Taxonomic Details

Type Species: Monticulipora ramosa (d’Orbigny, 1850)Species found in the Cincinnatian (

  • Parvohallopora communis (James, 1882)
  • Parvohallopora dalii (Milne Edwards & Haime, 1851)
  • Parvohallopora onealli (James, 1875)
  • Parvohallopora ramosa (d’Orbigny, 1850)
  • Parvohallopora subnodosa (Ulrich, 1890)
  • Parvohallopora subplana (Ulrich, 1882)
  • Parvohallopora congrua (Utgaard and Perry, 1964)
  • Parvohallopora rugosa
  • Parvohallopora weisbergiana (Dybowski, 1877)

Geologic Range
Late Ordovician

Stratigraphic Occurrences

Geographic Occurrences


Stratigraphic Distribution

Sequences (Formations)

  • C5 Sequence (Saluda, Lower Whitewater, Liberty, Waynesville)
  • C4 Sequence (Arnheim)
  • C3 Sequence (Mt. Auburn, Corryville)
  • C2 Sequence (Bellevue, Miamitown, Fairview: Fairmount, Mt. Hope)
  • C1 Sequence (Clays Ferry/Kope: McMicken, Southgate, Economy/Fulton; Lexington/Point Pleasant)

Identification in Hand Sample:

  • Zoarium Morphology: Ramose (branching)
  • Zoecia: Smoothly oval; may be lined; very uniform in shape and well separated
  • Mesozooids: Numerous, small, angular
  • Monticules: Prominent & regularly spaced, low & rounded to sharp & conical to continues sharp ridges
  • Maculae:

Species Differentiation
Parvohallopora species

Published Description

Steven Holland (UGA Strat Lab, 2013):

  • Parvohallopora is a ramose form characterized by numerous small mesozooids bearing numerous diaphragms, a lack of styles, with a smooth surface or regularly spaced monticules. Many species have lined zooecia. Diaphragms may be numerous in feeding zooids in the exozone (e.g., P. congrua, P. onealli, P. ramosa, P. subplana) or rare to absent in the exozone (e.g., P. subnodosa).

Karklins (1984)

  • Singh (1979, p. 226) erected Parvohallopora, of which M. ramosa d’Orbigny is the type species, and characterized it as having ramose zoria with polygonal autozooecia in endozones and polygonal to circular autozooecia in cross section in exozones. Basal diaphragms of autozooecia are common in endozones and can be sparse or lacking in exozones. Autozooecial wall laminae in Parvohallopora are broadly U- or V-shaped (Singh, 1979, pi. 43, fig. Ic, and pi. 38, fig. If, respectively). Parvohallopora is further characterized by maculae in zoaria of some species and numerous mesozooecia (mesopores of Singh) between autozooecia in most species. Parvohallopora is differentiated (Singh, 1979, p. 227) from Calopora elegantula (Hallopora of Singh, 1979, but see also Ross, 1969, 1970b), the type species of Calopora, by the smaller cross-sectional sizes of its autozooecia and mesozooecia and by the shape of its endozonal autozooecia in cross section, which are polygonal, instead of circular as they are in C. elegantula (Cornelliussen and Perry, 1973, text-fig. 22; McKinney, 1979, pi. 2, figs. 2, 3b). Singh also noted that Parvohallopora lacks the accessory autozooecial wall structures, such as spines and cysts, that are common in C. elegantula. P. ramosa has been regarded as a species of Calopora since Ulrich’s assignment (1882, p. 252).

Singh (1979)

  • Zoaria ramose. Zoarial surface smooth or with regularly spaced monticules. Exozone well developed. Zooecial surface-angle sharp. Zooecia in endozone polygonal in cross-section, in exozone polygonal or circular to subcircular. Diaphragm-zooecial lining unit present in many species. Laminae in ZCL merging, broad U- to V-shaped, distinctly dark at their proximal parts. Diaphragms in zooecia in endozone, absent in exozone of some species. Diaphragms planar or curved but rarely cystose. Mesopores abundant between most zooecia, rounded to subrounded, rarely polygonal in cross-section, always less than half the diameter of zooecial openings. Diaphragms in mesopores, planar to curved, forming short diaphragm-wall units.

Nickles & Bassler (1900; Under Monticulipora)

  • Zoarium massy, lobate or lamellate, encrusting or free; monticules usually present; zooecia prismatic, usually thin-walled, with cystiphragms both in mature and immature regions; apertures polygonal; mesopores few or wanting; acanthopores small, generally numerous

P. dalei

P. multitabulata

P. oneali

P. ramosa

P. rugosa

P. subnodosa