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Minutella

Sous-embranchement (subphylum) des Rhynchonelliformea  
Classe des Rhynchonellata 

Ordre des Thecideida 
Sous-ordre des Thecideidina 
Super-famille des Thecideoidea 
Famille des Thecidellinidae  
Sous-famille des Minutellinae  


Genus Minutella Hoffmann et Lüter, 2010


[Type-species = Minutella tristani Hoffmann et Lüter, 2010, p. 142]

Small endopunctate thecidellinine brachiopods, maximum length 2.5 mm. Ventral valve pseudodeltidium present; teeth small, covered with secondary shell material, single fibres well defined, rhombic or cubic, protruding. Dorsal valve with median septum; lophophore schizolophous; calcitic connection between intrabrachial ridge and brachial bridge always missing, in some cases secondarily filled with fine calcareous spicules; interbrachial lobes posteriorly highly raised, with reticulated canopying spicules, if present; tip of median septum often irregular, root-like; brachial bridge very broad; calcitic pole cone-like, never completely fused to floor of cardinal process, irregular appearance; two median adductor mus- cle scars on either side of visceral foramen; cardinal process massive, sub-quadrate, lateral lobes distally thickened, median lobe indistinct; lateral adductor muscle scars round to ovate, never extending beyond insertion of lateral lobes of cardinal process.

Holocene.


References:

  • Hoffmann J. & C. Lüter, 2010. Shell development in the thecidellinine brachiopods with description of a new recent genus. Special Papers in Palaeontology, 84, 137-160.

  •     Extant species of Minutella
  • M. minuta (Cooper, 1981)
  • M. tristani Hoffmann et Lüter, 2010
  • M. bruntoni Hoffmann et Lüter, 2010
  • Diagnosis
    Diagnosis
    Diagnosis

        Fossil species of Minutella
  • M. bulgarica Bitner et Motchurova-Dekova, 2016
  • Diagnosis



    Minutella minuta (Cooper, 1981)

    Type locality: MD.08 (St. 7, DC 57), Samper Bank, south-east of Madagascar (36°48'54"S 52°07'42"E, 380 m).

    Depth range: 30 - 380 m.

    Thecidellina minuta Cooper, 1981, p. 61
    Thecidellina minuta: Zezina, 1985, p. 209
    Thecidellina minuta: Lee & Robinson, 2003, p. 355
    Thecidellina minuta: Bitner, 2010
    Minutella minuta : Simon & Hoffmann, 2013

    Diagnosis from Hoffmann & Lüter ( 2010)

    Very small endopunctate thecidellinine bra- chiopod. Ventral valve pseudodeltidium present. Dorsal valve median adductor muscle scar planar; canopying spicules reticulated, completely covering brachial cavity; median septum narrow, straight, almost reaching anterior margin of valve; interbrachial lobes posteriorly highlyraised, brachial bridge very broad. Ventral valve floor granulose; hemispondylium of two thin plates with addi- tional ventral projections, fused to posterior part of valve, ventral projection fused medially and connected to valve floor in adult specimens.

    Minutella tristani Hoffmann et Lüter, 2010

    Type locality: North Andros Island, Bahamas (55 m)

    Depth range: 55 m.

    Diagnosis - Hoffmann & Lüter (2010)


    Small endopunctate thecidellinine brachiopods. Ventral valve pseudodeltidium present. Dorsal valve median adductor muscle scars bulging, not medially fused; canopying spicules, if present, reticulated, completely covering brachial cavity, creating a regular pattern of little holes; interbrachial lobes posteriorly highly raised; median septum wide, posteriorly heavily tapering; brachial bridge very broad, outer margin denticulate, inner margin with a row of characteristic branching calcareous spicules filling visceral gap, continuing around interbrachial lobes. Ventral vale floor heavily tuberculated forming regular longitudinal rows in posterior part of valve; hemispondylium with two plate-like prongs apically pointed, fused to posterior part of valve floor, ventrally not connected in adult specimens.


    Minutella bruntoni Hoffmann et Lüter, 2010

    Type locality: So Tiago, Tarrafal, Cape Verde (12 m)

    Depth range: 12 - 150 m

    Thecidellina barretti: Logan, 1977, p. 87-93.
    Thecidellina barretti: Logan, 1981, p. 735-744.

    Diagnosis - Hoffmann & Lüter (2010)

    Small endopunctate thecidellinine brachiopods. Ventral valve with pseudodeltidium. Dorsal valve median adductor muscles attached to single plate posterior of cal- citic pole, muscle plate medially fused or with minute median gap; calcitic pole flat, broad, very irregular, almost completely filling visceral foramen, leaving only two narrow slits; brachial cavities filled with spinose shell material, completely or incompletely covered by numer- ous branching canopying spicules, brachial cover irregular; median septum wide, posteriorly heavily tapering; interbrachial lobes posteriorly highly raised, brachial bridge very broad, inner margin with a row of characteristic branching spicules filling visceral gap and continuing around interbrachial lobes. Ventral valve floor heavily tuberculated and spinose with regular rows of spines in posterior part of valve; hemispondylium with two massive irregular plate-like prongs, apically only slightly pointed or blunt, fused to posterior part of ventral valve.

    Minutella bulgarica Bitner et Motchurova-Dekova, 2016

    Type locality: Yasen, Pleven District, Bulgaria (4325'N, 2431'E)

    Type horizon: Lower Badenian, Middle Miocene.

    Thecidellina sp.: Bitner, 1993, p. 151-152, pl. 6, fig. 6-7.

    Diagnosis - Bitner & Motchurova-Dekova (2016)

    Small-sized thecideide brachiopod, convex pseudodeltidium, hemispondylium with two plate-like prongs, straight and narrow median septum with a groove anteriorly, massive cardinal process, broad brachial bridge with denticulated inner margin.