Movement patterns of the sub-Antarctic pulmonate limpet Kerguelenella lateralis (Gould) (Mollusca: Gastropoda)

Summary Kerguelenella lateralis produces distinct spots on microalgal-coated rocks in the high intertidal zone at Kerguelen. Spots are the result of microalgal removal, corresponding in outline to the limpet's shell. Although limpet spots could be associated with homing behavior, K. lateralis does not exhibit this behavior. Limpets in low-and high-intertidal areas show high levels of sitespecific emigration and immigration. Rates of site-emigration (No. limpets leaving/day) are positively related with limpet density indicating that local limpet densities may influence population movements. Distances of displacement and rates of emigration and immigration are highly variable and do not differ in low-and high-intertidal sites. Lack of homing in K. lateralis may reflect characteristics of its sub-Antarctic environment: low levels of predation, few competitors, and protection from desiccation and wave action through occupation of cracks in the rocky substratum.     

Linnaeus' Neptunea (Mollusca: Gastropoda)

Three species of the arcto-boreal, large gastropod Neptunea , described by Linnaeus in 1758 and 1771, occur in large numbers over wide areas of the inshore North Atlantic and adjacent Arctic seas and are conspicuous among Pliocene and Pleistocene molluscs in the Icelandic, North Sea, and western Mediterranean basins. Selections of lectotypes for these species from shells in the collection of the Linnean Society of London, and designations of their type localities, establish the identity of Linnaeus' neptunes and more accurately determine their geographic and geologic distribution. The geographic range of Neptunea (Neptunea) antiqua (L.), the type species, now extends from southern Norway to the northern Biscay coast of France and from the westernmost Baltic Sea to southwestern Ireland; this species also occurs in Pliocene-Holocene marine deposits in West and East Germany, Sweden, the Netherlands, England and France. Its type locality is determined to be the North Sea. N. (Neptunea) despecta (L.) lives in the eastern Canadian Arctic, off southern Greenland, the Barents Sea, and North Atlantic as far south as Massachusetts and Portugal; it also occurs in Pliocene-Holocene strata of eastern Canada, east-central Greenland, Norway (including Svalbard), the Soviet Union, Sweden and England. Its type locality is determined to be the postglacial deposits at Uddevalla in southwestern Sweden. N. (Sulcosipho) contraria (L.) now extends from the southern Biscay coast of France to Cape Spartel, Morocco; this species also occurs in Pleistocene and lower Holocene sequences of the western Mediterranean. Its type locality is determined to be Vigo Bay, Spain. A closely related fossil species, N. (S.) angulata (S. V. Wood), occurs in Pliocene and Pleistocene deposits of the North Sea basin.     

Anatomy and affinities of cocculinid limpets (Mollusca, Archaeogastropoda)

The anatomy of seven cocculinid species, representing four genera, is described. Two new genera are erected, Paracocculina and Coccocrater, and a comparative account of all cocculinid species so far anatomically investigated is given. Definitions of six genera, mainly based on anatomical data, are presented. Variation at the species level is also discussed. The closest relatives of the Cocculinidae are found in the Bathysciadiidae, sharing a distinct gill type and similar coelomic conditions. Therefore, both families are united as the Cocculinoidea. The Lepetelloidea (Lepetellidae, Pseudococculinidae, Osteopeltidae, Bathyphytophilidae (?), Cocculinellidae, Addisoniidae and Choristellidae) are more distantly related and are classified, together with the Cocculinoidea, within the suborder Cocculiniformia. The Cocculiniformia are regarded as one of the earliest offshoots at the archaeogastropod level of organization, being secondarily modified in several respects.     

