Gastropod Genus Research Articles

New taxa of land snails from French Guiana

Three new species and a new genus of terrestrial gastropods are described from the Réserve naturelle des Nouragues in French Guiana. Cyclopedus anselini n. gen., n. sp. (forming new monotypical genus in the family Neocyclotidae Kobelt & Möllendorff, 1897) seems to be the smallest known cyclophoroid in the western hemisphere. The descriptions of the other two new species, Pseudosubulina theoripkeni n. sp. and P. nouraguensis n. sp., from the family Spiraxidae Baker, 1939, extend not only our knowledge of the geographical distribution of Pseudosubulina Strebel & Pfeffer, 1882 (previously known with certainty from Mexico only) but also the diagnosis of this genus, which now includes species with large penial stimulator and apertural dentition.

Finichnus, a new name for the ichnogenus Leptichnus Taylor, Wilson and Bromley, 1999, preoccupied by Leptichnus Simroth, 1896 (Mollusca, Gastropoda)

Tayloret al. (1999) proposed the ichnogenus Leptichnus for etching pits made by cheilostome bryozoans on calcareous substrates. Leptichnus has a Cretaceous (Maastrichtian) to Holocene range. The type ichnospecies is Leptichnus peristroma, with a holotype from the Coralline Crag Formation, Ramsholt Member (Pliocene), near Orford, Suffolk, England. Another ichnospecies named in the same paper is Leptichnus dromeus, with a holotype from the same locality. A third ichnospecies of Leptichnus, L. tortus, was named and described by Rosso (2008) from Upper Pleistocene sediments on the bottom of the Ionian Sea. We have recently learned that the name Leptichnus is preoccupied by a urocyclid terrestrial gastropod, LeptichnusSimroth, 1896, found in Kenya and Tanzania. The author, Heinrich Rudolf Simroth (1851–1917), apparently used the Greek roots leptos (‘flimsy, delicate, subtle’) and ichnos (‘track, footprint’) to note the narrow foot (and hence trail) of this African slug. Taylor et al. (1999) used the same roots in recognition of the shallow, delicate nature of the cheilostome etching pits. The descriptions of both taxa meet the requirements of the International Commission on Zoological Nomenclature (fourth edition of the International Code of Zoological Nomenclature, 1999). The ichnogenus LeptichnusTaylor, Wilson and Bromley, 1999, is thus a junior homonym of the gastropod genus LeptichnusSimroth, 1896. We propose the new name Finichnus nom. nov. to replace LeptichnusTaylor, Wilson and Bromley, 1999. To preserve the meaning of the original name, we are substituting the Greek finos (‘fine, delicate’) for leptos. The type ichnospecies of Finichnus is Leptichnus peristromaTaylor, Wilson and Bromley, 1999, by original designation. Editor. Sally Thomas

Phylogenetic and mixed Yule‐coalescent analyses reveal cryptic lineages within two South American marine snails of the genus Crepipatella (Gastropoda: Calyptraeidae)

AbstractThe presence of sibling species within the marine gastropod genus Crepipatella has complicated the taxonomy of members of the group. Since the establishment of the genus, 15 species have been described, but recent studies have indicated that there are only five valid species, two of which inhabit the coasts of Chile, namely C. dilatata and C. fecunda. The two species are morphologically indistinguishable as adults, but can be differentiated on the basis of their encapsulated developmental stages. The primary aim of this study was to reconstruct phylogeny within the genus, and to establish species limits of C. dilatata and C. fecunda, using mitochondrial DNA data. To this end, we used maximum parsimony, maximum likelihood, and Bayesian inference to reconstruct phylogenies using 589 bp of the cytochrome oxidase I (COI) gene. The mtDNA phylogenies were then used as input in a general mixed Yule‐coalescent (GMYC) analysis to estimate species boundaries. In addition, quarter likelihood mapping was used to test a posteriori the confidence of inner branch patterns in the phylogenetic tree. Both DNA tree‐based and GMYC methods provide support for five isolated lineages within this species complex. Our data also suggest that Late Pleistocene and Holocene fragmentation and subsequent range expansion events may have shaped contemporary genetic patterns of Crepipatella in South America.

