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Longvillia deficiens
Taxonomy
Strophomena deficiens was named by Reed (1917).
It was recombined as Longvillia deficiens by Candela and Harper (2014).
It was recombined as Longvillia deficiens by Candela and Harper (2014).
Synonymy list
| Year | Name and author |
|---|---|
| 1917 | Strophomena deficiens Reed pp. 903 - 904 figs. Plate XIX, figs. 6-10 |
| 1962 | Strophomena deficiens Williams p. 219 figs. PI. XXII, figs. 12-15 |
| 2014 | Longvillia deficiens 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.
†Longvillia deficiens Reed 1917
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| F. R. C. Reed 1917 | Shell semielliptical to subquadrate, concavo-convex to plano-convex, much compressed, widest at hinge-line; cardinal angles rectangular. Pedicle-valve gently concave to nearly fiat, slightly swollen near beak; beak small, pointed, rather retrorse, not incurved; hinge-area of moderate width, triangular, steeply inclined to plane of valve, with large broad triangular delthyrium covered by convex plate; interior of valve with pair of short small teeth on thin dental plates, posteriorly defining transverse subcircular short muscle-area, about one-third length of valve, composed of a pair of contiguous flabellate short radially ridged diductor scars feebly defined in front; weak submarginal concentric ridge occasionally present near edge of valve. Brachial valve gently convex; beak small, inconspicuous; hinge-area narrow and nearly in plane of valve; interior with short small strongly bilobed cardinal process (the oval faces of the lobes facing inwards) rising from small thick transverse hinge-plate ; crural plates long, thin, slightly arched back, very divergent, making angle of 10°-20° with cardinal line. Surface of shell covered with very numerous fine straight rounded closely placed subequidistant thread-like riblets, of which 30-40 are usually primaries, with 2-3 finer thread-like lines between them increasing by intercalation to 6-12 on margin, every third or fourth of these finer lines usually becoming rather larger near margin, and forming secondary riblets shorter than the primaries ; all covered by close concentric striation. Minute closely set pustules generally distributed over interior, fusing into sinuous radial lines near cardinal angles. | |
| A. Williams 1962 | Subquadrate, strongly convexo-concave Strophomena, with a brachial valve just over threefifths as long as wide and becoming roundedly geniculate in a ventral direction at about 18 ram. anterior of the umbo; ornamentation consisting of fine costellae, 4 or 5 per millimetre antero-medianly, cancellated by concentric lines and divided into sectors, up to 2 mm. wide, by thickened costae and costellae; ventral muscle-scar defined posteriorly and laterally by well-developed ridges of secondary shell built up forward of the divergent dental lamellae, pyriform in outline, over two-thirds as wide as long and extending forward for about two-fifths of the length of the valve; cardinal process lobes stout, expanded anteriorly; socket ridges strong, disposed parallel with the hinge-line and ankylosed to a broad, low, median ridge; adductor muscle-scars obscurely impressed anterior to the socket ridges and associated with three pairs of narrow ridges radiating from the muscle-field. |
Measurements
No measurements are available
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| Source: f = family, o = order, c = class, p = phylum, uc = unranked clade | |||||
| References: Hendy 2009, Aberhan et al. 2004, Nesnidal et al. 2013 | |||||
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) | Strophomena deficiens (165043) |