Constellaria polystomella

Phylum: Bryozoa
Class: Stenolaemata
Order: Cystoporata
Genus: Constellaria
Species: Constellaria polystomella (Nicholson, 1875)

Taxonomic Details

Includes Constellaria constellatai
History: (Nickles & Bassler, 1900)

  • 1875 Constellaria polystomella Nicholson, Pal. Ohio, II, p. 215, pl. xxii, 7, 7a.
  • 1882 Constellaria polystomella Whitfield, Geol. Surv. Wisconsin, IV, p. 257, pl. xii, 3,4.
  • 1896 Monticulipora (Constellaria) polystomella (in part) J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 118.
  • Cincinnati (Richmond): Delafield, Wisconsin; Wilmington, Illinois; Richmond & Versailles, Indiana; Blanchester, Waynesville, and other localities in Ohio.
  • Observation:Nicholson erronesously records this characteristic fossil of the Richmond beds as from Cincinnati, Ohio.

Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Distribution

Sequences (Formations)

  • C6 Sequence (Upper Whitewater, Elkhorn)
  • C5 Sequence (Saluda, Lower Whitewater, Liberty, Waynesville)
  • C4 Sequence (Arnheim)

Identification in Hand Sample
C. polystomella_diag

  • Zoarium Morphology: Erect, flattened branches or fronds (frondose)
  • Zoecia: polygonal
  • Mesozooids: More numerous in maculae
  • Monticules: Surface with depressed stellate (star-shaped) maculae
  • Spaces between rays elevated and occupied by rows of close apertures

Diagnosis: Differs from C. florida in having more numerous ridges in the “stars” and a clearer distinction between the stars (Davis, 1998)


Constellaria polystomella from Arnheim Formation of Butler County, Ohio (OUIP 1094)

Published Descriptions

Davis (1998):

  • Differs from Constellaria florida in having more numerous ridges in the “stars” and a clearer distinction between ‘stars’

McFarlan (1931):

  • (Genus description) Dendroid or frondescent zooaria with depressed stellate maculae.C. polystomella has more frondescent, stars occupy definite polygonal areas, each star circumscribed by a “hexagonal border”

Foerste (1924):

  • Specimens forming somewhat flattened branching fronds, many 20 mm. or more wide, and 3 or 4 mm thick. Stellate maculae mostly on boldly elevated prominences, many half a millimetre high, and 2 to 3 mm. across.
  • Locality and Horizon. A characteristic fossil of the Richmond, from the Waynesville upward in Ohio, Indiana, Kentucky, Illinois, and Wisconisn. Clay cliffs (No. 8550) and Streetsville.