Popular search terms:

Home / Our science / Data / Echinoid Directory

The Echinoid Directory

Rhabdobrissus Cotteau, 1889, p. 281

[=Rhabdobryssus Meissner, 1903, p. 1343 (nomen vanum); =Mortensenaster Lambert, 1922, p. 44, type species Metalia costae Gasco, 1876 ]

Diagnostic Features
  • Test ovate without anterior sulcus; posterior face truncate. Test depresed in profile.
  • Apical disc ethmolytic with four gonopores.
  • Anterior ambulacrum narrow and flush; plates as tall as wide; pore-pairs small and undifferentiated.
  • Paired ambulacra petaloid aborally; almost flush; narrow and parallel-sided, with occluded plates at distal end. Interporal zone extremely narrow.
  • Peristome D-shaped; downward-facing.
  • Labral plate short and wide; not extending beyond first ambulacral plate. Sternal and episternal plates forming plastron, the episternal plates strongly tapered posteriorly. Sternal - episternal plate suture weakly convex to anterior.
  • Ambulacral plates 6-10 enclosed by subanal fasciole.
  • Periproct on posterior truncate face; opening bounded by Iamb plates 5.a.5, 5.b.5; tapering adapically and open until 5.a.10/5.b.10.
  • Subanal fasciole present; shield-shaped. Anal branches developed.
  • Peripetalous fasciole thin; not indented behind anterior petals.
  • Larger primary tubercles present in interambulacral zones within peripetalous fasciole.
Distribution
Upper Miocene to Recent, West Africa, Mediterranean, Atlantic, East Pacific.
Name gender masculine
Type
Rhabdobrissus jullieni Cotteau, 1889, p. 283, by original designation.
Species Included
  • R. jullieni Cotteau, 1889; Recent, Liberia, Guinea.
  • R. costae (Gasco, 1876); Pliocene to Recent, Mediterranean, East Atlantic.
  • R. pacificus Clark, 1940; Recent, East Pacific.
  • R. sp. Lachkhem & Roman, 1995; Upper Miocene, Morocco.
Classification and/or Status

Spatangoida, Micrasterina, Brissidae.

Status unknown.
Remarks

Differs from Plagiobrissus only in having no frontal groove and virtually flush petals. Differs from Trachypatagus in having a shield-shaped rather than bilobed subanal fasciole.

This genus is often treated as a subgenus of Plagiobrissus and it is likely that juveniles of the two taxa are very similar.  Whether this taxon really turns out to be a monophyletic subset within Plagiobrissus, a paraphyletic assemblage or a discrete genus requires a modern gene-based study of the clade.

Cotteau, G. 1889. Comptes Rendus Congr. Internat.

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

Borghi, E. 1993. Un echinide attuale rinvenuto allo stato fossile: Plagiobrissus (Rhabdobrissus) costai (Gasco, 1876). Societa Reggiano di Scienze Naturali Anno XIII, 1, 1-6, 3 pls.