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Paleozoic scaphopods are among the most poorly known mollusks because of their featureless tubular shell morphology and fragmentary preservation. An apical orifice at the posterior end of a conch is a diagnostic character of Scaphopoda that distinguishes them from other groups of animals that produce similar calcareous tubes, but this structure is rarely preserved. A rich molluscan fauna from the Permian Akasaka Limestone in central Japan includes scaphopod shells, and past studies have reported four species, all of which were based on fragmentary specimens. This study recognizes six species in the Akasaka Limestone mainly on the basis of museum/institution collections, and a new genus (Minodentalium) and three species (Prodentalium onoi,M.hayasakai, andM.okumurai) are described, two known species (P.akasakensisandP.neornatum) are redescribed in more detail, and one species (Prodentaliumsp.) is described under open nomenclature. The following eight known species are allocated to the new genusMinodentalium:Plagioglypta furcataWaterhouse, 1980;Pl.girtyiKnight, 1940;Pl.subannulataEaston, 1962;Dentalium ingensDe Koninck, 1843;D. meekianumGeinitz, 1866;Pl.prosseriMorningstar, 1922;Dentalium priscumMünster in Goldfuss, 1842; andD.herculeumDe Koninck, 1863. All the species, except forM.hayasakai, are gigantic, reaching 200 mm or more in length. The species richness is the greatest known from a single locality/formation worldwide.UUID:http://zoobank.org/35405b9d-3ba7-40bf-87c5-3f2b550b1a6d

The turbinid gastropod Turbo (Marmarostoma) is common in the limestone bodies within the middle Miocene Sakurada and Kadono formations (Yugashima Group) on the Izu Peninsula, central Japan. The limestone bodies were originally deposited under a low-latitude, tropical climate in the northeastern Philippine Sea and then drifted northwards on the Philippine Sea Plate. This paper describes an additional species, Turbo (Marmarostoma) ishidai sp. nov., from the Ena Limestone on the south-western Izu Peninsula. This new species is characterized by its large shell size and shell form similar to the modern Australian endemic species Turbo (Marmarostoma) cepoides Smith, 1880, but differs in having thick tuberculate spiral cords on the shell surface of earlier teleoconch whorls instead of the smooth and broad spiral cords on and around the angled shoulder. The addition of this new species further highlights the presence of a biodiversity hotspot of this gastropod group in the northeastern Philippines Sea during the middle Miocene.

Di Martino, E., Taylor, P.D., Fernando, A.G.S., Kase, T. & Yasuhara, M. 3 June 2019, 2019. First bryozoan fauna from the middle Miocene of Central Java, Indonesia. Alcheringa 43, 461–478. ISSN 0311...

Predation pressure occurs as a result of predation frequency and prey vulnerability. Although quantifying these factors individually is essential to precisely understand predation effects on evolution, they have been generally less accessible. Here, using a modified form of Poisson function, we quantified the frequencies and vulnerabilities, as well as the resulting predation pressures, concerning the shell drillers versus prey interactions from the Eocene and Miocene periods. Our analysis quantitatively revealed that low-spired shells tend to show increased vulnerability except for two planispiral species that exhibit an unexpectedly low vulnerability. We then identified septal structures within the two species that resemble those in nautiloids and ammonoids but which provided a defensive role against the predators, enhancing the mean lifetime by approximately 20%. The current approach enables us to quantitatively trace how predation frequency and prey vulnerability have interacted, been transformed spatio-temporally, and been a driving force of evolution at geological time scales.

The extraordinarily large and aberrantly shaped shells of the Permian bivalve family Alatoconchidae (Ambonychioidea), thought to have a photosymbiotic mode of life like the modern fragine bivalve Corculum, are difficult to extract from their host limestone bodies; therefore, their morphologies have been reconstructed mostly based on broken shell pieces. The alatoconchid Shikamaia akasakaensis Ozaki, the type species of the genus from the middle Permian Akasaka Limestone of central Japan, was described based on only three fragmentary specimens; its shell characters were later reassessed from specimens from the Neo area, ca. 30 km NNE of the type locality. Because of the fragmentary nature of the type specimens of S. akasakaensis, this species is difficult to diagnose and cannot be compared taxonomically to the specimens from the Neo area or other known species. A shell reconstruction based on 19 specimens from the type locality shows that S. akasakaensis exhibits a very large, elongated elliptical shell form but clearly differs from the Neo specimens in its higher and longer dorsal crests and more dorsally reflected shell wings in the anterior portion, rendering the establishment of a new species (Shikamaia ozakii Asato and Kase sp. nov.) for the latter specimens. The outer shell consists of a very thin outermost prismatic layer that is underlain by thick layers of granular crystals in both species of Shikamaia, which suggests that the shell did not allow sufficient sunlight penetration to culture symbiotic microbes in the soft tissues of these animals. The “Corculum model” of photosymbiosis therefore is unlikely for the two species of Shikamaia. The discovery of the presence of a ventral gape, a previously unreported shell character, suggests extension of the soft body into the sediment through this opening during life. Three possible modes of life (fragine-like photosymbiosis, lucinid-like chemosymbiosis and normal suspension feeding) are discussed.

