The Echinoid Directory

Meoma Gray, 1851, p. 131

[=Rhyssobrissus Agassiz, 1863, p. 27 (objective); = Hemibrissus Pomel, 1869, p. 13, type species Spatangus ventricosus Lamarck, 1916; =Hernandezaster Sanchez Roig, 1949, p. 212; type species H. hernandezi Sanchez Roig, 1949 ]

Diagnostic Features
  • Test ovate with slight anterior sulcus.
  • Apical disc ethmolytic, with 4 gonopores; genital plate 2 projects beyond posterior oculars.
  • Anterior ambulacrum narrow and weakly sunken; pore-pairs small, simple isopores.
  • Other ambulacra narrow and prominently sunken; relatively straight with narrow interporal zone; extending to near ambitus. Distal plates of petals occluded.
  • Anterior petals defining an obtuse angle anteriorly.
  • Periproct large, on short, steeply undercut posterior face.
  • Peristome wider than long; kidney-shaped with projecting labrum.
  • Labral plate short and wide; not extending beyond first ambulacral plate.
  • Plastron fully tuberculate; formed of sternal and episternal plates; ovate. Episternal plates not strongly tapered to rear; paired.
  • Spines and tubercles within peripetalous fasciole often sightly larger, but tubercles not sunken.
  • Well-developed bilobed subanal fasciole only in juvenile; in adult only the adoral portion remains.
  • Peripetalous faciole indented in lateral interambulacra.
Distribution

Middle Eocene to Recent, Caribbean and central East Pacific.

Continental shelf sands - infaunal.

Name gender feminine
Type
Meoma grandis Gray, 1855, p. 132, by original designation.
Species Included
  • M. grandis Gray, 1851; Recent, central East Pacific.
  • M. ventricosa (Lamarck, 1816); Recent, Caribbean (Florida to northern South America).
  • M. antillarum (Cotteau, 1875); Eocene, Cuba.
  • M. antiqua Arnold & Clark, 1927; Middle Eocene, Jamaica and Cuba.
  • M. clevei (Cotteau, 1875); Miocene, Anguilla.
  • M. frangibilis Chesher, 1970: Recent, Caribbean.
  • M. cadenati Madsen, 1957; Recent, Sierra Leone.
  • M. caobaensis Sanchez Roig, 1952; Middle Eocene; Cuba.
  • M. tuberculata Hutton, 1873; Oligocene - Lower Miocene, New Zealand & Australia.
Classification and/or Status

Spatangoida, Micrasterina, Brissidae.

Monophyletic.

Remarks

Similar in plastron structure to Spatangus but has very different sunken petals and a peripetalous fasciole. Close to Macropneustes, but distinguished by having more deeply sunken petals and an indented peripetalous fasciole behind the anterior petals, with the interambulacral plates correspondingly differentiated.

Mortensen, T. 1951. A Monograph of the Echinoidea V, Spatangoida 2. C. A. Reitzel, Copenhagen.

Chesher, R. H. 1970. Evolution in the genus Meoma (Echinoidea: Spatangoida) and a description of a new species from Panama. Bulletin of Marine Science 20, 731-761.

Gray, J. E. 1851. Annals and Magazine of Natural History (2) 7, p. 131.

Zitt, J. 1985. Revision of Meoma (Echinoidea, Spatangoida) from Loma Caoba (Cuba, middle Eocene). Casopis pro mineralogii a geologii 30, 265-284, pls 1-4.