Taxonomic History (Nickles & Bassler, 1900)
- 1851 Dekayia aspera Milne-Edwards and Haime, Pol. Foss. Terr. Pal., p. 278, pl. xvi, 2, 2a.
- 1860 Dekayia aspera Milne-Edwards, Hist. Nat des Corall., III, p. 283.
- 1883 Dekayia aspera Ulrich, Jour. Cincinnati Soc. Nat. Hist., VI, p. 148, pl. vi, 5..
- 1888 Monticulipora (Dekayia) aspera James and James, Jour. Cincinnati Soc. Nat. Hist., XI, p. 28.
- 1896 Monticulipora (Dekayia) aspera J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 116.
- 1896 Dekayia aspera Ulrich, Zittel’s Textb. Pal. (Eng. ed.), fig. 455 (p. 274).
- 1874 Chaetetes attritus Nicholson, Quar. Jour. Geol. Soc. London, XXX, p. 503, pl. xxix, 4, 4a.
- 1875 Chaetetes attritus Nicholson, Pal. Ohio, II, p. 194, pl. xxi, 4.
- 1876 Dekayia attrita Nicholson, Ann. Mag. Nat. Hist., ser. 4, XVIII, p. 93, pl. v, 12, 12a.
- 1879 Dekayia attrita Nicholson, Pal. Tabulate Corals, p. 298, pl. xv, 1-1c.
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- C4 Sequence (Arnheim)
- C2 Sequence (Bellevue, Fairview: Fairmount, Mt. Hope)
- C1 Sequence (Clays Ferry/Kope: McMicken)
Identification in Hand Sample
- Zoarium Morphology: Ramose ; 6-10 mm in diameter
- Zoecia: Polygonal (10 in 2mm); acanthopores present, large (conspicuous as large spines)
- Mesozooids: Rare or absent between monticules; common in maculae
- Monticules: Low
- Maculae: Of larger cells and mesopores
Dekayia aspera from the Kope Formation of Foster, Kentucky (OUIP 36)
Brown & Daly (1985):
- Diagnosis: Zoaria ramose, robust, with small polygonal zooecia, diaphragms sparse to absent, no mesozooecia, and abundant small to large acanthopores.
- Description: Zooecia in endozone polygonal, typically long, with slender, pointed proximial tips, following irregular growth path upward and flaring gently outward form deep within endozone to base of exozone, many continuing to surface. Intermonticular zooecia in exozone polygonal, small (9+ in 2 mm; table 14), commonly originating deep within endozone or near base of exozone, bending abruptly and continuing directly to surface; exozone commonly deep. Zooecial opening polygonal to subpolygonal, locally with thin zooecial lining.
Zooecial walls thin throughout endozone, straight to irregular and locally crenulate, especially in curve below exozone. Walls thickening unevenly in exozone (0.029 mm ZWT), crenulate to irregular, and composed of locally distinct curved dark laminae continuous across zone of curved laminae. Walls in tangential view translucent and amalgamate in appearance.
Diaphragms absent in endozone, one or two appearing in curve just below exozone, and sparse (one to three) in early exozone, generally absent in outer exozone, which commonly infills with sediment. Diaphragms thin, generally horizontal, planar to slightly concave, and clearly seen to merge into zooecial walls but only rarely traceable as diaphragm-wall units. Sparse diaphragms within endozone generally associated with slightly thickened zooecial walls and probably reflecting an early exozone that failed to develop fully.
Mesozooecia absent, though some beading of tubes at crenulate walls reminiscent of mesozooecia.
Acanthopores common (5 A1M), variable in size (0.03 to 0.15 mm) from small (few) to very large (few), and typically large, with prominent lumen set within darkened concentric laminae, and located at zooecial corners. Prominent endacanthopores arising within endozone and continuing into basal part of exozone, conspicuously oblique to zooecia in many specimens, and composed of sharply laminated tissue with prominent translucent central core. Many endacanthopores arising within exozone and commonly continuing to surface. Many large endacanthopores inflecting into zooecial openings. No obvious exacanthopores observed.
Monticules low or flush with surface, composed of megazooecia, typically with large acanthopores and generally several irregularly polygonal to angular tubes that are probably proximal tips of growing zooecia.
- Discussion: Discussion: The prominent features of this species, numerous large and very large acanthopores, absence of diaphragms in endozone and sparseness in exozone, locally crenulate walls in endozone, and slightly thickened, uneven zooecial walls in exozone, make it an easily recognizable form. The Dillsboro specimens agree well with the concept provided by Boardman and Utgaard (1966) and show no marked differences with those reported recently by Anstey and Perry (1973) and Singh (1979). Examination of a plesiotype (USNM 96579) verified our interpretations. We did not recognize any unquestioned mesozooecia. Boardman and Utgaard (1966, p. 1104) suggested that some beaded chambers in the genus Dekayia may represent apparent mesozooecia produced by the plane of section oblique to crenulated zooecial walls rather than true mesozooecia.
