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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.

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.

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 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.

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.

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.

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.

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...

A new species of pachychilid freshwater gastropod, Sulcospira hunanensis sp. nov., is described from Hunan Province, China, based on morphological and molecular evidence. The new species is distinguished from its congeners by a combination of characters, including elongated shell with eight to nine whorls, spiral whorls with ribs, and stomach with outer and inner crescentic pads not connected to each other. Sulcospira hunanensis sp. nov. is the first confirmed report of this genus from Hunan Province, China. It is anticipated that further species will be found in this region, which currently remain unknown. Furthermore, based on morphological and molecular evidence, this study is the first record of Sulcospira tonkiniana in Guangxi Zhuang Autonomous Region, China, with Sulcospira krempfi supported as a synonym of Sulcospira tonkiniana.

Pronounced mitochondrial heterogeneity within putative species of Pleuroceridae has prevented meaningful systematic revisions of this critically imperilled freshwater family. Previous studies have demonstrated that this mitochondrial diversity often produces polyphyletic species on mitochondrial gene trees, but its significance is unclear. Hypotheses advanced to explain this pattern have included cryptic species, retained ancestral polymorphisms and introgression; other possible explanations such as doubly uniparental inheritance or the presence of pseudogenes have not been given due consideration. Previous analyses have not included adequate sampling, neither in terms of number of individuals nor in geographic coverage, to adequately test any of these hypotheses. To fully characterize mitochondrial heterogeneity in pleurocerids and robustly assess possible causal explanations, we collected 239 individuals representing four putative species from seven sites and sequenced the COI and 16S rRNA mitochondrial genes and the H3 nuclear gene for all individuals. We also used whole-genome shotgun sequencing to construct and annotate a mitochondrial genome for one individual. Characters with demonstrated utility in morphospecies delineation of gastropods (head–foot coloration, shell and radular morphology, pallial oviduct anatomy) were examined for a subset of individuals to determine whether morphology co-varied by haplotype clade. We found pronounced mitochondrial heterogeneity at both the population level and species level in three of the species examined, but our data reject paralogous nuclear copies of mitochondrial genes (NUMTs) and doubly uniparental inheritance as causal mechanisms, and there was no evidence of cryptic diversity. Mutation rates were found to differ significantly among mitochondrial lineages, and population genetic statistics revealed a signature of balancing selection that could be acting to maintain this diversity. The observed pattern is similar to that seen in lineages with inherited endosymbionts like Wolbachia infections, which merits further investigation. Although questions remain concerning the precise cause(s) of intraspecific mitochondrial diversity in pleurocerids, nuclear and/or genomic data, combined with anatomical and life history investigations in an integrative phylogenetic context, is the most promising avenue for resolving pleurocerid systematics.

The Painted Rocksnail, currently known as Leptoxis taeniata, is a federally threatened species native to the Mobile River basin in Alabama, USA. Presently restricted to four disjunct populations, the species is at considerable risk of extinction after a range decline of over 95% in the 20th century because of habitat alteration following impoundment of the Coosa River. Here, we reassess the identity and historical range of the Painted Rocksnail to improve communication and conservation efforts for the species. We determined that L. taeniata is a synonym of L. picta and that the name L. taeniata has been misapplied to the current concept of the Painted Rocksnail for which L. coosaensis is the oldest available name. Leptoxis coosaensis and L. picta are herein redescribed. After examination of historical material, we determined that records of the Painted Rocksnail outside the Coosa River drainage were misidentifications. Thus, we redefine the historical range of the Painted Rocksnail as restricted to the Coosa River and select tributaries above the Fall Line at Wetumpka, Alabama, rather than extending into the Alabama River as previously thought. Leptoxis coosaensis is in dire need of conservation, and management plans should take into consideration the revised historical range of the species.

Life histories, including anatomy and behavior, are a critically understudied component of gastropod biology, especially for imperiled freshwater species of Pleuroceridae. This aspect of their biology provides important insights into understanding how evolution has shaped optimal reproductive success and is critical for informing management and conservation strategies. One particularly understudied facet is seasonal variation in reproductive form and function. For example, some have hypothesized that females store sperm over winter or longer, but no study has explored seasonal variation in accessory reproductive anatomy. We examined the gross anatomy and fine structure of female accessory reproductive structures (pallial oviduct, ovipositor) of four species in two genera (round rocksnail, Leptoxis ampla (Anthony, 1855); smooth hornsnail, Pleurocera prasinata (Conrad, 1834); skirted hornsnail, Pleurocera pyrenella (Conrad, 1834); silty hornsnail, Pleurocera canaliculata (Say, 1821)). Histological analyses show that despite lacking a seminal receptacle, females of these species are capable of storing orientated sperm in their spermatophore bursa. Additionally, we found that they undergo conspicuous seasonal atrophy of the pallial oviduct outside the reproductive season, and there is no evidence that they overwinter sperm. The reallocation of resources primarily to somatic functions outside of the egg-laying season is likely an adaptation that increases survival chances during winter months.

Life histories of the imperilled freshwater gastropod genus Leptoxis are poorly known, and this information is required to achieve a basic understanding of the evolution of this diverse group and to develop management strategies for species conservation and recovery. We describe egg-laying behaviours and associated traits for all 13 extant Leptoxis species. We also explore patterns of shell growth and assess the extent to which intraspecific shell variation is a result of phenotypic plasticity or genetic differences. Each Leptoxis species exhibits one of three distinct oviposition strategies: deposition of single eggs, deposition of eggs in a single line or deposition in circular clutches. Temperature cues for initiating egg laying varied from 12 to 26 8C depending on the species. There were significant differences in clutch size among species and between populations of L. ampla and L. taeniata. Furthermore, 1- and 2-year-old female L. foremani laid significantly fewer eggs per clutch than females 4 years or older. Finally, discrete shell morphologies that are characteristic of any given species are genetically controlled and not an ecophenotypic response. Clutch egg laying likely represents increased parental investment compared with other behaviours and clutches may provide individual eggs protection from predation or passive dislodgement. Data from this study, including necessary conditions for successful culturing and period of oviposition for each species, can inform captive propagation efforts for imperilled Leptoxis species and aid in predicting how they will respond to future habitat alteration and climate change.

