Rafinesquina (Mesogeina) pseudoloricata ( Barrande, 1848 )

Colmenar, Jorge, 2016, Ordovician rafinesquinine brachiopods from peri-Gondwana, Acta Palaeontologica Polonica 61 (2), pp. 293-326 : 318-321

Rafinesquina (Mesogeina) pseudoloricata ( Barrande, 1848)

Figs. 17 , 18 .

1848 Leptaena pseudo-loricata ; Barrande 1848: 222, pl. 18: 9.

1853 Leptaena beirensis , n. s.; Sharpe in Ribeiro et al. 1853: 156, pl. 8: 8.

1853 Leptaena ignava , n. s.; Sharpe in Ribeiro et al. 1853: 157, pl. 8: 9.

1879 Strophomena pseudo-loricata Barr ; Barrande 1879: pl. 54: 4.

1951 Rafinesquina pseudoloricata (Barr) ; Havlíček 1951: 23, pl. 3: 1, 6, 7.

1966 Rafinesquina pseudoloricata (Barr) ; Schulz and Jordan 1966: 703–705, figs. 1–3.

1967 Rafinesquina pseudoloricata (Barr) ; Havlíček 1967: 77, pl. 10: 7–14; pl. 11: 8.

1971 Rafinesquina pseudoloricata (Barr) ; Havlíček 1971: 70–71, pl. 21: 2–3.

1983 Rafinesquina sp. 1 ; Villas 1983: pl. 2: 2.

1985 Rafinesquina pseudoloricata Barrande, 1848 ; Villas 1985: 103– 105, pl. 28: 1–8; pl. 29: 1–3, 5, 6, 8.

1985 Hedstroemina mundae (Sharpe, 1853) ; Young 1985: 345, pl. 34: 4–7; non figs. 1–2 (= Orthis? mundae ), figs. 3, 8, 9 (= Rafinesquina [ Mesogeina ] loredensis , described above) and fig. 10 (= Kjaerina [Villasina] almadenensis , discussed above).

1995 Rafinesquina cf. pseudoloricata ( Barrande, 1848) ; Villas 1995: 80, pl. 13: 2–7.

Material.—Internal and external moulds of 23 ventral valves and 10 dorsal valves: DPZ- 359, 362 from the Iberian Chains, Spain; MPZ 2015/1391–1397 from Bohemia ( Czech Republic); IGM- 2934, 2936, 2952A from the Portuguese Central Iberian Zone; upper middle Berounian–upper Berounian (lower–middle Katian, Ka1–2 stage slices).

Description.—Shell of large size (largest specimen 37 mm wide), lateral profile concavoconvex, semicircular in outline; maximum valve width at hinge line in young specimens and at mid valve in adults; cardinal angles from acute to obtuse. Ventral valve gently convex, ranging 67–99% as long as wide (x = 87%; n = 11; σn = 0.08) and 6–12% as deep as long (x = 9%; n = 5; σn = 0.04); ventral interarea curved, apsacline, 6% as long as valve length; delthyrium open. Dorsal valve gently concave, approximately 87% as long as wide; dorsal interarea anacline, 1% as long as valve length; notothyrium completely covered by medially grooved, convex chilidium.

Radial ornament unequally parvicostellate, with 6–8 ribs per 2 mm at 10 mm anteromedially from umbo, normally displaying irregular layout from beak to shell margin and all of them with rounded crests; between two costae there are up to 5 costellae. Concentric ornamentation consisting of fila disposed over the whole shell but more abundant and closer among them near shell margin; some specimens showing evidences of shell damage reflected as discontinuities in shell ornament ( Figs. 17A 3, D, 18C).

Ventral interior with strong teeth well differentiated from hinge line, dental plates extending forward approximately 12% of valve length and with average dental plates divergence angle of 99° (range 89–106°; n = 4); muscle field poorly impressed anteriorly, flabelliform, ranging 33–51% as long as valve length, approximately as long as wide and surrounded posterolaterally by narrow and thin muscle bounding ridges. Adductor scars lanceolate, faintly impressed located between diductors.

Dorsal interior with strong and divergent socket ridges (x = 96°; n = 4) bounding triangular and elongated dental sockets; bifid cardinal process with elongate or plate-like lobes in young specimens, but engrossed in adult specimens. Lobes weakly divergent anteriorly and myophores has striated posteroventral surface. Situated on low and delicate notothyrial platform, continuous anteriorly with broad and faintly impressed median ridge halving dorsal muscle field. Fine pseudopunctae with radial pattern visible in both interiors.

