The Echinoid Directory

Amblypygus L. Agassiz, 1840, p. 17

[?=Kutchypygus Srivastava, 1988, p. 150 (nomen nudum);?=Semiclypeus Mayr-Eymer, 1898, p. 48, type species Clypeus (Semiclypeus) pretiosus Mayr-Eymer, 1898 ]

Diagnostic Features	Test large, circular or ovoid in outline, aboral side low arched, subconical, margin broadly rounded, oral surface sunken towards the peristome. Apical disc subcentral, tetrabasal with four genital pores, large madreporite. Petals long, extending almost to margin, open, poriferous zones, tapering distally, pores conjugate, outer series elongate transversely; all ambulacral plates double pored. Periproct oral, very large, longitudinally elongate, midway between peristome and the posterior edge of the test Peristome large, subcentral, oblique, depressed. Bourrelets absent. Phyllodes undeveloped. No buccal pores. No naked sternal area.
Distribution	Eocene to Oligocene of India, Madagascar, Caribbean, West Indies, and the United States.
Name gender	masculine
Type	Amblypygus dilatatus L. Agassiz, 1840; by subsequent designation of Duncan & Sladen, 1883, p. 15.
Species Included	A. dilatatus L. Agassiz, 1840; Eocene of France. A. americanus Desor, 1858; Miocene, Caribbean and the United States. A. pentagonalis Duncan & Sladen, 1883; Middle Eocene (Lutetian-Bartonian), Kachchh, India Lambert & Thiery (1909-1925) list some further 10 species within this genus.
Classification and/or Status	Irregularia; Echinoneioida, Echinoneidae.
Remarks	The circular shape and large, flush periproct of Amblypygus resembles Holectypus, but the circular, notched peristome of Holectypus is quite different (Cooke, 1959, p. 27). The peristome and periproct of Amblypygus appears to be very similar to Echinoneus. These genera only differ in that the ambulacra of Echinoneus are less distinctly petaloid, with the outer pores not as transversely elongated as they are in Amblypygus. Amblypygus can be differentiated from pygaulids by its poorly developed (undifferentiated) phyllodes, which contain only a single offset series of pores in each column. Agassiz, L. 1840. Catalogus systematicus Ectyporum Echinodermatum fossilium Musei Neocomiensis, secundum ordinem zoologicum dispositus; adjectis synonymis recentioribus, nec non stratis et locis in quibus reperiuntur. Sequuntur characteres diagnostici generum novorum vel minus cognitorum, 20 pp. Oliv. Petitpierre, Neuchâtel. C. W. Cooke. 1959. Cenozoic echinoids of eastern United States. United States Geological Survey, Professional Paper, 321, 106 pp., 43 pls. J. Lambert & P. Thiery. 1909-1925. Essai de nomenclature raisonnee des echinides. Libraire Septime Ferriere, Chaumont, 607 pp., 15 pls. Srivastava, D. K. 2009. Taxonomic placement of a holectypoid echinoid genus Srivastava & Singh, 2001. Earth Science India 2:46-51.