The Echinoid Directory

Pseudopygaster Hawkins, 1922, p. 216

Diagnostic Features	Test subpentagonal; as wide as long; depressed, ambitus rounded; oral surface depressed towards peristome. Apical central, opening large; extending posteriorly to the ambitus. No plating preserved. Ambulacra simple throughout and narrow. No petals aborally and no phyllode expansion adorally. Pore pairs small, simple and uniserial at ambitus and above. Interambulacral plates low and wide, bearing a single large primary tubercle that is perforate and ?non-crenulate; areoles not confluent; tubercles adradially situated especially towards the apex. Remainder of plate with dense uniform granulation. Peristome very small and weakly sunken; no apparent buccal notches.
Distribution	Lower Jurassic (Pliensbachian), Iraq.
Name gender	masculine
Type	Pseudopygaster eos Hawkins, 1922, p. 216, by original designation.
Species Included	Only the type species.
Classification and/or Status	Stem group irregular. Monotypic; subjective junior synonym of Mesodiadema.
Remarks	Hawkin, H. L. 1922. Morphological studies on the Echinoidea Holectypoida and their allies. XII. Pseudopygaster, a new type of the Echinoidea Exocyclica from the Middle Lias of Persia. Geological Magazine 59, 213-222. Smith, A. B. & Anzalone, L. 2000. Loriolella, a key taxon for understanding the early evolution of irregular echinoids. Palaeontology 43, 303-324.