Ultrastructure of the ovary and oogenesis in six species of patellid limpets (Gastropoda: Patellogastropoda) from South Africa

Abstract. The ultrastructural features of the ovary and oogenesis have been described in 6 species of patellid limpets from South Africa. The ovary is a complex organ that is divided radially into numerous compartments or lacunae by plate-like, blind-ended, hollow trabeculae that extend from the outer wall of the ovary to its central lumen. Trabeculae are composed of outer epithelial cells, intermittent smooth muscle bands, and extensive connective tissue. Oocytes arise within the walls of the trabeculae and progressively bulge outward into the ovarian lumen during growth while partially surrounded by squamous follicle cells. During early vitellogenesis, the follicle cells lift from the surface of the underlying oocytes and microvilli appear in the perivitelline space. Follicle cells restrict their contact with the oocytes to digitate foot processes that form desmosomes with the oolamina. When vitellogenesis is initiated, the trabecular epithelial cells hypertrophy and become proteosynthetically active. Yolk synthesis involves the direct incorporation of extraoocytic precursors from the lumen of the trabeculae (hemocoel) into yolk granules via receptor-mediated endocytosis. Lipid droplets arise de novo and Golgi complexes synthesize cortical granules that form a thin band beneath the oolamina. A fibrous jelly coat forms between the vitelline envelope and the overlying follicle cells in all species.     

New species of Nystiellidae and Epitoniidae (Mollusca: Gastropoda) from the northeastern Pacific

Some nystiellid and epitoniid species from the eastern Pacific Ocean from Oregon to Alaska are discussed and six new species described herein: Eccliseogyra frausseni from deep water off southeastern Alaska; Iphitus clarki, Iphitus wareni, Murdochella turritelliformis and Epitonium nearense, all from the Aleutian Islands; and Claviscala dushaneae from deep water off Oregon.     

Regulated bradycardia in the pulmonate limpet Siphonaria (Gastropoda: Mollusca) during pollutant exposure: implication for biomarker studies

Although the cardiac activity of invertebrates is now widely used as a biomarker of marine pollution, few studies consider the intrinsic factors causing the variability of heart rate (HR), including the physiological states associated with metabolic depression and behavioural isolation. We examined the cardiac responses to copper exposure of a pulmonate limpet (Siphonaria capensis Quoy and Gaimard), known to adaptively depress heart rate (and metabolic rate) under naturally stressful conditions (hyposalinity). Analysis of variance was used to assess the effects of copper concentration (0-1000 microg/L), exposure time (0-2 h), and individual difference (eight limpets per concentration) on heart rate parameters. Minute by minute heart rate (HR) and heart rate variability (HRV), and bradycardia (< or =10 beats/min) were determined from continuous recording traces. Most of the HR variance was attributable to the interaction of concentration and individuals (35.8%). Considerably lower mean HRs for the higher range of copper concentrations (250 to 1000 microg/L), compared to the lower range (0 to 50 microg/L), were attributable to the virtually exclusive induction of bradycardia in the higher concentration treatments. With increasing concentration, bradycardia was induced sooner and became less interspersed with near normal heart rates (i.e., less episodic). This regulated bradycardial response is apparently associated with isolation (avoidance) behaviour rather than with copper uptake. These findings have implications for biomarker exercises which use heart rate, in cases where invertebrates depress metabolism.     

Studies on activity pattern of the patellid limpet Cellana toreuma (Reeve)

The habits and activity of Cellana toreuma (Reeve) have been studied in a field population. Activity is very high at ebb and flood tide, independent of the time of day, and sharply decreases during complete submergence or complete exposure. Duration of movement fluctuates with tidal amplitude; when neap tide, movement does not stop during low tide owing to continuous awash conditions. Vertical movement entirely coincides with tidal direction at day and night. In this way, the movement does not depend on light but chiefly the tide. Compared with a nocturnal limpet, C. nigrolineata (Reeve), the divergence in the behavioural patterns may be a function of the extent to which limpets are influenced by light. Duration of movement and distance increase with limpet size. Homing behaviour was not observed.     

