The Echinoid Directory

Toxaster Agassiz, 1840, p. 15

[=Echinospatagus d'Orbigny, 1853, p. 30 (objective); = Echinospatangus Peron, 1875, p. 33 (objective); =Mengaudia Lambert, 1917, p. 105, type species Toxaster collegnoi Sismonda, 1843 ]

Diagnostic Features	Test cordiform with distinct anterior sulcus; posterior face obliquely truncate. Apical disc ethmophract with four gonopores; central; posterior genital plates abut. Ambulacrum III sunken from apex to peristome; pore-pairs subpetaloid with elongate pores, but smaller than those in other ambulacra. Paired ambulacra petaloid; petals flush, the anterior pair flexed and about twice as long as the posterior pair; open distally. Both pore-pairs slit-like. Petaloid zones ending gradually. Peristome small, subcircular and inclined slightly towards the front. Labrum long and crescentic with handle extending to plate 5.a.2; extending to ambulacral plate 3 or 4. Sternal plates asymmetric with oblique suture. Episternal plates offset. Periproct small and towards the top of posterior truncate face No fascioles. Aboral surface with small scattered tubercles set in a groundmass of granules.
Distribution	Lower Cretaceous (Valanginian to Aptian, possibly higher), Europe, former Soviet Union, North Africa, North and South America.
Name gender	masculine
Type	Spatangus retusus Lamarck, 1816, p. 33, by subsequent designation of Cotteau, 1878, p. 117.
Species Included	T. renevieri Wright T. retusus (Lamarck, 1816) T. collegnoi Sismonda, 1843 T. granosus (d'Orbigny) Numerous species assigned, few of which are known in sufficient detail.
Classification and/or Status	Spatangoida, stem group (toxasterids). Presumably paraphyletic.
Remarks	Differs from Epiaster in having laterally elongate pore-pairs in the anterior ambulacrum aborally that resemble those in the paired ambulacra. It differs from Heteraster in having the two columns of pore-pairs equally developed in the paired petals.