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Macrocoelia concentrica
Taxonomy
Orthis expansa concentrica was named by Portlock (1843).
It was recombined as Rafinesquina concentrica by Reed (1917); it was recombined as Macrocoelia concentrica by Williams (1962); it was recombined as Colaptomena concentrica by Mitchell (1977) and Candela and Harper (2014).
It was recombined as Rafinesquina concentrica by Reed (1917); it was recombined as Macrocoelia concentrica by Williams (1962); it was recombined as Colaptomena concentrica by Mitchell (1977) and Candela and Harper (2014).
Synonymy list
| Year | Name and author |
|---|---|
| 1843 | Orthis expansa concentrica Portlock p. 452 figs. pl. xxxvii fig. 1 |
| 1917 | Rafinesquina concentrica Reed pp. 864 - 865 figs. Plate XI, figs. 13-16 |
| 1962 | Macrocoelia concentrica Williams p. 217 figs. Pl. XXII, figs. 3, 5, 6 |
| 1977 | Colaptomena concentrica Mitchell |
| 2014 | Colaptomena concentrica Candela and Harper pp. Supplement 1 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Macrocoelia concentrica Portlock 1843
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| F. R. C. Reed 1917 | Shell subquadrate to transversely semielliptical, wider than long; hinge-line straight, equal to maximum width of shell or slightly less than it; cardinal angles rectangular to subacute, rarely subalate. Pedicle-valve gently convex ; beak obtuse, small, rising a little above hinge-line, slightly incurved; hinge-area narrow, nearly at right angles to plane of valve, striated along its length ; interior of valve with pair of short strong large low teeth inclined at about 30° to hinge-line, rather far apart, with inner face crenulated; diductor muscle-scars large, broad, flabelliform, radially rigid, extending nearly half the length of valve, with short narrow deep median groove between them at their base in beak; adductors forming narrow oval median scars about half length of diductors and completely enclosed by them; low rounded strong continuous submarginal concentric thickening of shell. Brachial valve nearly flat or slightly concave; hinge-area very narrow; beak small, inconspicuous, not raised; interior with submarginal concentric thickening; cardinal process large, bilobed, composed of pair of closely placed triangular sessile lobes ; muscle-scars well marked, composed of subnabelliform posterior adductors, about one-fifth length of valve, rather deeply sunk, and elongate narrow anterior adductors of twice the length, indistinctly defined in front; low rounded median longitudinal ridge between adductors, and traces of radiating vascular sinuses in anterior lateral portions of valve. Small strongly pitted transverse circumscribed area on each side of beak adjacent to hinge-line. | |
| A. Williams 1962 | Subquadrate Macrocoelia about three-quarters as long as wide with a gently concavoto piano-convex lateral profile; ornamentation unequally parvicostellate with differentially thickened costae and costellae averaging about 6 per millimetre antero-medianly and cancellated by fine concentric lamellae, rugae developed in the postero-lateral areas of the shell at oblique angles to the hinge-line; dental lamellae short, widely divergent, teeth and sockets tuberculate, ventral muscle-scar flabellate over onehalf as long as pedicle valve; dorsal interior with wedge-shaped cardinal process lobes, just over one-half as long as their combined width, socket ridges inconspicuous, median and lateral ridges not conspicuously developed; up to 3 subperipheral rims developed beyond the 20-mm. growth-stage. |
Measurements
No measurements are available
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| Source: g = genus, f = family, c = class, p = phylum, uc = unranked clade | |||||
| References: Hendy et al. 2009, Nesnidal et al. 2013, Aberhan et al. 2004, Hendy 2009 | |||||
Age range: Burrellian or 456.60000 to 452.50000 Ma
Collections: one only
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Burrellian | United Kingdom (Scotland) | Macrocoelia concentrica (165046) |