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The Echinoid Directory

Gongrochanus Kier, 1962, p. 131

[=Cyrtoma McLelland, 1840, p. 185 (non Meigan, 1824); ?=Limpasiaster Aziz & Badve, 2001, p. 49, type species Limpasiaster ariyalurensis Aziz & Badve, 2001; ?=Progongrochanus Aziz & Badve, 2001, p. 45, type species Progongrochanus ariyalurensis Aziz & Badve, 2001, p. 45.]

Diagnostic Features
  • Test medium to large, adapical surface highly inflated with posterior region obliquely truncated; adoral surface flat, slightly depressed towards peristome.
  • Apical system tetrabasal, with three genital pores, no gonopore in genital plate 2.
  • Petals broad, strongly bowed, converging distally, but not completely closed; petal III longer than the other petals. Pore-pairs conjugate, outer pores slit-like, inner pores circular to slightly elongated transversely; ambulacral plates beyond petals with single pores.
  • Peristome subcentral, pentagonal, wider than long.
  • Periproct supramarginal, longitudinal, in notch extending ventrally to posterior margin.
  • Bourrelets strongly developed, tooth-like, jutting into peristome; basicoronal plates longer than wide.
  • Phyllodes as broad arcs, single pored, with two series in each half ambulacrum plus scattered pores in between. A distinct ridge is present in the median area of each phyllode in the type species.
  • Buccal pores present, but very small and rudimentary.
  • A broad sternal zone present both in the front and to the rear of the peristome.
Distribution
Upper Cretaceous (Maastrichtian-Senonian) of India, Tibet and Libya.
Name gender masculine
Type
Cyrtoma herscheliana McClelland, 1840, p. 185; by original designation (NHM E42324 lectotype).
Species Included
  • G. clericii (Checchia-Rispoli, 1933); Maastrichtian, Libya.
  • G. herschelianus (McClelland, 1840); Maastrichtian-Senonian, India.
  • ?G. acutus Wu & Mu, 1976; Maastrichtian, Tibet.
  • ?G. ariyalurensis (Aziz & Badve, 2001); Lower Maastrichtian, India.
  • ?G. tumidus (Aziz & Badve, 2001); Lower Maastrichtian, India.
Classification and/or Status
Irregularia; Cassiduloida; Faujasiidae; Stigmatopyginae.
Remarks

This genus is similar to Hardouinia and Stigmatopygus, having the same flattened oral surface, domed adapical surface, subcentral peristome and strongly projecting bourrelets. Both Lambert & Thiery (1909-1925) and Mortensen (1948) consider Gongrochanus a subjective junior synonym of Stigmatopygus. However, Gongrochanus is easily distinguished by the presence of only three gonopores (four gonopores present in the other genera) and by its more complex phyllode structure (Smith & Jefferey, 2000). This includes a broad band of intermediate pores in addition to the outer and inner series, as well as a distinct ridge in the median area of each phyllode in the type species. This ridge is not distinct in other species of this genus.

Gongrochanus is very similar to Procassidulus but is easily differentiated by its three gonopores (four in Procassidulus), having broader arc-like phyllodes, with stronger developed bourrelets and a cleft-like longitudinal periproct, which is distinctly oval in Procassidulus.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp.

J. Lambert & P. Thiery. 1909-1925. Essai de nomenclature raisonnee des echinides. Libraire Septime Ferriere, Chaumont, 607 pp., 15 pls.

T. Mortensen. 1948. A monograph of the Echinoidea: 4 (1): Holectypoida, Cassiduloida. Reitzel, Copenhagen, 363 pp., 14 pls.

A. B. Smith & C. H. Jeffery. 2000. Maastrichtian and Palaeocene echinoids: a key to world faunas. Special Papers in Palaeontology, 63, 406 pp.