The Oriental region is among the world's biologically most diverse regions, but also among the most biotically threatened, especially with regard to freshwater biota. The Cerithioidea comprise several families and are a major component of the freshwater gastropod fauna in the Oriental region. Among these, the Paludomidae include numerous taxa mostly described in the 19thcentury that are in many cases badly in need of revision. As an initial step towards a better understanding of the evolutionary systematics of the family, we here review the genus-group taxonomy and nomenclature of Asian Paludomidae. We show that Paludomus Swainson, 1840, Philopotamis Layard, 1855, GangaLayard, 1855, and OdontochasmaTomlin, 1930, are available names for morphology-based genus-group taxa of Asian Paludomidae. By selection of Melania modicella I. Lea & H. C. Lea, 1851, as type species of Rivulina I. Lea & H. C. Lea, 1851, and by the designation of a neotype for Paludomus (Hemimitra) retusa Swainson, 1840, Rivulina and Hemimitra Swainson, 1840, can both be regarded as synonyms of Paludomus s. str. By selection of Paludomus sulcatus Reeve, 1847, as its type species, Heteropoma Benson, 1856, becomes an objective junior synonym of Philopotamis Layard, 1855. Furthermore, we show that the type species of TanaliaGray, 1847, which has often been used for a subdivision of Paludomus or as a distinct genus, belongs to the Neritidae and that Odontochasma Tomlin, 1930, has been validly proposed as a replacement name for the preoccupied name Stomatodon Benson, 1862. Finally, we revise Paludomus (Odontochasma) stomatodon Benson, 1862, on the basis of available type material, describe its radula for the first time, and compare it with published data on radulae of other Asian paludomids. Taxonomic redundancy in the genus-group in Asian Paludomidae is estimated to be 50% and may be as high as 88% depending on taxonomic opinion.

Cerithium koperbergi is a rare gastropod of the family Cerithiidae from the tropical Indo-West Pacific. The species has a small, unusual shell and often inhabits deeper water, fore-reef habitats that are atypical for the genus. Anatomical investigations reveal that it possesses a combination of features heretofore considered diagnostic of two main cerithiid subfamilies: Cerithiinae and Bittiinae. While the shell is bittiine, the animal lacks mesopodial pedal glands and possesses a seminal receptacle (vs. a spermatophore bursa) in the lateral lamina of the oviduct, which are considered to be cerithiine features. Re-evaluation of the anatomy of Bittium reticulatum, the type species of Bittium, indicates the defining anatomical difference in oviduct anatomy between the two subfamilies does not stand up to closer scrutiny. Partial mitochondrial cytochrome c oxidase I (COI) sequences support the interpretation that C. koperbergi is a species complex around the western Pacific rim comprising three divergent mitochondrial lineages. Bayesian analysis of partial mitochondrial COI and 16S rRNA sequences confirm the placement of the C. koperbergi complex within a monophyletic Bittiinae, despite the apparent absence of a unifying anatomical feature. Species in the C. koperbergi complex are here united in Pictorium nov. gen. and two species are described as new. It is hypothesized that features of the midgut may be diagnostic of the Bittiinae, but more comparative data are needed.

The West Indies, well known for its distinctive geological history, is well suited for studies in biogeography and biodiversity. However, the lack of comprehensive studies for much of its unique fauna has hampered insights into their systematics, evolution and phylogeography. The scarcity of data is particularly pronounced for freshwater gastropods in the viviparous family Thiahdae — represented in the archipelago by Hemisinus Swainson, 1840 and Cubaedomus Morrison, 1951. Hitherto described only on the basis of shell morphology, we here redescribe Hemisinus lineolatus (W. Wood, 1828), the type species of Hemisinus, based on type material and museum collections. The anatomy of this species is also described, representing the first such comprehensive study of any Neotropical thiarid. The synonymy of Hemisinus buccinoides Reeve, 1860, with H. lineolatus is confirmed. The species is found to possess a mixture of distinctly thiarid features (e.g., operculum, rachidian, midgut, brood pouch) and feature...

The Cerithioidea is a large and diverse superfamily of marine, brackish, and freshwater snails. The complexity and variety of midgut features within this group have long been known, but have been underutilized as a resource of characters for phylogenetic analysis. Consequently, this group is an ideal system for assessing the utility of midgut anatomy at lower systematic levels. Midgut anatomy of 46 cerithioidean gastropods and two outgroup taxa (Campanilidae, Plesiotrochidae) is described. A subset of these taxa, combined with published and unpublished descriptions for several additional species, were coded for 28 midgut characters. These characters were integrated with a large multi-organ system data set for 56 taxa, comprising 123 characters from the shell, radula, foregut, kidney, nerves, sperm ultrastructure, and reproductive system. The morphological matrix was analysed using parsimony, and was combined with a molecular data set of 16S and 28S rRNA sequences, and then analysed using parsimony and Bayesian methods. Optimization of midgut characters on the resulting cladograms indicates that midgut characters provide conservative and informative sources of variation at all hierarchical levels, from basal nodes to within family-level taxa. Exploratory analyses including and excluding midgut characters demonstrate the impact of midgut characters in elucidating phylogenetic relationships of cerithioideans, particularly among and within freshwater clades. Statistical analyses of retention index values for characters mapped on both the morphological and morphological plus molecular topologies confirm that midgut characters have significantly higher phylogenetic signals than other morphological characters. In the case of cerithioidean phylogeny, the importance of midgut data as a resource of characters cannot be overstated. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 585–630.

The Cerithioidea is an ecologically important superfamily of basal Caenogastropoda with speciose marine, brackish water, and freshwater lineages primarily in tropical, subtropical, and warm temperate regions of the world. They often represent significant components of the communities where they occur and have given rise to several spectacular endemic radiations in rivers and ancient lakes. Earlier attempts to resolve the phylogenetic history of the group have been based on smaller taxon and character subsets with incongruent results. Here the monophyly and phylogeny of the group is evaluated with expanded morphological and molecular (16S, 28S rRNA) data sets. For morphological analyses, 151 characters (shell, operculum, radula, alimentary tract, kidney, nervous system, reproductive anatomy, and sperm ultrastructure) were scored for 47 cerithioideans (representing 17 families) and nine outgroup taxa. To test monophyly of the Cerithioidea, extended molecular data sets of 16S and 28S sequences for 57 and 44 taxa, respectively, were compiled using new and previously published sources. For combined analyses, a pruned molecular data set was combined with the morphological partition. The morphological data were analysed alone using only parsimony; molecular and simultaneous analyses were performed using both parsimony and Bayesian inference. The effect of excluding unconserved regions of the alignments was also explored. All analyses, with the exception of the individual 16S and 28S data sets, support monophyly of the Cerithioidea as currently formulated. Of the 12 families represented by more than one terminal, only two (Planaxidae, Potamididae) are always supported as monophyletic; Batillariidae, Cerithiidae, Pachychilidae, Pleuroceridae, Semisulcospiridae, Thiaridae, and Turritellidae are monophyletic in most but not all topologies. The combination of diverse data sources (morphology, 16S and 28S sequences) and inclusion of unconserved regions of the alignments improved the recovery of monophyletic families. At deeper levels, a consensus is beginning to emerge in the recognition of three main assemblages, but whether these represent clades or grades is still unclear; the resolution of these assemblages and the branching order within them are sensitive to exclusion of unconserved regions and choice of optimality criterion. No clear conclusion is reached with respect to the number of freshwater invasions, with two invasions supported on some topologies and three supported on others. Progress toward a robust and stable resolution of cerithioidean relationships will require (1) strategically coordinated sampling for additional morphological and molecular data; (2) comprehensive anatomical treatments for several poorly documented limnic lineages (e.g. Melanopsidae, Thiaridae) and comparative data for poorly understood organ systems (e.g. renal system); (3) the addition of poorly known, minute, and/or rare marine taxa, to provide novel character combinations, insight into putative homologies, and to help anchor basal nodes and break up long branches. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 43–89.