Anatomy and affinities of pseudococculinid limpets (Mollusca, Archaeogastropoda)

The anatomy of 12 pseudococculinid species, representing the two subfamilies and 10 (of 11 known) genera, is described in detail. Three new genera are erected, Yaquinabyssia, Copulabyssia and Amphiplica. Subfamilial and generic systematics are reconsidered and additionally based on anatomical characters. Characters defining subfamilies and genera (Pseudoeoeculininae: Pseudococculina, Notocrater, Tentaoculus, Mcsopelex, Bandabyssia, Kurilabyssia; Caymanabyssiinae: Caymanabyssia, Colotrachelus, Yuquinabyssia, Copulabyssia, Amphiplica) are the modifications in shell and radula, the number and arrangement of gill-leaflets, the size of the pedal gland, the degree of eye-reduction and the modifications of the seminal groove and of the copulatory organ. Separation of the Pseudococculinidae Hiekman, 1983 from the Cocculinidae Dall, 1882 at the superfamilial level is confirmed by great differences in their anatomy. Whereas the Cocculinidae are closely related to the Bathysciadiidae (Cocculinoidea). the Lepctcllidae, Pyropeltidae, Pseudococculinidae,? Bathyphytophilidae, Osteopeltidae, Cocculinellidae, Addisoniidae and Choristellidae form a clearly separated supcrfamily (Lepetelloidea). Both superfamilies compose the Cocculiniformia. a primitive but highly specialized arehaeogastropod suborder.     

A cladistic phylogeny of the family Patellidae (Mollusca: Gastropoda)

A phylogenetic hypothesis for the patellid limpets is reconstructed by cladistic analysis of morphological characters from 37 species, representing all but one of the living members of the family. Characters included in the analysis are derived from shell shape and microstructure, headfoot and pallial complex, radula and sperm. The species fall into four clades, providing the basis for a new phylogenetic classification into four monophyletic genera: Helcion (four species; southern Africa), Cymbula (eight species; southern Africa, eastern Atlantic, southern Indian Ocean), Scutellastra (17 species; southern and southwestern Africa, Australia, Indo-West Pacific, Eastern Pacific) and Patella (nine species; northeastern Atlantic and Mediterranean). The analysis suggests sister-group relationships between Helcion and Cymbula, and between Scutellastra and Patella. In combination with present-day patterns of geographical distribution, this phylogenetic hypothesis is used to discuss the historical biogeography of the Patellidae. Scutellastra may have originated in southern Africa and dispersed across the Pacific, or alternatively may be a primitively Tethyan group. Both Helcion and Cymbula appear to have originated in southern Africa, but three Cymbula species have dispersed respectively to northwest Africa, St Helena and the southern Indian Ocean. The patellids of the northeastern Atlantic form a single clade, Patella (including P. pellucida), which may have arrived by northward dispersal of an ancestor from southern Africa, or possibly by vicariance of a widespread ancestral Tethyan distribution. The known fossil record of patellids is too fragmentary to permit choice between these alternatives.     

Tissue Hemoglobins of Gastropoda (Mollusca)

The distribution and content of tissue hemoglobins in the radular muscle, subradular cartilages, myocardium, and nerve tissue of gastropods are analyzed.     

Molecular phylogenetics of Caenogastropoda (Gastropoda: Mollusca)

Caenogastropoda is the dominant group of marine gastropods in terms of species numbers, diversity of habit and habitat and ecological importance. This paper reports the first comprehensive multi-gene phylogenetic study of the group. Data were collected from up to six genes comprising parts of 18S rRNA, 28S rRNA (five segments), 12S rRNA, cytochrome c oxidase subunit I, histone H3 and elongation factor 1alpha. The alignment has a combined length of 3995 base positions for 36 taxa, comprising 29 Caenogastropoda representing all of its major lineages and seven outgroups. Maximum parsimony, maximum likelihood and Bayesian analyses were conducted. The results generally support monophyly of Caenogastropoda and Hypsogastropoda (Caenogastropoda excepting Architaenioglossa, Cerithioidea and Campanilioidea). Within Hypsogastropoda, maximum likelihood and Bayesian analyses identified a near basal clade of nine or 10 families lacking an anterior inhalant siphon, and Cerithiopsidae s.l. (representing Triphoroidea), where the siphon is probably derived independently from other Hypsogastropoda. The asiphonate family Eatoniellidae was usually included in the clade but was removed in one Bayesian analysis. Of the two other studied families lacking a siphon, the limpet-shaped Calyptraeidae was associated with this group in some analyses, but the tent-shaped Xenophoridae was generally associated with the siphonate Strombidae. The other studied hypsogastropods with an anterior inhalant siphon include nine families, six of which are Neogastropoda, the only traditional caenogastropod group above the superfamily-level with strong morphological support. The hypotheses that Neogastropoda are monophyletic and that the group occupies a derived position within Hypsogastropoda are both contradicted, but weakly, by the molecular analyses. Despite the addition of large amounts of new molecular data, many caenogastropod lineages remain poorly resolved or unresolved in the present analyses, possibly due to a rapid radiation of the Hypsogastropoda following the Permian-Triassic extinction during the early Mesozoic.     

