The Echinoid Directory

Loriolia Neumayr, 1881, p. 570

[=Heterotiara Pomel, 1883, p. 105 (objective) ]

Diagnostic Features
  • Test depressed, flattened above and below; ambitus rounded.
  • Apical disc large, pentagonal; projecting distinctly into the posterior interambulacrum, plating caducous.
  • Ambulacra straight, much narrower than interambulacra with series of large primary tubercles with a narrow perradial zone of secondaries. Plating trigeminate; acrosaleniid style compounding above the ambitus; at ambitus and adorally the primary tubercle overlaps all three elements; all elements reaching perradial suture. Occasionally there is one plate with four elements at the ambitus. Pore-pairs uniserial and undifferentiated; no phyllode development adorally.
  • Interambulacral plates wider than tall, each with a primary tubercle; areoles large and confluent from ambitus adorally; small secondary flanking tubercle on adradial side on oral surface. Interradial zone with fine granules only, becoming naked and slightly depressed adapically.
  • Ambulacral and interambulacral tubercles similar in size; perforate and crenulate.
  • Peristome less than half test diameter, deeply invaginated with small buccal notches.
  • Spines and lantern unknown.
Lower Cretaceous (Neocomian - Aptian), Europe, North America.
Name gender feminine
Pseudodiadema bourgueti var.  foucardi Cotteau, 1851, p. 286, by original designation.
Species Included
Classification and/or Status
Euechinoidea, Calycina, Phymosomatoida, Emiratiidae.

Distinguished from Polydiadema by its lack of phyllodes: in Polydiadema there is adoral crowding of pore-pairs and the peristome is less sunken, whereas in Loriola the peristome is strongly sunken and pore-pairs remain uniserial to the edge. Furthermore in Loriola the apical disc is pentagonal and projects strongly into the posterior interambulacrum whereas in Polydiadema the apical disc is more or less circular. Finally in Polydiadema the apical disc is obviously smaller than the peristome, whereas in Loriola the apical disc is larger than the peristome. Tiaromma has quadrigeminate plating irregularly developed adapically whereas Loriola has strictly trigeminate plating adapically. Colpotiara has no primary tubercles on adoral plates and is thus readily distinguished.

L. inaequalis (Agassiz) (Callovian, France) was placed in Loriola by Lambert & Thiery (1911, p. 181). However, this species has short phyllodes, a flush peristome and no strong elongation of the apical disc to the posterior. It is better treated as a Polydiadema.

Neumayr, M. 1881. Zeitschrift der Deutschen Geologischen Gesellschaft 33, p. 570.