Partial nucleotide sequences ( approximately 8000 bp) of the mitochondrial DNA of two cerithioidean gastropod species-Cerithidea djadjariensis and Batillaria cumingi-were determined. The order of mitochondrial genes (eight protein genes, two ribosomal RNA genes, and nine transfer RNA genes) was identical between these two species. and remarkably different from the previously reported order in other gastropods. The results indicate that the genome structure of the common ancestor of Cerithioidea and its sister group, Hypsogastropoda, is almost identical to that of the common ancestor of Gastropoda; moreover, independent mitochondrial genome rearrangements were identified between the lineages of Cerithioidea and Hypsogastropoda. The rearrangements within Cerithioidea can be explained by the inversion of a single tRNA gene, two translocations of a single tRNA gene, and three translocations of a genome fragment containing a tRNA gene and protein-coding gene(s).

Pachychilid gastropods are a conspicuous element of the freshwater macro-invertebrate fauna of South-East Asia. In this region, three spatially separated groups of pachychilids can be differentiated mostly by means of their brooding strategy. The largest group comprises about 100 described species and displays an extended Sundaland distribution that ranges from north-east India in the west to southern China in the east and Borneo in the south-east. The most conspicuous synapomorphy shared by females is a subhaemocoelic brood pouch in which developing embryos are retained. Mitochondrial phylogenies based on partial sequences of the genes cytochrome oxidase C subunit I (COI) and 16S rRNA (16S) support the monophyly of this group of subhaemocoelic brooders. Amongst them, the two genera Brotia and Paracrostoma form a sister pair of clades both together forming the sister taxon of a third clade. This third clade itself is split into three subclades, which occupy separate ranges except for the overlap of two of them in Borneo. The subclades comprise species from (A) Thailand, Cambodia, and northern Borneo; (B) Java and south-western Borneo; and (C) Vietnam and southern China. In contrast with their spatial structuring, all species share a widely corresponding anatomy. Characteristic key features are a pallial oviduct with a seminal receptacle and an embryonic shell with a smooth, dome-like inflated apex. Differences in the histology of the pallial oviduct are not congruent with phylogenetic patterns as suggested by the mitochondrial trees. Given the lack of obvious distinguishing morphological characteristics, all species of the subclades A to C are assigned to a single genus, Sulcospira, with Adamietta as a junior synonym.

The Batillariidae are a family of cerithioidean gastropods consisting of 14 living species, classified in six to eight genera. They are abundant on sandy mudflats and sometimes on rocky shores, on continental margins in the warm-temperate to tropical regions of the northwestern Pacific Ocean, Australasia and the Americas. Using samples from all 14 nominal batillariid species, we present a molecular phylogenetic hypothesis constructed from two genes, mitochondrial 16S rRNA and nuclear 28S rRNA, with taxa from four marine cerithioidean families as outgroups (Cerithiidae, Modulidae, Planaxidae, Potamididae). The Batillariidae as traditionally conceived are not monophyletic, because the Neotropical ‘batillariids’Lampanella and Rhinocoryne are sister to the Planaxidae. The monophyletic Batillariidae sensu stricto are restricted to the northwestern Pacific and Australasia; we suggest a revised generic classification consistent with our phylogenetic hypothesis and recognize the four genera Batillaria, Pyrazus, Velacumantus and Zeacumantus. We propose a definition of the family using shell characters, as a basis for a review of the extensive fossil record. Batillariids appeared in the Late Cretaceous or Palaeocene, and the extinct genera Pyrazopsis, Vicinocerithium and Granulolabium became diverse in the Tethyan realm before the group disappeared from Europe at the end of the Miocene. The Batillariidae s. s. reached Australia and New Zealand by the Late Oligocene, and the genera Pyrazus, Velacumantus and Zeacumantus still survive in this refugium of Tethyan fauna. Two lineages, Batillaria and the extinct Tateiwaia, migrated north to China and Japan in the Early Miocene, to establish the present disjunct distribution of this relictual group in southern Australasia and the Oriental region.

Morphological and molecular studies have been inconclusive in assessing monophyly of the Pleuroceridae s.l and the affinity of western North American Juga to Asian members of the family currently grouped in the Semisulcospirinae. In part, this has been hampered by the rarity of anatomical accounts for Asian pleurocerids (s.l.). The present study provides a comprehensive anatomical description of ‘Melania’jacqueti— a Vietnamese species of uncertain generic placement forgotten in the scientific literature for over 100 years. This investigation confirmed that ‘Melania’jacqueti and Juga possess a number of features that differentiate them from eastern North American species, including features of the kidney, prostate and pallial oviduct. However, comparative data remain inadequate to allow phylogenetic analysis based on morphological data alone. Consequently, a data set of partial mitochondrial 16S ribosomal RNA gene sequences for 51 pleurocerids (s.l.) and five outgroups (Melanopsidae, Thiaridae), was assembled. Parsimony, Bayesian and Maximum Likelihood analyses are largely congruent and support monophyly of the Pleuroceridae s.l., and of two large clades: (i) a clade of eastern North American species, and (ii) an Asian–American clade with ‘Melania’jacqueti as the critical basal offshoot, decisively anchoring Juga within the Semisulcospirinae as sister to all remaining Asian forms. Given the morphological disparity between these two clades, this result is consistent with restriction of the concept of Pleuroceridae s.s. to eastern North American species, and elevation of the Asian–American clade to the rank of family — the Semisulcospiridae. Examination of available genus-group names for Oriental semisulcospirids supports placement of ‘Melania’jacqueti in the genus Hua. Molecular calibration of the basal split between Semisulcospiridae and Pleuroceridae suggests they diverged in the Cretaceous (approximately 90 million years ago). The origin and diversification of these clades are roughly coincident with the subdivision of Laurasia by epicontinental seas and the opening of the Atlantic basin, consistent with a primarily vicariant explanation for their modern biogeographical distributions modified by dispersal in Juga.

