The Echinoid Directory

Platipygus de Loriol, 1902, p. 17

[=Platypygus de Loriol, 1902, p. 3]

Diagnostic Features	Test of moderate to large size, subcircular with an obliquely truncated and slightly concave posterior; inflated adapically, greatest height posterior of centre, with a flat adoral surface. Apical system tetrabasal with four gonopores. Petals long and lanceolate, closing distally. Pores conjugate, inner pores circular, outer pores elongated transversely; pores beyond petals with single pores. Peristome slightly anterior, subpentagonal. Periproct supramarginal, longitudinal to trigonal, high on oblique posterior truncation, forming a subtrigonal sulcus which expands to form a short, transverse, depressed subanal region, with a distinct notch in the roof of the periproct. Bourrelets strongly developed, tooth-like, pointed; basicoronal plates longer than wide. Phyllodes broad, single pored, with two series in each half-ambulacrum, the outer series of pores distinctly arranged in a V-shape. Buccal pores small, midway between the end of each phyllodes and the peristome. Naked sternal zone both anterior and posterior of the peristome that is fine and granular.
Distribution	Upper Cretaceous (Campanian-Early Oligocene) of Madagascar and Argentina.
Name gender	masculine
Type	Cyrtoma posthumum Ortmann, 1902; p. 369 ; by monotypy.
Species Included	P. postumus (Ortmann, 1902); Late Eocene-Early Oligocene, Argentina. P. lamberti (Besairie, 1930); Campanian, Madagascar.
Classification and/or Status	IIrregularia; Cassiduloida; Faujasiidae; Stigmatopyginae. Subjective junior synonym of Stigmatopygus d'Orbigny, 1856.
Remarks	Platipygus is very similar to Stigmatopygus, but has a wider subanal indentation, with a very well developed subanal platform (Smith & Jefferey, 2000). Both genera have a distinct notch in the roof of the periproct and similar V-shaped phyllodes. Platipygus is not sufficiently distinct from Stigmatopygus to warrant generic distinction, and should therefore be considered a junior subjective synonym. P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp. A. B. Smith & C. H. Jeffery. 2000. Maastrichtian and Palaeocene echinoids: a key to world faunas. Special Papers in Palaeontology, 63, 406 pp.