Pleurotomaria yokoyamai Hayasaka is a remarkably large gastropod commonly found in the middle Permian allochthonous Akasaka Limestone of central Japan. Its supraspecific systematics have however been unsettled. Examination of a museum collection and newly obtained material reveal previously unreported shell characteristics such as the presence of a long labral slit in the outer lip and a slit-like umbilicus surrounded by an accretionally growing callus pad. On the basis of these and previously known shell characters, a new genus Nipponomaria is proposed. We include Pleurotomaria? anatolica Enderle from the Permian anthracolithic limestone of northwestern Turkey as a member of this new genus.

Based upon large cerithiform gastropod specimens from the middle Miocene beds of Java, Indonesia and the Philippines, a new genus and new species, Megistocerithium magoi, is described herein. Ten fragmentary specimens from the lower and upper Miocene beds of the Philippines are tentatively referred to this species. M. magoi Kase sp. nov. is amongst the largest fossil cerithioidean gastropods (except for Turritellidae). It was a dweller in intertidal sandy mudflats, probably in close proximity to mangrove forests. No species considered to be congeneric with this species have been found in the Cenozoic. On the other hand, M. magoi Kase gen. et sp. nov. shares apertural characters with the Middle Jurassic species Eustoma tuberculosa, the type species of a genus belonging to the yet to be well-recognized family Eustomatidae. M. magoi Kase gen.et sp. nov. is possibly a relict of the Mesozoic Eustomatidae. It is assumed to have been a grazer on mangrove litter like the potamidid genera Terebralia and ...

The late early to middle Miocene limestone bodies in the Sagara and Izu Peninsula areas of central Japan are reefal deposits that were deposited under a tropical climate and provide a window into the paleodiversity of tropical volcanic islands in the northeastern Philippine Sea Plate. Specimens from the early middle Miocene Megami Limestone in the Sagara area and from the middle Miocene limestone blocks within the Yugashima Group on the Izu Peninsula are described as Turbo (Marmarostoma) histrioides sp. nov. and Turbo (Marmarostoma) izuensis sp. nov., respectively. Discovery of these two new species raises the number of Marmarostoma species from four to six in the Sagara and Izu Peninsula areas, demonstrating that the subgenus was more diverse in the northeastern Philippines Sea Plate during the middle Miocene than it is today. In particular, there are double the number of Marmarostoma species (four species) from the middle Miocene in the Izu Peninsula compared with the modern fauna on the tropical islands of the Izu-Ogasawara Arc. The highest richness of modern species of Marmarostoma is found in the central Indo-West Pacific, where molecular phylogenetic studies have suggested that the subgenus rapidly diversified in the late Oligocene or early Miocene. Nevertheless, Miocene species of this subgenus are sparse in the central IWP, being incongruent to the diversity pattern expected from the molecular studies. The findings reported herein provide an insight into the origin of the central IPW biodiversity hotspot.

The Permian large gastropod “Pleurotomaria” yokoyamai Hayasaka was found for the first time from the Capitanian (upper Guadalupian) Iwaizaki Limestone in the South Kitakami Belt, Northeast Japan. A smaller planispiral gastropod Porcellia sp. was found in association with it. These taxa have been scarcely reported, except from the coeval Permian limestones at Akasaka in Southwest Japan and in the Balya Maden area, western Turkey. The Akasaka Limestone was deposited as a low-latitude atoll on a mid-Panthalassan seamount, whereas the Iwaizaki Limestone was laid down as a patch reef within a terrigenous clastics-dominated facies on a shallow marine continental shelf. The occurrence of this unique assemblage suggests that the Iwaizaki Limestone originated also in a Permian low-latitude domain, and that the South Kitakami Belt likely formed a part of the continental margin of South China, representing its eastern extension to Northeast Japan.

Calyptraphorus is a distinctive stromboidean gastropod genus with its earliest fossil record from the Campanian (Cretaceous). The genus survived the K-Pg biotic crisis and was thought to have become extinct before the end of the Eocene. Calyptraphorus sp. is described on the basis of a single specimen recovered from the mid-Pliocene Tartaro Formation in northern Luzon, the Philippines. The specimen is similar to Eocene congeners recorded from the southeastern United States and Pakistan. It is left unnamed because the single available specimen is too incomplete for comparison with other known species. The significance of this discovery is that it extends the recorded stratigraphic range of the genus from the end of the Eocene to the Pliocene, leaving a hiatus of approximately 30 Myr, which classifies Calyptraphorus sp. as a Lazarus taxon. The genus apparently survived as a refugee taxon in the tropical Western Pacific, keeping the population density very low and/or the geographic distribution lim...

