The Echinoid Directory

Contributed by Dinesh Srivastava, June 2009

Echinocyamus lowraliensis Srivastava et al., 2009, p. 100

Diagnostic Features
  • Test small, low, elongate pentagonal in shape.
  • Apical system central, monobasal with four circular genital pores; distance between anterior genital pores less than between two posterior ones. Madreporite with a small, oval hydropore at the centre; ocular plates small, triangular and each one perforated by minute ocular pore.
  • Ambulacra flush with the test, petaloid, open, slightly lyrate, I & V longest, II & IV shortest and widest, III narrowest. Poriferous zones consist of rounded, obliquely placed pore pairs of almost identical diameter, conjugated across each ambulacral plate. Numerous very small accessory pores present in almost straight lines near the circumferential sutures of ambulacral coronal plates aborally, scattered in central regions of plates near the peristome.
  • Peristome large, central, elongate pentagonal, and situated in shallow infundibulum.
  • Periproct elongate oval, smaller than peristome, bounded by first and second paired interambulacral plates, positioned about midway between the peristome and the posterior ambitus.
Distribution Middle Miocene Gaj Formation, Gujarat, India
Type Holotype: GSI Type No. 21425; Paratypes: GSI Type Nos. 21426, 21427, 21428, 20771, 20773 Museum of the Geological Survey of India,  Kolkata, India.
Classification and/or Status Clypeasteroida; Laganiformes; Fibulariidae

 A species of Echinocyamus van Phelsum, 1774
Remarks This species resembles to some extent Echinocyamus chipolanus Cooke, 1942 described from the sediments of the Chipola Formation (Miocene) of Florida (Cooke, 1942). However, E. lowraliensis lacks an arched aboral surface, has shorter petaloids, and the periproct is closer to the posterior ambitus. Moreover, E. lowraliensis specimens appear to reach a larger test size than E. chipolanus.

Cooke, C. W. 1942. Cenozoic irregular echinoids of eastern United States. Journal of Palaeontology 16. 29-30.

Srivastava, D. K., Mooi, R. & Jain, R. L. 2009. The clypeasteroid echinoid genus Echinocyamus from the Gaj Formation (middle Miocene) of Kathiawar, Gujarat, India. Journal of the Palaeontological Society of India 54, 97-102.