Molecular phylogeny of the western North American pebblesnails, genus Fluminicola (Rissooidea: Lithoglyphidae), with description of a new species

The northwestern North American freshwater gastropod genus Fluminicola (Caenogastropoda, Lithoglyphidae) was previously hypothesized to be paraphyletic based on morphologic data, with F. virens positioned outside the clade containing other congeners. We further evaluated the phylogenetic relationships of Fluminicola using mitochondrial cytochrome c oxidase subunit I (COI) gene sequence data from 22 of 24 previously described congeners, a new congener (F. gustafsoni) that closely resembles F. virens morphologically, representatives of four other lithoglyphid genera, and several outgroups. A Bayesian analysis resolved two well supported Fluminicola clades, consistent with morphological heterogeneity. The clade composed of F. virens and F. gustafsoni was sister to the rest of the Lithoglyphidae; the clade containing the remaining congeners was sister to Somatogyrus. Our results confirm that Fluminicola is paraphyletic. However, this genus cannot be revised until the phylogenetic relationships of its possibly extinct type species are resolved. The new species described herein, F. gustafsoni, differs from F. virens in its smaller size, medium-convex and prominently shouldered teleoconch whorls, weakly angled shell aperture, presence of a well-developed rectangular wing on the outer marginal radular teeth, vertically oriented coiled oviduct, and in its COI sequences. Fluminicola gustafsoni is distributed in riverine habitats in the lower Snake River watershed.

Isolation, characterization and cross-species amplification of 15 microsatellite markers for the African species of the freshwater gastropod genus Bellamya

We isolated and characterized microsatellite markers for African species of the freshwater gastropod genus Bellamya. Fifteen out of 21 primer combinations, isolated from unpublished sequences, yielded in polymorphic products. The number of alleles ranged from 8 to 22 among the 37 scored individuals. The observed heterozygosity HO ranged from 0.571 to 0.919 and the expected heterozygosity HE ranged from 0.626 to 0.937. Evidence of null alleles were observed at three polymorphic loci. Cross-species amplifications were carried out for five additional African viviparid species and resulted in several polymorphic microsatellite markers, a high number of monomorphic loci as well as a few unsuccessful amplifications.

Rediscovery of Leptoxis compacta (Anthony, 1854) (Gastropoda: Cerithioidea: Pleuroceridae)

The Mobile River Basin is a hotspot of molluscan endemism, but anthropogenic activities have caused at least 47 molluscan extinctions, 37 of which were gastropods, in the last century. Nine of these suspected extinctions were in the freshwater gastropod genus Leptoxis (Cerithioidea: Pleuroceridae). Leptoxis compacta, a Cahaba River endemic, has not been collected for >70 years and was formally declared extinct in 2000. Such gastropod extinctions underscore the imperilment of freshwater resources and the current biodiversity crisis in the Mobile River Basin. During a May 2011 gastropod survey of the Cahaba River in central Alabama, USA, L. compacta was rediscovered. The identification of snails collected was confirmed through conchological comparisons to the L. compacta lectotype, museum records, and radulae morphology of historically collected L. compacta. Through observations of L. compacta in captivity, we document for the first time that the species lays eggs in short, single lines. Leptoxis compacta is restricted to a single location in the Cahaba River, and is highly susceptible to a single catastrophic extinction event. As such, the species deserves immediate conservation attention. Artificial propagation and reintroduction of L. compacta into its native range may be a viable recovery strategy to prevent extinction from a single perturbation event.

