Sous-embranchement (subphylum) des Rhynchonelliformea
Classe des Rhynchonellata
Ordre des Terebratulida
Sous-Ordre des Terebratellidina
Super-famille des Platidioidea


Genus Leptothyrella Muir-Wood, 1965
[Type species= Leptothyris ignota (Muir-Wood, 1959 - p. 308)]

Very similar to Phaneropora but lacking beak ridge tubercles and with narrow de- scending loop branches extending between crura and distal extension of high, septal pillar; lophophore zygolophous.


Diagnosis from volume 5 of the
Treatise on Invertebrate Paleontology (2006)

Extant Species of Leptothyrella
  • L. ignota (Muir-Wood, 1959)
  • L. incerta (Davidson, 1880)
  • L. fijiensis Bitner, 2008
  • Diagnosis

    Leptothyrella ignota   (Muir-Wood, 1959)

    Type locality: "Station 120, off Zanzibar at 1585 fathoms. One specimen, no. ZB. 1555. Station 185, Gulf of Aden at 1093 fathoms".
    Depth range: 850 - 2881 m

    No Diagnosis available for this species

    Diagnosis of the genus Leptothyris - original from Muir-Wood, 1959, p. 308
    Shell elongate-oval, tapering to umbo, moderately coarsely punctate. Valves biconvex, smooth, with row of tubercles diverging from umbo of pedicle valve. Loop with descending branches attached to high plate-like septum, no ring or hood developed (= pre-campagiform stage, or platidiiform stage of Beecher). Cardinal process small. Inner socket ridges raised above sockets and continuous with crural bases ; no hinge plates. Lophophore spirolophous, with septum posteriorly placed to spires. No true dental lamellae, but margin of delthyrium thickened.

    Leptothyrella incerta   (Davidson, 1880)

    Type locality: "dredged by the Challenger Expedition on March 25, 1878, west of St Thomas, Danish West Indies, at a depth of 390 fathoms".
    Depth range: 225 - 5300 m

    Platidia (?) incerta Davidson, 1878

    Magasella incerta Davidson, 1880

    Platidia (?) incerta Davidson: Fischer & Œhlert, 1891.

    Diagnosis Álvarez (2017) in Álvarez et al (2017)
    Shell small, thin, nearly white, smooth except for weakly defined concentric growth lines, elongated, tear-like shaped, gently biconvex with dorsal valve almost flat, anterior commissure rectimarginate; endopunctate.
    Ventral valve subpentagonal to elongate oval in outline with greatest width anteriorly to midlength. Beak in ventral valve pointed, high, nearly straight, beak ridges strong, pedicle aperture, large, hypothyrid, deltidial plates very narrow, disjunct, pedicle collar short and sessile. Hinge teeth small supported by short, thick, ‘recessive’ dental plates.
    Dorsal valve subcircular, longer than wide. Internally, the dental sockets are short but widely open laterally, inner socket ridges strong, no cardinal process or inner hinge plates are present. Crura very long, slender, flattened distally and anteromedially convergent, crural processes weakly developed, septal pillar plate-like at its base with high, narrow distal extremity (axial loop phase). Descending loop branches extending between crura and distal extension of the high, septal pillar, ascending branches absent.
    Typically, the adults of this species have a zygolophous lophophore (as it is reported also in species of Platidia), heavily spiculate.

    Leptothyrella fijiensis  Bitner, 2008

    Type locality: "Fiji Islands, Bligh Water, MUSORSTOM 10, 16°56.17’S, 178°07.86’E, 640-687 m.”
    Depth range: 144 - 963 m

    Diagnosis - (Bitner, 2008)
    Leptothyrella having rows of small tubercles at both sides of the beak, short, recessive dental plates, and descending branches attached to the rod-like septum.