Shaleria (Shaleria) ornatella ( Davidson, 1871 ), 1939

Musteikis, Petras & Cocks, L. Robin M., 2004, Strophomenide and orthotetide Silurian brachiopods from the Baltic region, with particular reference to Lithuanian boreholes, Acta Palaeontologica Polonica 49 (3), pp. 455-482 : 466-468

Shaleria (Shaleria) ornatella ( Davidson, 1871)

Figs. 5L–O, 6B–H.

Strophomena ornatella Davidson 1871: 309 , pl. 43: 16–20.

Strophomena impressa Munthe 1902: 233 , figs. 3, 4 nomen nudum.

Shaleria ornatella (Davidson) Caster 1939: 34 .

Shaleria aff. ornatella (Davidson) ; Bassett and Cocks 1974: 17.

Shaleria (Protoshaleria) ornatella (Davidson) Harper and Boucot 1978: 162 , pl. 35: 1–10.

Shaleriella tenuis Nikiforova, Modzalevskaya, and Bassett 1985: 23 , pl. 5: 1–6.

Shaleria (Janiomya) ornatella (Davidson) ; Rong and Cocks 1994: 661, fig. 11.

Remarks.—The type locality, from which the lectotype was selected by Cocks (1978: 129), is from the Upper Ludlow of Shropshire, England. Shaleriella tenuis of Nikiforova et al. (1985), from the Pridoli Skala Horizon of Podolia, has dorsal side septa, whose presence is characteristic of Shaleria rather than their absence from Shaleriella , and should thus be reassigned to the former genus, and is also placed here within the synonomy of S. (S.) ornatella . S. (S.) tenuis is also listed from the Ludlow–Pridoli of Belarus by Modzalevskaya and Pushkin (1989: 96), but cannot be confirmed without illustration. There is considerable variation in the ornamentation of the species: some specimens have zig−zag rugellae between some, or in some cases nearly all, of the parvicostellae, whilst in some populations these rugellae are rare or even apparently absent. The convexity also varies from flat to medium, but the profile does not show the geniculation or rather square anterior outline present in S. (S.) ezerensis (see below). Harper and Boucot (1978:162) erected the separate subgenus Protoshaleria within Shaleria , with S. ornatella as its type species, on the basis that Protoshaleria had a single pair of “brace plates” in contrast to the “second pair of brachial ridges which flank the brace plates and are almost identical to them, and commonly two pairs of parallel−sided diductor tracks in the pedicle valve”. However, as can be seen from the excellent illustrations of the type species of Shaleria in Harper (1973: 13), these features are variably developed in the topotype population and thus a separate subgenus is not warranted. As discussed in Bassett and Cocks (1974: 17), Munthe (1902) figured specimens from Gotland as “ Strophomena impressa Lindström ”; however, that name was never published by Gustav Lindström and the species name is a nomen nudum.

From Baltica Shaleria aff. ornatella ( Davidson, 1871) was identified from the Ludlow Hemse, Eke and Burgsvik Beds of Gotland by Bassett and Cocks (1974: 17), but this is now here revised to S. (S.) ornatella . The same species name also includes the specimens termed Shaleriella tenuis Nikiforova et al. (1985: 23) , from the Pridoli of Podolia. Shaleria is widespread in the East Baltic Upper Ludlow and Pridoli. It was illustrated under the name of Brachyprion dzwinogrodensis by Rybnikova (1967), but, as discussed above under Brachyprion , that species name is a nomen dubium. We have identified Shaleria from the boreholes,

such as Gėluva−114 and others, from central Lithuania and Šešuvis−11 and others from western Lithuania, as S. (S.) ornatella .

Distribution.—The distribution of S. (S.) ornatella in Lithuania is from the Vievis and Lapės formations (Pridoli) in east Lithuania; Neris, Mituva, Ventspils (Ludfordian), Minija and Jūra (Pridoli) formations in central Lithuania; upper part of the Rusnė Formation, Mituva, Ventspils, Pagėgiai (Ludfordian), Minija and Jūra (Pridoli) formations in west Lithuania (Appendix).

Shaleria (Shaleriella) ezerensis ( Rybnikova, 1966) Figs. 5P, 6A, I–P.

Brachyprion ezerensis Rybnikova 1966: 80 , pl. 1: 9, 10.

Brachyprion ezerensis Rybnikova ; Rybnikova 1967: 193, pl. 21: 1,2.

Shaleriella delicata Harper and Boucot 1978: 161 , pl. 34: 11–25, 29.

Shaleriella delicata Harper and Boucot ; Cocks and Rong 2000: 302, fig. 192: 2a–c.

Remarks.—The type locality of S. (S.) ezerensis is from the Ezere borehole of Latvia from 926.8 m from the Pridoli Jūra Formation ( Rybnikova 1966, 1967). From her figured dorsal interior ( Rybnikova 1967, pl. 21: 2A) it should also be referred to Shaleria , but the species shows the characteristics of the subgenus Shaleriella discussed above. We consider it the same as the species described as the type species of Shaleriella by Harper and Boucot (1978), There is some confusion as to the type locality of S. delicata ; the caption to the figure of the holotype states “Eke Marl, Gotland, USNM loc. 10039." That locality ( Harper and Boucot 1978: 63) is stated to be “Hemse Marl, Gogs Lau parish, north−road−ditch, Ronehamn quadrangle, Gotland.” All Harper and Boucot’s (1978: pl. 34) figured specimens come from either USNM loc 10038 or USNM loc 12834; the latter is within the Eke Beds. Material from both the Hemse Marl and the immediately overlying Eke Marl in the Natural History Museum both contain shaleriids similar to the holotype of S. delicata , and we assume here that the Hemse Marl at USNM loc. 10039 is correct, with the plate caption an error. S. delicata was listed from the Ludlow of Belarus by Modzalevskaya and Pushkin (1989: 95), but is considered here as a synonym of S. (S.) ezerensis .

Distribution.—In Lithuania the species is here recorded from the Lapės Formation (Pridoli) in east Lithuania; Dubysa, Neris, Mituva, Ventspils (Gorstian and Ludfordian), Minija and Jūra (Pridoli) formations in central Lithuania; Rusnė (Gorstian), Mituva, Ventspils, Pagėgiai (Ludfordian), Minija and Jūra formations in west Lithuania (Appendix Table 1).