Dalejina, Havlicek, 1953

Modzalevskaya, Tatiana L., 2003, Silurian and Devonian brachiopods from Severnaya Zemlya (Russian Arctic), Geodiversitas 25 (1), pp. 73-107 : 82

Dalejina ex gr. hybrida (Sowerby in Murchison, 1839) ( Fig. 9 )

ex gr. Orthis hybrida J. de C. Sowerby in Murchison, 1839: 630, pl. 13, fig. 11.

Rhipidomella ex gr. hybrida – Nikiforova & Andreeva 1961: 117, pl. XX, figs 1-4.

MATERIAL EXAMINED. — One specimen from loc. 13, bed 89, Matusevich River, October Revolution Island ( Männik et al. 2002: figs 2, 5); Vodopad Formation.

REMARKS

The combination of small size (L = 6.2 mm, W = 7.2 mm, T = 3.3 mm), rounded general outline, biconvex shell with fine ribs (about 45 at the anterior margin) which increase by intercalation of secondary or, seldom, preliminary ones, has generally been considered to be diagnostic features of Dalejina . The specimens from Severnaya Zemlya are more similar to those from the Omnutakh and Meik formations (Llandovery) of East Siberia ( Nikiforova & Andreeva 1961: 117, pl. XX, fig. 2; Lopushinskaya & Doroshenko 1991). They were assigned to D. hybrida , although this species is known to be characteristic for the Wenlock Limestone in Britain. The lectotype of D. pentlandica (Davidson, 1869) , described from the Telychian (Pentland Hills, Cocks 1978: 71), is characterized by a larger size, finer ribs, and a bigger convexity of dorsal valve.

Figures

FIG. 9. — Dalejina ex gr. hybrida (Sowerby in Murchison, 1839), complete shell (N 2/12991), loc. 13, bed 89, Vodopad Formation; A, ventral view; B, dorsal view; C, lateral view; D, anterior view. Scale bar: 3 mm.