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Trivia perobsoleta
Taxonomy
Trivia sphaericulata perobsoleta was named by Sacco (1894). Its type specimen is BS.043.12.007, a shell, and it is a 3D body fossil.
It was recombined as Trivia (Trivia) perobsoleta by Schilder and Schilder (1971); it was recombined as Trivia perobsoleta by Schilder (1932), Fehse and Landau (2002) and Fehse and Grego (2006).
It was recombined as Trivia (Trivia) perobsoleta by Schilder and Schilder (1971); it was recombined as Trivia perobsoleta by Schilder (1932), Fehse and Landau (2002) and Fehse and Grego (2006).
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1894 | Trivia sphaericulata perobsoleta Sacco p. 49 figs. pl. 3, fig. 33 |
| 1932 | Trivia perobsoleta Schilder p. 107 |
| 1971 | Trivia (Trivia) perobsoleta Schilder and Schilder p. 17 |
| 2002 | Trivia perobsoleta Fehse and Landau pp. 93 - 94 figs. l/5a, b; 5/3a-d |
| 2006 | Trivia perobsoleta Fehse and Grego p. 91 |
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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.
†Trivia perobsoleta Sacco 1894
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. Fehse and B. Landau 2002 | Shell large, solid, and spherical. Spire covered by callus. Body whorl globosely inflated and rounded, about 95% of total height, with the terminals not produced and rounded. Dorsum strongly elevated and evenly rounded, without a dorsal sulcus. Dorsum bearing subobsolete ribs in 70% of specimens, 30% smooth and glossy with no ribs. Base and outer lip are evenly convex. Aperture wide and somewhat curved, especially in the adapically portion. Outer lip very broad in mid-portion, narrows abruptly towards the terminals. The lip is rounded in cross section, but anteriorly concave and sloping steeply inwards. Outer margin of the lip slightly angularly callused. The lip bears 18-24 fine denticles, which are only barely continued as ribs on the outer lip. Siphonal and anal canals follow the shell profile. The anal canal is indistinct. Columella nearly straight, tapering steeply inwards, without an inner carinal ridge, bearing 14-18 weak denticles, which are distinctly continued as fine ribs onto the columellabut obscurely so onto the base. The inner fossular margin slightly protrudes. Fossula shallow and clearly delimited from the rest of the columella.
Range of variation — The characteristic features of this species are the large size, very globular shape, very weakly developed terminals, the curved aperture and, most importantly, the character of the ribs, always obsolete on the sides ofthe shell and subobsolete to lacking on the dorsum. These ribs can be variable in strength, sometimes barely visible, whilst in other specimens they are reasonably strongly developed on the dorsum, but invariably absent on the sides even in well-preserved, non-eroded material. |