Schizotreta sp. 2

Hansen, Jesper & Holmer, Lars E., 2011, Taxonomy and biostratigraphy of Ordovician brachiopods from northeastern Ny Friesland, Spitsbergen 3076, Zootaxa 3076 (1), pp. 1-122 : 39

Schizotreta sp. 2

Pl. 7, Figs. 7–13

Material. Eight dorsal and 10 ventral valves from sample JH-153, including the figured specimens, TSGF 17020– 17022.

Description. Shell slightly to moderately convex. Outline elongate-oval to subcircular. Valves thin-walled. Larval shell subcircular and smooth. Postlarval shell with growth lines, very weak sporadic ridges, and fine radial striae. Micro-pits variable in size and moderately dense to dense. Pits unordered or partly ordered in radial rows.

Dorsal pseudointerarea absent.

Anterior slope of ventral valve gently concave.

Remarks. This species is represented only by small fragments, making detailed comparisons with other species impossible. This species appears to be distinguished from Schizotreta sp. 1 by its lack of lamellae and denser, less-ordered micro-pitting. Schizotreta marginalis sp. nov. is apparently distinguished by always having micro-pits of subequal size and by its larger dorsal valves that nearly always have concentric lamellae. However, better material is needed for more detailed comparisons to determine whether they are three separate species.

Occurrence. Uppermost beds of Nordporten Member, Kirtonryggen Formation, Basissletta in northeastern Ny Friesland, Spitsbergen.