A new polyconitid rudist, Magallanesia canalicu- lata gen. et sp. nov., of probably late Albian age, is described from the Pulangbato area, central Cebu Island, the Philippines in the western Central Pacific and Takuyo-Daini Seamount, now located in the Northwest Pacific. It is similar to Praecaprotina Yabe and Nagao, 1926, a Japanese-Central Pacific endemic genus of late Aptian - early Albian age, but differs in having canals that developed by partitioning of the large ectomyophoral cavity in the posterior part of the left valve. Its discovery strengthens the evidence for Pacific endemism in Albian times. Several other clades of canaliculate rudists flourished or evolved at the same time in different regions of the Tethyan Realm, suggesting the presence of common global biological and/or environmental factors stimulating the evolution of the canals despite such endemism. Furthermore, the finding of a canaliculate polyconitid provides evidence in favour of the evolutionary hypothesis of a polyconitid origin for the Late Cretaceous canaliculate rudist family Plagioptychidae Douvill� 1888.

Patellogastropods are poorly recorded in sedimentary rocks. This hinders our understanding of their evolutionary and migratory history in the geologic past. The Middle Pleistocene Ichijiku Formation in the Boso Peninsula, central Japan, consists of sand wave deposits formed at 50 to 130 m water depth by unidirectional currents on a sea floor and contains an unusually well preserved and highly diverse patellogastropod assemblage. A total of 12 patellogastropod taxa have been collected: seven species of Cellana (Nacellidae), four species referred to as living Lotiidae, and one undetermined species of the family Lottiidae. Of the seven species of Cellana, five are described as new (Cellana yamamotoi sp. nov., C. bosoensis sp. nov., C. igniculus sp. nov., C. kobayashii sp. nov., and C. kamatakiensis sp. nov.), one is related to the modern C. toreuma (Reeve), and one poorly preserved taxon is unnamed but probably extinct. The assemblage represents a window into a Middle Pleistocene patellogastropod co...

The evolutionary history of the major boring-bivalve superfamily Pholadoidea remains unclear.Opertochasma somaensisn. sp., preserved in situ in fossilized wood from upper Kimmeridgian to lower Tithonian strata within the Upper Jurassic shallow marine Nakanosawa Formation, northeast Japan, is described. This new species represents one of the oldest body fossils of pholadoidean boring-bivalves and the first fossil record from the Jurassic in the circum-Pacific regions. The authochthonous occurrence in fossilized wood, the presence of microscopic file-like sculpture on the anterior shell slope, the short clavate burrow, and other shell features demonstrate thatO. somaensisn. sp. was a filter-feeding, obligate wood-borer with anterior-boring locomotion, and also that the complex shell morphology unique to Pholadoidea was established by the Late Jurassic. The documentation of the new species and taxonomic review on the Jurassic species previously described, show that the superfamily Pholadoidea was widely distributed along the Northern Hemisphere middle latitudes in the latest Jurassic. The Pholadoidea likely evolved by exploiting woody substrata which had become abundant during the Late Jurassic with floral diversification in the middle latitudes. It is notable that the xylophagous mode of life, referable to modern Teredinidae and Xylophagaidae, was most probably established in the Jurassic and provided an important background for the establishment of chemosynthesis-based, sunken wood-associated communities.

Cellana nigrolineata is amongst the most common and largest patellogastropod limpets in Japan, and has two color morphs. Analyses of anatomical and morphological characters, shell structure, and mitochondrial COI data (658bp) of these color morphs suggested that they represent intraspecific genetic variation. Molecular analysis demonstrated that the species can be subdivided into three genetically distinct groups: (Clade 1) Honshu, Shikoku to Eastern Kyushu, (Clade 2) Western Kyushu and (Clade 3) Southern Kyushu. Clade 1 and Clade 2 + 3 are distributed on the coastlines adjacent to two warm-water currents, the Kuroshio and Tsushima Currents, respectively. The southern population (Clade 3) is currently isolated by inhospitable sandy shores. The subdivision of these groups likely dates from the glacial period of Plio-Pleistocene time.

The enigmatic fossil Moniopterus japonicus Hatai et al., 1974 from the early Middle Miocene Moniwa Formation of northern Japan has been described as the only known example of fossil sea-snake eggs and also as fossilized pupal chambers of a coleopteran insect. A reexamination of the holotype provides no evidence in support of these previous interpretations. Scanning electronic microscopy and computed tomography observations on the holotype reveal that the calcareous lining, previously interpreted as eggshell, is instead composed of irregular spherulitic prisms, thin in the middle and becoming thicker toward both ends. In addition to the elongate oval shape and the presence of an opening at the more pointed end, these observations strongly suggest that M. japonicus is a boring of the mytilid boring bivalve Lithophaga isolated from the host rock. This reinterpretation is further supported by the occurrence of similar isolated and in situ borings with Lithophaga shells within the type and a nearby locality. Regarding this fossil as an ichnofossil makes the generic name Moniopterus a junior synonym of Gastrochaenolites Leymerie, 1842 and the species name japonicus is a senior synonym of Gastrochaenolites torpedo Kelly and Bromley, 1984. G. torpedo should thus be replaced with Gastrochaenolites japonicus (Hatai et al., 1974).