A New Record of Cymatium encausticum (Ranellidae: Tonnoidea: Gastropoda) from Korea

The Cymatium Roding, 1798 is a small- to large-sized marine gastropod genus. Three species has been reported thus far for Cymatium in the Korean waters. In general, Cymatium encausticum (Reeve, 1844) is known to occur in tropical seawaters including the Philippine Islands along with its congeners C. gutturnium, C. springsteeni, and C. exile. A single individual of the species was collected from Jejudo Island by SCUBA diving and morphological features were observed using a stereomicroscope. This is the first study to report the occurrence of Cymatium encausticum (Reeve, 1844) from the Korean waters, providing a detailed description of the species with the illustration for the shell morphology.

New species and genera of colloniids from Indo-Pacific coral reefs, with the definition of a new subfamily Liotipomatinae n. subfam. (Turbinoidea, Colloniidae)

ABSTRACT The genus Liotipoma McLean & Kiel, 2007, was proposed for a remarkable small-shelled gastropod genus from coral reefs of the Indo-Pacific that resemble the family Liotiidae Gray, 1850 in having fine axial lamellae and a thickened terminal lip, but differ in having the solid calcareous operculum of the family Colloniidae Cossmann, 1916. The genus was originally assigned to the otherwise Cretaceous subfamily Petropomatinae Cox, 1960 of the family Colloniidae, because the inner side of the operculum is multispiral, conical and projecting, as in the Mesozoic genera assigned to Petropomatinae. Here the genus Liotipoma is assigned to a new colloniid subfamily Liotipomatinae n. subfam., because its axial lamellae are unknown in the Cretaceous genera of Petropomatinae. Four genera are now recognised; all species are known from shell grit samples collected by diving or dredging at coral reefs from recent MNHN expeditions to New Caledonia, the Loyalty Islands, Espiritu Santo (Vanuatu) and Wallis Island, an...

Geometric morphometric analysis of shell shape variation in Conus (Gastropoda: Conidae)

Geometric morphometric techniques allow for the direct quantification and analysis of variation in biological shape and have been used in studies in systematic biology. However, these techniques have not been used for species discrimination in the gastropod genus Conus, a major taxon of significant tropical reef predators recognized for their peptide-based toxins. Here, we used landmark digitization and analysis to show that five species commonly studied for their conotoxins –Conus consors, Conus miles, Conus stercusmuscarum, Conus striatus, and Conus textile – can be effectively distinguished from each other by their shape, as manifested in the results of a principal components analysis (PCA) and the generated thin-plate splines. Two piscivorous species, C. stercusmuscarum and C. striatus, show clear overlaps in the PCA plot, although each taxon clusters within itself, as does each of the others. The loadings on the first two principal components show that the forms of the shells' aperture and spire are particularly important for discrimination. Phylogenetic analysis using neighbour-joining methods shows that group separations are comparable with published phylogenetic schemes based on molecular data and feeding mode (i.e. piscivory, vermivory, molluscivory). The results of this study establish the utility of geometric morphometric methods in capturing the interspecific differences in shell form in the genus Conus. This may lead to the utilization of these methods on other gastropod taxa and the creation of species-recognition programs based on shell shape. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165, 296–310.

Permian (Capitanian) gastropods from the Akasaka Limestone (Gifu Prefecture, Japan)