Three European melanopsids: Melanopsis parreyssii (Philippi, 1847) from Ochiul Mare (Romania), Fagotia acicularis (A. Ferussac, 1828) from a spring near Crisul Negru (Romania), and Holandriana holandri (C. Pfeiffer, 1828) from Lake Skutari (Montenegro), as well as Melanopsis costata Oliver, 1804 from Iraq, are considered is this paper. Eight partial sequences of ribosomal 18S, and seven of mitochondrial COI were analysed. Maximum likelihood trees based on 18S confirm the placement of the Melanopsidae within the Cerithioidea, as well as the monophyly of the latter group. The COI-based tree confirms the placement of the Melanopsidae within the Cerithioidea, but does not confirm the monophyly of either Melanopsidae or Cerithioidea. The results suggest that Fagotia should be synonymised with Melanopsis, Holandriana is a distinct genus, and Melanopsis costata is not congeneric with M. parreyssii. The application of molecular clock, with one point calibration for COI for the Hydrobiidae, estimated the times of divergence as 2.53±0.56 Mya for M. parreyssii and F. acicularis, 9.49±1.67 Mya for M. parreyssii and H. holandri, and 10.71±1.88 Mya for F. acicularis and H. holandrii. 2.5 Mya coincides with the beginning of the glacial period in Europe, and 8–12 Mya was the time when Lake Pannon covered the largest area.

We document a case of shell convergence in sympatric freshwater cerithioidean gastropods that has caused confusion in traditional classifications emphasizing shell features. Based on the comparative study of the operculum, radula, and embryonic shell obtained from dry remains of soft bodies, we present evidence that “Melania” pisum is not a thiarid species closely related to Balanocochlis glans (Busch, 1842), as has been supposed with respect to the very similar shells of both species. The species is transferred to the family Pachychilidae, because it shows various typical character states for the family. It is tentatively placed within the genus Sulcospira, which is endemic to Java. We assume that a similar shell shape has evolved in both species of not closely related gastropods through convergence, which once more reveals that purely shell-based classifications are particularly problematic.

The minute syrnolopsine gastropods endemic to Lake Tanganyika have been allied to a number of freshwater, marine and terrestrial groups as a consequence of superficial conchological similarity. Although early anatomical studies confirmed the cerithioid organization of this clade, their close relationship to other lake species was not consistently recognized. In several recent cladistic analyses based on molecular data, the higher taxonomic placement and sister group relationships of syrnolopsines have been unstable. The present analysis confirms that syrnolopsines possess a spermatophore-forming organ – a synapomorphy of the Paludomidae – corroborating their placement in this family. Consistent with the molecular data, syrnolopsine monophyly is supported by two characters that occur exclusively in this group (salivary gland ducts that bypass the nerve ring and a linear albumen gland). Several characters in Martelia tanganyicensis– the most diminutive syrnolopsine – are only evident in the smallest lake species thus far investigated (Bridouxia, Stormsia) namely reduction of ctenidial leaflets, sorting area, intestine length and number of statoconia. These features are interpreted as being correlated with reduction in size. Nevertheless, close examination reveals differences in detail that allow more refined hypotheses of homology and are consistent with their independent origin.

Pleurocerid gastropods are ecologically prominent and diverse members of the North American freshwater malacofauna. However, their systematic study has been greatly complicated by pronounced conchological variability. Almost 1,000 taxa have been described north of Mexico, although this inflated estimate has been reduced by serial synonymization to 152 or 153 nominal species, comprising seven genera. Pleurocerid diversity is not evenly spread across continental watersheds. Only nine nominal species, placed in the genus Juga, are found in the drainages west of the Rocky Mountains. Juga was expressly erected to house the western taxa, but there are no diagnostic conchological characters to separate them from eastern con-familials and they had previously been regarded as western lineages of Elimia (formerly known as Goniobasis ). Consequently, identification keys have used biogeographic criteria to distinguish Juga (west of the Continental Divide) from Elimia (east of the Continental Divide) taxa. Until recently, the systematic validity of the genus Juga was rather tenuous, resting primarily on hints of oviductal groove structural distinctions. However, molecular phylogenetic data have now clearly demonstrated Juga’s separate evolutionary history. In a study of North American pleurocerid relationships, three species of Juga, including the type species Juga silicula (Gould, 1847), formed a robust clade sister to all of the genotyped eastern taxa. A subsequent study incorporating a global sampling of Cerithioidea emphasized the phylogenetic distinctiveness of Juga, finding it to be sister to the eastern Asian pleurocerid genera Hua and Semisulcospira. However, not all Juga species have been incorporated into molecular phylogenies and there are morphological and karyological lines of evidence to suggest that some nominal taxa occurring in the Columbia River drainage may actually be geographically disjunct members of the eastern genus Elimia. A century ago, a species of pleurocerid, Goniobasis columbiensis Whiteaves, 1905, was described from material collected in 1883 by J.B. Tyrrell at the headwaters of the Columbia River that represented ‘the first non-plicate Goniobasis, of the type of G. livescens, that has been found in the Pacific drainage system.’ Goodrich examined Whiteave’s type material and found that the ‘shell characters and opercula are identical with those of livescens of Lake Erie,’ but concluded that they were more likely to represent mislabeled eastern specimens rather than a geographically disjunct western population. More recently, a karyological study of North American pleurocerid taxa included a single Juga species, J. hemphilli (Henderson, 1935), sampled from Benton County, Oregon that exhibited an identical ideogram to E. livescens (Menke, 1830). Though constrained by the lack of karyological data for other Juga taxa, this surprising result suggested to us that J. hemphilli might well represent a cryptic western Elimia lineage. Henderson described Juga hemphilli, together with two subspecies, from lower Columbia River drainage locations, although Goodrich subsequently listed it, together with Whiteave’s G. columbiensis, as a species incerta. The goal of our study was to phylogenetically test, using gene trees, the hypothesis that Juga hemphilli is a cryptic western member of the genus Elimia. Specimens of J. hemphilli dallesensis (Henderson, 1935), sampled from the type locality, were kindly provided by F.G. Thompson (Fig. 1) and, together with the representatives of all extant eastern North American pleurocerid genera except for Lithasia (Table 1), they were sequenced for a portion of the nuclear large subunit ribosomal gene (28S). The choice of this gene fragment was driven by the need to avoid a potentially confounding issue – within-species mitochondrial (mt) polyphyly – that has complicated freshwater cerithioidean molecular phylogenetic studies using exclusively mt markers. –24 This is especially pertinent for North American pleurocerid taxa where pronounced within-population mt heterogeneity may occur and the only available case of mt/ nuclear genome comparison is surprisingly incongruent. Mobile basin Leptoxis picta (Lea, 1841) and L. taeniata (Tyron, 1873) were indistinguishable in terms of allozyme frequencies at nine loci but exhibited highly divergent mt genotypes, both in terms of sequence divergence [19% for mt large RNA subunit (16S)] and phylogenetic placement. In addition to the target nuclear rDNA marker, we also took advantage of the extensive GenBank submissions of pleurocerid mt 16S