The micro-bivalve Carditella iejimensis inhabits the sediment surface within submarine caves at Ie Island, Okinawa, Japan. A comparison of the δ 18 O values ( δ 18 O aragonite ) of empty and living shells indicates that the shell is formed over several seasons, and that the main cause of mortality is low water temperature. According to this hypothesis, it is likely that the shells with heaviest δ 18 O aragonite values (− 0.4‰) among the recent dataset formed under or close to the lower limit of growth temperature for the species. Assuming an unchanging temperature tolerance of the species during the Holocene, samples with δ 18 O aragonite values heavier than − 0.4‰ indicate unusually low temperatures and enrichment of δ 18 O of sea water ( δ 18 O seawater ). The δ 18 O aragonite record of C. iejimensis from sediment cores recovered from Daidokutsu cave shows no clear long-term trend in sea surface temperature or δ 18 O seawater in the East China Sea during the past 7000 years, and indicates anomalously cool and dry events (enrichment in δ 18 O seawater ) at around 6300 and 5550 cal. years BP. These events may have been related to changes in the activity of the East Asian monsoon, related in turn to weakening solar activity. In contrast, these anomalies appear to be obscured during the last 1000 years, including a weak Asian summer monsoon event during the Little Ice Age, thereby indicating that the mode of the East China Sea climatic and hydrologic response to decadal- to centennial-scale variability in the intensity of East Asian monsoon has varied over the past 7000 years.

Two new troglobitic species of the freshwater crab genus Sundathelphusa (Parathelphusidae), S. waray, n. sp., and S. lobo, n. sp., are described from two caves in Samar, Philippines. This discovery brings the number of cavernicolous species of Sundathelphusa in the Philippines to nine. It is the first record of freshwater and true cavernicolous crab species from Samar. These two new species are morphologically closely related to S. cavernicola Takeda, 1983 and S. hades Takeda and Ng, 2001, but differ distinctly in the shape of carapace and the presence of long corneous spines in the dactyli. The new species are characterized by the non-pigmented body, greatly reduced eyes and long ambulatory legs that are associated with previously known troglobitic crabs. The presence of corneous spines on the distal two segments of the ambulatory legs is suggested as troglomorphic adaptation to subterranean habitat. A key to the cavernicolous freshwater crabs of the Philippines is also provided.

A 5000-year fossil series of minute submarine cave bivalves was studied using morphometric and evolutionary analyses. The obtained results indicate that the shapes of larval shells of studied species were labile, whereas the size of the larval shell was stable in each species studied. This result is different than that previously reported in most other studies in which size change is more common than shape change. This unique evolutionary pattern of these bivalves might be attributed to their refugial lifestyle.

Color markings of the potamidid gastropods Vicarya yokoyamai Takeyama, 1933 and Vicarya verneuili (d’Archiac, 1851), tropical and subtropical, mangrove-swamp and/or nearby intertidal dwellers during the Miocene in Southeast Asia, Pakistan, Korea and Japan, have been reconstructed. This reconstruction was based on preserved original color markings and UV-light photography associated with computer graphic processing of specimens of V. yokoyamai and V. verneuili from Japan, the Philippines and Indonesia. The results strongly suggest that the two Vicarya species have basically the same spiral color bands on the thick subsutural spiny cord, fine spiral cords of the whorl surface and shell base. Some individual variation was detected in V. yokoyamai, such that the fine spiral cords are suggested to have color pigment the same as or lighter than the whorl surface, and the thick subsutural spiny cords are pigmented either totally or only at the tips of the robust spines. The color markings reconstructed ...

We measured the δ18O values of the whole shells of the cavernicolous micro-bivalvia Carditella iejimensis obtained from sediments within a submarine cave (31 m water depth) at Ie Island (Okinawa Island, Japan) in the subtropical Northwest Pacific. Our results show no significant millennial-scale trend in the δ18O record, implying that both springtime temperature and the δ18O of sea water at 30 m depth around the Okinawa Islands have been stable for the past 3000 years at values similar to those of today. Moreover, we found one exceptionally light δ18O value from specimens spanning the past 250 years. The δ18O-derived temperature represents a departure of 2.1 °C from the average value for the past 250 years, being equal to the departure recorded during unusually high temperatures in the spring of 1998. This finding may imply that such high springtime sea surface temperature has been a rare event over the past 3000 years.

A chambered nautilus shell from the early Pleistocene deep-water sediments in the Bolinao area of Pangasinan province, northwestern Luzon, Philippines is described. Although the shell is fragmentary, the shell features indicate that the specimen is referable with reservation to the extant Nautilus pompilius Linnaeus, 1758. This finding represents the first and oldest fossil record of N. pompilius and complements the Plio-Pleistocene gap of the nautiloid fossil records. Taphonomic implications for Cenozoic nautiloids were briefly discussed.