A gastropod fauna from the Permian (Capitanian) Akasaka Limestone from Japan is described. It is one of the most diverse known Permian gastropod faunas and consists of at least 74 species level taxa. Forty taxa have been identified to species level; the remainder are treated in open nomenclature because of insufficient preservation. In addition, three types of neritimorph opercula are present. One family, seven genera and 28 species are described as new by Nützel. New taxa are the family Araeonematidae, the genera Coeloconulus, Asamiella, Costataenia, Akasakiella, Cerithiozone, Yochelsonistylus and Permocerithium, and the species Anomphalus japonicus, Anematina parva, Araeonema panthalassica, Coeloconulus panae, Trochonodus permianus, Goniasma fortecarinata, G.? nodifera, Vebericochlis mazaevi, Costataenia hayasakai, Trypanocochlea parva, Cerithiozone ornata, Cerithioides angulatum, Stegocoelia akasakaensis, Yochelsonistylus seussae, Y. felixi, Knightella hydrobiformis, Palaeostylus? irregularis, P. attenuatus, P. minutus, P. lateapicatus, Permocerithium nudum, Protorcula permiana, Medfrazyga convexa, M. rectecostata, Acteonina koizumii, Heterosubulites fusiformis, Nanochilina japonica and Streptacis orientalis. The gastropod fauna of the Akasaka Limestone has previously been known for containing some of the largest species from the Permian and the entire Palaeozoic, with specimens as large as 40 cm. The fauna is strongly dominated by molluscs and especially by gastropods and bivalves. The dominance of these groups represents a modern aspect of this fauna. Among the gastropods, high-spired caenogastropods form the most diverse and abundant group. Most of the new gastropod genera are related to Cerithioidea and some have anterior siphonal canals. This suggests an early radiation of these caenogastropods in the Asia/Panthalassa realm. The relatively large number of new taxa suggests that gastropod faunas of this region have been poorly sampled or preservation of such faunas is only sporadic. Several of the present genera and a few species are also known from Permian deposits in China, Malaysia, and Vietnam. Some of the genera are cosmopolitan.

Speciation and dietary specialization in Drupa, a genus of predatory marine snails (Gastropoda: Muricidae)

Claremont, M., Reid, D.G. & Williams, S.T. (2012) Speciation and dietary specialization in Drupa, a genus of predatory marine snails (Gastropoda: Muricidae). —Zoologica Scripta, 41, 137–149.We test the competing predictions of allopatric speciation and of ecological speciation by dietary specialization in Drupa, an Indo‐Pacific genus of carnivorous marine gastropods in the family Muricidae. We use a well‐resolved molecular phylogeny (reconstructed from one nuclear and two mitochondrial genes) to show the validity of the traditional species D. elegans, D. rubusidaeus, D. clathrata, D. morum and D. speciosa.‘Drupa ricinus’ is shown to consist of three species: D. ricinus s. s., D. albolabris and a new species, possibly endemic to Japan. ‘Purpura’aperta is transferred to Drupa. Despite potential widespread dispersal and a high degree of range overlap among sister species, range sizes between sister species are highly asymmetric, suggesting that speciation has been predominately peripatric. The exception is the sister pair D. ricinus s. s. and D. albolabris, which have symmetric range sizes and are sympatric over broad Indo‐Pacific ranges. Such symmetry and extensive sympatry are contrary to the predictions of the (peripatric) allopatric model of speciation. Nevertheless, contrary to the predictions of an ecological speciation model based upon dietary specialization, broad dietary range appears to be identical between the species. Small differences in microhabitat preferences (or hypothetical dietary specialization at a fine taxonomic scale) may have been significant in the speciation process or, if initial divergence was allopatric, in permitting subsequent sympatry. Broad dietary shifts appear to have accompanied more ancient divergences within the genus Drupa.

Unraveling Cryptic Diversity in the Indo-West Pacific Gastropod GenusLunella(Turbinidae) using Elliptic Fourier Analysis*

Morphological variation in shell shape was quantitatively evaluated among newly identified cryptic species in two species complexes (coronata and cinerea groups) belonging to the gastropod genus Lunella (Turbinidae) using elliptic Fourier descriptors (EFDs). Sympatric species of the coronata group show greater phenotypic diversity than the entirely allopatric cinerea group. We suggest that if morphological divergence is driven most strongly in sympatry, cryptic species are more likely to occur in taxa with allopatric speciation. Discriminant analysis showed that one species (L. aff. coronata ophiolite) was significantly different and could be distinguished from its two sister species (L. coronata (Gmelin, 1791), L. aff. coronata Oman) by shell outline with a high degree of success. In pairwise analyses two pairs from the cinerea group were also significantly different and species could be determined with a modest degree of success: L. aff. cinerea Fiji with L. aff. cinerea SW Pacific and L. aff. cinerea Indian Ocean with L. aff. cinerea central Indo-West Pacific (cIWP). The remaining species could not be accurately identified by shell shape alone in this study. We also used a combination of shell shape and shell sculpture to determine that the coronate form of L. coronata, which occurs along the east coast of Africa and along the Arabian Peninsula into India, corresponds to L. coronata sensu stricto. We were unable to assign either a holotype for L. cinerea (Born, 1778) or a figured specimen of L. versicolor (Gmelin, 1791) to genetic lineages with any statistical confidence, although the shell outline of the former is most similar to L. aff. cinerea cIWP and the latter to L. aff. cinerea SW Pacific. Finally, using morphometrics, in combination with other shell characters, two fossil species, one from the cinerea group from the Pleistocene and one Japanese species from the Eocene, were compared with extant species. Using this method in combination with other characters, we suggest that the Japanese L. kurodai Itoigawa, 1955 is most likely a member of the coronata group and the Pleistocene cinerea fossil is most similar to L. cinerea cIWP.

