Elliptoglossa vulgaris, Hansen & Holmer, 2011

Hansen, Jesper & Holmer, Lars E., 2011, Taxonomy and biostratigraphy of Ordovician brachiopods from northeastern Ny Friesland, Spitsbergen 3076, Zootaxa 3076 (1), pp. 1-122 : 24-27

Elliptoglossa vulgaris sp. nov.

Pl. 3, Figs. 1 –13; Table 3

1975 Elliptoglossa sylvanica Cooper var. recidiva new variety ―Krause & Rowell, pp. 30–32, Fig. 25; Pl. 3, Figs. 16–19.

2006 Elliptoglossa sylvanica Cooper ―Nikitina et al., p. 159, Figs. 14.13, 14.

Derivation of name. Latin ‘ vulgaris ’, common; refers both to the abundance with which it occurs in the succession and its apparently wide geographic distribution.

Holotype. Pl. 3, Figs. 8–9; TSGF16962 , dorsal valve; 97 m above base of Olenidsletta Member, Valhallfonna Formation, sample JH-136; Profilstranda at Basissletta, Ny Friesland, Spitsbergen.

Material. 1047 specimens from samples with A84042, A84135 , A84137 , A84165 , A84167 and A84270 and from samples F2-scratch, F3478, F3505, F3518, F3535, F3542, F3546, F3560, F3596, F3599, F3664, F3675 ½, F3680, F3747, F3748, F3749, F3789, F4997, F5006, F5032, F5105B, F5268, F5273, F5690, JH-9, JH-10, JH-12– 15, JH-24, JH-35, JH-36, JH-38, JH-45, JH-46, JH-49, JH-51–54, JH-57, JH-129, JH-131, JH-136, JH-139, JH- 140, JH-157, JH-184, JH-188, JH-190 and JH-191. The figured specimens are TSGF 16962, TSGF 16963, TSGF 16965, TSGF 16980, TSGF 16982, TSGF 16983 and TSGF 16985.

Diagnosis. Equivalved and slightly biconvex Elliptoglossa with L/W ratio 1.35–1.80; ornamentation consisting of fine growth lines; limbus narrow and weakly developed.

Description of Svalbard material. Shell minute, thin-walled, with elongate-ellipsoid outline. Anterior margin rounded with a slightly pointed beak. Shell slightly biconvex, deepest at 30–40% of valve length, widest at or slightly anterior to mid-valve. L/W ratio 1.24–1.88. Largest measured specimen 2.8 mm long and 1.6 mm wide. Subcircular larval shell generally 0.15–0.35 mm long. Ornamentation consisting of fine growth lines. Micro-ornamentation absent.

Dorsal pseudointerarea vestigial, nearly orthocline, 1–3% as long and 27% as wide as valve. Median groove absent. Visceral area and vascular imprints weakly impressed or obscure. Pits not present on valve floor. Limbus developed in posterior part of valve. Dorsal visceral area extends anterior of mid-valve. Very fine striation present on valve floor just anterior to pseudointerarea. Transmedian muscle scars located at 30% of valve length. Outside lateral muscle scars located at 33% of valve length and middle lateral muscle scars located at 35% of valve length. Transmedian, outside lateral and middle lateral muscle scars about equal in size and forming a crescent, located slightly closer to axis of symmetry than to lateral valve border. Central muscle scars diamond- to teardrop-shaped, 3–11% as long as valve, bounding vascula media at 31–56% of valve length and with anteromedian point. Anterior lateral muscle scars forming one small scar along axis of symmetry at 43–78% of valve length. Median ridge thin, developing anterior of anterior lateral muscle scars. Main branches of vascula lateralia nearly straight in proximal 67% of valve length and located at about 25% of valve width from valve margin; beginning to converge and branch at 67% of valve length. Main branches of vascula media subparallel in proximal 42% of valve length, meeting elongate central muscle scars at that point. Anterior lateral muscle scars small, suboval, located at 73–78% of valve length.

