Arcella guadarramensis González-Miguéns, Soler-Zamora, Villar-Depablo, Todorov & Lara, 2022, SP. NOV.

ARCELLA GUADARRAMENSIS GONZÁLEZ- MIGUÉNS & LARA, SP. NOV.

(FIG. 8)

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 57A3452C-3C46-44F2-A5C9-48496E34BB57.

Holotype: MA-Algae11251.

Specific diagnosis: Test diameter: clade L: 114.60– 125.90 µm, average 120.30 µm (N = 6); aperture 19.60– 30.00 µm, average 23.63 µm. clade M 141.50–149.95 µm, average 146.06 µm (N = 4); aperture 31.25–34.50 µm, average 33.08 µm. Besides a difference in size, both clades have an identical morphology. Colour ranges from transparent to yellow-orange. Subhemispherical test shape, with flattened edges and dimples in the surface that gives the test a golf ball shape. No ribs or keels on the aboral side. Hexagonal building units are visible, which gives the test a rough appearance; little pores can be seen at the vertices. Building units can also be appreciated at the oral side of the test, with pores at the vertices and a central aperture. The aperture is invaginated outwards forming a short ring or lip.

Intraspecific variability: The building units may vary slightly in shape. Some building units may be collapsed, giving a rough surface. There may be certain deformations in the test that prevent it from having a perfectly circular morphology.

Diagnosis with closely related species: Arcella guadarramensis can be diagnosed by its specific sequences of the mtDNA markers and by its phylogenetic placement. Arcella guadarramensis differs morphologically from similar-looking G. succelli by (1) its morphometric differences with G. succelli (see Morphometrics and morphology; Fig. 2), both, clade N and O, are notably smaller than G. succelli and (2) the rough outlook of the test.

Habitat: Wet Sphagnum moss, in a fen.

Type locality: Spain, Madrid, Puerto de Canencia (40°52’N 3°45’W).

Etymology: The name is derived from River Guadarrama, a river with a name of Arabic roots: wadi, river, and ar-rama, sandy. We propose this name as a reference to the type locality in ‘Sierra de Guadarrama’, a mountain range named after this river.

We provide a key (Supporting Information, Table S3) and a new figure (Supporting Information, Fig. S3) to facilitate the identification of the new species.