The Echinoid Directory

Allobrissus Mortensen, 1950, p. 162

Diagnostic Features
  • Test ovate without anterior sulcus; depressed in profile.
  • Apical disc ethmolytic, with 4 gonopores; anterior of centre. Madreporite plate projecting far to the posterior of the other apical disc plates.
  • Anterior ambulacrum narrow and flush; pore-pairs small, simple isopores (no penicillate tube-feet).
  • Other ambulacra petaloid and depressed, the anterior pair almost at 180 degrees. Petals sunken, narrow and straight-sided; closed distally.
  • Periproct large; on short, vertical truncate face; oral side framed by Iamb plates 5a5/5b5.
  • Peristome wider than long; kidney-shaped.
  • Labral plate short and wide, in broad contact with following sternal plates. Not extending beyond half-way down first ambulacral plate.
  • No large primary tubercles differentiated. Aboral tubercles coarser around anterior half of test.
  • Plastron very broad and distinctly bowed laterally.
  • Well-developed peripetalous and subanal fascioles. Subanal fasciole bilobed; usually enclosing 4 penicillate tube-feet on each side. Peripetalous fasciole indented in all interambulacra.
Distribution
Recent, West Pacific.
Name gender masculine
Type
Brissus agassizii Doderlein, 1855, p. 36, by original designation.
Species Included
  • B. agassizii Doderlein, 1885; Recent, Japan.
  • B. meridionalis Mortensen, 1950, Recent, Australia and Norfolk Island.
Classification and/or Status

Spatangoida, Micrasterina, Brissidae.

Monophyletic; subjective junior synonym of Brissus Gray, 1825.

Remarks

Differs from Brissus only in the form of its globiferous pedicellariae: in Allobrissus these have a blade that terminates in a slit bordered by long curved teeth, whereas in Brissus the blade ends in a transversely oval opening surrounded by about seven teeth. Although a valid distinction identifying two modern species as a clade, this does not provide a suitable character for genus level distinction.

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