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Malletia tsubetsuensis
Taxonomy
Malletia tsubetsuensis was named by Matusubara et al. (2020). Its type specimen is KRMSHA 2-4-MG-009-1, a shell, and it is a 3D body fossil. Its type locality is Mogami, which is in an Aquitanian marine shale in the Tsubetsu Formation of Japan.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 2020 | Malletia tsubetsuensis Matusubara et al. p. 13 figs. Figures 6.7, 6.8, 6.12, 6.14–6.19a–b |
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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.
†Malletia tsubetsuensis Matusubara et al. 2020
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| T. Matusubara et al. 2020 | A large-sized Malletia with transversely elongate elliptical, weakly inflated shell; rounded, short anterior margin; broader posterior margin; obliquely subtruncated posterior end; two blunt ridges extending from beak to posterior ventral margin and to posterior corner; growth lines strengthen on posterior ridges; anterior hinge series with 5–7 teeth; posterior hinge series with 29–35 teeth. Description.—Shell large for genus (shell length to 53.5 mm), longer than high (H/L ratio 0.60–0.69), elliptical, inequilateral, weakly inflated; beaks small, prosocline, situated at about one-third to two-fifths anteriorly for shell length (BP/L ratio 0.32–0.38); anterior margin evenly rounded; posterior dorsal margin longer than anterior one, nearly straight; posterior end subangulated; posterior margin obliquely truncated, may have a shallow notch near dorsal margin. External sculpture consisting of weak, fine, rather irregular commarginal growth lines and a few, feeble to
weak radial ridges on the posterior portion of shell; two blunt posterior ridges extending from beak to posterior ventral corner and from beak to posterior end; a few feeble radial ridges may be appeared in front of posterior ridge; growth lines becoming coarser on posterior ridges. Anterior hinge series with 5–7, hook-shaped teeth; posterior hinge series with 29–35, smaller teeth; anterior adductor muscle scar ovate, weakly impressed; posterior adductor muscle scar and pallial line indistinct; ventral margin smooth. |
Measurements
No measurements are available
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| Source: superf = superfamily, c = class | |||||
| References: Sanchez Roig 1926, Aberhan et al. 2004 | |||||
Age range: Aquitanian or 23.04000 to 20.45000 Ma
Collections: one only
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Aquitanian | Japan (Hokkaido) | Malletia tsubetsuensis (type locality: 219254) |