Sediment samples from approximately 100 submarine caves on tropical islands in the Indian, Pacific and Atlantic oceans were examined to elucidate the global diversity and distribution of obligate submarine-cave snails of the family Neritiliidae. Shells accumulated from the Indo-West Pacific samples comprise five genera and nine species of extant neritiliids, whereas there were none from the Atlantic. Four new genera and four new species are herewith described: Laddia lamellata , Micronerita pulchella , Teinostomops singularis and Siaesella fragilis ; previously known species include Laddia traceyi comb. n., Pisulina adamsiana , Pisulina biplicata , Pisulina maxima and Pisulina tenuis . Of these nine species, seven have wide, largely overlapping distributions; species richness is highest in and around the Indonesian and Philippine region, as in countless cases of shallow-water fishes, corals, echinoderms, bivalves and other gastropods. Examination of protoconch morphology revealed five species with a fairly long, planktotrophic larval period and four species with non-planktotrophic early development. No clear relationship was found between distribution range and dispersal capability deduced from the developmental mode, whereas the non-planktotrophs had higher levels of geographic differentiation in shell morphology. Fossil assemblages from cryptic environments suggest a Tertiary origin of the submarine-cave Neritiliidae. The oldest extant genus, Laddia , appeared in the Miocene, while two other Tertiary genera, Bourdieria and Pisulinella , have become extinct. The submarine-cave Neritiliidae thus do not seem to have remained in the same cave systems or the same local regions for millions of years, but seem to be relatively young, active colonizers of both continental and oceanic islands, having repeatedly expanded their distributions over the Indo-West Pacific. Despite the fact that they are undoubtedly restricted to caves and similar cryptic habitats, transoceanic dispersal appears to have played as important a role in forming present distributions as did tectonic events, in species with or without a planktotrophic larval period.

Aim Cenozoic dynamics of large-scale species diversity patterns remain poorly understood, especially for the Western Pacific, in part, because of the paucity of well-dated fossil records from the tropics. This article aims to reveal the spatiotemporal dynamics of species diversity in the Western Pacific through the Cenozoic, focusing on the tropical Indo-Australian Archipelago (IAA) biodiversity hotspot. Location Tropical and north-western Pacific Ocean. Methods We analysed well-preserved fossil ostracodes from the tropical Western Pacific and combined their diversity data with other published data from the region to reconstruct Cenozoic dynamics of species diversity in the tropical and north-western Pacific Ocean. We fitted generalized additive models to test for differences in richness over time and across geographical regions while accounting for sample-size variation among samples. Results Low-, mid- and high-latitude regions all show a similar diversity trajectory: diversity is low in the Eocene and Oligocene, increases from the Early Miocene to the Plio-Pleistocene but then declines to the present day. Present-day high biodiversity in these regions was established during the Pliocene with a remarkable diversity increase at that time. Latitudinal diversity patterns are relatively flat and never show a simple decline from the tropics to higher latitudes. Main conclusions Western Pacific Cenozoic ostracodes exhibit a spatiotemporal pattern of species diversity that is inconsistent with the commonly reported and persistent pattern of declining diversity from the tropics to the extratropics. While this inconsistency could be interpreted as evidence that ostracodes are a contrarian clade, Atlantic ostracodes display a standard latitudinal species diversity gradient. Contrasting patterns between oceans suggest an important role for regional factors (e.g. plate tectonics and temporal geomorphological dynamics) in shaping the biodiversity of the Western Pacific.

Identification of tracemakers is of primary importance for evaluating the biotic interactions inferred from bore holes in fossil shell assemblages. Domicile bore holes in the subapical whorls of gastropods produced by spionid polychaeteDipolydorasp., supposed to be commensal with hermit crabs, are common in dead gastropod assemblages from deepwater habitats in the Philippines. These holes exhibit unique features and support a new criterion for the interpretation of nonpredatory borings in fossil gastropods. Diagnostic of these bore holes are: small circular to elliptical outer opening, the presence of weak dissolution of the columella beneath the bore hole, and the presence of a hollowed tube composed of detritus held together with mucus within some gastropod whorls anterior to the hole. The two selection factors of subapical whorls and elongate shells are supplementary criteria for recognition of these holes. Bore holes are recognized here in a deepwater gastropod assemblage from the upper Pliocene Shinzato Formation of Okinawa, Japan, and namedPolydorichnus subapicalisn. igen. and isp. These holes are identical to modern examples exhibiting similar site and species selectivity.P. subapicalishas its oldest fossil record in the upper Miocene of the Philippines, was common in offshore assemblages from the Miocene onward, and is a good indicator of occupation by a hermit crab and for commensalism between polychaetes and hermit crabs.

A sediment layer (43 cm thick) and surface sediments (5 cm thick) in a submarine limestone cave (31 m water depth) on the fore-reef slope of Ie Island, off Okinawa mainland, Japan, were examined by visual, mineralogical and geochemical means. Oxygen isotope analysis was performed on the cavernicolous micro-bivalve Carditella iejimensis from both cored sediments and surface sediments, and the water temperature within the cave was recorded for nearly one year. These data show that: (1) water temperature within the cave is equal to that at 30 m deep in the open sea; (2) the biotic and non-biotic environments within the cave have persisted for the past 2000 years; (3) mud-size carbonate detritus is a major constituent of the submarine-cave deposit, and may have come mainly from the suspended carbonate mud produced on the emergent Holocene reef flat over the past two millennia; (4) the δ 18 O-derived temperature (Tδ18O )o fC. iejimensis suggests that the species grows between April and July; (5) the Tδ18O of C. iejimensis from cored sediments implies that there were two warmer intervals, at AD 340±40 and AD 1000±40, which correspond to the Roman Warm Period and Medieval Warm Period, respectively. These suggest that submarine-cave sediments provide unique information for Holocene reef development. In addition, oxygen isotope records of cavernicolous C. iejimensis are a useful tool to reconstruct century-scale climatic variability for the Okinawa Islands during the Holocene. © 2006 Published by Elsevier B.V.