We did not recognize any exacanthopores, though Singh (1979, p. 207) reported their presence. Exacanthopores arise in the exozone, and though we did recognize many acanthopores arising in that region, we consider them to be endacanthopores because they are generally large in size and all are located at zooecial wall corners.
- Zoarium ramose 6-10 mm. in diameter, characterized by the very large acanthopores, conspicuous externally as small spines. Surface more or less smooth, with maculae of larger cells and mesopores. Mesopores lacking except, in the maculae. Zooecia polygonal, 10 in 2 mm. Diaphragms absent in the (im), and few to absent in the (m).
The species ranges from the McMicken to the Fairmount and is especially characteristic of the latter horizon.
- Owing to the unusually characteristic surface features of this well-known species, the rather meager description of Edwards and Haime is sufficient for its recognition, and coupled with his figure leaves no doubt as to the identity of the form. The internal characters, however, are equally interesting and characteristic, and I, therefore, take the liberty of appending a further description of this important species.
- Zoarium consisting of somewhat flattened stems attaining a diameter of several cm. Surface smooth except for the unusually conspicuous spines caused by the projection at the surface of the large set of acanthopores. This gives an unmistakable appearance to the species. The zooecia are polygonal and thin walled, and mesopores are practically absent. No monticules or maculae of any kind.
- In tangential sections the zooecia are thin walled, polygonal, and in complete contact at all points. An occasional smaller zooecium, probably a young individual, is seen. The most striking feature of such sections is the enormous acanthopores, at times nearly as big as an ordinary zooecium. Interspersed among these large acanthopores, and plainly visible, even in the mature region, are a number of smaller acanthopores of about the size normal to D. frondosa. The wall structure is much the same, also, as in the latter species.
- In longitudinal section, the zooecia are seen to bend very gradually outward from the immature region and to reach the surface at nearly a right angle. No diaphragms or other structures are present, except rarely a diaphragm or two near the surface. The large acanthopores are shown by longitudinal sections to extend into the immature region, and sometimes to cross over from one zooecium to another. They are in fact a very conspicuous feature of such sections. This is the only feature that causes longitudinal sections of this species to differ from similar section of D. magna.
- The maximum difference, so far as I have noticed, occurs in Dekayia aspera, where the smallest acanthopores are so minute that they must usually escape notice, except in sections very carefully prepared and ground as thin as is compatible with retaining structural details.
- In Dekayia aspera as shown in fig. 10, pl. IX, and fig. 10, pl. X, the walls in the mature regions are slightly thicker than in D. subfrondosa (thinner than D. perfrondosa), and the large set of acanthopores is extravagantly developed. The small acanthopores are of the normal size for Heterotrypa Ulr. That the large acanthopores are sometimes suppressed in D. aspera, at least in portions of the zoarium, seems practically certain.
- The main difference between it and such forms as D. subfrondosa and D. perfrondosa is in the almost total absence of diaphragms in D. aspera (and a few closely allied forms). Yet in D. perfrondosa these structures may be comparatively few in the zooecia, though never entirely lacking as in occasionally the case in D. aspera.
- Corallum dendroid, branching frequently and dichotomously and arising from a broad basal explanation; branches varying from two to eight lines in diameter according as they are near the top or at the base of the corallum; surface usually with low and rounded monticules, four or five in about one-half inch; formed of cells very little larger than the average and often with a limited number of smaller interstitial cells; spines conspicuous with thick walls and small cavity occupying angles of cells; corallites polygonal; tabulae wanting in the axial region and remote in the peripheral. (Pol. Foss. Des Terr. Pal., 1851, p. 277. Ulrich, Jour. Cin. Soc. Nat. Hist., vol. 6, 1883, p. 149.) (Chetetes attritus Nich., Quar. Jour. Geol. Soc. Lond., vol. 30, 1874, p. 503: Dekayia multispinosa Ulrich, Ibidem, p. 154.)
In a previous paper several other synonyms were given for this species.* While the species is a variable one it has been deemed best in the present instance to increase the number of species, perhaps unwisely. All seem to agree that Nicholson’s attrita is the same as D. aspera, and D. multispinosa differs mainly in a larger number of surface spines. Internally the structure of the two is the same.
*Jour. Cin. Soc. Nat. Hist., vol. I, 1888, p. 28.