With few exceptions, spermatozoa-encapsulating packages in molluscs are known mostly from cephalopods and pulmonate gastropods. Among non-stylommatophoran gastropods, the marine Cerithioidea are second only to the Neritimorpha in the number of species that posess a spermatophore, but they have only rarely been found in freshwater taxa of this superfamily. We describe and compare here the sperm packages of 11 paludomid cerithioideans as part of an ongoing study on the evolution and systematics of the thalassoid (i.e., “marine-like”) endemic species flock from Lake Tanganyika. Stereomicroscopic and SEM examination revealed unexpected complexity in shape and structure of spermatophores within paludomids. In addition, we present a survey of other Cerithioidea, which revealed that spermatophores are in general structurally simple and confirmed their presence in 12 marine species (five families) and 15 limnic species (four families), including those of 10 thalassoid species for which spermatophores are described herein. Based on histological sections of the male genital tract, we hypothesize that spermatophores are formed anteriorly, wholly or in part, by the so-called spermatophore-forming organ, and which is considered a synapomorphy of the Paludomidae. In addition, we briefly discuss functional aspects inferred from morphological study of the spermatophore-forming organ, with possible implications for spermatozoan transfer and fertilization. Finally, we place the features of the spermatophores and the spermatophore-forming organ in a phylogenetic framework of cerithioidean and paludomid systematics, which suggests that the spermatophore-forming organ is a synapomorphy of Paludomidae, that a bifurcate spermatophore structure is plesiomorphic, and that the evolution of structurally complex, spiny spermatophores has occurred independently in disparate lineages within the thalassoid species flock.

Summary Spermatogenesis in Serpulorbis squamigerus and S. variabilis was studied with light and electron microscopy. In spite of their unusual method of accomplishing internal fertilization by the use of spermatophores, the genesis and structure of vermetid eusperm is in most respects typical of Hypsogastropoda (sensu Ponder and Lindberg, 1997). However, vermetid eusperm have evolved a complex acrosome with a number of unique features not previously described in this taxon. Parasperm of vermetids are easily distinguished by their unique shape, but are more similar in their development to parasperm of some Hypsogastropoda than they are to those of Cerithioidea and Campaniloidea. One feature that was thought previously to provide a link with Cerithioidea and related groups, is the presence of the tail brush in mature parasperm. However, in Serpulorbis variabilis the tailbrush is reduced or lost in some parasperm at maturity and in S. squamigerus it is completely replaced by the terminal bulb, which is synap...

Siliquariid Tenagodus (synonym: Siliquaria) snails are obligatory sponge commensals, with uncoiling and laterally slitted shells embedded inside Demospongiae hosts, and shell apertures facing the outside allowing for respiratory and gill-filter-feeding activities. Live-collected animals observed in situ within hosts provide the first detailed functional morphological study of the group, and form the basis for systematic revision of the western Atlantic members of type genus Tenagodus (Siliquariidae, synonym: Tenagodidae). Three species are recognized. Overall anatomical features of wide-ranging Atlantic T. modestus (Dall, 1881) and T. squamatus (de Blainville, 1827) [ = T. anguillae Morch, 1861] are similar to those previously described for New Zealand Pyxipoma. A third species, Tenagodus barbadensis sp. nov., is described from Barbados, based on shell characters. The three species live embedded in a few species of halichondriid and thrombid sponges at depths ranging from c. 20 to several hundred metres and show several characters not previously documented for the family. These include a short compressed-S-shaped osphradium, an anal opening positioned in the posterior mantle cavity, and cuspidate inner marginal radular teeth. Presence of shell septa sealing earlier parts of the shell, first described in the early 1800s but subsequently disputed, was verified. Observations on living T. squamatus demonstrated the use of the large tight-fitting operculum in plunger-like fashion, flushing the mantle cavity and discharging waste material (including faeces from the posteriorly located anus) through the shell slit into the host sponge's aquiferous canal system. Uncoiling shells, shell and mantle slits, and specialized opercular, gill and gut morphology are interpreted as adaptive traits of the sessile mode of life embedded in sponge tissue. Actively maintained linkage between snail and sponge water-flow systems provides mutual benefits; these include the allowance for rapid defensive withdrawal and return-to-feeding position of the snail (by using the sponge canal system as a vent or reservoir for displaced water), sanitation of the mantle cavity (waste material can leave the snail through the shell slit at the posterior end of the mantle cavity, avoiding fouling of the gill-feeding system), and by providing increased water flow and, potentially, extra nutritional particles for the sponge (food and waste particles stemming from the snail's activity). The lectotypes selected herein are Serpula anguina Linnaeus, 1758, Tenagodus anguillae Morch, 1861, and Siliquaria modesta Dall, 1881. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140, 307–333.

A thiarid gastropod, Vinundu westae new genus and new species, is described from Lake Tanganyika, and the species Nassopsis guillemei Martel & Dautzenberg, 1899 is transferred to this new genus from Edgaria (� Lavigeria). The shell of Vinundu has equal axial and spiral macrosculpture, producing characteristic regular nodes at the sculptural intersections. Reproduction in Vinundu is oviparous, in contrast to the ovoviviparous habit of its sister group, Lavigeria. Radular teeth and isotope values indicate that this is a grazer. Vinundu species are readily distinguished from their sister clade Lavigeria by conchological, anatomical and molecular characters. The two Vinundu species are common in deep water, rocky habitats of this clear-water, ancient lake.

The radiation of gastropods in Lake Tanganyika is an ideal system for testing competing hypotheses of species flock formation. Yet, much of the basic biology of these species remains unknown. In an ongoing effort to understand the evolution of Tanganyikan gastropods, we here describe Stanleya neritinoides. Alcohol-preserved material of the soft parts is rare, consequently, the systematic position of the species, and a repeated suggested affinity to Tanganyicia rufofilosa, have been based primarily on features of the shell. However, features of the radula and operculum are unique and do not suggest an affinity to any other Tanganyikan species. Thus, S. neritinoides has remained a particularly poorly known and enigmatic member of the species flock. This investigation confirmed that several aspects of internal and external anatomy are shared between S. neritinoides, T. rufofilosa, and other Tanganyikan gastropods, but that S. neritinoides is unique in features of the radula and seminal receptacle. Moreover, S. neritinoides differs from T. rufofilosa in features of the foregut, midgut, hindgut, kidney, nervous system, reproductive system and reproductive strategy. These new data are inconsistent with an interpretation of identity of Stanleya and Tanganyicia. In addition, given the pervasive differences between the two, a sister-group relationship between the two is unlikely. More precise systematic placement of S. neritinoides awaits the establishment of a phylogenetic framework for all Tanganyikan gastropods.