Mesozoic gastropod assemblages currently emerged from Kutch, western India constitute one of the most diverse communities known during the Bathonian–Oxfordian worldwide. The present paper describes part of the Jurassic gastropod faunas of the family Pleurotomariidae from Kutch, comprising ten species belonging to three genera, of which eight species are new. They are: Bathrotomaria reticulata (Sowerby), B. waageni sp. nov., B. calloviana sp. nov., B. buddhai sp. nov., B. prasantai sp. nov., B. dhosaensis sp. nov., B. tewarii (Maithani); Leptomaria daityai sp. nov.; L. asurai sp. nov. and Obornella wuerttembergensis (Sieberer). The assemblage shows a strong Tethyan affinity at generic level, but has a distinctly endemic species content, and thus merits a distinct subprovince within the Indo-Madagascan Faunal Province. The genus Pleurotomaria is discussed in historical perspective and shown to be Mesozoic genus. The six species of Bathrotomaria described herein are considered to have evolved from t...

Despite being limited to caves, many anchialine taxa have disjunct insular distributions, which raises questions about their origins and colonization history. This study deals with the new gastropod Neritilia cavernicola sp. n. (Neritopsina: Neritiliidae) from anchialine caves on two islands in the Philippines that are separated by the deep Bohol Strait and situated 200 km apart along the coastline of Cebu Island. Neritilia cavernicola is an obligate stygobiont and most closely resembles Neritilia littoralis, which lives in interstitial waters of the Nansei-shoto Islands, Japan. Its eggs and larval shells are identical to those of other Neritilia species, despite their different adult habitats. This suggests a marine planktotrophic phase (as occurs in amphidromous riverine species of Neritilia), and consequent migration between islands via ocean currents. Here we present the first genetic structure for anchialine cave organisms; comparisons of 1276 bp sequences from mitochondrial cytochrome oxidase I show no evidence of genetic isolation between the islands. All individuals evidently are part of a panmictic population and the low vagility of adults and their seemingly isolated cave habitats do not limit gene flow in N. cavernicola. This migration model, based on marine larval dispersal, may be widely applicable to anchialine stygobites with insular distributions, as many such organisms (including shrimps, crabs and fishes) are phylogenetically allied to amphidromous species.

We propose two new methods, an “endobiont method” and a “model method,” to quantitatively evaluate shell-peeling predation against snails and hermit crabs in fossil gastropod assemblages. The endobiont method, based on the frequency of peeled and pagurized shells, provides the minimum and maximum estimates of predation against hermit crabs. The model method, based on the frequency distribution of shell repairs per shell in peeled and unpeeled shells, estimates directly the frequencies of predation against hermit crabs and snails. Our two methods were applied to a deep-water gastropod assemblage from the Pliocene Shinzato Formation, Okinawa, Japan. Results show that peeling predation, irrespective of the high frequency of repaired breaks (thought to be an indication of high predatory attacks on snails in previous studies), is mostly attributable to hermit crabs rather than to snails in elongate shells, whereas it is the reverse in spherical shells. The results suggest that the frequency of repaire...

During a recent biological investigation of submarine caves of Grand Cayman, the Caribbean Sea, two species of Heteromysoides were collected. One species, referred to Heteromysoides spongicola Bacescu, 1968, is known only by the type specimens; therefore, this discovery marks the second record of occurrence and a new habitat record for the species. The other species is considered new and is described as H. stenoura, a 10th species of the genus. The new species closely resembles H. simplex Hanamura and Kase, 2001, known from the submarine caves of Okinawa, north-western Pacific, in the possession of a spiniform process on the eyes and a simple termination to the third thoracic endopod. However, the new species can be readily distinguished from the Pacific congener by a distally narrow telson and a more developed cornea in the eyes.

A new neritiliid gastropod, Neritilialittoralis, lives in a unique, intertidal, subterranean, brackish environment on Amami-ohshima Island, Japan. It lives exclusively on rubble that is embedded deeply in coarse-grained sand whose interstices are filled with a mixture of subsoil water and seawater. Empty shells of this species were also found in tide pools at the foot of limestone terraces on Okinawa Island, where a large volume of karst-related freshwater gushes out. The species is characterized by a very small, white shell and unpigmented skin. Neritilia has previously been found in freshwater streams, rivers, estuaries, and in anchialine and phreatic waters, and the present find expands its range of known habitats and has implications for the history of the invasion of freshwater by neritiliids. The spiral protoconch suggests that the larva of N.littoralis is long-lived, planktotroph and a very effective disperser, and all the individuals collected appear to be part of a panmictic population.

