Psychocidaridae

Psychocidaridae is a family of sea urchins in the order Cidaroida. The genus Psychocidaris is extant while the other genera are only known from fossils. The family has been in existence since the Lower Jurassic (Toarcian) and the range includes Europe, Ukraine, North America, North Africa and the West Pacific.[2]

Psychocidaridae
Temporal range: Lower Jurassic–Recent
Fossil of Balanocidaris marginata
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Echinoidea
Subclass:
Perischoechinoidea
Order:
Cidaroida
Family:
Psychocidaridae

Ikeda, 1936 [1]
Genera
See text

Characteristics

All Cidaroids are regular and have the test composed of twenty columns of plates with two ambulacral columns alternating with two interambulacral columns. The pedicellariae are exclusively globiferous or tridentate. In addition, Psychocidarids are characterized by having no plates between the ambulacra. Instead they have a single primary tubercle 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]

Genera

According to the World Register of Marine Species (WoRMS), the following genera are included in the family:[1]

  • Balanocidaris Lambert, 1910a †
  • Caenocidaris Thiéry, 1928 †
  • Oedematocidaris Smith & Wright, 1989 †
  • Psychocidaris Ikeda, 1935
  • Roseicidaris Vadet, 1991 †
  • Sardocidaris Lambert, 1907 †
  • Tylocidaris Pomel, 1883 †

Of these, Psychocidaris is the only extant genus while the other genera are known from fossils. The only living species and the type species of the genus is Psychocidaris ohshimai.[1]

Psychocidaris ohshimai

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 the Philippines and the Bonin Islands, Japan.[3]

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References
  1. Cidaridae WoRMS. Retrieved 2011-08-28.
  2. Family Psychocidaridae Ikeda, 1936 The Echinoid Directory. Retrieved 2011-08-28.
  3. Psychocidaris Ikeda, 1935 The Echinoid Directory. Retrieved 2011-08-28.
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