Sub-seasonal oxygen and carbon isotope variations in shells of modern Radix sp. (Gastropoda) from the Tibetan Plateau: potential of a new archive for palaeoclimatic studies

Carbon and oxygen isotope ratios have been measured for nine aragonite shells of the gastropod genus Radix from the lake Bangda Co (30°29′N, 97°04′E, 4450 m a.s.l.) at the south-eastern edge and from two characteristic sites at the lake Kyaring Co (31°09′N, 88°17′E, 4650 m a.s.l.) on the central Tibetan Plateau. Radix shells were sampled for isotope ratio analysis with high spatial resolution along the ontogenetic spiral of growth providing the basis of isotope records with a sub-seasonal time-resolution. δ18O values of shells from Bangda Co are on average ∼−15.0‰ relative to PDB and the pattern exhibits a clear onset and progression of the summer monsoon precipitation indicated by a strong “amount effect”. This pattern mirrors the precipitation pattern in the respective year and region as expected for a small (surface area ca 0.3 km2) and shallow (<5 m) lake or habitat with short water residence times and little evaporative 18O enrichment of the lake water. In contrast, δ18O values of Radix shells from Kyaring Co habitat A which is connected to the deep (several tens of metres) and big (surface area ca 660 km2) lake, average at ∼−13.0‰ consistent with a higher evaporation rate and longer water residence time. The latter is supported by more 18O enriched water in this habitat. The δ18O values of Radix shells from Kyaring Co habitat B are nearly as low as shells from Bangda Co due to the similar habitat characteristic but isotopic patterns of these shells exhibit a weaker “amount effect”. In both lake systems δ13C values of the shells are coupled with oxygen isotopes because a large amount of isotopically light carbon is washed from mountain slopes into the lake during the rainy season. Although other processes influence the isotopic patterns, e.g. biological productivity (δ13C) or temperature (δ18O), these influences are minor compared with the monsoon signal or the effect of evaporation in the Radix shell records. The overall weaker amount effect in Radix shells from Kyaring Co habitat B compared with shells from Bangda Co are consistent with a current decreasing monsoon influence from the south-eastern edge towards the central Tibetan Plateau. Thus, fossil shells of the gastropod genus Radix are a valuable archive for reconstructing climatic and environmental changes on the Tibetan Plateau and provide information about former habitat sizes and depths.

Underestimated diversity of hydrobiid snails. The case of Pseudamnicola (Corrosella) (Mollusca: Caenogastropoda: Hydrobiidae)