Re-examination of more than 7,000 gastropod specimens previously assigned to Neritilia rubida (Pease, 1865) or Neritilia consimilis (von Martens, 1879) from streams and rivers in the tropical and subtropical Indo-Pacific revealed three species: N. rubida, N. vulgaris new species, and Platynerita rufa new genus and new species. Neritilia consimilis from Mauritius is synonymized under N. rubida, the latter originally described from Tahiti. The three species herein recognized have extensive, largely overlapping distributions centred in the west Pacific: N. rubida ranges from Madagascar to French Polynesia, N. vulgaris from Madagascar to Samoa, and P. rufa from the Philippines to French Polynesia. Conchological and anatomical traits indicate that the three species are a polyphyletic group and that N. rubida is more closely related to N. succinea (Recluz, 1841) and N. manoeli (Dohrn, 1866), both in the Atlantic, rather than to the sympatric N. vulgaris. We suggest that their larval dispersal capabilities across the ocean have hindered the geographic isolation of populations and that ecological segregation may have played a more important role in genetic differentiation and speciation in freshwater neritiliids.

A new species of Palaumysis, P. pilifera, the fourth species of the genus, is reported from two submarine caves of Okinawa, southwestern Japan. The new species closely resemble the two species previously reported from the Pacific by possessing a multi-segmented inner flagellum in the antennule, but it differs from them in having the terminal spine of the male fourth pleopod bearing rows of fine setules (or hairs) near midlength, as opposed to a naked spine in the latter two species. The present discovery extends the geographical limit of the genus further north to 26 ° N in the western North Pacific. Additional information on the colour pattern and ecological feature of P. simonae BĂcescu & Iliffe, 1986, are provided on the basis of newly collected material from a submarine cave on Palau.

Time-stratigraphic patterns of stable carbon isotopic ratios recorded in terrestrial organic matter from Cenomanian–Maastrichtian successions for the Russian Far East can be correlated to those of carbonate carbon from well-studied successions for other parts of the world. Age-indicative biostratigraphy based on regional ammonoids and inoceramid bivalves are well established in Japan and can be applied to the whole Cretaceous succession except for the Upper Cenomanian–Lower Turonian and the upper part of the Maastrichtian (zones lacking macrofossils). Globally correlative carbon isotopic events previously documented with carbonate carbon from Europe and with carbonate carbon and marine organic matter from the U.S. Western Interior are recognized with similar magnitude through uppermost Cenomanian–Lower Campanian. In ascending order these events are: positive ‘spike’ across the Cenomanian–Turonian boundary; step-like leveled segment followed by negative shift (Lower–Middle Turonian); trough-like negative excursion (Middle–Upper Turonian); positive rebound coupled with following broad peak (Coniacian); and positive peak (basal Campanian) followed by modest negative excursion. The parallel fluctuation of the δ 13 C value between the terrestrial organic matter and carbonate suggests carbon isotopic equilibrium between surface seawater and atmospheric CO 2 and demonstrates that the isotopic curve of terrestrial organic carbon can be used to monitor carbon isotopic fluctuations of CO 2 in the ocean–atmosphere system. In the Upper Campanian and Maastrichtian, a negative δ 13 C excursion within chron 33r and a following rapid rebound can be correlated with the same distinctive carbon isotopic feature of carbonate observed in the deep sea cores from South and North Atlantic, the Indian, and the Pacific Oceans. Within this interval, the δ 13 C value of terrestrial organic matter also reflects carbon isotopic fluctuation of the global CO 2 reservoir with relatively minor regional/local ‘noise’.

生きている化石の宝庫として海底洞窟は1960年代より世界的に知られていたが,そこの堆積物に関する研究は行われていなかった.サンゴ礁における古環境解析のための新たなる地質記録としての有効性を検討するため,我々は沖縄県伊江島の海底洞窟(通称“大洞窟”)から堆積物のコア試料(長さ43cm)を採取した.堆積物はシルトからなり,葉理や生痕などの堆積構造は見られない.堆積物粒子は石灰質岩片を主とし,コッコリス,底生有孔虫や浮遊性有孔虫などを含む.貝化石の産状と14C年代測定の結果,コア試料は1,500年間以上の記録を有していることが分かった.また,平均堆積速度は2～4cm/100年と算出された.以上のことから,海底洞窟堆積物はサンゴ礁の後期完新世の環境・気候変動を解明できる記録媒体として有効であるといえる.

A well-supported phylogeny of the Neritopsina, a gastropod superorder archaic in origin, radiated ecologically and diverse in morphology, is reconstructed based on partial 28S rRNA sequences. The result (Neritopsidae (Hydrocenidae (Helicinidae + Neritiliidae) (Neritidae + Phenacolepadidae))) is highly congruent with the fossil records and the character distribution of reproductive tracts in extant taxa. We suggest that the Neritopsina originated in subtidal shallow waters, invaded the land and became fully terrestrial at least three times in different clades, by the extinct Dawsonellidae in the Late Palaeozoic and by the Helicinidae and Hydrocenidae in the Mesozoic. Invasion of fresh- and brackish waters is prevalent among the Neritopsina as the Jurassic and freshwater ancestory is most probable for helicinids. The Phenacolepadidae, a group exclusively inhabiting dysoxic environments, colonized deep-sea hydrothermal vents and seeps in the Late Cretaceous or Early Cenozoic. Submarine caves have served as refuges for the archaic Neritopsidae since the Early to Middle Cenozoic, and the marine neritopsine slug Titiscania represents a highly specialized but relatively recent offshoot of this family. The Neritiliidae is another clade to be found utilizing submarine caves as shelter by the Oligocene; once adapted to the completely dark environment, but some neritiliids have immigrated to surface freshwater habitats.

