Species

Gorbyoceras textumaraneum (Roemer, 1861)

Taxon description

Kröger & Isakar, 2006

Diagnosis. Gorbyoceras with slightly cyrtoconic adult body chamber, shell slightly compressed, and relatively large adult size of more than 40 mm in cross section. Slightly irregularly spaced annulations, approximately three at the distance equal to the diameter. Approximately 35 irregularly spaced longitudinal ridges around the entire circumference of the shell. Approximately 15 growth lines between two successive ridges of annulations. Sutures straight, nearly transverse, one suture at each groove of the annulations. Siphuncle eccentric in juvenile, subcentral in more adult growth stages, septal perforation approximately one tenth of the diameter of the shell.

Synonymy list

1861 Orthoceras textum-araneum — Roemer , pp. 58-59, fig. 7;3a,b

1889 Orthoceras textum-araneum — Rüdiger , pp. 52

1930 Spyroceras textum-araceum (Ferd. Roemer) — Teichert , pp. 280, fig. 5:6

1962 Spyroceras textum-araneum — Balashov , pp. 108, fig. 48:1

1984 Gorbyoceras textumaraneum — Dzik , pp. 121, 125, fig. 35:4; text fig. 49.15

2006 Gorbyoceras textumaraneum (Roemer, 1861) — Kröger & Isakar , pp. 158, fig. 8C, 10C,D; 12A,B

2025 Gorbyoceras textumaraneum (Roemer, 1861) — Kröger , pp. 43, fig. Figs 11D, 12D–E, L–M, 18

Selection of related publications

Kröger, B. 2025. The Lyckholm acme of cephalopods – Review of the late Katian (Vormsi–Pirgu regional stages) Ordovician cephalopods of Estonia. European Journal of Taxonomy 978, 1-168. DOI:10.5852/ejt.2025.978.2801

Teichert, C. 1930. Die Cephalopoden-Fauna der Lyckholm-Stufe des Ostbaltikums. Paläontologische Zeitschrift 12, 3/4, 264-312. DOI:10.1007/BF03044452

Classification

Organism group	Biota
Kingdom	Animalia
Phylum	Mollusca
Class	Cephalopoda
Subclass	Orthoceratia
Order	Orthocerida
Suborder	Orthoceratina
Family	Proteoceratidae
Genus	Gorbyoceras
Species	alternestriatum
	clathratoannulatum
	stumburi
	textumaraneum