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Leptella pseudoretroflexa
Taxonomy
Leptella pseudoretroflexa was named by Reed (1917) [Leptella? pseudoretroflexa
? = Strophomena retroflexa, Salter, Davidson 1870. (pars), Mon. Brit. Foss. Brack., vol. iii, pt. vii, p. 298, pl. xlii, fig. 17 (non figs. 15, 16).
= Strophomena retroflexa, Salter, Davidson 1883. (pars) vol. v, Silur. Suppl, pp. 195, 227
(non pi. xv, figs. 7, 8).].
It was recombined as Isophragma pseudoretroflexum by Williams (1962) and Candela and Harper (2014).
It was recombined as Isophragma pseudoretroflexum by Williams (1962) and Candela and Harper (2014).
Synonymy list
| Year | Name and author |
|---|---|
| 1917 | Leptella pseudoretroflexa Reed pp. 874 - 875 figs. Plate XIII, figs. 18-26 |
| 1962 | Isophragma pseudoretroflexum Williams p. 162 figs. Pl. XV, figs. 14-16, 20 |
| 2014 | Isophragma pseudoretroflexum 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.
†Leptella pseudoretroflexa Reed 1917
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| F. R. C. Reed 1917 | Shell transversely semicircular to semielliptical, subalate, with pointed cardinal angles, widest along hinge-line, compressed, flattened, weakly piano- to concavoconvex ; cardinal angles acute, usually pointed at about 60°, and often slightly produced ; hinge-line straight, minutely crenulated along whole length (?). Pediclevalve flat or slightly concave, very shallow; beak small, slightly elevated, pointed, not incurved; hinge-area triangular, inclined to plane of valve at 45°-60°, with narrow convex, triangular deltidium covering delthyrium. Brachial valve gently convex, deeper than other valve, with very weak median depression occasionally present; beak small, inconspicuous ; hinge-area triangular, rather narrower than that of opposite valve, inclined nearly at right angles to plane of valve, with small convex triangular deltidium covering fissure. Surface of valves covered with numerous small straight radiating ribs of equal size regularly arranged, closely placed, increasing rarely by intercalation at about half their length, so as to number 60-90 on margin; interspaces rather wider than ribs, coarsely pitted; fine concentric striation present. Interior of pedicle-valve with pair of small stout teeth and numerous coarse irregularly spaced and broken rugae radiating outwards and becoming more prominent and thicker towards margin of valve, where they unite with a thick interrupted submarginal concentric ridge outside which the external ribbing shows; muscular scar broad, indistinctly defined in front, transverse in shape, about one-third the length of shell, composed of pair of flabelliform diductors embracing broad adductors. Interior of brachial valve with similar coarse irregular radiating rugae, but without concentric submarginal thickening; cardinal process small, prominent, with stout basal stalk, and with posterior face faintly trilobed (?); crura short, blunt, stout, diverging at about 45° to hinge-line ; low median ridge grooved along middle, extending from thick hinge-plate, increasing in height and thickness anteriorly and nearly reaching margin; adductor scars elongate, oval, contiguous to median ridge, about one-third length of valve. | |
| A. Williams 1962 | Elongately semi-oval Isophragma with a dorsal median sulcus passing into a low fold at the 6-mm. growth-stage; ornamentation multicostellate with a modal count of 4 costellae per millimetre antero-medianly; submedian septa of the brachial valve over three-quarters as long as the valve and slightly divergent, being one-quarter of their length apart anteriorly. |