Eunotia feremiserabilis, Bąk & Kociolek & Lange-Bertalot & Łopato & Witkowski & Zgłobicka & Seddon, 2017

Bąk, Małgorzata, Kociolek, John P., Lange-Bertalot, Horst, Łopato, Daria, Witkowski, Andrzej, Zgłobicka, Izabela & Seddon, Alistair W. R., 2017, Novel diatom species (Bacillariophyta) from the freshwater discharge site of Laguna Diablas (Island Isabela = Albemarle) from the Galapagos, Phytotaxa 311 (3), pp. 201-224 : 214-215

Eunotia feremiserabilis sp. nov. Lange-Bertalot, Bąk & Kociolek

Figs 121–156

Description: —Light microscopy—Frustules in girdle view rectangular, 5–6 μm broad, without dorsal or apical spines. Valves of smaller specimens more distinctly dorsiventral than longest ones where convex dorsal and concave ventral margins almost parallel. Ends slightly dorsally reflexed, obtusely rounded. Length 8–27 μm, breadth 1.6–2.2 μm (n=30). Terminal raphe nodules close to valve pole. Striae rather coarse, 14–15/10 μm, almost equidistant throughout, distally becoming irregular 20–30/10 μm. Areolae not discernible in LM.

Scanning electron microscopy:—External view ( Figs 149–153 ). Valve face and valve mantle positioned at right angle. Transition of valve face towards mantle gradual. Raphe branches terminate on valve face at approximately midpole or somewhat longer but not extending to dorsal margin ( Fig. 149 —arrows). Narrow striae with ca. 45 areolae in 10 μm alternate with much broader virgae ( Fig. 151 —arrow). On junction between valve face and mantle uniseriate (rarely two) areolae set off from striae by unperforated sternum, i.e. hyaline ventral line. External opening of areolae simple, round to transversely elliptic. Internally each stria positioned in shallow groove. Internal openings of areolae transversely elliptic, becoming round towards valve apices. Internally sternum positioned near ventral valve face/ mantle junction. Distal raphe ends terminate in helictoglossae ( Fig. 156 —arrow). Helictoglossae positioned about mid-point of valve apex.

Type: — ECUADOR. Galápagos Islands: Isabela (Albemarle) Island, Diablas wetlands, 0.95731°S, 90.98685°W, 23 July 2012, holotype (designated here):—Slide no. 20779 (species code—7876 MCCDRS) in Coll. Herbarium ( CDS) of the Charles Darwin Foundation at Galapagos, represented by Fig. 127 .

Type locality: —Floating moss, at the mouth of the stream to the lagoon in the Diablas wetlands—a permanent, brackish coastal lagoon network located at sea level on the south side of Isabela Island.

Etymology: —Latin “fere” means almost and Latin “miserable” refers to the poor set of characteristics for differential diagnosis vs. similar small-celled Eunotia taxa.

Distribution: —Species so far found only in the type location.

Comments: —A review of the diatomological literature points out that no one species could be seriously confused with E. feremiserabilis , the new species from Galapagos. Eunotia botuliformis F.Wild, Nörpel & Lange-Bertalot in Lange-Bertalot (1993: 29) and E. subarcuatoides Alles, Nörpel & Lange-Bertalot (1991: 188) are broader (2.7–3.8 and 3.0–4.5 vs. 1.6–2.2). Eunotia neofallax Nörpel-Schempp & Lange-Bertalot in Lange-Bertalot et al. (1996: 73), E. groenlandica Nörpel-Schempp & Lange-Bertalot in Lange-Bertalot & Metzeltin (1996: 51), E. pseudogroenlandica Lange-Bertalot & Tagliaventi in Lange-Bertalot, Bak & Witkowski (2011: 202) and E. leptopaludosa Lange-Bertalot in Lange-Bertalot et al. (2011:138) differ by distinctly reflexed ends.

Figures

FIGURES 121–148: Eunotia feremiserabilis sp. nov. LM images. Figs 121–136, 142–148: valve views, size diminution series, Figs 137– 141: frustules in girdle view. Fig. 127 is of the holotype. Figs 138–141, 144–146: with DIC, differential interference contrast, remaining bright field. Scale bar = 10 μm.

FIGURES 149–156: Eunotia feremiserabilis sp. nov. SEM images. Figs 149–153: external valve views. Note the raphe branches on the valve face but not extending to the dorsal margin (arrows in Fig. 149). Striae narrow, alternate with much broader virgae (arrow in Fig. 151). Figs 154–156: internal valve views. Distal raphe ends terminate in helictoglossae (arrow in Fig. 156).