The Echinoid Directory

Maretia Gray, 1855, p. 48

[=Thrichoproctus A. Agassiz 1872, p. 139, (nomen nudum); = Plagiopatagus Lutken Ms (nomen nudum)

Diagnostic Features
  • Test ovate with or without slight anterior sulcus; depressed in profile with flat base and low, moderately sharp ambitus.
  • Apical disc ethmolytic, with 4 gonopores; genital plate 2 projects far to the posterior of the posterior oculars.
  • Anterior ambulacrum narrow and flush adapically; pore-pairs small, simple isopores. Other ambulacra petaloid and flush.
  • Anterior paired petals bowed with adapical pore-pairs in anterior column of anterior petals rudimentary; remainder large and conjugate; Posterior petals bowed to lanceolate, converging distally.
  • Periproct on short steeply undercut truncate face.
  • Peristome wider than long; kidney-shaped.
  • Labral plate narrow and elongate; only just contacting sternal plates; extending to third ambulacral plate.
  • Paired sternal plates narrow and triangular with tuberculation confined to posterior.
  • Aboral tuberculation heterogenous with scattered coarse tubercles in all but the posterior interambulacrum. Primary tubercles sunken. On oral surface lateral tubercles arranged in distinct rows, with slightly sunken areoles and spiral parapet.
  • Well-developed shield-shaped subanal fasciole.

Middle Eocene USA, to Recent, Indo-West Pacific, possibly wider.

Shallow water sands to shell gravels - infaunal.

Name gender feminine
Spatangus planulatus Lamarck, 1816, p. 326, by original designation.
Species Included
  • M. planulata (Lamarck, 1816); Pliocene to Recent, Indo-West Pacific.
  • M. sp. aff. planulata (Lamarck, 1816) Holmes, 2014; Upper Miocene, Australia.
  • M. carinata Bolau, 1873; Recent, South Sea Islands.
  • M. cordata Mortensen, 1948; Recent; Malay archipelago.
  • M. tuberculata Agassiz & Clark, 1907; Recent, Japan.
  • Maretia sp. Henderson, 1975; Upper Miocene, New Zealand.
  • Maretia subrostrata (Clark, 1915); Middle Eocene, SE USA.
  • Others not checked.
  • ? M. aequipetala Gregory, 1892; Pliocene, England
Classification and/or Status

Spatangoida, Micrasterina, Maretiidae.

Almost certainly paraphyletic.


Traditionally distinguished from the similar Eupatagus on the development of fascioles. Whereas Maretia posesses only a subanal fasciole, Eupatagus has in addition a peripetalous fasciole. Lovenia has an inner fasciole, a frontal notch and deeply sunken aboral tubercles that distinguish it from Maretia.

A review of species attributed to this genus is given by Kroh (2007) and Homes (2014).

Holmes, F. C. 2014. A late Miocene record of the echinoid Maretia (Echinoidea, Spatangoida) from Victoria, Australia. Memoirs of Museum Victoria 72, 63-72.

Kroh, A. 2007. Hemipatagus, a misinterpreted loveniid (Echinodermata, Echinoidea). Journal of Systematic Palaeontology 5, 163-192.

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