Sinochonetes wangi Racheboeuf, 1987

Modzalevskaya, Tatiana L., 2003, Silurian and Devonian brachiopods from Severnaya Zemlya (Russian Arctic), Geodiversitas 25 (1), pp. 73-107 : 80-82

Sinochonetes wangi Racheboeuf, 1987 ( Fig. 8 )

Sinochonetes wangi Racheboeuf, 1987: 11 , pl. 3, figs 15-21.

MATERIAL EXAMINED. — Shells embedded in the coquina from loc. 21581, Krasnaya Bay, Komsomolets Island ( Männik et al. 2002: fig. 1); Severnaya Zemlya or Pod”emnaya formations.

REMARKS

The dimensions of the shells vary from 6.5 to 9.6 mm in length and from 10.0 to 14.0 mm in width; the average L/W ratio is 0.63. Anderidia diverges anteriorly and fuses with cardinalia posteriorly at 60°. Cardinal process is internally bilobed with additional, poorly developed lateral lobes, and is posteriorly closed by chilidium. The external and internal morphology of both valves are typical of the genus Sinochonetes , and our specimens are morphologically identical with S. wangi described from the lower Emsian(?) strata of Ellesmere Island (Canadian Arctic). S. wangi differs from the type species, S. minutisulcatus Hou & Xian, 1975 (Siegenian of South China, Hou & Xian 1975: 25, pl. 1, figs 3, 4), in having finer costellae (7-10 per 1 mm), more numerous spines (five), and a poorly developed ventral sinus.

A B C

Class RHYNCHONELLATA Williams, Carlson, Brunton, Holmer & Popov, 1996 Order ORTHIDA Woodward, 1852

Figures

FIG. 8. — Sinochonetes wangi Racheboeuf, 1987; A-C, interior view of pedicle valves (N 18/12991, 19/12991, 20/12991), loc. 21581, Severnaya Zemlya or Pod’’emnaya formations; D, ventral view of a complete valve (N 21/12991); E, external view of a shelly limestone with pedicle and brachial valves; F, L, complete valve (N 22/12991); F, dorsal view; L, posterior views with a pseudodeltidium and chilidium; G, dorsal valve, showing enlarged external surface with a fine striae (N 23/12991); H, posterior view of a pedicle valve, showing a delthyrium, covered by pseudodeltidium posteriorly (N 24/12991); I, K, dorsal valves with well preserved spines near cardinal margin (NN 25/12991, 26/12991); J, internal mould of a dorsal valve, showing a median septum and anderidia (N 27/12991). Scale bars: A-D, 2.5 mm; E, 5 mm; F-K, 2 mm; L, 1 mm.