Valhalloceras floweri Evans & King, 1990

Kröger, Björn & Pohle, Alexander, 2021, Early-Middle Ordovician cephalopods from Ny Friesland, Spitsbergen - a pelagic fauna with Laurentian affinities, European Journal of Taxonomy 783 (1), pp. 1-102 : 76-77

Valhalloceras floweri Evans & King, 1990

Figs 5H–N , 6C , 8B , 50B

Valhalloceras floweri Evans & King, 1990: 628–629 , pl. 1 figs 5–11, text-fig. 3.

Diagnosis

As for genus, by monotypy.

Material examined

Specimen FMNH-P30343 from Profilstranda section, adjacent to Hinlopenstretet, Spitsbergen, bed PO 123.3, 120.3 m above base of Olenidsletta Member, V2 a trilobite zone, and specimens FMNH-P30340 , P30346 , P30348 , and P30350 from bed PO 131, 128 m above base of Olenidsletta Member, V2 b trilobite zone, Blackhillsian, Floian.

Description

Specimen FMNH-P30343 is the externally most complete specimen ( Fig. 5H–I ). It is a slightly crushed curved conch with a length of more than 30 mm which grows from 7.3 mm in height and 9.5 mm in width to 10 mm in height and 14 mm in width at a length of 15 mm (width expands with 17°, height with 10°). The cross section is depressed (rW: 1.3–1.5) and nearly elliptical at the adapical end of the specimen. The surface is ornamented with irregularly spaced fine growth lines, which run almost transversally at the ventral side and form a shallow broad sinus at the dorsal side. The internal characters of specimen FMNH-P30343 are not preserved. Three specimens with similar relative conch shape (rW: 1.3–1.6) occur in bed PO 131 and are better preserved internally. In specimen FMNH-P30340 from bed PO 131 at the Profilstranda section, the septal necks are orthochoanitic and the connecting rings are thickened and concave (figs 6C, 50B). The septal perforation is 1.7 mm in diameter and the connecting ring at approximately midlength between two chambers is 1.4 mm in diameter (0.11–0.14 of corresponding conch height). Approximately six chambers occur at a distance similar to the corresponding conch height.

Remarks

The type specimen of this species comes from a coastal outcrop between Lundehuken and Papegoyneset, adjacent to Hinlopenstretet, from a level near the top of V 2 in the terminology of Fortey (1980) (see Evans & King 1990). This is only a few kilometers south of the Profilstranda section, and at a level almost identical to beds PO 131, where the majority of our specimens of V. floweri were collected (see Fig. 1 ). Evans & King (1990) described and discussed Valhalloceras floweri in detail based on a single specimen, which expands laterally with an angle of 12° and dorsally with an angle of 19°, and which has a relative conch width (rW) of 1.4. Both values are closely similar to the specimens described herein. The specimens are also almost identical in conch cross section shape, conch curvature, in relative septal spacing and in the shape of the septal necks. However, the only available median section from specimens from our collection shows a siphuncle with contracted segments. This difference can be an effect of different preservation. In the type specimen, the septa and partly the connecting rings are strongly recrystallized and partly only traces of the former outlines are preserved ( Evans & King 1990: pl. 1 figs 8, 10–11). Alternatively, the difference can be true and reflect different growth stages and ontogenetic change, because the figured siphuncle in the type is from a corresponding conch height of ca 7 mm, compared with the specimen figured herein ( Fig. 50B ) with a corresponding conch height of ca 14 mm. Depending on the interpretation of the differences, the genus Valhalloceras has tubular to concave or exclusively concave segments, respectively. In the former interpretation the genus would be transitional between Oncocerida and Ellesmerocerida and in the latter it would be a bassleroceratid, similar to Lawrenceoceras , but with orthochoanitic, instead of loxochoanitic septal necks. More material is needed to definitively solve this problem. Here we place the genus provisionally within the Phthanoncoceratidae , because the presence of tubular connecting rings during early growth stages is assumed to be real.

