Reticulariopsis talenti Lenz & Johnson, 1985

Modzalevskaya, Tatiana L., 2003, Silurian and Devonian brachiopods from Severnaya Zemlya (Russian Arctic), Geodiversitas 25 (1), pp. 73-107 : 94

Reticulariopsis talenti Lenz & Johnson, 1985 ( Figs 24 B-F; 25)

Reticulariopsis talenti Lenz & Johnson, 1985: 91 , pl. 15, figs 1-11.

Reticulariopsis ? sp. – Lenz & Johnson 1985: 91, pl. 15, figs 12-16.

MATERIAL EXAMINED. — Four isolated shells, mainly embeded in the rock matrix, from loc. 21581, Komsomolets Island ( Männik et al. 2002: fig. 1); Severnaya Zemlya or Pod”emnaya formations.

REMARKS

Small specimens (L = 5.1-5.5 mm, W = 6.3-6.9 mm, T = 3.7-4.0 mm) are characterised by ventribiconvex as well as biconvex shells with poorly developed sinus and fold. Serially sectioned internal structure shows small triangular teeth support- ed by short anteriorly divergent dental plates. Dental sockets are longitudinal and narrow. Crural plates are wide, triangular, jointed near the bottom of the shell. Crura are thin, fluently merging with primary lamellae of spiralia. The coils of spiralia are directed laterally and comprise four whorls. No ctenophoridium is found ( Fig. 25 ). Shells of similar size, with laterally ovate outline, are characteristic of Reticulariopsis ? sp. ( Lenz & Johnson 1985: 91). In the Garra Formation (Wellington area in New South Wales, Australia), this type of shells occurs 4 m below R. talenti . There is no evidence of its co-occurrence together with R. talenti also from Severnaya Zemlya. Smaller size, acute apical angle, weakly developed sinus and fold are reliable criteria for discriminating R. talenti from Reticulariopsis ? warreni Perry, 1984 described from the Delorme Formation, Mackenzie District of the Yukon ( Perry 1984: 121, pl. 41, figs 29-46).

Figures

FIG. 24. — A, Eohowellella sp., ventral view of a pedicle valve (N 64/12991), loc. 2, bed 79, Samojlovich Formation; B-F, Reticulariopsis talenti Lenz & Johnson, 1985; B, ventral view; C, dorsal view; D, lateral view; E, posterior view of a complete shell (N 65/12991); F, posterior view of a complete shell (N 66/12991), showing delthyrium, loc. 21581, Severnaya Zemlya or Pod’’emnaya formations. Scale bar: A, 5 mm; B-E, 2 mm; F, 2.5 mm.

FIG. 25. — Selected transverse serial sections, illustrating the development of internal structures in Reticulariopsis talenti Lenz & Johnson, 1985 (N 67/12991). Measurements: length 5.1 mm, width 6.3 mm, thickness 4.0 mm; loc. 21581, Severnaya Zemlya or Pod’’emnaya formations. Numerical designations are the same as on Fig. 11. Scale bar: 1.4 mm.