The Echinoid Directory

• Test subquadrate in outline with shallow but distinct anterior sulcus; posterior face truncate. Test longer than wide and depressed in profile.
• Apical disc ethmophract with four gonopores; distinctly posterior of centre.
• Anterior ambulacrum sunken from apex to peristome; pore-pairs heterogeneous, formed of a mixture of elongate 'petal-type' pores and smaller circumflexed pore-pairs.
• Other ambulacra petaloid and flush. Anterior petals flexed forwards, with pore-pairs in posterior column much better developed than those in anterior column. Posterior petals much shorter and straighter.
• Peristome subcircular and facing obliquely forwards.
• Plastron plating amphisternous.
• Periproct towards top of posterior truncate face; subcircular.
• Tuberculation unknown (based on internal moulds).

Lower Cretaceous (Barremian to Albian), Japan.

Washitaster? macroholcus Nisiyama, 1950, p. 44, by original designation.

• P. barremicus (Tanaka & Okubo, 1954); Barremian, Japan.
• P. japonicus (Tanaka & Okubo, 1954); Albian, Japan.
• P. macroholcus (Nisiyama, 1950); Barremian, Japan.

Spatangoida, stem group (toxasterids).

Subjective junior synonym of Heteraster d'Orbigny, 1853.

Differs from Toxaster in having pores in the frontal ambulacrum a mixture of wide and narrow forms. Also the anterior petals have fewer plates in the anterior column than the posterior column. This last character it shares with Washitaster, which differs only in having the apical disc more towards the posterior and the frontal ambulacrum more excavated and enlarged. Washitaster is therefore treated as a subgenus of Heteraster.

Nisiyama, S. 1968. The echinoid fauna from Japan and adjacent regions part II. Palaeontological Society of Japan Special Papers 13, 1-491, pls 1-30.