The freshwater gastropod genus Pseudamnicola Paulucci, 1878 belongs to the family Hydrobiidae Stimpson, 1865 and has been cited in Europe, Africa and Asia. The Ibero-Balearic region is considered one of the areas showing the greatest diversity of hydrobiids although few works have provided complete morphological descriptions. Seven Pseudamnicola species have been described based only on shells and some features of the male and female genitalia. This paper provides the largest set of anatomical and morphological data currently available for hydrobiids and describes five new species of Pseudamnicola (Corrosella) from the Iberian Peninsula: P. (C.) manueli sp. nov., P. (C.) bareai sp. nov., P. (C.) marisolae, sp. nov., P. (C.) iruritai sp. nov. and P. (C.) andalusica sp. nov. Two further species, P. (C.) luisi Boeters, 1984 and P. (C.) falkneri (Boeters, 1970), whose distribution areas overlap, are re-described for comparison. The new species are morphologically well differentiated, the most satisfactory characters being female and male genitalia, radula and nervous system, and are well supported by molecular data, with genetic distances between 5.39 and 11.15% for the mitochondrial DNA cytochrome c oxidase subunit I sequence. All the species inhabit a mountain region whose tectonic episodes are here invoked to explain the creation of an area of endemisms.

Freshwater Biogeography and Limnological Evolution of the Tibetan Plateau - Insights from a Plateau-Wide Distributed Gastropod Taxon (Radix spp.)

BackgroundThe Tibetan Plateau is not only the highest and largest plateau on earth; it is also home to numerous freshwater lakes potentially harbouring endemic faunal elements. As it remains largely unknown whether these lakes have continuously existed during the Last Glacial Maximum (LGM), questions arise as to whether taxa have been able to exist on the plateau since before the latest Pleistocene, from where and how often the plateau was colonized, and by which mechanisms organisms conquered remote high altitude lentic freshwater systems. In this study, species of the plateau-wide distributed freshwater gastropod genus Radix are used to answer these biogeographical questions.Methodology/Principal FindingsBased on a broad spatial sampling of Radix spp. on the Tibetan Plateau, and phylogenetic analyses of mtDNA sequence data, three probably endemic and one widespread major Radix clade could be identified on the plateau. Two of the endemic clades show a remarkably high genetic diversity, indicating a relatively great phylogenetic age. Phylogeographical analyses of individuals belonging to the most widely distributed clade indicate that intra-plateau distribution cannot be explained by drainage-related dispersal alone.Conclusions/SignificanceOur study reveals that Radix spp. persisted throughout the LGM on the Tibetan Plateau. Therefore, we assume the continuous existence of suitable water bodies during that time. The extant Radix diversity on the plateau might have been caused by multiple colonization events combined with a relatively long intra-plateau evolution. At least one colonization event has a Palaearctic origin. In contrast to freshwater fishes, passive dispersal, probably by water birds, might be an important mechanism for conquering remote areas on the plateau. Patterns found in Radix spp. are shared with some terrestrial plateau taxa, indicating that Radix may be a suitable model taxon for inferring general patterns of biotic origin, dispersal and survival on the Tibetan Plateau.

New species and records of springsnails (Caenogastropoda: Cochliopidae: Tryonia) from the Chihuahuan Desert (Mexico and United States), an imperiled bio-diversity hotspot

We describe 13 new, narrowly localized species of the aquatic gastropod genus Tryonia from springs in the Chihuahuan Desert (Chihuahua and Texas): T. allendae n. sp., T. angosturae n. sp., T. chuviscarae n. sp., T. contrerasi n. sp., T. julimesensis n. sp., T. metcalfi n. sp., T. minckleyi n. sp., T. molinae n. sp., T. oasiensis n. sp., T. ovata n. sp., T. peregrina n. sp., T. taylori n. sp. and T. zaragozae n. sp.. These novelties are distinguished by shell and other morphologic characters and are well differentiated genetically from each other and from other congeners (mtCOI sequence divergence &gt;1.9%). We also provide two new records for T. seemani (Frauenfeld, 1863), which is distributed near the southern limit of the Chihuahuan Desert (Durango State) and previously had been thought to be possibly extinct. Bayesian analysis of a mtCOI dataset resolved two clades composed of novelties described herein: one (containing four species) is distributed in several drainages in Chihuahua, the other (containing three species) is a local species flock in the Río Conchos basin (also in Chihuahua) that lives in the warmest waters yet recorded for Tryonia (41–44°C). (The phylogenetic relationships of the other new species were not well supported.) Both of these clades contain sympatric species pairs; co-occurrence of Tryonia congeners previously had been reported only in Ash Meadows (southern Nevada). Some of the species described herein are from previously unsurveyed localities and may help delineate new areas of endemism within the Chihuahuan Desert. One of the new species (T. julimesensis) became extinct between 1991 and 2001 and another (T. oasiensis) disappeared from its single known locality shortly after it was first discovered in 2009 and also may be extinct. The other species treated herein are at risk of extirpation owing to the declining extent and condition of their unprotected habitats.

