Syracosphaera elevata Archontikis, Young, Cros, 2020

Archontikis, Odysseas A., Young, Jeremy R. & Cros, Lluïsa, 2020, Taxonomic Revision and Classification of Extant Holococcolithophores Previously Placed in the Genus Anthosphaera Kamptner emend. Kleijne 1991, Acta Protozoologica 59, pp. 121-139 : 137

Species Syracosphaera elevata Archontikis, Young, Cros sp. nov. HOL

Synonymy: Holococcolithophore sp. 2 ( Anthosphaera affinity?) Cros (2001), p. 97, Pl. 75, Figs. 3–4 .

Anthosphaera sp. type C Cros and Fortuño (2002), p. 60, Figs. 88C, 88D; Young et al. (2003), p. 90, Pl. 42, Figs. 8, 11.

Derivatio nominis: From Latin elevatus –a –um (adjective), elevated; referring to the elevated arch of CFCs.

Description: Coccosphere, most probably spheri- cal in shape but usually seen collapsed/flattened, with c. 250 BCs and 5–12 CFCs. BCs are characteristically minute (<1 µm) and partially calcified with an elliptical rim. BCs’ rim structure consists of an outer ring of tiny rhombohedral crystals that are loosely connected with an assembly of irregularly arranged, tiny crystallites in the central structure, thus leaving somewhat broad per- forations; a few BCs with only a rim sometimes occur ( Plate 6 , Fig. 3 ). CFCs consist of a similarly constructed rim, possessing though, a high arch (height> 2 x width) with a low triangular apical spine.

Remarks: The BCs are similar to those of S. marginiporata , although without the perforate microstructure. The CFCs with the very high arch are unique and quite different to those of S. marginiporata .

Dimensions: Coccosphere diameter c. 6 μm. BCs 0.4–0.8 μm long x c. 0.4 μm wide. CFCs c. 0.5 μm long x 0.5–0.8 μm wide; distal process is 1.2–2.0 μm high.

Holotype: Specimen illustrated in JRYSEM-177-72 ( Plate 6 , Fig. 1 ), stub 302-02, curated at the NHM, Lon- don, UK.

Paratype (s): Specimens illustrated at Plate 6 , Figs. 3–4 .

Type locality: Station 69–11, 42.5m water depth, collected from the western Mediterranean Sea (37°43N, 0°42W), cruise MATER II, October 1999 .

Number of specimens studied: 9

Distribution: Northwestern Mediterranean and Alboran Seas

Figures

Plate 3. Scale bars = 1μm 1–2. Syracosphaera lafourcadii (Lecal) Archontikis, Young, Cros comb. nov. HOL Complete coccospheres composed of CFCs that bear low distal processes (see arrows) and BCs with distal covers made of irregularly ar- ranged crystallites. 3–4. Syracosphaera origami (Cros and McGrane) Archontikis, Young, Cros comb. nov. HOL Coccospheres with highly ornamented CFCs showing triangle-shaped distal processes (fig. 3, arrow) and BCs with an organic base-plate in proximal view (fig. 4, arrow a) and a rim that supports delicate struts of crystallites holding the origami-like paper boat distal covers (fig. 4, arrow b) in distal view.

Plate 6. Syracosphaera elevata Archontikis, Young, Cros sp. nov. HOL Scale bars = 1μm 1. Holotype; flattened coccosphere with high-arched CFCs and tiny and partially calcified BCs. 2. Paratype; coccosphere with CFCs that bear distal processes made of delicate microcrystals (arrow a), and BCs with a loose assembly of irregularly arranged microcrystals at their distal cover (arrow b). 3. Paratype; BCs’ central structure may lose its crystal assembly (arrow). 4. Paratype.

Fig. 1. Map of the sampling locations, where Anthosphaera was observed.