Freshwater snails of the genus Pseudopotamis Martens, 1894 exemplify one of the most enigmatic distributional patterns among limnic organisms in Australasia. These viviparous cerithioidean gastropods are endemic to the Torres Strait Islands, located on the Sahul shelf corridor between Australia and New Guinea. The occurrence of the two constituent species is highly restricted: P. supralirata (Smith, 1887) on Prince of Wales Island, and P. semoni Martens, 1894 on Hammond Island. Long recognized erroneously as members of the heterogeneous, polyphyletic and widespread Thiaridae, morphological and molecular data presented here reveal that the taxon has to be placed within Pachychilidae, a family otherwise absent from Australia. Comparison with other South East Asian pachychilids, in particular Brotia H. Adams, 1866, Tylomelania Sarasin & Sarasin, 1897, and Jagora Kohler & Glaubrecht, 2003 suggests that Pseudopotamis is most closely related to taxa endemic to Sulawesi (Celebes), thus occurring disjunctly about 2000 km to the west of the Torres Strait. It is only with the Sulawesi pachychilids that Pseudopotamis shares its peculiar uterine brood pouch. Consequently, all pachychilid taxa east of the much-debated Wallace's line (east of Bali, Borneo and the Philippines) possess this uterine incubatory structure. In this paper the historical background of the discovery, the taxonomic history, and an evaluation of the systematic position of Pseudopotamis is provided, including molecular genetic data (genes of cytochrome c oxidase subunit I and 16S ribosomal DNA). Finally, based on the phylogenetic assignment and the recent distribution, implications for a historical biogeography are discussed utilizing a recently developed model for the palaeogeography in Australasia. According to these available data, we favour early vicariant event(s) over recent dispersal.

Lakes provide ideal natural laboratories for the study of evolutionary processes. Research on an assumed adaptive radiation of a species flock of viviparous freshwater gastropods in the Malili lake system on Sulawesi, Indonesia, known for a century, led to the unexpected discovery of new taxa. Three new species of Tylomelania Sarasin & Sarasin, 1897, T. bakara n.sp., T. kruimeli n.sp. and T. helmuti n.sp., are described based on their easily recognizable and distinct shell morphologies. Unique combinations of radular and embryonic shell characters support their status as distinct species. Two of the new species are lacustrine: T. bakara is restricted to a single location with a specific substrate and habitat in Lake Towuti, while T. kruimeli is distributed throughout Lake Mahalona. In contrast, T. helmuti is fluviatile and occurs in a stream system draining into Lake Towuti. The discovery of new species within the species flock under investigation is surprising, since the range of forms seemed known and, after preliminary studies, even a reduction in the number of species recognized as valid was expected. This example highlights the importance of extensive and systematic collecting even on a rather small geographical scale for studies on the phylogeny and evolutionary biology of freshwater gastropods.

The new genus Jagora of the family Pachychilidae Troschel, 1857 is described for the type species Melania asperata Lamarck, 1822 from the Philippines. In addition to J. asperata, a second endemic species of the new genus, J. dactylus (I. Lea & H.C. Lea, 1850), is recognized on the basis of shell morphometry and molecular genetic data (cytochrome C oxidase I and 16S rRNA). The taxonomic history of J. asperata and J. dactylus is revised and the recent distribution documented on basis of available museum material and the authors’ own field collections. J. asperata occurs on Luzon and its satellite islands Leyte and Samar, while J. dactylus is restricted to the Visayan islands Bohol, Cebu, and Guimeras. The morphology of the two species is presented and illustrated in detail, and compared to taxa of the closely related genus Brotia H. Adams, 1866 to which they were previously assigned. Among the South-east Asian freshwater Cerithioidea of the family Pachychilidae, which were previously subsumed under Brotia for their more or less similar shell morphology and operculum, three distinct lineages can be distinguished, in particular by means of distinct reproductive anatomy: (1) the species of Brotia sensu stricto from mainland South-east Asia, Sumatra, Borneo and Java, which all exhibit a subhaemocoelic brood pouch; (2) the pachychilid species endemic to Sulawesi, currently assigned to the genera Brotia and Tylomelania, as well as both species of Pseudopotamis endemic to the Torres Strait Islands, which possess a uterine brood pouch; (3) the females of the Philippine Jagora, which carry egg capsules, embryos and advanced juvenile stages within the mantle cavity — a unique reproductive feature. Associated with this mode of ovoviviparity, Jagora is characterized by additional unique properties of the reproductive system including a deeply incised and long sperm gutter in the medial lamina, a very short and posteriorly positioned spermatophore bursa formed by the medial lamina, and a prominent lateral ridge functioning as a seminal receptacle. These characteristics are exclusive to Jagora and are consequently considered to represent autapomorphies of this clade which is endemic only to the Philippines. The zoogeographical implications are discussed in connection with a recently developed palaeogeographical reconstruction.