Ultrastructure of spermatozoa in Orthalicidae (Mollusca,Gastropoda, Stylommatophora) and its systematic implications

Sperm morphology of orthalicid gastropods Clessinia pagoda, Spixia tucumanensis, Plagiodontes daedaleus (Odontostominae) and Drymaeus hygrohylaeus, D. poecilus, Bostryx stelzneri (Bulimulinae) are examined and described for the first time using transmission electron microscopy. Spermatozoa show the general characteristic of Pulmonata: an acrosomal vesicle, sperm nucleus helical, mitochondrial derivative forming a continuous sheath with paracrystalline material and coarse fibers associated with axonemal doublets. Features in the acrosomal complex and shape of the nucleus distinguish orthalicid sperms from other stylommatophoran. The acrosomal pedestal is traversed by fine striations in all species examined except in S. tucumanensis. The structure and thickness of the perinuclear sheath with a single or double layer of electron-dense material ensheathing the nuclear apex is characteristic of the group. The presence of a subnuclear ring in Drymaeus, Bostryx and Clessinia species is also reported. A data matrix of eleven species per 34 characters (16 sperm plus 18 anatomical and shell characters) from orthalicids plus other stylommatophoran and systellommatophoran representative species was constructed. Three cladistic analyses (sperm-based, anatomical-based and a combined sperm + anatomical-based) were performed to test the phylogenetic potential of sperm ultrastructure in orthalicid systematics and understand how sperm characters affect the topology and resolution of the obtained trees. Stylommatophora resulted in a monophyletic clade in the sperm-based and in the combined-character analysis. Orthalicidae is monophyletic only in the combined-character cladogram. Within Orthalicidae, Odontostominae is recovered as a monophyletic clade in all analyses, while Bulimulinae is paraphyletic in all trees except in the combined phylogeny. The present study and cladistic analyses performed support the hypothesis that characters on sperm ultrastructure are informative for stylommatophoran systematic and phylogenetic approaches, providing synapomorphies at familiar, subfamiliar and generic level.     

A new genus and two new species of freshwater Gastropoda from the Ceyhan River Basin in the eastern Mediterranean (Mollusca: Gastropoda: Truncatelloidea)

In a survey of the mollusc fauna of the Ceyhan River Basin, including rivers, natural lakes, dam lakes and springs between June 2008 and September 2014, a total of 20 species of Gastropoda and 8 species of Bivalvia were identified. Two of these species are new to science, and for one of them a new genus is erected: the hydrobiid Hemite ceyhanensis gen. n., sp. n., and the bithyniid Pseudobithynia cocussusica sp. n.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:DE5FFC19-13CD-4B81-B74E-80059E781518     

Taxonomic status of the `Patella miniata' species complex (Mollusca: Gastropoda) in southern Africa