Remarks.—The unequally parvicostellate ornamentation, with 6–8 ribs per 2 mm at 10 mm anteromedially from umbo, the pseudopunctae development, the semicircular shell outline with the maximum valve width at hinge line in young specimens and at mid valve in adults and the cardinalia of the studied material from the Portuguese Central Iberian Zone and from the Spanish Iberian Chains and Spanish Central Iberian Zone, warrants their inclusion within the Bohemian species Rafinesquina (Mesogeina) pseudoloricata ( Barrande, 1848) . The Spanish collections had already been assigned to this species by Villas (1983, 1985, 1995), and are partly re-figured herein.

Two of the valves from Portugal, now revised, were used by Sharpe (in Ribeiro et al. 1853) to characterize two different species, Leptaena beirensis and L. ignava . The former based on one ventral valve and the latter on one dorsal valve. The same author (Sharpe in Ribeiro et al. 1853: 157) doubts about the validity of L. ignava in the remarks of both species arguing that “This shell ( L. beirensis ) closely resembles the next described, L. ignava , and perhaps they may prove the opposite valves of one species. (…) Only one valve of this shell ( L. ignava ) has been seen, and it may perhaps prove to be the ventral valve of the preceding species, L. beirensis , to which it is very nearly allied”. Sharpe (in Ribeiro et al. 1853) did not compare his species with the Bohemian R. (Mesogeina) pseudoloricata described by Barrande (1848) little before. After the study of the type material of L. beirensis and L. ignava , as well as additional material from their type localities, I can confirm their synonymy, due to their identical radial and concentric ornamentation, pseudopunctae development, shell outline and cardinalia. In addition, the comparison of this material with topotypes of R. (Mesogeina) pseudoloricata from Bohemia, suggests inclusion of the Portuguese material to the Bohemian species and, therefore, L. beirensis and L. ignava , are junior synonyms of R. (Mesogeina) pseudoloricata .

Young (1985) also proposed to synonymize L. beirensis and L. ignava with the poorly known Orthis mundae Sharpe in Ribeiro et al. 1853, which he included to Hedstroemina . Young (1985) assigned to that reinterpreted species a wide range of rafinesquinines, which have been separated herein into three species of two different genera: Kjaerina (Villasina) almadenensis , Rafinesquina (Mesogeina) loredensis , and R. (Mesogeina) pseudoloricata . If the proposal by Young (1985) was right O. mundae would be a junior synonym of R. (Mesogeina) pseudoloricata . The only preserved valve or O. mundae displays some similarities in ornamentation to R. (Mesogeina) pseudoloricata , but clearly it is not sufficient to give a definite conclusion on its taxonomic status.

Stratigraphic and geographic range.—lower–middle Katian (Ka1–2), Upper Ordovician of Bohemia: Zahorany and Bohdalec formations (see Havlíček 1967); Germany: “Lederschiefer” pebbles from East Thuringia (see Schulz and Jordan 1966); Morocco: middle part of the Lower Ktaoua Formation(see Havlíček 1971); Portugal: Porto de Santa Anna Formation at Louredo locality; Spain: base of the Piedra del Tormo Member of the Fombuena Formation from the Iberian Chains.

Figures

Fig. 17. Ventral valves of rafinesquinine brachiopod Rafinesquina (Mesogeina) pseudoloricata (Barrande, 1848); lower–middle Katian (Ka1–2), Upper Ordovician; Zahorany Formation, Bohemia, Czech Republic (A, B); Upper Tiouririne Formation, Morocco (C); Porto de Santa Anna Formation, Portuguese Central Iberian Zone, Portugal (D); Peña del Tormo Member of the Fombuena Formation, Iberian Chains, Spain (E, F). A. MPZ 2015/1391, internal mould (A1), latex cast of interior (A2) and exterior (A3). B. MPZ 2015/1392, internal mould of an incomplete valve. C. MPZ 2015/1393, ventral internal mould. D. IGM-2952A, latex cast of ventral exterior. E. DPZ-359, internal mould of an incomplete valve. F. DPZ-362, internal mould (F1) and latex cast of exterior (F2). Scale bars 2 mm.

Fig. 18. Dorsal valves of rafinesquinine brachiopod Rafinesquina (Mesogeina) pseudoloricata (Barrande, 1848); lower–middle Katian (Ka1–2), Upper Ordovician; Zahorany Formation, Bohemia, Czech Republic (A–C); Peña del Tormo Member of the Fombuena Formation, Iberian Chains, Spain (D); Porto de Santa Anna Formation, Portuguese Central Iberian Zone, Portugal (E, F). A. MPZ 2015/1394, dorsal internal mould (A1) and latex cast of dorsal interior (A2), detail of cardinalia in anteroventral (A3) and posteroventral (A4) views. B. MPZ 2015/1395, internal mould (B1) and latex cast of interior B2). C. MPZ 2015/1396, latex cast of dorsal exterior. D. MPZ 2015/1397, latex cast of interior of a small valve. E. IGM-2934, latex cast of interior. F. IGM-2936, latex cast of dorsal exterior. Scale bars 2 mm.