Dowlingoceras tornense Kröger, 2025, sp. nov.

Dowlingoceras tornense sp. nov. urn:lsid:zoobank.org:act: 9E94767A-9B7E-440B-84D7-12F695042F30 Figs 25A–B, 27I Diagnosis Dowlingoceras with compressed elliptical conch-cross section (CHI = 1.3); mature body chamber with maximum conch height of ca 45 mm near its base and height to length ratio of ca 1, with a nearly straight, simple peristome and apparently lacking or only with a very shallow hyponomic sinus; angle of expansion of the phragmocone ca 12°. Etymology The Estonian “ torni ”, ‘towerʼ, refers to the type locality. Type material Holotype ESTONIA • Vormsi Island, Hosholm shore (tower locality); Adila Formation, Pirgu Regional Stage; GIT 840-254. Paratype ESTONIA • same data as for holotype; GIT 840-273. Description The holotype preserves parts the phragmocone and the mature body chamber. Where preserved (near the peristome), the conch surface is apparently smooth. The conch height and width at the base of the mature body chamber are 45 mm and 34 mm, respectively (CHI = 1.3). There, the shape of conch cross section is apparently elliptically to oval compressed. The ventral side is slightly more narrowly curved. In lateral view, the conch is straight. The body chamber is 46 mm long with a nearly straight, simple peristome and apparently without a hyponomic sinus. The lateral outline of the body chamber is slightly convex, reaching the greatest conch height 47 mm at ca mid-length location of the body chamber. The phragmocone increases in height from 38 mm to 45 mm at a length of 32 mm (angle of expansion = 12°). The sutures form a shallow lobe at the lateral sides of the phragmocone, a sharp saddle on the ventral side and a rounded saddle on the dorsal side; they are 8 mm apart where the conch height is 42 mm (RCL = 0.19). The septal foramen is nearly marginal with a diameter of 5 mm where the conch height is 43 mm (RSH = 0.12). A natural cut of the siphuncle shows a fusiform, elongated, Dowlingoceras -like siphuncular segments (length 6 mm, height 3.8 mm, SCR = 0.63). Comparison The conch shape, including the shape of the mature body chamber is similar to that of D. kallholnense Frye, 1987. However, the mature body chamber of D. tornense sp. nov. is greater in height, width, and length than that of D. kallholnense (40 mm, 36 mm, 40 mm, respectively, in D. kallholnense) and the conch cross section is more compressed (CHI = 1.1 in D. kallholnense).

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Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2025-03-03
DOI
https://doi.org/10.5281/zenodo.14988519
Primary Topic
Ichthyology and Marine Biology
Type
article
Field-Weighted Citation Impact
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article

Dowlingoceras tornense Kröger, 2025, sp. nov.

Zenodo (CERN European Organization for Nuclear Research)
Ichthyology and Marine Biology
article

Dowlingoceras tornense Kröger, 2025, sp. nov.

article en

Abstract

Dowlingoceras tornense sp. nov. urn:lsid:zoobank.org:act: 9E94767A-9B7E-440B-84D7-12F695042F30 Figs 25A–B, 27I Diagnosis Dowlingoceras with compressed elliptical conch-cross section (CHI = 1.3); mature body chamber with maximum conch height of ca 45 mm near its base and height to length ratio of ca 1, with a nearly straight, simple peristome and apparently lacking or only with a very shallow hyponomic sinus; angle of expansion of the phragmocone ca 12°. Etymology The Estonian “ torni ”, ‘towerʼ, refers to the type locality. Type material Holotype ESTONIA • Vormsi Island, Hosholm shore (tower locality); Adila Formation, Pirgu Regional Stage; GIT 840-254. Paratype ESTONIA • same data as for holotype; GIT 840-273. Description The holotype preserves parts the phragmocone and the mature body chamber. Where preserved (near the peristome), the conch surface is apparently smooth. The conch height and width at the base of the mature body chamber are 45 mm and 34 mm, respectively (CHI = 1.3). There, the shape of conch cross section is apparently elliptically to oval compressed. The ventral side is slightly more narrowly curved. In lateral view, the conch is straight. The body chamber is 46 mm long with a nearly straight, simple peristome and apparently without a hyponomic sinus. The lateral outline of the body chamber is slightly convex, reaching the greatest conch height 47 mm at ca mid-length location of the body chamber. The phragmocone increases in height from 38 mm to 45 mm at a length of 32 mm (angle of expansion = 12°). The sutures form a shallow lobe at the lateral sides of the phragmocone, a sharp saddle on the ventral side and a rounded saddle on the dorsal side; they are 8 mm apart where the conch height is 42 mm (RCL = 0.19). The septal foramen is nearly marginal with a diameter of 5 mm where the conch height is 43 mm (RSH = 0.12). A natural cut of the siphuncle shows a fusiform, elongated, Dowlingoceras -like siphuncular segments (length 6 mm, height 3.8 mm, SCR = 0.63). Comparison The conch shape, including the shape of the mature body chamber is similar to that of D. kallholnense Frye, 1987. However, the mature body chamber of D. tornense sp. nov. is greater in height, width, and length than that of D. kallholnense (40 mm, 36 mm, 40 mm, respectively, in D. kallholnense) and the conch cross section is more compressed (CHI = 1.1 in D. kallholnense).

Zenodo (CERN European Organization for Nuclear Research)
Finnish Museum of Natural History (FI)
Life below water
Openalex Percentile: Top 46%
Ichthyology and Marine Biology
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