pseudostome

plural pseudostomes

1. biologyThe oral opening on the pseudembryo of an echinoderm.

   The sarcodic body of the pseudembryo begins to shrink, the pseudostome and the two lower bauds of cilia disappear, and afterwards the two upper bands, and the embryo then becomes fixed to a stone, seaweed, or some other object.

   1903, Day Otis Kellogg, Thomas Spencer Baynes, William Robertson Smith, The Encyclopædia Britannica: A-ZYM, page 637

   2 more examples

   In all the cases which I have observed, the ciliated bands so characteristic of the pseudembryonic form have made their appearance before the rupture of the vitelline sac; and frequently the pseudembryo has become somewhat reniform, a depressed ciliated patch indicating the position of the pseudostome.

   1865, Wyville Thomson, “On the Embryogeny of Antedon rosaceus, Linck (Comatula rosacea of Lamarck”, in Philosophical Transactions of the Royal Society of London, page 521

   On one side of the body it has formed an arch forwards, its apex nearly touching the second band; and in the wider space thus left between the third band and the fourth, the pseudostome forms a deep involution of the sarcode, keyhole-shaped, richly ciliated, shallow anteriorly and deepening posteriorly into the short curved pseudocele, which merely dips under the fourth band, breaking through immediately behind it as a small round anal aperture.

   1954, The Record of Zoological Literature - Volume 2, page 759

2. biologyA false osculum or secondary opening which replaces the original osculum of a sponge.

   Synonyms: pseudoproct, pseudoscule

3. broadlyA false opening that resembles a stoma but without any true aperture.

   It is flattened ventrally and is smooth around the pseudostome area.

   2003, Ken J. Clarke, Guide to the Identification of Soil Protozoa - Testate Amoebae, page 22

   2 more examples

   The opening is via a pseudostome situated on the chamber or at the top of a neck which flares out to form a collar.

   1985, Gérard Bignot, Elements of Micropalaeontology, →ISBN, page 123

   Members of the Arcellina (testate amoebae), especially the terrestrial species, are surrounded by resistent tests with only one small pseudostome.

   2012, Jürgen Bereiter-Hahn, O. Roger Anderson, Wolf-Ernst Reif, Cytomechanics: The Mechanical Basis of Cell Form and Structure, →ISBN

   Synonyms: pseudostoma

4. A North American rodent, Geomys bursarius.

   Synonyms: plains pocket gopher, pouched rat, pocket gopher