Silurian and Devonian brachiopods from Severnaya Zemlya (Russian Arctic) Author Modzalevskaya, Tatiana L. All-Russia Geological Research Institute (VSEGEI), Srednij pr. 74, St. Petersburg, 199106 (Russia) modz @ IB 2567. spb. edu. text Geodiversitas 2003 25 1 73 107 journal article 10.5281/zenodo.5375016 1638-9395 5375016 Hyattidina remota n. sp. ( Figs 22 A-D; 30) HOLOTYPE . — N 58/12991, CNIGR Museum , St. Petersburg ( Fig. 22 A-C), conjoined valves; L = 8.4 mm , W = 8.4 mm , T = 5.6 mm . ETYMOLOGY. — From remotus (Latin): far. TYPE LOCALITY . — Loc. 13, Matusevich River, October Revolution Island. FORMATION. — Golomyannyj Formation. AGE. — Llandovery, Aeronian. MATERIAL EXAMINED. — 19 conjoined well preserved valves from loc. 13, bed 48, Matusevich River, October Revolution Island ( Männik et al . 2002 : figs 2, 5); Golomyannyj Formation. MEASUREMENTS (IN MM). — L = 6.8-8.4, W = 7.3-8.4, T = 5.0-5.6. DIAGNOSIS. — Small shells, rounded in outline, biconvex in lateral profile, plicate; ventral fold and dorsal sulcus are well developed; wide dorsal sulcus limited by the flanking sinuses. DESCRIPTION Biconvex shells with rounded outline, plicate. Ventral beak acute, with open delthyrium, curved over the dorsal valve. Rounded ventral sinus limited laterally by rounded plicae, which originate from the anterior half of the valve. Smooth surface covered sometimes anteriorly by concentric growth lines. The internal structures consist of long, low dental plates located fairly close to the valve walls. Teeth small, deeply inserted into the dental sockets ( Fig. 30 ). Crural bases arise from the cardinal plate and progressively curve inward to join the primary lamellae of the spiralia. Spiralia directed laterally comprising five whorls. Jugum simple, placed in the middle of the shell, comprising a pair of joined lamellae without a jugal saddle. COMPARISON All hyattidinids possess long, low dental plates, a simple jugum without jugal saddle and spiralia directed laterally. The specimens show some characteristics of Hyattidina junea (Billings, 1866) (such as the pattern of the ventral sinus and dorsal fold), illustrated by Twenhofel (1928: 223 , pl. XXX, figs 4-6) from the Gun River and Jupiter formations of Anticosti Island. But the Severnaya Zemlya shells are smaller and characterized by a wider dorsal fold, limited by the flanking sinuses.