Exanthemachrysis fresneliae Veron 2023, sp. nov.
Creators: name: Véron, Benoît
name: Rougier, Etienne
name: Taylor, Anthony
name: Goux, Didier
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Chromista
Haptophyta
Pavlovophyceae
Pavlovales
Pavlovaceae
Exanthemachrysis
Exanthemachrysis fresneliae

description: Exanthemachrysis fresneliae Véron sp. nov.
PhycoBank: 103626
Figs 1–6
Diagnosis
The new species differs from the only species of the genus, i.e., Exanthemachrysis gayraliae, mainly by the presence of ovoid pedunculated knob-scales arranged helically on the AF but also by a slightly shorter AF. The benthic stage is pseudo-palmeloid. The pyrenoid is in E. fresneliae at the end of the C whereas it is in the centre of the C in E. gayraliae.
Etymology
The epithet given to the species is dedicated in honour of Dr Jacqueline Fresnel who worked at the Université de Caen Normandie, reinvestigated in details E. gayraliae and who described 22 taxa, mostly haptophytes.
Type material
Holotype FRANCE • Normandy, Chausey Islands, Epi-silty; 48°52′ N, 1°49′ W; alt. 0 m; 1974; Jacqueline Fresnel leg.; Jacqueline Fresnel isol.; AC35; GenBank nos: JF714227, JF718767; CN[35NM1 – AC35-1M].
Description
Metabolic non-phototactic slightly bean-shaped motile cells. Single green-brownish chloroplast with a bulging PY, helicoidal and parallel thylakoids with an eyespot located at the thylakoids-pyrenoid interface. Sinusoidal anterior flagellum bears stalked knob-scales, rigid posterior flagellum with a long distal attenuation and a short haptonema. Cell membrane strewn with same shape and same size knobscales.
The non-motile palmelloid cells form colonies surrounded by non-stratified mucilage.
Microscopy and related analysis
The dominant stage is palmelloid with slightly ovoid cells (4.80 µm ± 0.57 × 4.21 µm ± 0.56, n = 51) forming colonies of sister cells remaining coated with a common non-stratified mucilage (Figs 1A–B, 2–3). Some cells can retain flagellar and haptonematal bases (Fig. 2).
Non-phototactic swimming cells have a marked flattened oval shape (4.69 µm ± 0.61 × 2.76 µm ± 0.35, n = 50) with an anterolateral pit giving a slight bean shape to the side-view (Fig. 1C). The parietal C is green-brownish (Fig. 1C) with helicoidal and parallel arrangement of TH (Fig. 2) and a bulging terminal PY (Figs 1–3) adjacent to a deep pit (Fig. 3). A discreet E is located on the outer periphery of the C between the chloroplast stroma and the PY (Fig. 3). The AF (approximately 8–9 µm) is covered by a layer of ovoid KS (42 nm × 37.5 nm) produced in the Golgi body (Fig. 5C) aligned in continuous helicoidal rows from the base (Fig. 4). The PF (about 5–6 µm) is composed of two parts of almost equal length. The proximal part, comparable in diameter to the AF, tapers into a thinner distal part and the H, regular in diameter, measures about 2–3 µm. All three appendages emerge at the surface of the cell from the pit (Fig. 5A–B). Both the PF and H, as well as the cell membrane, are sporadically covered with KS identical (Fig. 5C) to those present on the AF (Fig. 4A,C).
Taxonomic outcome: a revised description of the genus Exanthemachrysis
Due to the description of a second species in the genus Exanthemachrysis, a revision of the genus is necessary. The description based on E. gayraliae (Lepailleur) Bendif & Véron has become too general and can now be emended following the description of E. fresneliae sp. nov. and other Pavlovophyceae described since, providing information unknown in 1970.
description: Published as part of Véron, Benoît, Rougier, Etienne, Taylor, Anthony & Goux, Didier, 2023, New species of Pavlovophyceae (Haptophyta) and revision of the genera Exanthemachrysis, Rebecca and Pavlova, pp. 21-47 in European Journal of Taxonomy 861 on pages 26-29, DOI: 10.5852/ejt.2023.861.2063, http://zenodo.org/record/7710258