| Psychocidaridae | |
|---|---|
 | |
| Fossil ofBalanocidaris marginata | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Cidaroida |
| Superfamily: | Histocidaroidea |
| Family: | Psychocidaridae Ikeda, 1936[1] |
| Genera | |
See text | |
Psychocidaridae is afamily ofsea urchins in the orderCidaroida. The genusPsychocidaris isextant while the other genera are only known fromfossils. The family has been in existence since theLower Jurassic (Toarcian) and the range includes Europe, Ukraine, North America, North Africa and the West Pacific.[2]
All Cidaroids are regular and have thetest composed of twenty columns of plates with two ambulacral columns alternating with two interambulacral columns. Thepedicellariae are exclusively globiferous or tridentate. In addition, Psychocidarids are characterized by having no plates between the ambulacra. Instead they have a single primarytubercle with a large mamelon, the ball-like surface that articulates with the spine. In most genera this is imperforate and non-crenulate. The pores are in pairs that are not connected by grooves. The spines are broad and either spindle, gland or club-shaped.[2]
According to theWorld Register of Marine Species (WoRMS), the followinggenera are included in the family:[1]
Of these,Psychocidaris is the onlyextant genus while the other genera are known fromfossils. The only living species and thetype species of the genus isPsychocidaris ohshimai.[1]
P. ohshimai is characterized by having gland-shaped spines on the apical (top) surface with a mat of hairs forming an overgrowth and by the oral spines having longitudinal flanges. It is found in thePhilippines and theBonin Islands, Japan.[3]