Corystus or Stereopneustes?
recently read Henk van Noordenburg´s new book "Sea urchins of the
the name Stereopneustes relictus should not be used. Stereopneustes is a junior synomym of Corystus.
I suppose, that Henk remembered Dr. A. B. Smith´s webpage (The Echinoid Directory) Stereopneustes with the only species Stereopneustes relictus de Meijere 1902 and his accompanying remarks:
Similar in all aspects of test plating and appearance to Corystus Pomel 1883. Differing from the type species in having the posterior face undercut so that the periproct is inframarginal.
Subjective junior synonym of Corystus.
On the webpage Corystus one can find the following feature:
Periproct marginal, on vertically truncate face (in coincidence with H. van Noordenburg´s sentence: The periproct is transversely elongated and situated halfway down the truncated almost vertical end of the test.)
A link "C. relictus de Meijere 1902" leads to Stereopneustes with the only type species Stereopneustes relictus de Meijere 1902. Starting on the webpage Corystidae Stereopneustes is neither mentioned under "Key of genera" nor under "Thumbnails".
Checking my own specimens (unfortunately only three of each kind) I found both Corystus and Stereopneustes (see picture). The form of the posterior end and the position of the periproct show clearly distinguishable features. Intermediates are not known to me.
Surely not a reason for two different genera, but what´s about two different species or sub-species?
With concern to Corystidae it might be of interest, that an application is pending to rename Corystidae to Corystusidae:
CORYSTIDAE Foster & Philip, 1978 (Echinodermata, Echinoidea): proposed emendation of spelling to CORYSTUSIDAE to remove homonymy with CORYSTIDAE Samouelle, 1819 (Crustacea, Brachyura)