosiensis. On smaller geographic scales, ISSRs revealed significant population structure, even over the distance of a few hundred meters. Unlike other freshwater mollusks like mussels, E. potosiensis showed no evolutionary patterns relating to biogeography. The species does show population-level genetic structure, which may have implications in conservation efforts.

A temporarily exposed 6-m succession of raised reefal limestone terrace south of Sharm Obhur (Jeddah) was investigated with regard to macrofossil gastropods and their palaeoenvironmental implications. The studied succession consists of two distinct layers. The lower layer consists of white limestone (4 m thick) of Late Pleistocene age, while the upper layer consists of shell-rich calcareous clay (2 m thick) and belongs to the last interglacial marine isotope stage 5e (MIS 5e). Its lithology was correlated with a nearby temporarily exposed 3-m succession, indicating that the deposition of the MIS 5e was not continuous, as indicated by the occurrence of a 0.4-m-thick weathered layer between the lower white limestone and upper calcareous clay. The studied 6-m succession yielded a very rich gastropod fauna with 90 species belonging to 4 subclasses, 5 orders, 16 superfamilies, 33 families and 64 genera. The clayey layer showed higher species richness (65 species) than the limestone layer (18 species), indicating a rapid change in the coral reef environment during the deposition of the interval of MIS 5e. It is assumed that, after the weathering interval, the sea level could not rebound to the same level as it was during the deposition of the white limestone, leading to deposition of calcareous clay in a shallow platform or embayment, allowing proliferation of gastropod species. Littorinimorpha and Neogastropoda species represent about 75% of the total recorded gastropod taxa, whereas Vetigastropoda and Caenogastropoda represent only 25% of the total recorded taxa. Superfamilies Cerithioidea and Stromboidea dominated the clay layer, whereas no particular species dominated the limestone layer.

Several deep-water mollusks collected during the Marion Dufresne MD55 expedition off SE Brazil have been studied in recent papers. The present work focuses on eight species belonging to the cerithioidean families Cerithiidae, Litiopidae, Modulidae and Planaxidae. Three species have their geographic distributions greatly expanded: Bayericerithiumbayeri Petuch, 2001 from Pernambuco to Rio Grande do Norte and Ceará states (north) and to Bahia and Espírito Santo states (south), Brazilian coast; Ittibittium oryza (Mörch, 1876), from the Caribbean to the SW Atlantic; and Angiola lineata (Costa, 1778), from Trindade Island, Brazil to the Abrolhos Slope, nearly 870km westward. Four species reported herein had their bathymetric ranges greatly expanded: Alaba incerta (d’Orbigny, 1841) from 0-40m to 300m; B.bayeri from 0-2m to 120m (live specimens); Litiopa melanostoma Rang, 1829 from 0-805m to 1,550m; Fossarus orbignyi Fischer, 1864 from 0-40 to 830m (shells only).

Melanopsidae were collected from 23 localities in central and south-eastern Europe, the Aegean Islands and Israel. This study considered Melanopsis from the Aegean Islands, the Peloponnese and Israel, and Esperiana esperi, Holandriana holandrii and Microcolpia from continental Europe. Shells and radulae were described and illustrated, showing continuous variation of shell characters and differences in radulae among genera. Phylogenetic analyses were conducted on single-locus datasets (COI, 18S, 28S, ITS2 and H3) and on a concatenated dataset. Molecular data showed a differentiation not paralleled in morphology, reflecting morphostatic evolution. In all species with ribbed shell-forms, the ribbed and unribbed forms did not differ genetically. Within Melanopsis, four clades representing five species were distinguished. Melanopsis buccinoidea is found in Khios and Lesbos Islands, M. astropaliae in Naxos, Samos and Tinos Islands, M. wagneri in Rhodes Island and the Peloponnese, and M. costata and M. saulcyi in Israel. Molecular results and the ICZN rule of priority restrict the range of M. buccinoidea to the North Aegean Islands. ‘Melanopsis’ parreyssi belongs to the genus Microcolpia. Esperiana esperi belongs to a clade separate from Microcolpia.

While Africa’s lacustrine gastropod fauna, in particular of Lake Tanganyika, has received much attention, the continent’s riverine malacofauna has long been neglected. Pseudocleopatra is a relatively poorly known paludomid gastropod genus with species found throughout the lower reaches of the West African Volta and Congo rivers. In the course of ongoing systematic revisions of African paludomids, we present here a morphometric analysis and revision of the recent species assigned to the genus, i.e., P. togoensis, P. voltana, P. dartevellei and P. bennikei, to improve taxonomic acuity for this group. We use available museum material for geometric morphometrics, multivariate ratio analysis and comparisons of radular and opercular characters. Our results demonstrate that the four recent species of Pseudocleopatra are clearly distinguishable on the basis of ratios of shell measurements as well as radular and opercular characters. Pseudocleopatra has generic-level synapomorphies including: concentric opercula with relatively large paucispiral nuclei, and rachidian radular teeth with usually 13–20 cusps. On the basis of this characterisation, the nominal species Cleopatra broecki is transferred to Pseudocleopatra. Additionally, the nominal taxon P. bennikei is synonymized with P. broecki n. comb. The phylogenetic relationships of Pseudocleopatra are currently unknown, but the observed tendency of some fossil taxa assigned to Pseudocleopatra towards thalassoidism, i.e., the resemblance to marine gastropods, has led to the hypothesis that some of the thalassoid endemics in Lake Tanganyika may have originated from or be related to Pseudocleopatra. Should this hypothesis be correct, which is in need of testing by molecular genetic methods when suitable samples become available, Pseudocleopatra may play a crucial role in understanding of the evolution of thalassoidism in African Paludomidae.

In this study, we determined the complete mitochondrial genome (mt genome) of Semisulcospira gottschei for the first time and then compared it with the mt genome of species belonging to Cerithioidea. The mt genome consists of 13 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs) and non-coding region with a total length of 16,101 bp. The type of constitutive genes and the direction of the coding strand which appeared in the mt genome were the same as the ones observed in Cerithioidea except for the tRNA-Q and tRNA-R positions. The S. gottschei mt genome had a non-coding region with an AT-rich loop between tRNA-F and tRNA-C regions. In regard to molecular phylogeny, two types of analysis were performed to confirm the introgressive hybridization of S. gottschei and to identify the phylogenetic location among the species in Caenogastropoda. As a result, S. gottschei used in this study belonged to the same clade as other non-introgressed S. gottschei. As for the molecular phylogenic analysis of species belonging to Caenogastropoda, S. gottschei was found to be the closest to S. coreana taxonomically and to be included in Cerithioidea.

Turritella duplicata (Linnaeus, 1758) is a marine suspension-feeding gastropod found in shallow-marine and tidal flat environments throughout Southeast Asia and the Indo-West Pacific. It was studied on a tidal flat in the national park of Nopparat Thara in the district of Krabi, southern Thailand. Turritella duplicata was found primarily in the lower intertidal zone, and 90 specimens were gathered and measured. Their geographical positions on the flat were mapped, revealing zonations in population distribution, both parallel and perpendicular to the shore-line. The size distribution of the shells indicates that the population consists exclusively of adults. δ18O sclerochronology performed on three shells shows variations of up to 1.5‰ associated with seasonal changes in water parameters, suggesting longevity of about three years and seasonally controlled growth rates. The absence of juveniles and observed population distribution coupled with the sclerochronological data suggest that reproduction ...

Semisulcospira paludiformis, collected from Hainan Island, China, was described by Yen in 1939. While the type specimens of S. paludiformis were destroyed in World War II, the systematic classifica...