A reappraisal of the taxonomy and biodiversity of the extant coccolithophore genus Palusphaera (Rhabdosphaeraceae, Prymnesiophyceae)

The genus Palusphaera Lecal-Schlauder emend. R.E. Norris is a distinctive modern coccolithophore that accommodates monomorphic, monothecate coccospheres with one type of spine-bearing heterococcoliths. Having examined a set of scanning electron microscopy images from our collections, we were able to demonstrate that four distinct species of Palusphaera exist in the modern oceans, including the type species Palusphaera vandelii, an informally proposed form, Palusphaera sp. 1 (type robusta) that is herein taxonomically ratified as Palusphaera crosiae sp. nov., and a distinctive morphotype, which is formally described as Palusphaera bownii sp. nov. Biometric analyses and observations on the morphologies of numerous P. vandelii specimens revealed the existence of a further form, and its commonly distinguished coccolith morphotypes are therefore taxonomically separated from Palusphaera vandelii and established as a discrete species, Palusphaera probertii sp. nov

Taxonomic Revision and Classification of Extant Holococcolithophores Previously Placed in the Genus Anthosphaera Kamptner emend. Kleijne 1991

19 pages, 2 figures, 6 plates, 1 tableThe genus Anthosphaera Kamptner emend. Kleijne is one of the most taxonomically confused modern coccolithophores and its species¿ level taxonomy has long been in a state of flux. Based on review of imaged specimens from our collections, we attempt to rectify the nomenclatural problems and elucidate the obfuscated taxonomy of the genus. Review of included formally and informally described species shows that they are a distinctive group with shared characters, including ten different morphotypes of probable species level. Two of these, including the type species A. fragaria, have been shown to form life-cycle associations with heterococcoliths of the Syracosphaera molischii type. Hence, all species are transferred to Syracosphaera and the new combinations S. periperforata, S. lafourcadii, and S. origami are proposed. In addition, various informally described morphotypes are now formally described as Syracosphaera molischii var. pertusa, S. periperforata var. cylindrata, S. periperforata var. tridentata, S. rotaconica, and S. elevataO.A.A. was supported by the Natural Environmental Research Council (grant number NE/S007474/1)With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI

Syracosphaera marginiporata Knappertsbusch 1993

Species Syracosphaera marginiporata Knappertsbusch 1993 HOL Synonymy: Anthosphaera sp. type B Cros and For- tuño (2002), p. 60, Figs. 88B, 112C–112D; Percopo et al. (2011), p. 256, Fig. 30. Syracosphaera marginiporata HOL Šupraha et al. (2018), p. 27, Fig. 4c. Description: Coccosphere, spherical but usually seen collapsed, with c. 80–140 tiny BCs and c. 5–10 CFCs. BCs elliptical, with a single-crystallite-width rim and a rounded central structure, formed from sev- eral, usually large, angular crystals typically with open- ings in between. The rim appears separated from the central structure, i.e. there is a gap, where the perforate cycle would be. CFCs with a large central arch attached to the rim by robust lateral columns of large crystallites; vertical process extends as a large thin leaf with rounded to somewhat straight sides that are constructed by small crystallites arranged in characteristically ordered disposition. Remarks: BCs’ central structure is made by a few crystallites; it is perforated and bears no apical boss or any other structure on top. The perforate cycle does not possess any crystallites. The central structure is not attached to the rim by any visible calcification, but both the rim and the distal cover are supported by an organic baseplate. Dimensions: Coccosphere diameter c. 4 μm. BCs c. 0.6 μm long x 0.4 μm wide. CFCs’ distal process is c. 1 μm high.Published as part of 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, pp. 121-139 in Acta Protozoologica 59 on page 129, DOI: 10.4467/16890027AP.20.010.13265, http://zenodo.org/record/835697

Syracosphaera periperforata var. tridentata Archontikis, Young, Cros 2020, var. nov.

Syracosphaera periperforata var. tridentata Archontikis, Young, Cros var. nov. HOL Derivatio nominis: From Latin tridentatus –a –um (adjective), from trident, the three-prong weapon; refer- ring to the three-pointed upper structure of CFCs. Description: Coccosphere, spherical but usually seen collapsed, composed of c. 50–85 BCs and c. 6–10 CFCs. BCs broadly elliptical with a rim of one to two microcrystals wide. Perforate cycle irregular with c. 8 large perforations, separated by narrow struts, which usually do not show obvious obliquity. The central structure dome-shaped with a low apical boss. CFCs subcircular to circular in outline. A single-layered distal process, whose opening in the arch is placed low, bears an upper margin structure with three pointy edges; the rim shows one to two rings of crystallites. Remarks: The central structure of the BCs is similar to that of S. periperforata var. periperforata with a conical shape and an apical boss. However, the perforate cycle is less regular and bears less struts. The CFCs are also different, showing a characteristic upper margin structure with three pointy edges and a low arch. Dimensions: Coccosphere diameter c. 7.5 μm. BCs c. 0.9–1.1 μm long x c. 0.8–1.0 μm wide. CFCs c. 1.0– 1.2 μm long and wide; distal process maximum 1.0 μm high and wide. Holotype: Specimen illustrated in JRYSEM-303-76 (Plate 4, Fig. 5), stub TS 17-8-09, curated at the NHM, London, UK. Paratype: Specimen illustrated at Plate 4, Fig. 6. Type locality: Station RV 001, 10m water depth, col- lected off Rovinj, northeastern Adriatic Sea (45°04N, 13°63E) on 17 August 2009. Number of specimens studied: 7 Distribution: Sub-tropical watersPublished as part of 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, pp. 121-139 in Acta Protozoologica 59 on page 134, DOI: 10.4467/16890027AP.20.010.13265, http://zenodo.org/record/835697