Ventral pseudointerarea vestigial, orthocline, well-defined and narrow, 29% as wide as valve. Flexure lines absent. Pedicle groove broad, shallow, and subtriangular with slightly convex sides, 3% as long and 17% as wide as valve. Pedicle groove slightly raised above valve floor. Visceral area and vascular imprints weakly impressed or obscure. No pits on valve floor. Limbus present in posterior part of valve. Pedicle nerve impressions subparallel, reaching about 30% of valve length just behind inner posterior corner of middle lateral muscle scars. Anterior lateral muscle scars located at 45% of valve length. Middle lateral muscle scars elongate, diamond-shaped, located at 36% of valve length and bounded posterolaterally by slightly smaller triangular central muscle scars. Angular outside lateral muscle scars more weakly impressed but about the same size as and bounding central muscle scars. Mantle canal system baculate. Vascula lateralia diverging slightly at 30% of valve length, where branches extend to about 30% of valve width from lateral valve margin. From mid-valve length, branches parallel valve margin at a distance of about 20% of valve length.

Remarks. The specimens from Spitsbergen are identical to the Dapingian Elliptoglossa sylvanica Cooper var. recidiva Krause & Rowell, 1975 from Nevada. The species is distinguished from the Upper Ordovician E. sylvanica Cooper, 1956 by the lack of fine radial lines on the umbo, the slightly convex profile, and the shallower posterior part of the valve floor. For these reasons, we here erect a new species containing the Spitsbergen material and the variety from Nevada. The infrasubspecies variety Elliptoglossa sylvanica var. recidiva was introduced after 1961 by Krause & Rowell (1975) and is therefore not protected by ICZN [See International Commission on Zoological Nomenclature (1999) Art. 45.6.4]. For that reason we introduce the new name E. vulgaris . The new species differs from all other known species of the genus in the same characters by which E. sylvanica is defined. Nikitina et al. (2006) described some specimens from the Darriwilian of South Kazakhstan that are similar to E. vulgaris and are therefore included therein. The species is highly common in the middle part of the Olenidsletta Member in the Valhallfonna Formation.

Occurrence. 60, 75–98 and 113 m above base of Olenidsletta Member and 18, 26, 30 and 50–54 m above base of Profilbekken Member, Valhallfonna Formation, Basissletta in northeastern Ny Friesland, Spitsbergen. Lower part of Antelope Valley Formation (Dapingian), Nevada ( Krause & Rowell 1975). Lower Darriwilian Uzunbulak Formation, South Kazakhstan ( Nikitina et al. 2006).

Plate 3

Elliptoglossa vulgaris sp. nov.

Valhallfonna Formation.

1–2. TSGF16985 , paratype, exterior of conjoined valves, lateral view. Profilbekken Member, 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184 .

3–5. TSGF16963 , paratype, valve exterior, detail of larval shell, and detail of postlarval exterior. Olenidsletta Member, 97 m above base. Coll. J. Hansen, 28.07.2008, sample JH-136 .

6–7. TSGF16965 , paratype, dorsal valve interior, oblique lateral view. Olenidsletta Member, 97 m above base. Coll. J. Hansen, 28.07.2008, sample JH-136 .

8–9. TSGF16962 , holotype, dorsal valve interior, oblique lateral view. Olenidsletta Member, 97 m above base. Coll. J. Hansen, 28.07.2008, sample JH-136 .

10. TSGF16980 , paratype, dorsal valve interior. Profilbekken Member, 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184 .

11–12. TSGF16983 , paratype, ventrolateral and ventral views of dorsal valve. Profilbekken Member, 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184 .

13. TSGF16982 , paratype, ventral valve interior. Profilbekken Member, 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184 .

Obolid sp. 1

Valhallfonna Formation, Olenidsletta Member, 94 m above base. Coll. J. Hansen, 21.07.2008, sample JH-52.

14. TSGF16785, exterior of whole specimen.

15–17. TSGF16784, exterior of whole specimen, detail of larval shell, and detail of postlarval ornamentation.

18. TSGF16786, lateral view of whole specimen.

19. TSGF16783, valve interior with pseudointerarea.

Obolid sp. 2

Valhallfonna Formation, Olenidsletta Member, 90 m above base. Coll. J. Hansen, 20.07.2008, sample JH-45.

20. TSGF16812, valve exterior.

21–22. TSGF16813, valve exterior and detail of micro-sculpturing on ridges.

Figures

FIGURE 1 Locality maps of the Svalbard Archipelago. a) Locations of sites yielding Lower Palaeozoic fossils mentioned in this paper. b) Geological map of the Basissletta plain, northeastern Ny Friesland; redrawn from Fortey & Bruton (1973). The base map is based on aerial photos made available by the Norwegian Polar Institute and on field observations made by the authors in 2008.