The Echinoid Directory

Tithonia Pomel, 1883, p. 49

[?=Oustechinus Lambert, 1931, p. 92, type species Oustechinus bassae Lambert, 1931 ]

Diagnostic Features
  • Test cordiform; depressed above and below
  • Apical disc disjunct; anterior portion compact; tetrabasal with posterior gonopores opening on ocular plates II and IV. Posterior oculars immediately above periproct; bordering onto opening, or just separated by small catinal platelets
  • Paired ambulacra flush; all five ambulacra apetaloid; no visible pore-pairs except close to the peristome
  • Plates in ambulacrum III smaller than those in other ambulacra aborally
  • Frontal ambulacrum flush adapically but groove develops and deepens towards ambitus and continues to peristome
  • Plastron plating with large labral plate; amphisternous and in contact with succeeding plates in both columns. Adjacent ambulacral zones very narrow
  • Peristome subcircular; inclined anteriorly and opening into distinct frontal groove
  • Periproct towards top of truncate posterior face
  • Aboral tuberculation comprises fine tubercles set in groundmass of granules
Distribution
Middle Jurassic (?Bathonian, Callovian) to Lower Cretaceous (Berriasian), North Africa, southern Europe
Name gender feminine
Type
Nucleolites convexus Catullo, 1827 , p. 28, by monotypy.
Species Included
  • T. convexa (Catullo, 1827); Tithonian of Italy and North Africa
  • T. oxfordiana Gaillard, Neraudeau & Thierry, 2011; Oxfordian, France 
  • T. transversa (d\'Orbigny, 1853); Berriasian, southern Europe
  • T. praeconvexa Jesionek-Szymanska, 1963; Callovian, Europe, former Soviet Union [?=?T. pictaviensis (Lambert & Thiery, 1924) ; Bathonian, France]
  • T. berriasensis (de Loriol, 1867); Berriasian
  • T. muensteri (Desor, 1842); Berriasian
  • T. exile (Eichwald, 1865) [includes T. heinzi (Coquand, 1880)]; Barremian, North Africa, Russia
Classification and/or Status

Irregularia; Stem group Atelostomata; Tithoniidae

Monophyletic

Remarks

Distinguished from Tetraromania by having the labral plate abutting two plates rather than a single plate. In addition, the posterior ambulacra radiating from the apex of the periproct. The posterior ocular plates are either in contact with the periproct or is only slightly removed from it. Metaporinus lacks the frontal groove leading to the peristome and has the posterior ambulacra distinctly removed from the periproct.

See Gaillard et al. (2011) for a recent description, including plating diagrams, and discussion of mode of life.

Gaillard, C., Neraudeau, D. & Thierry, J. 2011. Tithonia oxfordiana, a new irregular echinoid associated with Jurassic seep deposits in Sout-East France. Palaeontology 54, 735-752.

Jesionek-Szymanska, W. 1963. Echinides irreguliers du Dogger de Pologne. Actes Palaeontologica Polonica 8(3), 293-396, pls 1-7.

Solovjev, A. 1971. Late Jurassic and Early Cretaceous disasterids of the USSR. Transactions of the Palaeontological Institute, Academy of Sciences of the USSR 131, 1-120, pls 1-16 [in Russian]