Corrections to three gastropod genera, established by Kutassy on Late Triassic type species from Dachstein Limestone localities of Budapest (Hungary)

Corrections to three gastropod genera, established by Kutassy on Late Triassic type species from Dachstein Limestone localities of Budapest (Hungary)

Evolution of corallivory in the gastropod genus Drupella

Although muricid gastropods in the genus Drupella are well-known consumers of Indo-Pacific corals, their evolutionary and ecological history is unclear, as is their relationship to the apparently facultative coral-feeder Ergalatax margariticola, which has been reported to feed upon corals in Hong Kong. We use a well resolved molecular phylogeny (reconstructed from one nuclear and two mitochondrial genes) to show that the monophyletic genus Drupella falls into the muricid subfamily Ergalataxinae and that the genus includes ‘E. margariticola’, which is composed of two cryptic species. We show that genetic structure within the here reassigned ‘Drupella margariticola’ species complex does not relate to feeding mode, but instead seems to correspond to broad patterns of habitat ecology found in other gastropod taxa. Our analyses suggest that Drupella originated in the late Miocene (approximately 9.6 Ma) and diversified approximately 5.0 Ma, much later than the appearance of modern coral reefs in the early Cenozoic. Thus, it is possible that corallivory in Drupella evolved in response to the major expansion and reorganization of reefs that took place in the early Miocene.

A large range extension and molecular phylogenetic analysis of the monotypic North American aquatic gastropod genus Cincinnatia (Hydrobiidae)

The freshwater gastropod genus Cincinnatia (Hydrobiidae: Nymphophilinae) contains a single species, C. integra (Say, 1821), which is distributed across much of eastern North America from the Great Lakes region to the Texas Gulf Coastal Plain. Here we use morphological and molecular evidence to evaluate the taxonomic status of a Cincinnatia population that was recently discovered in an upper reach of the Rio Panuco basin (northeastern Mexico) c. 700 km distant from its most closely proximal congeners. The Panuco basin population cannot be consistently differentiated from C. integra by its shells, although it differs from previously reported material of this species in several details of reproductive anatomy. The Panuco basin population differs from specimens from the type locality area and five other populations of C. integra by 1.5–2.6% mtCOI sequence divergence, but was no more differentiated than most of the other populations and was not consistently resolved as a monophyletic subunit of Cincinnatia using these molecular data. Based on this evidence we treat this population as belonging to C. integra pending a more comprehensive study of morphological and genetic variation across the broad geographic range of this species. This new record represents a large range extension not only for Cincinnatia, but also for the entire North American nymphophiline radiation, whose previously recorded southern limit was the Cuatro Cienegas basin in Coahuila.

The genus Benthofascis (Gastropoda: Conoidea): A revision with descriptions of new species

The conoidean gastropod genus Benthofascis Iredale, 1936 is examined. This genus of Conorbidae has extant species. Three previously described species from the Recent including the type species B. biconica (Hedley), B. sarcinula (Hedley), and B. lozoueti Sysoev &amp; Bouchet are reviewed. Three new species from the Recent, B. conorbioides sp. nov., B. pseudobiconica sp. nov., and B. angularis sp. nov. are described from Australia. One of these (B. angularis) is the first Benthofascis species described from Western Australia. Two fossil species originally described as Conorbis from the Miocene and Oligocene of Australia (C. atractoides Tate and C. otwayensis Long, respectively) are for the first time assigned to Benthofascis, thus extending the geologic record of the genus to the Oligocene.