Pseudothecosomata

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iPseudothecosomata
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Orthogastropoda
Superorder: Heterobranchia
Order: Opisthobranchia
Suborder: Thecosomata
Infraorder: Pseudothecosomata
Families

In the suborder Pseudothecosomata of sea butterflies some groups possess a shell, some are without, and others have developed a relatively tough gelatinous, cartilaginous internal structure so-called 'pseudo-conchs'. The lateral and posterior foot lobes are joined as a ciliated proboscis that leads to the mouth, and the wings are united ventrally to form a single plate.

A more general description of the pseudothecosomes is given under the entry Sea butterfly

[edit] Taxonomy

  • Superfamily Peraclidoidea
    • Family Peraclididae
      • Genus Peracle
  • Superfamily Cymbulioidea
    • Family Cymbuliidae
      • Genus Corolla
      • Genus Cymbulia
      • Genus Gleba
    • Family Desmopteridae
      • Genus Desmopterus

[edit] Description

Superfamily Peraclidoidea

Family Peraclididae C.W. Johnson, 1915

The left-coiled shell resembles the shell of most snails. The columella is somewhat elongated into a curved rostrum. There is an operculum and a gill.

Genus Peracle Forbes, 1844

  • Peracle apicifulva Meisenheimer, 1906 (synonym of Peracle diversa)
  • Peracle bispinosa Pelseneer, 1888 -- Two-spine Pteropod
    • Distribution : Florida, Bermudas, Cuba, Venezuela, Oceanic.
    • Length : 7.5 mm
  • Peracle depressa Meisenheimer, 1906
    • Distribution : Cuba, Brazil, Argentina, Oceanic, Equatorial Atlantic
  • Peracle diversa di Monterosato, 1875
    • Distribution : Florida, Bermuda, Cuba, Argentina, Mediterranean
    • Length : 4 mm
  • Peracle moluccensis Tesch, 1903
    • Distribution : Panama, Brazil, British Isles, Oceanic
    • Length : 3 mm
  • Peracle philiporum R.W. Gilmer, 1990
    • Distribution : Bahamas
    • Length : 4.5 mm
  • Peracle reticulata (d'Orbigny, 1836) Reticulate Pteropod
    • Distribution : Oceanic, Florida, Texas; Mediterranean
    • Length : 6 mm
    • Description : the shell, which shows a hexagonal pattern, is rather heavy and compels this little animal to flap continuously to keep afloat.
  • Peracle triacantha P. Fischer, 1882
    • Distribution : Oceanic, Cuba, Bermuda, Venezuela, Mediterranean
    • Length : 5 mm
  • Peracle valdiviae Meisenheimer 1905
    • Distribution : Oceanic, Argentina
    • Length : 5 mm


Superfamily Cymbulioidea

Family Cymbuliidae J.E. Gray, 1840

Instead of an external calcareous shell, they possess a pseudoconch, consisting of conchioline, a cartilaginous tissue. The mantle and the gill have disappeared as well. They breathe through the skin. They prefer warm water. In Europe, they can only be found in the Mediterranean.

Genus Corolla (Dall, 1871

They are preyed upon by the gymnosome pteropods of the genus Cliopsis.

  • Corolla calceola (A. E. Verrill, 1880) -- Atlantic Corolla
    • Distribution : Oceanic
    • Length : 40 mm
  • Corolla intermedia (Tesch, 1903)
    • Distribution : Florida, Oceanic
    • Length : 39 mm
  • Corolla ovata Quoy & Gaimard, 1832
    • Distribution : Florida, Bermuda, Oceanic
    • Length : 40 mm
  • Corolla spectabilis (Dall, 1871 Spectacular Corolla
    • Distribution : Florida, Bermuda, Venezuela, Brazil, Oceanic.
    • Length : 40 mm

Genus Cymbulia Peron and Lesueur, 1810

  • Cymbulia parvidentata Pelseneer, 1888
    • Distribution : Bermuda, Oceanic
    • Length : 35 mm
  • Cymbulia peronii de Blainville, 1818
    • Distribution : Florida, Mexico, Brazil, Argentina, Oceanic
    • Length : 65 mm
  • Cymbulia sibogae Tesch, 1904
    • Distribution : Brazil, Argentina, Oceanic
    • Length : 24 mm

Genus Gleba Forskal, 1776

  • Gleba chrysosticta Troschel, 1854
  • Gleba cordata Niebuhr, 1776
    • Distribution : Florida, Bermuda, Oceanic
    • Length : 45 mm


Family Desmopteridae (Dall, 1921

Genus Desmopterus Chun, 1889

The species are protandric hermaphrodites. There is no shell, no proto-conch and no longer any supporting tissue. The body consists almost completely of the two big parapodia (winglike flaps).

  • Desmopterus cirropterus Gegenbaur, 1855
  • Desmopterus gardineri Tesch, 1910
    • Distribution : Indian Ocean.
  • Desmopterus pacificus Essenberg, 1919
    • Distribution : California, Oceanic
    • Description : shorter wing plate tentacles.
  • Desmopterus papilio Chun, 1889
    • Distribution : Seychelles, Florida, Bermuda, Venezuela, Brazil, Adriatic Sea, tropical and subtropical oceanic waters.
    • Length: body length between 0.5 – 2.0 mm, swimming wings between 2.0- 4.0 mm..
    • Description : There is no shell. The animal has wings that are disc-shaped and transparent. The body is large and situated centrally between the lateral wings. These can unite to form a plate with on each side long, ciliated tentacles trailing behind. Most of the time, Desmopterus papilio hangs motionsless, but flaps away in a loop pattern when disturbed. There are reddish-brown spots at the margin of the wings.

[edit] References

  • Lalli, C.M. & Gilmer, R.W. (1989) Pelagic Snails. The biology of holoplanktonic gastropod molluscs. Stanford University Press: Stanford, California.
  • Giovine, F., 1988. The genus Peracle in the Mediterranean (Heterobranchia: Peraclidae). -- La Conchiglia, 20(226-227): 22-24, 5 figs.
  • Sakthivel, M., 1972. Studies on Desmopterus Chun, 1889 species in the Indian Ocean. -- 'Meteor' Forschungsergebnisse, (D)10: 46-57, 8 figs.
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