Strophomena pectenoides Andreeva, 1961

Modzalevskaya, Tatiana L., 2003, Silurian and Devonian brachiopods from Severnaya Zemlya (Russian Arctic), Geodiversitas 25 (1), pp. 73-107 : 76

Strophomena pectenoides Andreeva in Nikiforova & Andreeva, 1961 ( Fig. 2 )

Strophomena ? pectenoides Andreeva in Nikiforova & Andreeva, 1961: 184, pl. XXXIX, figs 1-6. — Lopushinskaya 1976: 39, pl. III, figs 16-19.

MATERIAL EXAMINED. — 10 isolated valves from loc. 13, beds 21, 112, Matusevich River, loc. 32, bed 21, Ushakov River, October Revolution Island ( Männik et al. 2002: figs 2, 5); Vodopad Formation.

REMARKS

The specimens have a well developed narrow interarea, small chilidium, and narrow pseudodeltidium. There is a flattened dorsal umbo and a convex median part passing into a prominent sulcus. The shell is covered by fine rounded ribs which intercalate with even finer secondary ones. Low massive dental plates, teeth, and a large subquadrate muscle field with small oval adductors are developed in the ventral interior. The shells are similar to Strophomena kulumbensis Lopushinskaya, 1967 from Chamba, Talikit and Meik formations of East Siberia, but differ from that in possessing more frequent, unequal multicostellae and a chilidium larger than the pseudodeltidium (Lopushins k a y a 1 9 6 7: 8 9, p l. X X, f i g s 3-6). O. N. Andreeva ( Nikiforova & Andreeva 1961: 185) attributed pectenoides to Strophomena with a query, because there were no specimens with a ventral muscle field, and noted their resemblance to Coolinia pecten (Linnaeus, 1758) . However, the available facts show that the taxon belongs to Strophomena .

Figures

FIG. 2. — Strophomena pectenoides (Andreeva, 1961); A, dorsal view of a brachial valve (N 4/12991), loc. 13, bed 112, Vodopad Formation; B, C, brachial valve (N 3/12991); B, dorsal view; C, posterior view; D, surface sculptering of the specimen (N 5/12991), loc. 32, bed 21, Vodopad Formation. Scale bars: A, B, 10 mm; C, D, 2 mm.