The Echinoid Directory

Polycidaris Quenstedt, 1857, p. 644

[=Pachycidaris Thiery, 1928, p. 179, type species Pachycidaris thieryi Collignon & Lambert, 1928;?= Megacidaris Thiery, 1875, type species Cidaris horrida Merian, in Agassiz, 1840 ]

Diagnostic Features	Test moderately large. Apical disc dicyclic with large Y-shaped ocular plates. Test tending to separate along adradial sutures which are weakly imbricate, especially adapically; plating otherwise tesselate. Interambulacral zones composed of relatively numerous (8+) plates that are wider than tall. Primary tubercle large and central; perforate and crenulate with circular to ovate areole; areoles incised and confluent at the ambitus and orally but just separated adapically. Scrobicular tubercles only slightly differentiated from extrascrobicular tuberculation, which is heterogeneous and developed on adradial and interradial margins. Ambulacra rather straight; pore-pairs small and non-conjugate. Perradial zone rather narrow with irregularly sized marginal tubercles; every second or third larger. All elements simple and reaching the perradius. Primary spines long, cylindrical and with cortex. Ornamented with rather strong thorns widely scattered along the shaft; the area between the thorns granular (presumably the bases of cortical hairs).
Distribution	Upper Triassic (Carnian) to Lower Cretaceous (Albian); Europe.
Name gender	feminine
Type	Cidarites multiceps Quenstedt, 1857, p. 644 [=Cidaris spinosa Agassiz, 1840, p. 71] by original designation.
Species Included	P. spinosa (Agassiz, 1840); Oxfordian, Europe. P. regularis (Munster, 1841); ?Carnian, Italy. P. suevica (Desor, 1856); Oxfordian, Germany [see Radwanska 2003]. P. trouvillensis (Cotteau, 1876); Oxfordian, France. P. gauthieri (Cotteau, 1878); Bajocian, France. P. legayei (Rigaux & Sauvage, 1873); Portlandian, France. P. horrida (Merian, in Agassiz, 1840); Bajocian, Europe. P. phillipsii (Agassiz & Desor, 1847); Hauterivian-Albian; UK. P. muricata (Roemer, 1836; Valanginian-Hauterivian, Europe.
Classification and/or Status	Cidaroida, Polycidaridae. ?Possibly paraphyletic.
Remarks	Similar to Procidaris and Dicyclocidaris in test morphology, but distinguished by its coarsely thorned primary spines. Also the adradial sutures are more nearly vertical. The distinction of the various species ascribed here is extremely difficult because of the generally bad state of preservation of most material. Distinguished from Paracidaris (Anisocidaris), which can sometimes have a very similar appearance, by its irregularly thorned spines and non-conjugate pore-pairs. A well preserved specimen of P. legayi with apical disc has been illustrated and described by Vadet (2004). Quenstedt, A. 1856-1858. Der Jura. Laupp, Tubingen. 842 pp. [p. 644 published May 1857] Vadet, A. 2004. Echinides fossiles du Boulonnais. Du Bajocien au Tithonien: les "Cidaris". Annales de la Societe d\'Histoire Naturelle du Boulonnais 3, 1-35. Radwanska, U. 2003. A monograph of the Polish Oxfordian echinoids. Part 1, Subclass Cidaroidea Claus, 1880. Acta Geologica Polonica 53, 143-165.