The soft parts and radula of Pisulina adamsiana and Pisulina maxima (Gastropoda: Neritopsina) are described for the first time on the basis of specimens collected alive from nine submarine caves of tropical to subtropical Pacific islands. To clarify the systematic position of Pisulina within the Neritopsina the fresh- and brackish-water genus Neritilia is also examined anatomically. The close relationship between Pisulina and Neritilia is confirmed by 19 unique, unreversed, possible synapomorphies: (1) an inclined protoconch; (2) spiral ridges on the larval shell; (3) almost perpendicularly arranged prisms of the outer shell layer; (4) open-pit eyes; (5) female flap on the foot with a ciliated neck furrow from the mantle cavity; (6) caeca on the visceral mass and corresponding shell pores; (7) reduced left ctenidium; (8) right hypobranchial gland composed of single-type cells; (9) two complicated pairs of oesophageal glands; (10) another pair of ovoid glands in the oesophageal floor; (11) inner lateral tooth of radula with a largely expanded lobe; (12) elongated outer lateral tooth with an oblique, comb-like blade; (13) a lateromarginal plate; (14) single large aperture of the digestive gland into the stomach; (15) strongly curved rectum on the pallial roof; (16) transverse slit-shaped vaginal opening situated far back from the female opening and anus; (17) absence of independent duct from the seminal receptacle to the albumen gland; (18) very long, club-shaped spermatophore sac extending to the pericardium; and (19) doubled seminal vesicle. Pisulina and Neritilia constitute an independent family Neritiliidae, together with the Miocene genus Pisulinella. The discovery of the open-pit eye in Pisulina and Neritilia, hitherto unknown in Orthogastropoda, suggests that the genera evolved from an ancestral species that lived in dark submarine caves.

A new species of the peracaridan order Bochusacea, Thetispelecaris yurikago, is described from a submarine cave on Grand Cayman Island, the Caribbean Sea. The new species is the fourth species of the order and family, and the second of the genus. Recent studies have strongly suggested a close phylogenetic affinity between cave-dwelling and deep-sea taxa in the Bochusacea as recognized in other cavernicolous/deep-sea crustaceans such as amphipods and copepods. The morphology of the gut and female reproductive system is observed for the first time in the Bochusacea: the stomach is complex with structures such as ridges, processes, spinules, and hairs in the lumen; paired gonopores are located near the base of the fifth pereiopods on the sternite.

The genus Palaumysis (Crustacea: Mysidacea) was established by Bacescu and Iliffe (1986b) to accommodate the marine cave mysid P. simonae and currently contains only the sole type species. Re-examination of the paratypes of P. simonae and further specimens from the Palau Islands has shown that this species possesses a rudimentary antennal scale, as opposed to having no scale according to the original description, resulting in a substantial revision of the genus, and also provides new information for this poorly known mysid. Furthermore, a second species, P. philippinensis sp. nov., is reported from a submarine cave on the Philippines. The new species differs from P. simonae in having the carapace with a small unfused lobe posteroventrally, the inner flagellum of the antennule consisting of five segments and the antennal scale with a long terminal seta. Larval forms of the new species in the marsupium are also illustrated.

The El Niño/Southern Oscillation (ENSO) system during the Pliocene warm period (PWP; 3-5 million years ago) may have existed in a permanent El Niño state with a sharply reduced zonal sea surface temperature (SST) gradient in the equatorial Pacific Ocean. This suggests that during the PWP, when global mean temperatures and atmospheric carbon dioxide concentrations were similar to those projected for near-term climate change, ENSO variability--and related global climate teleconnections-could have been radically different from that today. Yet, owing to a lack of observational evidence on seasonal and interannual SST variability from crucial low-latitude sites, this fundamental climate characteristic of the PWP remains controversial. Here we show that permanent El Niño conditions did not exist during the PWP. Our spectral analysis of the δ(18)O SST and salinity proxy, extracted from two 35-year, monthly resolved PWP Porites corals in the Philippines, reveals variability that is similar to present ENSO variation. Although our fossil corals cannot be directly compared with modern ENSO records, two lines of evidence suggest that Philippine corals are appropriate ENSO proxies. First, δ(18)O anomalies from a nearby live Porites coral are correlated with modern records of ENSO variability. Second, negative-δ(18)O events in the fossil corals closely resemble the decreases in δ(18)O seen in the live coral during El Niño events. Prior research advocating a permanent El Niño state may have been limited by the coarse resolution of many SST proxies, whereas our coral-based analysis identifies climate variability at the temporal scale required to resolve ENSO structure firmly.