The species boundaries between members of the southern African `Patella miniata' species complex (Patella miniata miniata, P. miniata sanguinans and P. compressa) are poorly defined on morphological grounds. Doubt also exists whether all populations of P. miniata miniata constitute a single taxon, with `P. cf. miniata' having uncertain affinities. The status of P. adansonii (known only from shells) is also obscure. Protein gel electrophoresis was employed to resolve these taxonomic uncertainties. In addition, a population of P. safiana from southern Angola was included in the study as a reference population. Electrophoretic analysis of 16 enzyme loci revealed four distinctive groupings. All populations of P. miniata miniata and P. cf. miniata proved closely related and separated from P. compressa populations at I=0.85; the P. miniata sanguinans populations clustered out at I=0.79; and P. safiana separated at I=0.69. Phylogenetic analyses, using P. safiana as an outgroup, indicated that P. miniata miniata, P. miniata sanguinans and P. compressa form a closely related monophyletic group in which P. miniata miniata and P. compressa are more closely related to each other than either one of them is to P. miniata sanguinans. Morphological analyses (shells, radula, sperm microstructure) revealed differences that mirrored the differences detected by the allozymes. Thus, it was concluded that P. miniata sanguinans and P. miniata miniata warrant full specific status and we therefore raise the former to P. sanguinans. Patella miniata miniata and P. cf. miniata are geographic variants of the same species, P. miniata, and P. adansonii is sunk within this species. Furthermore, the suggestion that P. miniata and P. compressa may be ecomorphs of the same species are not supported and both warrant specific status. Thus, the `Patella miniata' species complex in southern Africa is a closely related monophyletic group of three species, with P. miniata and P. compressa being more closely related to each other than either one is to P. sanguinans.     

Ultrastructure of the spermatozoa of five species of South African bivalves (Mollusca), and an examination of early spermatogenesis

Transmission electron microscopy of the spermatozoa of five species from three families of bivalves has shown that each species has a sperm with unique morphology. However, the morphology of the acrosomes of each species is typical of the subclass of bivalve to which they belong. An examination of spermatogenesis in the five species, along with a re-examination of material from six other species of bivalves, has revealed that pre-spermiogenic cells possess flagella. In addition, acrosome formation begins in the spermatocytes with the formation of proacrosomal vesicles in the Golgi body. During spermiogenesis the proacrosomal vesicles coalesce at the presumptive posterior of the spermatid, with a larger vesicle produced by the Golgi body. The single acrosomal vesicle eventually migrates to the anterior of the spermatid where it assumes its mature form. © 1994 Wiley-Liss, Inc.     

Radular myoglobin and protein variation within and among some littorinid species (Mollusca: Gastropoda)

The radular muscles of several littorinid species, including Littorina littorea, L. saxatilis, L. obtusata, L. striata and Melarhaphe neritoides, contain myoglobin (Mb). Here we report on the presence of radular Mb in eight other littorinids: L. compressa, L. arcana, L. fabalis, Nodilittorina punctata, N. trochoides, N. radiata, Littoraria undulata and Littoraria cingulifera. Using native polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF) we compared the Mb and soluble protein (SP) profiles of these species. This suggested that: (1) L. saxatilis and L. arcana may have specific Mb/SP profiles, (2) Littoraria spp., Nodilittorina spp. and L. striata share similar Mb patterns, (3) Mb is remarkably diverse in the genus Littorina, (4) L. littorea shows intraspecific Mb/SP variation, (5) L. saxatilis does not show geographic Mb/SP differences, and (6) IEF uncovers substantial hidden Mb/SP heterogeneity not shown by PAGE (particularly for Melarhaphe neritoides). Hence, littorinid Mb/SP may be a useful taxonomic marker whose ecophysiological significance deserves further study, even if its genetic basis remains unclear.     

Functional morphology of the Conus proboscis (Mollusca: Gastropoda)

The extended proboscis of the toxoglossan gastropod Conus may exceed four times its contracted length and 1.5 times the shell length. The proboscis wall consists of cuboidal epidermis and circular, crossed helical and longitudinal muscle layers. Between the proboscis wall and its lumen, free longitudinal muscles and nerves course through haemocoel. A thick layer of connective tissue and columnar epithelium surround the proboscis lumen. In C. Catus , muscle comprises about 70% of the volume of the proboscis (exclusive of its lumen) and haemocoel about 20%, in both moderately extended and contracted states. Differentiation along the length of the proboscis includes gradual replacement of muscle by connective tissue distally in the proboscis wall, and a subapical sphincter muscle that probably prevents back-slippage of the detached radular tooth prior to its use in feeding and aids injection of the tooth into the prey during capture.