Scheltema Amelie H.

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Amelie H.

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  • Preprint
    A natural history of the deep-sea aplacophoran Prochaetoderma yongei and its relationship to confamilials (Mollusca, Prochaetodermatidae)
    ( 2008-11-10) Scheltema, Amelie H. ; Ivanov, Dmitry L.
    Previously published studies are woven together into a natural history of a deep-sea aplacophoran mollusc species, Prochaetoderma yongei Scheltema, 1985, and its confamilial species in the Prochaetodermatidae. This amphi-Atlantic species occurs in sometimes great numbers at upper bathyal depths, rivaling polychaetes in numerical dominance. It appears to be an opportunist, with wide geographic and depth distribution, rapid development from lecithotrophic larva to settlement and maturity, and omnivory. A short illustrated morphological description using characters useful for identifying all prochaetodermatid species should prove useful to nontaxonomists whose business is the deep-sea benthic fauna.
  • Preprint
    Seasonal occurrence of balanomorph barnacle nauplius larvae in the region of the Antarctic Peninsula
    ( 2010-03-01) Scheltema, Rudolf S. ; Scheltema, Amelie H. ; Williams, Isabelle P. ; Halanych, Kenneth M.
    Plankton samples taken along the west coast of the Antarctic Peninsula and in Bransfield Strait show widespread occurrence of Bathylasma corolliforme nauplius larvae during the austral spring, mid-October to the third week of December. During autumn, between the first week of May and early June there was a complete absence of balanomorph nauplii. This evidence shows periodicity in reproduction. There is a seemingly close correlation between the presence of these nauplii and the published data on phytoplankton biomass and seawater surface temperature.
  • Article
    Bathymetric zonation of deep-sea macrofauna in relation to export of surface phytoplankton production
    (Inter-Research, 2010-01-28) Wei, Chih-Lin ; Rowe, Gilbert T. ; Hubbard, G. Fain ; Scheltema, Amelie H. ; Wilson, George D. F. ; Petrescu, Iorgu ; Foster, John M. ; Wicksten, Mary K. ; Chen, Min ; Davenport, Roe ; Soliman, Yousria ; Wang, Yuning
    Macrobenthos of the deep, northern Gulf of Mexico (GoM) was sampled with box cores (0.2 m2) along multiple cross-depth transects extending from depths of 200 m to the maximum depth of the basin at 3700 m. Bathymetric (depth) zonation of the macrofaunal community was documented for 6 major taxa (a total of 957 species) on the basis of shared species among geographic locations; 4 major depth zones were identified, with the 2 intermediate-depth zones being divided into east and west subzones. Change of faunal composition with depth reflects an underlying continuum of species replacements without distinct boundaries. The zonal patterns correlated with depth and detrital particulate organic carbon (POC) export flux estimated from remotely-sensed phytoplankton pigment concentrations in the surface water. The Mississippi River and its associated mesoscale eddies, submarine canyon, and deep sediment fan appear to influence the horizontal zonation pattern through export of organic carbon from the ocean surface and the adjacent continental margin. On the local scale, near-bottom currents may shape the zonation pattern by altering sediment grain size, food availability, and larval dispersal. This study suggests a macroecological relationship between depth, export POC flux, and zonation; parsimonious zonal thresholds need to be tested independently for other continental margin ecosystems.
  • Article
    Hard and soft anatomy in two genera of Dondersiidae (Mollusca, Aplacophora, Solenogastres)
    (Marine Biological Laboratory, 2012-06-01) Scheltema, Amelie H. ; Schander, Christoffer ; Kocot, Kevin M.
    Phylogenetic relationships and identifications in the aplacophoran taxon Solenogastres (Neomeniomorpha) are in flux largely because descriptions of hard parts––sclerites, radulae, copulatory spicules––and body shape have often not been adequately illustrated or utilized. With easily recognizable and accessible hard parts, descriptions of Solenogastres are of greater use, not just to solenogaster taxonomists, but also to ecologists, paleontologists, and evolutionary biologists. Phylogenetic studies of Aplacophora, Mollusca, and the Lophotrochozoa as a whole, whether morphological or molecular, would be enhanced. As an example, morphologic characters, both isolated hard parts and internal anatomy, are provided for two genera in the Dondersiidae. Five species are described or redescribed and earlier descriptions corrected and enhanced. Three belong to Dondersia: D. festiva Hubrecht, D. incali (Scheltema), and D. namibiensis n. sp., the latter differentiated unambiguously from D. incali only by sclerites and copulatory spicules. Two species belong to Lyratoherpia: L. carinata Salvini-Plawen and L. californica (Heath). Notes are given for other species in Dondersiidae: L. bracteata Salvini-Plawen, Ichthyomenia ichthyodes (Pruvot), and Heathia porosa (Heath). D. indica Stork is synonymized with D. annulata. A cladistic morphological analysis was conducted to examine the utility of hard parts for reconstructing solenogaster phylogeny. Results indicate monophyly of Dondersia and Lyratoherpia as described here.
  • Preprint
    A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale
    ( 2006-02-01) Caron, Jean-Bernard ; Scheltema, Amelie H. ; Schander, Christoffer ; Rudkin, David
    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we reinterpret Odontogriphus based on 189 new specimens including numerous exceptionally well-preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that likely originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian until at least the Middle Cambrian.
  • Article
    Biogeography, diversity, and evolution through vicariance of the hydrothermal vent aplacophoran genus Helicoradomenia (Aplacophora, Mollusca)
    (National Shellfisheries Association, 2008-03) Scheltema, Amelie H.
    Species of the neomenioid aplacophoran genus Helicoradomenia Scheltema & Kuzirian are found only in areas of hydrothermal vents, oceanic ridges, and back-arc basins and have been collected widely in the East Pacific, Southwest Pacific, and the Triple Junction in the Indian Ocean, but not in the Atlantic. As with other vent taxa, species diversity of Helicoradomenia in the East Pacific is greatest south of the subduction zone of the Pacific Plate under the North American Plate, which divided the ridge system into two sectors during the Eocene: the northern Juan de Fuca system and southern East Pacific Rise. Diversity of Helicoradomenia species reflects, in smaller numbers, the diversity of the vent limpets in the two sectors. Two Helicoradomenia sister species are illustrated with the characters that separate them, H. juani Scheltema and Kuzirian (1991) from the northern sector and H. acredema Scheltema (2000) from the southern. They apparently speciated when the vicariant event of subduction of a once continuous ridge occurred.