Monticulipora molesta

Classification
Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Monticuliporidae
Genus: Monticulipora
Species: Monticulipora molesta (Nicholson, 1881)

Taxonomic Details

Taxonomic History (Nickles & Bassler, 1900)

  • 1881 Monticulipora (Peronopora) molesta Nicholson, Genus Monticulipora, p. 224, pl. vi, 2-2d.
  • 1882 Monticulipora mammulata var. molesta Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 236.
  • 1889 Monticulipora mammulata Nicholson, Manual Pal., p. 355.
  • 1895 Monticulipora molesta J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 68.
  • 1897 Monticulipora mammillosa (in error) Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 577, pl. xvii, 1-3.

Stratigraphic Occurrences

M.molesta_strat

Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C2 Sequence (Bellevue)

Identification in Hand Sample

  • Zoarium Morphology: Frondescent to lobate; can be encrusting or erect
  • Zoecia: Prismatic/polygonal, thin-walled; acanthopores small (but usually numerous); granulose wall structure
  • Mesozooids: Few or wanting
  • Monticules: Usually present; conical to elongate
  • Maculae: Typically with clusters of mesozooids and larger zooecia

Diagnosis: Can be differentiated from M. mammulata in the morphology of its Zoarium: M. mammulata is massive to hemispherical, whereas M. molesta is frondescent to lobate

Monticulipora molesta from the Waynesville Formation (OUIP 1722)

Published Description

McFarlan (1931):

  • A species distinguished from the preceding (Monticulipora mammulata) by its frondescent growth. It shows the same succession of (m) and (im).
    Characteristic of the Bellevue.

James (1895):

  • Corallum usually frondescent, forming extended and undulated, lobed or palmate expansions, varying in thickness from two to five lines; rarely massive; surface with numerous prominent conical or elongated monticules, one-half to one line apart, of corallites not differing in size from the average; calices polygonal, thick-walled, sub-equal with a few interstitial corallites; corallites of two kinds, the larger more numerous, thin-walled and polygonal, mostly with tabulae forming a series of lenticular vesicles along one side of the visceral chamber and a moderate number of straight or slightly concave tabulae extending to the opposite wall; smaller corallites comparatively few, angular, varying in size, and with numerous, complete, horizontal tabulae; no spiniform tubuli. (Genus Montic., 1881, p. 224.)
    It is to be noted that this species is similar to the one following (M. mammulata) in its outward appearance. It furnishes an example of the difficulty of accurately settling the specific name of a species without the examination of minute sections. In a previouis paper, indeed, both were placed together, but it is now deemed best because of the difference in internal structure to separate them. The presence of vesicular tabulae in this form distinguishes it from the other (mammulata as here considered) which has horizontal and complete tabulae.

Nicholson (1881):

  • Spec. Char. – Corallum usually frondescent, having the form of extended and undulated, sometimes lobed or palmate, expansions, which may attain a considerable size, and vary in thickness from two to four or five lines. Rarely, the corallum is massive. Surface covered with numerous prominent, conical, or slightly elongated monticules, placed at distances of half a line to a line apart, and composed of corallites which do not differ conspicuously in size from those forming the mass of the corallum. Calices polygonal, thin-walled, sub-equal, from 1-85th to 1-90th inch in diameter, with a few smaller interstitial apertures scattered amongst them. Corallites of two kinds, large and small. The large corallites are much the most numerous, are thin-walled and polygonal, and are furnished for the most part with incomplete tabulae. In these tubes the tabulae form a series of lenticular vesicles along one side of the visceral chamber, and a moderate number of straight or slightly concave tabulae extend from these to the opposite side of the cavity of the corallite. The small corallites are comparatively few in number, are angular in shape and variable in size, and are crossed by numerous, complete, horizontal tabulae.
  • Obs. – In its general form and mode of growth, as well as in almost all its superficial characters, this species precisely resembles M. mammulata, D’Orb., and without the preparation of thin sections it is often quite impossible to definitely determine to which of the two types a given specimen may belong. Almost the only superficial character that is of any use in this connection is the comparative paucity of the small interstitial corallites in this form (Pl. VI. fig. 2a), as compared with what we find in M. mammulata. The monticules also are most uniformly of a pronounced and markedly elevated character than is the case in all specimens of the latter. The normal mode of growth in M. molesta is certainly that of an expanded frond, composed of two strata of corallites, which diverge in opposite directions from an imaginary mesial plane to open on the two flat surfaces of the expansion (Pl. VI. fig. 2). As in the case of M. mammulata, the central line of the corallum is not marked by any even imperfectly developed calcareous lamina, such as exists in M. frondosa, D’Orb., and M. pavonia, D’Orb. Though usually frondescent, I possess one large massive and lobate specimen (four inches in length, three inches in width, and two and a half inches in height) which is proved by microscopic examination to be unquestionably identical with the more ordinary examples of the species.
  • As regards its internal structure, tangential sections (Pl. VI. figs. 2b, 2c) show that the large corallites of the colony are polygonal and thin-walled, the lines of demarcation between adjoining tubes not being persistent, and the walls (in all the slides I have examined) exhibiting a peculiar granular appearance. The visceral chamber of each of the large corallites is also crossed by a delicate lamina, which is deeply excavated on one side in a crescentic or triangular manner, and the presence of which is due to the intersection of the peculiar vesicular tabulae on one side of the tube. Interspersed among the large corallites, but never in large numbers, are smaller angular interstitial corallites, which are recognizable not only by their dimensions, but also by wanting the peculiar excentrically perforated tabulae of the large tubes.
  • Vertical sections (Pl. VI, fig. 2d) show that the walls of all the corallites are thin, and that there is a conspicuous difference in the tabulation of the large and small tubes respectively. The small corallites are uniformly provided with numerous, close-set, complete, and horizontal tabulae. On the other hand, the large corallites possess the same singular incomplete tabulae as are seen in such forms as M. sclwynii, Nich., M. cincinnatiensis, James, M. newberryi, Nich. That is to say, the tabulae are twofold, those on one side of the tube forming a longitudinal series of lenticular vesicles, while those on the other side run from these vesicles to the opposite wall, and are either straight or slightly concave. Occasionally, one of the large corallites shows only complete tabulae, but this is probably due to its being intersected on one side.
  • Good observers regard this as the real type of the M. mammulata of D’Orbigny; and its superficial characters, undoubtedly, would justify such a reference, as they agree very well with the description given by Milne-Edwards and Haime. For reasons previously stated, however, superficial characters alone will not settle this point, and I have preferred to regard another externally similar species as the type of M. mammulata; thought I quite admit that the present form might be selected in its place with perfect propriety. From the form which I have called M. mammulata, D’Orb., the present species is entirely separated by its minute structure, and, especially, by the smaller number of the interstitial corallites, the absence of “spiniform corallites,” the greater thinness of the walls, and the presence of incomplete tabulae in the large corallites.