Evidence for sublethal predation and regeneration among living and fossil ascophoran bryozoans

Virginia Museum of Natural History Special Publication 01/2008; 15:1-7.

ABSTRACT Evidence for partial predation on ascophoran bryozoans was hitherto mainly found in borings of the frontal shield. However, during this and many other studies, borings are only observed rarely. Indeed, many predators (e.g. nudibranch gastropods) are known to gain access to the internal organs via the operculum while leaving no traces of frontal wall damage. This type of predation may, nevertheless, be evidenced by the presence of intramural buds underneath undamaged zooecia, indicated by the presence of one or more orificial rims within the primary one, and implies that the damage occurred during lifetime of the colony. This skeletal signature was observed to occur in Late Cretaceous Acanthostega, as well as in Miocene to Recent Lepraliomorpha, and in Recent Hippothoomorpha. Its infrequent presence may suggest that ascophorans are not important target species for many predators, that not all taxa are able to secrete intramural buds, and/or that only certain types of feeding mechanisms trigger this type of regeneration. Information on feeding habits of modern predators on ascophorans, and reactions of different ascophoran taxa to various types of predation, are needed to verify exactly when and why intramural buds are formed in preyed zooecia.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although the lyrula is a character trait that is often used in taxonomic descriptions of certain ascophoran bryozoan taxa, its function as well as its position relative to the operculum remained ill-defined ever since the term was introduced in the late 19th century. The presence of a variety of other orificial and peristomial structures of different shape and position has added to the terminological confusion. Here we show that, in contrast to the condyles that are positioned at the (disto)lateral orifice margins below the level of the operculum, all structures at the proximal margin are situated above the operculum, and that they all serve the same ultimate function: to partition the orifice and peristome into a distal part that is occupied by the tentacles, and a proximal part through which water can freely flow into and out of the ascus during tentacle protrusion and retraction, respectively. Finally, we provide amended definitions of the terms lyrula, central and lateral denticle, as well as peristomial groove and ridge.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The cheilostome genera Herentia Gray and Therenia David and Pouyet, placed in the recently established family Escharinidae Tilbrook, were hitherto generally regarded as synonyms of Escharina Milne Edwards. Here we resurrect and define both genera, and revise their eastern Atlantic and Mediterranean species, which turn out to be species complexes. Besides presenting a re-description of the genotype of Herentia, H. hyndmanni (Johnston) from the British Isles, new species from Madeira (Herentia andreasi n. sp.) and the Adriatic Sea (Herentia majae n. sp.) are introduced. The ancestrula of H. hyndmanni, a kenozooid with an almost completely calcified, gymnocystal frontal shield, is here documented for the first time. For Therenia it can be shown that the type species T. porosa (Smitt) from Florida differs from the eastern Atlantic and Mediterranean congeners, all of which were hitherto referred to as this species. Consequently, three new species (Therenia cryptooecium n. sp. from Ghana, Therenia peristomata n. sp. from Madeira, and Therenia rosei n. sp. from the Mediterranean Sea) are described. Both genera show a Paleogene origin and distribution in the Tethyan and Atlantic regions, and persist today in tropical to warm-temperate zones of the Atlantic and Mediterranean Sea. Investigation of poorly studied, low-to mid-latitude regions are likely to yield more new species of Herentia and Therenia. Introduction Until recently, the genus Escharina Milne Edwards, 1836 was used to accommodate taxa with a wealth of different morphologies, including, among others, species of the genera Herentia Gray, 1848 and Therenia David and Pouyet, 1978. Both genera were usually considered as junior synonyms of Escharina (e.g. Hayward and Ryland 1979; 1999; Cook 1985; Zabala and Maluquer 1988). Their tangled history was set off by the valid introduction of the genus Herentia by Gray (1848, pp. 122, 148) without, however, specifically selecting a genotype from the four species he mentioned as belonging to this genus. The first species was Lepralia hyndmanni Johnston, 1847 from the British Isles but the list also contained three other taxa that belong to distinct genera by modern standards (see Brown, 1952, p. 229). Without referring to Gray's genus, Hincks (1877, p. 527) then instituted the new genus Mastigophora, with L. hyndmanni as the type species. Anticipating what was to come, presumed specimens of Mastigophora hyndmanni from a variety of locations were later considered by Hincks (1880, p. 281)
    Journal of Natural History 06/2008; 10(21-22):1509-1547. DOI:10.1080/00222930802109140 · 0.93 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sixteen bryozoan species have been identified in the Basyayla section, Mut Basin, southern Turkey. Five of these species are described here, including two new to science representing new genera: Basyaylella elsae gen. et sp. nov. and Ostrovskia triforamina gen. et sp. nov. The other three described species (Exidmonea sp., Biflustra savartii, and Margaretta sp.) show unusual features that have not been reported previously. Based on bryozoan data, the Basyayla sequence represents a tropical to subtropical, normal marine environment, with seafloor composed of fine sedimentary particles in a low-energy setting.
    Acta Palaeontologica Polonica 09/2013; 58(3). DOI:10.4202/app.2011.0100 · 1.72 Impact Factor


Available from
May 31, 2014