Ecophenotypic plasticity, or nonheritable variation of the phenotype with local conditions, has been invoked in order to partly explain conchological differences within freshwater snail species as responses to fluvial conditions and stream size (Adams, 1915; Lam & Calow, 1988; Minton, Norwood & Hayes, 2008; Minton et al., 2011), river substrate (Urabe, 1998, 2000) and presence or absence of predators (Holomuzki & Biggs, 2006; Hoverman & Relyea, 2007; Lakowitz, Bronmark & Nystrom, 2008). In the freshwater gastropod family Pleuroceridae, Dillon (2011) and Dillon & Robinson (2011) used similarities in allozyme loci to conclude that conchological differences (e.g. presence or absence of carinae, slenderness or robustness of shells) in multiple species of Pleurocera and Elimia were attributable to intraspecific ecophenotypic plasticity. However, no analysis of shell morphology was performed by Dillon (2011) or Dillon & Robinson (2011) to test for either an ecophenotypic or genetic component of the observed variation. In order to understand the effects of ecophenotypic plasticity on the presence or absence of carinae on the shell of one species of Pleuroceridae, we cultured two populations of Leptoxis ampla (Anthony, 1855), one with a carinate shell morphology and one with a smooth shell morphology (Fig. 1). In culture, these snails were exposed to uniform environmental conditions. Therefore, observed morphological differences among juveniles raised from egg to adult were not affected by the environment. Culturing methods are ideal for analysing variation in shell morphology in the Pleuroceridae because not only can environmental conditions be controlled, but complications arising from translocation experiments (such as transfer of disease vectors and the potential for mating with native populations) are avoided. Although culturing methods have not previously been used for studying ecophenotypic plasticity in Pleuroceridae, they have been successfully applied to other freshwater gastropod families such as Planorbidae (Hoverman & Relyea, 2007) and Lymnaeidae (Lam & Calow, 1988; Lakowitz et al., 2008). Leptoxis ampla is a federally threatened pleurocerid restricted to the upper Cahaba River and certain tributaries in central Alabama. Throughout most of its range the shell morphology is smooth (Fig. 1), but one population from the lower Little Cahaba River in Bibb County, AL, USA, possesses a distinct shell phenotype characterized by 3–4 carinae on the upper part of each whorl (Fig. 1). Based on analyses of L. ampla populations cultured in a uniform environment we show that the presence or absence of this discrete character is the result of heritable genetic differences rather than ecophenotypic plasticity. The carinate form of L. ampla from the Little Cahaba River was described as L. mimica (Goodrich, 1922) based on the presence of its distinctive carinae (Fig. 1). This was later synonymized with L. ampla (Fig. 1), because of similarities in overall shell morphology (Burch & Tottenham, 1980). Populations above and below the confluence of the Little Cahaba River and Cahaba River possess a smooth shell morphology. The carinate form was historically found in both the Little Cahaba River and Six Mile Creek in Bibb County, AL, USA (Goodrich, 1922), but recent survey work indicates that it is now restricted to the lower Little Cahaba River (unpublished ADCNR survey data). The morphological pattern seen in L. ampla is not an example of clinal variation as in, for example, Lithasia geniculata (Minton et al., 2008) or Io fluvialis (Adams, 1915), since there is no intergradation in morphology and the carinate form is restricted to a single tributary near the centre of the species’ historical range. In mid-March 2010, we collected 45 adult individuals of L. ampla from the Cahaba River with smooth shells and 45 individuals from the Little Cahaba River with carinate shells and placed them into artificial culture systems at the Alabama Aquatic Biodiversity Center (AABC) in Marion, AL, USA (see Table 1 for locality information). No differences in body pigmentation or shape of egg clutches were observed between populations. Fifteen snails (three replicates per population) were placed in 20-l acrylic tanks equipped with 0.84-cm bulkhead fittings allowing constant exchange of well water acclimated to ambient outdoor temperature (c. 8 l/h). Each 20-l culture tank had water from a shared source, but independent aeration and drainage. A 15 l/min powerhead attached to each tank lid created a constant flow regime. Females in all treatments attached eggs to tank walls in concentric clutches from late March to early June 2010. Within 90 d of hatching, cultured juveniles from each population showed the same phenotype as their parental population

A new species, Brotia praetermissa, is described from Borneo. The type material was found unidentified in the spirit collection of the Natural History Museum, London. It was collected by A. Everett in the nineteenth century. Using morphological characters, the new species is affiliated with the Brotia pago-dula species group. Representatives of this group can easily be recognized by the wrinkled apical shell of their protoconch. The species described herein is the only known representative of the likely mono-phyletic B. pagodula group in Borneo, while all other Brotia species known from this island are assigned to the Brotia testudinaria group. This finding renders it most likely that Borneo has been colonized twice by species of the genus Brotia, by the ancestor of B. praetermissa and that of the Brotia testudinaria group.

Tanganyicia rufofilosa is an enigmatic gastropod endemic to Lake Tanganyika and unique among lake species in possessing a brood pouch within the head-foot. However, the only existing anatomic studies of the species are incomplete. Hence, the affinity of this species to other Tanganyikan gastropods and the evolution of viviparity among limnic Cerithioidea are unclear. The anatomic redescription and reinterpretation of reproductive homologies presented here revealed several features from the midgut and kidney that are informative concerning the phylogeny of Lake Tanganyika gastropods. In addition, the complex reproductive anatomy of both sexes is described. A rare accessory gland is present in males that is hypothesized to function in spermatophore formation and to be homologous to the ‘penis’ of some cerithioideans, an otherwise predominantly aphallic group. The structurally unique brood pouch, restricted to the mesopodial portion of the foot, is described and demonstrated to be unknown among viviparous cerithioideans. In contrast to the view that the cerithioideans of Lake Tanganyika represent an endemic radiation of Thiaridae, based on these new data T. rufofilosa appears to be allied to the Paludomidae.

Summary The structure of the spermatozoa of four species of Melanopsis (Melanopsidae) is described by light and transmission electron microscopy. All species produce two types of spermatozoa, euspermatozoa (fertilizing) and paraspermatozoa (non-fertilizing). The eusperm of all species are about 42–44 μm long and have a morphology similar to that of other cerithioideans. The head is composed of a laterally flattened nucleus and conical acrosome of approximately equal size. The nucleus has a shallow posterior fossa which houses a centriolar derivative from which the axoneme emerges. The four equal-sized mitochondria of the midpiece are non-helically arranged around the axoneme. Each mitochondrion has an anterior flange and the cristae are plate-like. This midpiece arrangement suggests that the Melanopsidae are more closely related to the Modulidae, Potamididae and possibly Pachychilidae than to other cerithiacean taxa. Posterior to the midpiece is a 10–12 μm-long glycogen piece in which the glycogen granule...

The Pleuroceridae Fischer, 1885, is one of three freshwater gastropod families currently recognized in the superfamily Cerithioidea Ferussac, 1819 (Mollusca: Caenogastropoda Cox, 1960). Despite considerable literature justifying various proposed generic names of North American pleurocerids, no study has been conducted examining phylogenetic relationships of the recognized genera. In an effort to expand our understanding of evolutionary relationships of North American pleurocerid genrea, we examined a large portion of the mitochondrial 16S rRNA gene among 32 extant North American taxa. Multiple sequence alignment of the amplified region for our taxa resulted in a matrix consisting of 900 nucleotides including insertions and deletions. Based on analysis of nucleotide substitution patterns, we employed two approaches in our phylogenetic analysis: (1) all substitutions received equal weighting and (2) transversions were weighted 2X and 4X transitions to compensate for transition saturation among distantly related taxa. The molecular phylogeny based on the mitochondrial 16S rDNA sequences supports the monophyly of Pleurocera Rafinesque, 1819, Elimia H.&A. Adams, 1854, and Juga H.&A. Adams, 1854, but depicts the genera Lithasia Haldeman, 1840, and Leptoxis Rafinesque, 1819, as polyphyletic. The genus Pleurocera is sister to Elimia, which in turn is sister to a paraphyletic assemblage including representatives of Leptoxis, Lithasia, and the monotypic genus Io Lea, 1831. Juga, a genus restricted to west of the North American continental divide is the basal-most clade and is sister to all the aforementioned genera found east of the continental divide.

