Ericiolus sheldoniae Archontikis, J.G. Millán, A. Winter & Jer. R. Young, 2023

Archontikis, Odysseas A., Millán, Josué G., Winter, Amos & Young, Jeremy R., 2023, Taxonomic re-evaluation of Ericiolus and Mercedesia (Prymnesiophyceae) and description of three new species, Phycologia 62 (2), pp. 179-193 : 186

Ericiolus sheldoniae Archontikis, J.G. Millán, A. Winter & Jer. R. Young sp. nov.

Figs 21–29

DESCRIPTION: Coccosphere shape unknown, possibly saddle-shaped or sub-spherical but seen collapsed. It shows 30–60 star-shaped triradiate nannoliths with three coplanar bifurcate rays, equally positioned and angled. The rays are symmetrically arranged (120° angle between them) and bifurcate near the centre of the nannolith. The bifurcations are parallel-sided and directed radially, and show upturned tips that are directed distally. On the distal side of the nannolith, laths extend vertically down from the centre of the nannolith, in between the rays ( Fig. 23 ) and to about one-quarter from their tips. The laths form a calyx that is slightly thickened along its distal edge. On the proximal side of the nannolith, axial grooves run along the rays from the bifurcation to the nannolith centre where they unite to form a small central pore ( Fig. 22 ); laths are usually seen collapsed in proximal view.

DIMENSIONS: Coccosphere diameter 3.0–5.3 μ m; nannoliths 0.4–0.8 μ m long and wide. Ray 0.2–0.4 μ m long. Laths 0.2–0.3 μ m long.

HOLOTYPE: Stub no. AB2019 80m, deposited at the Algal Collection of the US National Herbarium ( US Alg. Coll. – 238319). Specimen shown in Fig. 21 .

PARATYPE: Stub no. AB2019 140m, deposited at the Algal Collection of the US National Herbarium ( US Alg. Coll. – 238322). Specimen shown in Fig. 24 .

TYPE LOCALITY: 32°12.72 ʹ N, 64°31.5 ʹ W, depth 80 m, 22 November 2022 , BATS Cruise, Hydrostation ‘S’.

NUMBER OF SPECIMENS STUDIED: 17.

DISTRIBUTION: Subtropical low-photic waters.

ETYMOLOGY: After Dr. Emma Sheldon (Geological Survey of Denmark and Greenland) in recognition of her contributions to the field of Cretaceous coccolithophore biostratigraphy.

REMARKS: The species shows similarities to both E. bendifii sp. nov. and E. mattioliae sp. nov. The presence of three coplanar rays with bifurcation near the nannolith centre is more reminiscent of E. bendifii sp. nov., but instead of having a spine that is terminated by a knob, the species bears a calyx of three laths. The laths nearly extend to the nannolith rays but unlike in E. mattioliae sp. nov., they do not rise from them. In addition, whilst the bifurcations are long and similar to E. bendifii sp. nov., the ray tip extensions are short as shown in E. mattioliae sp. nov.

Figures

Figs 21–29. SEM micrographs of Ericiolus sheldoniae sp. nov. Fig. 21. Holotype. Collapsed coccosphere bearing nannoliths with three coplanar rays showing bifurcation near the centre (arrow) and a calyx structure on distal side. Scale bar = 2 μm. Fig. 22. Detail of Fig. 21. Proximal view of a nannolith showing a central pore (arrow) and the interior side of broken laths. Scale bar = 0.5 μm. Fig. 23. Detail of Fig. 21. Distal view of a nannolith showing a calyx formed of delicate laths. The calyx develops in between the bifurcated rays of the nannolith. Scale bar = 0.5 μm. Fig. 24. Paratype. Nannoliths, each bearing a calyx; in a few nannoliths, the calyx is seen collapsed. Arrow indicates the delicate laths of the calyx in side view. Scale bar = 2 μm. Fig. 25. Individual nannoliths with lath-made calyx completely or partially collapsed (arrow). Scale bar = 1 μm. Fig. 26. Individual nannoliths showing partially collapsed delicate laths at their centre. Scale bar = 1 μm. Fig. 27. Collapsed coccosphere with a dense layer of nannoliths showing a calyx of laths occasionally completely or partially collapsed (arrow). Scale bar = 2 μm. Fig. 28. Individual nannoliths that may show collapsed or partially developed calyces (arrow). Scale bar = 2 μm. Upper right side with three coccoliths of Florisphaera profunda His. Okada & Honjo. Fig. 29. Collapsed coccosphere with saddle-like shape and numerous nannoliths showing lath-made calyces distally. Scale bar = 2 μm.