Warburgoceras longitudinale (Angelin in Angelin & Lindström, 1880) comb. nov.

Figs 18F, 39C

Cyrtoceras longitudinale Angelin in Angelin & Lindström, 1880: 11, pl. 16, fig. 5.

Uranoceras (?) longitudinale – Mutvei 1957: 245, text-figs 6c, 7b, 10, 11, 20, 21, pl. 4, fig. 3, pls 6, 7, 17, 18. ― Dzik & Korn 1992: 84, 85, text-fig. 1.

Uranoceras longitudinale – Dzik 1984: 150, 154, text-fig. 59.2.

Diagnosis

Same as for genus by monotypy.

Type locality and horizon

Osmundsberget, Dalarna, Sweden, Boda Limestone, Boda Core Member, late Katian, Ordovician.

Material

Four specimens, two from Kallholn (PMU 26919, 26921), one from Osmundsberget (NRM Mo 154065) and one from Unskarsheden (PMU 26920); Boda Limestone, late Katian, Dalarna, Sweden.

Remarks

This species was extensively described by Mutvei (1957). Additionally, the ventromyarian periphract was figured in three specimens with the mature body chamber preserved (Mutvei 1957: pl. 4.3, fig. 4; pls 6, 7). Two more specimens with complete mature body chambers are in the collections of the NMR and PMU. Both body chambers are nearly identical in maximum conch height (58 mm), which is reached at the peristome. The body chamber contracts only very slightly close to the peristome and has a length of 90–100 mm (NRM Mo 154065, PMU 26919) (height/length ratio of body chamber ca. 0.6).

Comparison

Warburgoceras longitudinale comb. nov. is very similar to Redpathoceras bullatum sp. nov. with respect to ornamentation (both species have a similar distinctively longitudinally lirate surface; Fig. 18F), and are identical in angle of expansion, conch curvature, conch cross section and mature size (Fig. 39C). They differ, however, in two main aspects: (1) the mature body chamber of R. bullatum sp. nov. is inflated, with a maximum height at the mid-length, whereas the body chamber of W. longitudinale comb. nov. opens gradually, (2) the conch of R. bullatum sp. nov. displays deeply concave septa of truncation at regular distances. This similarity strongly suggests a close phylogenetic relationship between the two species, genera and higher taxa to which they belong (see discussion above).

Stratigraphic and geographic range

Boda Limestone, late Katian, Dalarna, Sweden.