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Archinacella instabilis
Taxonomy
Metoptoma instabilis was named by Billings (1865). It is not extant.
It was recombined as Archinacella instabilis by Ulrich and Scofield (1897), Rohr et al. (2008) and Wagner (2023).
It was recombined as Archinacella instabilis by Ulrich and Scofield (1897), Rohr et al. (2008) and Wagner (2023).
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1865 | Metoptoma instabilis Billings p. 251 |
| 1897 | Archinacella instabilis Ulrich and Scofield pp. 829, 836 |
| 2008 | Archinacella instabilis Rohr et al. pp. 95 - 98 figs. pl. 1 f. 1-17; pl. 2 f. 1-5; txt. f. 3 |
| 2023 | Archinacella instabilis Wagner p. 3937 |
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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.
†Archinacella instabilis Billings 1865
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. M. Rohr et al. 2008 | Cap=shaped, symmetrical to nearly symmetrical, subovate shell; rapidly expanding from apex through one quarter to one half revolution; dorsum convexly arched, apex overhangs the margin on some specimens; apertural margin planar; surface smooth or with growth stoppages on some specimens; repair of broken shell evident on one specimen. Continuous interior muscle scar present around apex, no accessory muscle scars observed. |