Figures

Fig. 5. Cyrtoconic cephalopods from the Olenidsletta Member, Floian, Ordovician, Profilstranda section, Ny Friesland, Spitsbergen. A–C. Lawrenceoceras larus sp. nov., FMNH-P30351, holotype, from bed PO 131. A. Lateral view with siphuncle on left side. B. Ventral view, prosiphuncular side. C. Adoral view of septum and septal perforation.D–E. Lawrenceoceras ebenus sp. nov., FMNH-P30335, holotype, from bed PO 123.3. D. Lateral view with siphuncle on left side. E. Ventral view, prosiphuncular side. F–G. Olenidslettoceras farmi gen. et sp. nov., FMNH-P30334, holotype, from bed PO 123.3. F. Lateral view with siphuncle on left side. G. Ventral view, prosiphuncular side. H–N. Vallhalloceras floweri King & Evans, 1990. H–I. Specimen FMNH-P30337, from bed PO 131. H. Lateral view, siphuncle on right side I. Ventral view, prosiphuncular side. J–L. Specimen FMNH-P30343 from bed PO 123.3, J. Lateral view with siphuncle on left side. K. Ventral view, prosiphuncular side. L. Dorsal view, antisiphuncular side.M–N. Specimen FMNH-P30338 from bed PO 131. M. Lateral view with siphuncle on left side. N. Ventral view, prosiphuncular side. O–Q. Cyclostomiceras profilstrandense sp. nov., specimen FMNH-P30336, from bed PO 123.3. O. Lateral view with siphuncle on left side. P. Ventral view, prosiphuncular side. Q. Dorsal view, antisiphuncular side. Scale bar = 10 mm for all figures.

Fig. 6. Median sections of cyrtoconic cephalopods from the Olenidsletta Member, Floian, Ordovician, Profilstranda section, Ny Friesland, Spitsbergen. A. Lawrenceoceras ebenus sp. nov., FMNH-P30335, holotype, from bed PO 123.3. B. Lawrenceoceras larus sp. nov., FMNH-P30355, paratype, from bed PO 131. C. Vallhalloceras floweri Evans & King, 1990, FMNH-P30340, from bed PO 131. D. Olenidslettoceras farmi gen. et sp. nov., FMNH-P30334, holotype, from bed PO 123.3. Scale bar = 5 mm for all figures.

Fig. 8. Reconstruction and interpretation of details of connecting ring and septal necks in cyrtoconic cephalopods from the Olenidsletta Member, Floian, Ordovician, Profilstranda section, Ny Friesland, Spitsbergen. A. Lawrenceoceras ebenus sp. nov., FMNH-P30335, holotype, see also Fig. 7B. B. Vallhalloceras floweri Evans & King, 1990, FMNH-P30340, see also Fig. 50B. C. Olenidslettoceras farmi gen. et sp. nov.,FMNH-P30334, holotype, see also Fig. 50A.D. Nyfrieslandoceras bassleroceroides gen. et sp. nov., FMNH-P30353, holotype, see also Fig. 49C. Black: septal neck and septum. Dark grey: connecting ring. Light grey: cameral deposits. Without scale.

Fig. 50. Median sections of phragmocones of oncocerids from the Olenidsletta Member, Floian, Ordovician, Profilstranda section, Ny Friesland, Spitsbergen. A. Olenidslettoceras farmi gen. et sp. nov., FMNH-P30334, holotype, from bed PO 123.3, see Fig. 8C for interpretation. B. Vallhalloceras floweri Evans & King, 1990, FMNH-P30340, see Fig. 8B for interpretation. Scale bars = 1 mm for both figures.

Fig. 1. The Profilstranda-Olenidsletta Member (PO) section adjacent to Hinlopenstretet, Ny Friesland, Spitsbergen. A. Map of the outcrop area adjacent to Hinlopenstretet (Basissletta area in the north and the Olenidsletta in the south; inset is Svalbard, with Spitsbergen as its largest island). The river names D, and E, and the promontory name F are the same as in Fortey & Bruton (1973: fig. 1) (modified from Kröger et al. 2017). B. Aspect of the PO section from north-northeast. C. Outcrop situation 07/2016, view from bed PO 3 toward the south with middle and upper part of the Olenidsletta Member in the background.