Parvohallopora rugosa

• Zoarium Morphology: Ramose (branching); 3-8 mm in diameter
• Zoecia: Smoothly oval; may be lined; uniform in shape and well separated
• Mesozooids: Numerous, small, angular; in some cases, completely isolating zooecia
• Monticules: Prominent & regularly spaced, sharp & conical to continues sharp ridges; several mm apart; characterized by more numerous mesopores

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McFarlan (1931) (in reference to Hallopora rugosa):

• Distinguished from H. ramosa by the transversely elongate monticules often forming discontinuous ridges.
  Characteristic of the McMillan, its best development above that of H. ramosa.

Nicholson (1881):

• Obs. – This form was originally defined as a distinct species by Milne-Edwards and Haime (Pol. Foss., p. 268, Pl. XX. figs. 6, 6a), and is at first sight readily distinguished typical examples of M. ramosa, D’Orb., by its external characters. In place, namely, of the conical monticules of the latter, the surface now exhibits numerous well-defined elevations, which are transversely elongated, so as to constitute so many discontinuous transverse ridges (Pl. II. fig. 3). These ridges vary in length, but they do not extend around the stems, and are usually sharp-edged, and are placed about half a line apart. In spite of this conspicuous difference, the more minute external and internal characters of M. rugosa, E. and H., are precisely similar to those of M. ramosa, D’Orb. Not only are the characters of the calices and interstitial tubes identical, but no difference of the smallest specific weight can be detected on a comparison of corresponding thin sections of the two forms. This will be rendered evident by a comparison of tangential and vertical sections of the type-form of M. ramosa, D’Orb., with similar sections of M. rugosa, E. and H. In the latter, as in the former, the corallum is composed conspicuously of two series of corallites, the large ones being oval or subpolygonal, about 1-90th to 1-80th inch in diameter, and surrounded by numerous small tubes (fig. 19, A). The structure of the walls of the corallites is also the same, and both show exactly corresponding features in longitudinal sections (fig. 19, B). Upon the whole, therefore, there can be no hesitation in concluding that the mere external difference in the form of the monticules, being unaccompanied by any features of internal or structural difference, ought not to be allowed to count as of more than varietal value.

Milne-Edwards & Haime (1850):

• Corallum in general free; its basal plate flat or concave, and completely covered with a concentrically wrinkled epitheca. Upper surface regularly convex, in general hemispherical, and presenting obtuse tuberosities, about one line broad, and varying very much in height. In some specimens these tubercles appear to have been worn away, and their existence is indicated only by the presence of small groups of large calices, with thick walls; the calices are unequal in size, generally polygonal, sometimes almost circular; the largest are about one-fifth of a line in diameter; the walls are not perforated; the tabulae are horizontal, complete, and placed at about one-twelfth of a line from each other. Some vestiges of septa are often visible. Young specimens are flat and discoidal.

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