The Echinoid Directory

Pholidocidaris Meek & Worthen, 1869, p. 78

[=Praepholidocidaris Frest & Strimple, 1977, p. 102, type species Praepholidocidaris pellaensis Frest & Strimple, 1977 ]

Diagnostic Features	Test much wider than high, discoidal, with flat oral surface and gently rounded apical surface; not larger than 50 mm diameter. Apical disc small. Genital plates large with multiple gonopores arranged in an arc and surrounded by a low rim; one genital plate larger than the others, but no obvious hydropores seen. Ocular plates smaller and possibly exsert. All plates covered in small scattered tubercles. Ambulacra more or less straight with 4-6 columns of unequal plates in each zone on both upper and lower surfaces. Ambulacra about twice the width adorally and somewhat petaloid in shape, with large circular pore-pairs surrounded by a deep, well-marked peripodial area. Aboral pore pairs smaller and simpler. All ambulacrals with a small perforate tubercle. Interambulacral zones wide; composed of 4-6 columns of subhexagonal, imbricate plates. Adradial interambulacral plates larger and with a single large perforate primary tubercle; interradial plates with only secondary tuberculation. All oral plates with primary tubercle. Other plates with only secondary tuberculation. Peristome and lantern unknown. Spines relatively short, stout and straight, without cortex or ornament.
Distribution	Lower Carboniferous, USA, Europe.
Name gender	feminine
Type	Lepidocentrus irregularis Meek & Worthen, 1869, p. 78, by original designation.
Species Included	P. irregularis (Meek & Worthen, 1869); Lower Carboniferous, USA. P. tenuis Tornquist, 1897; Lower Carboniferous, Europe. P. pellaenesis (Frest & Strimple, 1977); Lower Carboniferous, USA. P. tornacensis Jackson, 1929; Visean, Belgium.
Classification and/or Status	Stem group Echinoidea; Proterocidaridae. Presumed monophyletic.
Remarks	This taxon is close to Perischocidaris, from which it differs in having four columns of ambulacral plates rather than six. The large primary tubercles on adambulacral interambulacral plates distinguishes this from Proterocidaris. The genus was most recently redescribed by Frest & Strimple (1977). Jackson, R. T. 1912. Phylogeny of the Echini, with a revision of Palaeozoic species Memoirs of the Boston Society of Natural History 7, 491 pp. 76 pls. Meek & Worthen 1869. Proc. Acad. nat. Sci. Philadelphia 1869, p. 78. Frest, T. J. & Strimple, H. L. 1977. Praepholidocidaris, a new echinoid from the Pella Formation (Mississippian) of Iowa. Proceedings of the Iowa Academy of Sciences 84, 98-105.