The Echinoid Directory

Archaechinus Kier, 1957, p. 891

Diagnostic Features
  • Test ovate with faint, more or less obliterated, anterior sulcus; posterior face truncate. Test depressed above and below.
  • Apical disc ethmolytic with three gonopores (no gonopore in genital plate 2); anterior of centre.
  • Anterior ambulacrum non-petaloid, with small pore-pairs; weakly depressed.
  • Other ambulacra petaloid aborally and weakly sunken, the posterior being slightly longer than the anterior pair. Petals extending more or less to ambitus; parallel-sided and open distally.
  • Peristome D-shaped and downward-facing.
  • Labral plate longitudinally elongate and moderately large; extending to third ambulacral plate.
  • Plastron narrow with symmetical sternal and episternal plates. Episternal plates not strongly indented by adjacent ambulacral plates and opposite.
  • Periproct on posterior truncate face; opening between interambulacral plates 5a/b and 8a/b.
  • Bilobed subanal fasciole present; oral band passing midway through plates 5.a.3/5.b.3; aboral portion passing across 5.a.4-6 and 5.b.4-6. Peripetalous fasciole present; near ambitus anteriorly and not indented in lateral interambulacral zones; passing close to ends of petals.
  • Aboral tuberculation heterogeneous with larger tubercles set in a groundmass of smaller granules.
Lower Eocene (Upper Auradu Series), Somalia.
Name gender masculine
Archaechinus auraduensis, Kier, 1957, p. 891, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

Spatangoida, Micrasterina, Macropneustidae.



Differs from Macropneustes in having three gonopores rather than four.

Kier, P. M. 1957. Tertiary Echinoidea from British Somaliland. Journal of Paleontology 31, 839-902.