Phylogenetic analyses of partial sequences spanning approximately 450 nucleotides near the 5’end of the 18s rDNA strongly support the monophyly of Apogastropoda and its constituent clades, Caenogastropoda and Heterobranchia. Representatives of the architaenioglossan groups Cyclophoroidea, Ampullariidae and Viviparidae invariably emerge within Caenogastropoda in all analyses. While the Cyclophoroidea and Ampullariidae are monophyletic, the varying position of Viviparidae in all outcomes contradicts its hypothesized sister group relationship with Ampullariidae, and thus the monophyly of Ampullarioidea. Because of the position of Viviparidae, Architaenioglossa does not emerge as a clade in any of our analyses. Campanile consistently emerges between Cyclophoroidea and Cerithioidea, or in a clade with Cyclophoroidea and Ampullariidae, a position not predicted by previous morphological studies. Maximum parsimony analyses of sequence data show Caenogastropoda to comprise a series of sequentially diverging higher taxa. However, maximum likelihood analyses as well as maximum parsimony analyses using only trans-versions divide Caenogastropoda into two clades, one containing the architaenioglossan taxa, Campaniloidea and Cerithioidea, the other containing the higher caenogastropod taxa included in Eucaenogastropoda (Haszprunar, 1988) [= Hypsogastropoda (Ponder & Lindberg 1997)l. Denser taxon sampling revealed insertions to be present in the 18s rDNA gene of several caenogastropod taxa. Earlier reports (Harasewych et al. 1997b) of reduced sequence divergence levels in Caenogastropoda are shown to be restricted to Hypsogastropoda. Based on a broader taxonomic sampling, divergence levels within Caenogastropoda are comparable to those found within Heterobranchia.

The most basal gastropods (Patellogastropoda and Vetigastropoda) normally show external fertilization correlated with the possession of the so-called primitive type of sperm (aquasperm sensu Rouse & Jamieson 1 ). By contrast, in Neritimorpha and derived gastropods (Apogastropoda) fertilization is always internal and spermatozoa have become extensively modified (introsperm). In the Apogastropoda, the sperm are usually deposited in the female by a penis, but some Caenogastropoda (e.g. Cerithioidea, Vermetoidea, Triphoroidea, Janthinoidea, among others) have long been known to be aphallic, 2 a feature commonly associated with open pallial gonoducts. In aphallic gastropods, sperm transfer is achieved by means of water currents entering the mantle cavity or is more often linked with the formation of spermatophores or spermatozeugma. In species of Cerithioidea and Vermetoidea, the development of

Using sperm ultrastructure the systematic placement and affinities of the caenogastropod family Plesiotrochidae are re-examined. The simultaneous hermaphrodite, Plesiotrochus crinitus Thiele, 1930, produces both euspermatozoa (uniflagellate, fertile sperm) and paraspermatozoa (bi- or triflagellate, infertile sperm). Features of each type of sperm clearly indicate that the Plesiotrochidae are closely related to the Campanilidae (Campaniloidea) and are not, as previously believed, referable to the superfamily Cerithioidea. Significant sperm synapomorphies of Plesiotrochus (Plesiotrochidae) and Campanile (Campanilidae) include the morphology of the eusperm midpiece (seven to nine straight mitochondria surrounded by a segmented, accessory sheath of membrane-bound vesicles) and morphology of the anucleate parasperm head (axial core of mitochondria surrounded by a bilaterally symmetrical arrangement of axonemes and dense vesicles). The characteristic substructure of the cerithioidean eusperm midpiece (four straight mitochondria each containing parallel, cristal plates) is not observed in Plesiotrochus or Campanile. Euspermatozoa of Plesiotrochus differ from Campanile principally in details of the acrosomal complex (Plesiotrochus with apical bleb, probable absence of an accessory membrane; Campanile without apical bleb, accessory membrane well developed), the transverse profile of all midpiece mitochondria (thin in Plesiotrochus; thick in Campanile), and morphology of the annulus (double ring in Plesiotrochus; single ring in Campanile). In addition, all observed paraspermatozoa of Plesiotrochus are anucleate, whereas in Campanile anucleate and nucleate paraspermatozoa are present. On the basis of sperm synapomorphies of Plesiotrochus and Campanile, the Plesiotrochidae are transferred from the Cerithioidea to the Campaniloidea.

Cette etude decrit la biologie de la reproduction de V.S.: mode de reproduction, fecondation, type de developpement des larves

We here describe a new species of cyclopid copepod, Eucyclops bathanalicola sp. nov., parasitic on a gastropod endemic to Lake Tanganyika, Bathanalia straeleni (Cerithioidea, Paludomidae). E. bathanalicola is distinguished by the possession of praecoxal claws on the maxillules, by the modified maxillae which lack any trace of an endopod on the powerful distal claw, and by the reduction of the maxillipeds to minute unarmed lobes. In the character states exhibited by the female body, antennules and swimming legs 1–5, the new species closely resembles a typical free living Eucyclops. The impact of the adoption of parasitism as a life habit is expressed primarily in the modification of the postmandibular mouthparts. As a member of the Cyclopidae, this species represents a unique foray into a parasitic lifestyle from an otherwise free-living group of copepods inhabiting Lake Tanganyika. This is the first record of a parasitic copepod on a mollusc host within this ancient lake and only the second family of freshwater gastropods reported to host copepods. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 146, 275–285. No claim to original US government works.

In the study of gastropod shell morphology, determination of comparable ontogenetic stages is crucial, because all the states that various shell features go through during ontogeny are preserved on the shell. The protoconch/teleoconch transition and marks of episodic growth are among the few ways of defining discrete, comparable, growth stages. In gastropods with determinate growth the attainment of adulthood may provide additional shell markers permitting comparison among individuals and taxa. Adulthood is reflected in shell morphology in ways as diverse as shell deposition covering all the previous whorls and radically changing the shape of the shell through to slight changes in the trajectory of the suture. While the very prominent adulthood-related changes of shell morphology have been used as systematic characters, the more moderate changes have not been studied in detail and their potential systematic value has been ignored. In this paper we give a detailed account of adult modifications of the shell appearing with cessation of growth. Our study group comprises eight closely related species of Lavigeria from Lake Tanganyika. We show that the ways adulthood is manifested are quite diverse. We describe eight characters of the aperture, the suture and the sculptural ornamentation. Character occurrence varies greatly among species. We show that characters appear in suites and that in many cases their appearance is connected to size. We use size as a proxy for adulthood and test whether character occurrence alone or its connection to size can help resolve species relationships. In both cases our characters confirm the monophyly of our ingroup and yield cladograms with various degrees of resolution of ingroup relationships. The coding method that yields the greater character congruence is the one that takes into consideration the connection between appearance of a character and size. This study demonstrates that ontogenetically correlated character transformations may nevertheless be phylogenetically independent. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140, 223−240.