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Leptaena zeta
Discussion
Lectotype designated by Cocks 1968.
Taxonomy
Leptaena zeta was named by Lamont (1947) [= Strophomena rhomboidalis Davidson 1871 p. 281 pars, pl. 39, fig. 20.
= Leptaena rhomboidalis var. Q. Reed 1917: 872, pl. 13, figs. 8, 9.]. Its type specimen is B 73355, a valve (pedicle valve), and it is a 3D body fossil. Its type locality is Penkill, which is in a Telychian carbonate limestone in the Penkill Formation of the United Kingdom.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1947 | Leptaena zeta Lamont p. 200 |
| 1968 | Leptaena zeta Cocks pp. 309 - 310 figs. PI. 9, figs. 1-6 |
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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.
†Leptaena zeta Lamont 1947
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| L. R. M. Cocks 1968 | Very large Leptaena with mainly parallel-sided muscle area.
Exterior: Shape semicircular with variably pronounced alae. Geniculation between 70 and 90 degrees, and trail proportionately shorter than is usual for the genus. Ornament of subequal parvicostellae and rugae which are usually continuous but are often irregular. Medium-sized interarea with prominent growth lines. Delthyrium mainly closed by large chilidium which appears bilobed as it wraps round the cardinal process lobes. Small foramen plugged by adventitious material. Pedicle interior: Strong grooved teeth and widely divergent small dental plates, the latter joined to a pair of muscle bounding ridges which flare outward from the valve floor. The ridges are usually subparallel but occasionally curve inwards anteriorly, though never meeting and usually completely open (PL 9, figs. 2, 3). Very small median ridge sometimes developed in the muscle area between the small lanceolate adductor scars, themselves inside the strongly impressed diductor scars which often have radiating striae across them. The central area outside the muscle field is coarsely pustulate. Brachial interior: Strong erect cardinal process lobes very close to the chilidium with faint blade between them. The lobes rest on the posterior end of a strong platform pad, which is often grooved postero-laterally to act as a socket plate. The platform anterior edge is trilobed, surrounding on three sides the pair of prominent subcircular adductor scars. A faint extension of the central platform sometimes extends further anteriorly to become a very small median septum. The central area which merges laterally with the platform is coarsely pustulate. |
Measurements
No measurements are available
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| Source: g = genus, c = class, p = phylum, uc = unranked clade | |||||
| References: Nesnidal et al. 2013, Hendy et al. 2009, Aberhan et al. 2004 | |||||