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Leptaena (Leptaena) haverfordensis
Taxonomy
Leptaena haverfordensis was named by Bancroft (1949) [Lectotype designated by Cocks (1968, p. 304).]. Its type specimen is SM A32 163, a valve (internal mould of ventral valve), and it is a 3D body fossil.
It was recombined as Leptaena (Leptaena) haverfordensis by Rubel (2011).
It was recombined as Leptaena (Leptaena) haverfordensis by Rubel (2011).
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1949 | Leptaena haverfordensis Bancroft p. 6 figs. Pl. 1 : 19, 20, 23, 24 |
| 1968 | Leptaena haverfordensis Cocks pp. 304 - 305 figs. PI. 5 figs. 4-15 |
| 1995 | Leptaena haverfordensis Baarli pp. 36 - 37 figs. PI. 1 1 :2--4, 6-7, 9-10, 1 2-14, 1 7 |
| 1997 | Leptaena haverfortensis Smelror et al. |
| 2011 | Leptaena (Leptaena) haverfordensis Rubel |
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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 (Leptaena) haverfordensis Bancroft 1949
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| L. R. M. Cocks 1968 | Large Leptaena with oval-sided pedicle valve muscle area. Socket plates variably present. | |
| B. G. Baarli 1995 | The outline of the shell is subcircular to subrectangular and resupinate. Maximum width is at the hinge line, which often continues laterally as pronounced ears on large valves. The angle of geniculation varies between 70° and 1 1 0°. Some small valves have trails extended anteromedially into a point, as noted by Temple ( 1 987). In the pedicle valve, the periphery of the disc at its junction with the trail is formed into a variably pronounced rim with a complementary hollow in the dorsal valve. The ventral beak bears a small round foramen, commonly sealed. The umbo is low and inconspicuous, with a ventral beak that is short and erect. The ventral interarea is apsacline, low, triangular and horizontally striated. The delthyrium is wide, with angles of 90- 1 00° and a convex pseudodeltidium. The dorsal interarea is also low and anacline. The chilidium is large in comparison to the pseudodeltidium, convex, and extending ventrally beyond the hinge line.
The number of rugae on the disc varies between 7 and 1 2 . They are absent from the trail and less pronounced near the umbo. The radial ornament is finely multicostellate, with 3- 4 costa per millimeter at the 10 mm growth stage. Interior of pedicle valve: The delthyrial cavity is shallow and of variable width and length with a pedicle callist. The teeth are fairly small, bluntly triangular with posterior faces flush with the wall of the delthyrium. The dental plates are well developed, but short. They are fused anteriorly with strong muscle-bounding ridges that curve evenly and most often meet medially. Some muscle scars may be slightly flabellate. The muscle scars are deeply impressed, occupying 1/6-13 of the total disk width and I/Z-% of the total disc length. The diductor scars are broadly oval to triangular, often enclosing well-impressed oval to lanceolate adductor scars. The adductor scars are situated on a platform divided by a thin median ridge extendingjust anterior of the muscle scars. The extra muscular area is coarsely tuberculate and often overprinted by rugae. Interior of brachial valve: The cardinalia are relatively strong. The cardinal-process lobes are strongly elongate, fairly thin, and extending anteriorly at a slight angle. The lobes are widely separated. The notothyrium platform is weakly developed, if present. The socket ridges are very thin and widely divergent. The dental sockets are shallow, small, and subparallel to the hinge line. The muscle scars are well developed. Rounded, broad posterior scars are divided by a low median ridge. The smaller, elongate, and oval anterior scars are divided anteriorly by a thin and sometimes deep myophragm that continues anterior of the muscle scars. The scars occupy 1/2-% of the total disc width and 14 of the disc length. |