Eothele tubulus Ushatinskaya, 1987

Skovsted, C. B., Knight, I., Balthasar, U. & Boyce, W. D., 2017, Depth related brachiopod faunas from the lower Cambrian Forteau Formation of southern Labrador and western Newfoundland, Canada, Palaeontologia Electronica (Oxford, England: 1990) 17 (15), pp. 1-52 : 37-39

Eothele tubulus Ushatinskaya in Voronova, Drosdova, Esakova, Zhegallo, Zhuravlev, Rozanov, Sayutina, and Ushatinskaya, 1987

Figure 19

*1987 Eothele tubulus Ushatinskaya in Voronova,

Drosdova, Esakova, Zhegallo, Zhuravlev,

Rozanov, Sayutina, and Ushatinskaya, p. 50,

plate 22, figures 1–6, plate 23, figure 3. 2007 Eothele sp. Skovsted and Peel, figure 2C. 2010 Eothele tubulus Ushatinskaya in Voronova et al.; Skovsted and Peel, p. 760, figure 4.1-

4.19. 2016 Eothele tubulus Ushatinskaya in Voronova et al.; Ushatinskaya and Korovnikov, p. 460,

figure 2a-i, figure 3f. Holotype. GSC N 90245 ( Voronova et al., 1987, plate 22, figure 1), from sample N42, collected from unnamed rock unit above Sekwi Formation, 10 m below locality GSC 95527, Mackenzie Mountains, Northwest Territories, Canada. Material. 244 ventral and 33 dorsal valves from the Forteau Formation of the Bonne Bay area, western Newfoundland (GM07-2-1, GM07-3-1, GM07-4-1, GM07-5-1, GM11-4-2, GM11-5-E, GM11-6, GM11- 6-11, GM11-6-13, GM11-9A-2, GM11-9A-8T, GM11-9A-9, GM11-9A-10, GM11-9A-12, GM11-14, GM11-14-2, GM11-14A-5, GM11-14C, GM11-14G- 1, GM11-14G-3B, GM11-14G-C, ICS1518, ICS1519, ICS1421, JSP1982−01). Diagnosis. (Emended from Skovsted and Peel, 2010). Species of Eothele with elongate lenticular pedicle foramen and reduced internal pedicle tube. Differs from E. spurri and E. granulata by the smaller pedicle opening, its lenticular shape, the short internal pedicle tube, the less pronounced anterior flexing of the ventral valve and the less pronounced ventrally directed flexure of the dorsal umbo. Description. Sub-circular, dorsibiconvex shell. Ventral valve low cone-shaped with procline, slightly convex pseudointerarea and concave anterior slope ( Figure 19.1 ). Pedicle foramen lenticular, situated on the ventral pseudointerarea, just below the ventral larval shell ( Figure 19.2-3 ). Dorsal valve sub-circular with larval shell at posterior margin ( Figure 19.7 ) and ventrally deflected commissural plane of the posterior margin ( Figure 19.8 ). Dorsal pseudointerarea arcuate and raised substantially above valve floor ( Figure 19.11-12 ), with wide, triangular but poorly defined median groove. Ventral larval shell with one high tubercle at posterior margin and two low tubercles anteriorly ( Figure 19.1- 3 ). Dorsal larval shell with two high tubercles close to posterior margin ( Figure 19.8 ). Larval shells finely pitted (diameter of pits 2-3 µm; Figure 19.2 ), adult shell pustulose with pustules increasing in diameter away from the apex (diameter 7-10 µm; Figure 19.1-3 ).

Ventral valve interior with rounded anterior muscle fields bisected by elongate and slightly thickened central lobe of visceral area anterior to pedicle tube ( Figure 19.5 ). Arcuate impressions of vascula lateralia are present lateral to anterior muscle fields ( Figure 19.6 ). Dorsal valve interior with low median ridge with large central muscle scars on either side ( Figure 19.9-10 ). Faint impressions of vascula lateralia and umbonal muscle scars inserted beneath dorsal pseudointerarea.

Remarks. Eothele tubulus was originally described from the lower Cambrian of the Mackenzie Mountains of Northwest Territories in Canada ( Voronova et al., 1987), but the species was recently redescribed based on collections from the Kinzers Formation of Pennsylvania by Skovsted and Peel (2010), who also included a few specimens from the Forteau Formation of western Labrador illustrated by Skovsted and Peel (2007) in the species. The new collections from Gros Morne now available allow us to confirm the presence of E. tubulus in the Forteau Formation and complement the description by Skovsted and Peel (2010) with new data, in particular the morphology of the dorsal valve but also aspects of the ventral valve interior. As outlined by Skovsted and Peel the species differ from other species in the genus (i.e. E. spurri , E. granulata ) by the lower umbonal region and more evenly lens-shaped pedicle foramen and the short pedicle tube. The dorsal valve also differs by the less pronounced umbonal flexing.

Eothele tubulus was recently reported from the Toyonian to Amgan stages of the Siberian Platform ( Ushatinskaya and Korovnikov, 2016). Although fragmentary and slightly younger than the material from Laurentia, the illustrated specimens from Siberia are remarkably similar to the material from Newfoundlan described herein and likely belong to the same species.

Distribution. Assemblage 3, Mackenzie Mill member, Forteau Formation of the Bonne Bay area, western Newfoundland. Cambrian Series 2, Stage 4 (Dyeran Stage) of North-West Territories and Pennsylvania.

Figures

FIGURE 19. Eothele tubulus Ushatinskaya in Voronova et al., 1987 from the Forteau Formation of western Newfoundland. 1-3, Ventral valve NFM F-2575 from Deer Arm Limestone, sample GM07-5-1; 1, external view; 2, detail of larval shell showing pitted larval and pustulose adult shell ornament; 3, detail of posterior margin in oblique view showing oval opening of pedicle tube. 4, Ventral valve NFM F-2573 from Deer Arm Limestone, sample GM07-4-1. 5- 6, Ventral valve NFM F-2568 from Deer Arm Limestone, sample GM07-3-1; 5, internal view; 6, oblique view showing median tongue and imprints of vascula lateralia. 7-8, Dorsal valve NFM F-2576 from Deer Arm Limestone, sample GM07-5-1; 7, external view; 8, oblique posterior view. 9-10, Dorsal valve NFM F-2521 from Deer Arm Limestone, sample GM07-5-1; 9, oblique lateral view; 10, oblique posterior view. 11-12, Dorsal valve NFM F-2569 from Mackenzie Mill member, sample GM07-2-1; 11, internal view showing dorsal pseudointerarea; 12, oblique lateral view. All scalebars equal 500 µm except in figures 2-3 that equals 100 µm.