Eunotia tetraodon Ehrenberg, 1838: p. 192, pl. 21/fig. 25.

Bukhtiyarova, Lyudmila N., 2019, The genus Eunotia Ehrenb. (Bacillariophyta) in the Cheremsky Nature Reserve, Ukrainian Polissya, and refined terminology relevant to the raphe system morphology, PhytoKeys 128, pp. 1-31 : 15

Eunotia tetraodon Ehrenberg, 1838: p. 192, pl. 21/fig. 25. Figs 34 , 35

Himantidium tetraodon (Ehrenb.) Bréb. ex Kützing, 1849

Eunotia robusta var. tetraodon (Ehrenb.) Ralfs, 1861

Eunotia diadema var. tetraodon (Ehrenb.) A. Cleve, 1953

Eunotia serra var. tetraodon (Ehrenb.) Nörpel in Krammer and Lange-Bertalot 1991

Illustrations.

Topachevsky and Oksiyuk 1960: p. 323, pl. 119/fig. 1 (as Eunotia robusta Ralfs); Bahls 2012: 6 exemplars; Bąk et al. 2012: pl. 15/4 exemplars; Ector et al. 2012: p. 270-271, 1 exemplar; Pavlov and Levkov 2013: pl. 16/figs 1-9, 10, 11 (SEM); Kulikovskiy et al. 2016: p. 133, pl. 29/figs 6-10; Malakhov et al. 2017: p. 67, fig. 10 (SEM); Bahls et al. 2018: pl. 21/fig. 2.

Diagnosis.

Morphometric data: length 40 µm, width c8-10, m10-13, p4-8 µm; striae density c11-15, p16 in 10 µm. Pavlov and Levkov 2013: length 25-62 µm, width 9.5-16 µm, striae density 6-10, m12-16 in 10 µm.

Frustule bi-symmetric, bipolar, biraphid with mirror-symmetric, mantle-offset, brevisslit type of raphe. Valves dorsiventral, with strongly convex, four-times strongly undulate dorsal and weakly concave ventral margins, gradually narrowed to the protracted poles that continue the dorsal arc of valve margin. Striae basal, uniserial, distant, irregularly spaced, on dorsal side shortened intermediate striae present. Areolae small with round outer foramina. Raphe system consists of two short filiform slits on ventral valve mantle that follow pole margin and finish on about 0.5 of pole width by small round pore (see Pavlov and Levkov 2013: pl. 26/fig. 11) connected with helictoglossae; tr-fissures absent.

Ecology.

Freshwater epiphytic species.

Distribution.

Species was recorded in most European countries and on all continents except Antarctica (M. Gury in Guiry and Guiry 2019). In Ukraine. Volyn region, Manevychi district, Lake Bile; Rivnenska region, Bog Gala ( Topachevsky and Oksiyuk 1960 - as Eunotia robusta Ralfs); Volyn region, the Cheremsky Nature Reserve, Lake Redychi ( Malakhov et al. 2017); Lake Redychi, epiphyton on Fontinalis sp.

Comments. In Ukraine this species is quite rare. Only five reliable records exist that were accompanied by illustrations, including this paper, and all are from Ukrainian Polissya and Carpaty. Initially this species was reported by Topachevsky and Oksiyuk (1960) as E. robusta however their illustration corresponds to E. tetraodon . The next reports came almost 60 years later ( Malakhov et al. 2017, present paper).

Figures

Figures 28 - 35. Species of Eunotia Ehrenb. from the Cheremsky Nature Reserve. 28, 28 a, 29 Eunotia dorofeyukiae Lange-Bert. & Kulikovskiy 28 a arrow indicates pore outer on the raphe slit distal end 29 arrow indicates rimoportula at the venral corner of pole where raphe slit distal end finishes on the outer valve surface 30, 30 a Eunotia neocompacta S. Mayama 30 a arrow indicates rimoportula at the venral corner of pole, absence of a hyaline field indicates absence of terminal fissure 31 Eunotia praerupta Ehrenb. 32 Eunotia sp. 6. 33 Eunotia sp. 7. 34, 35 Eunotia tetraodon Ehrenb. Figs 28 - 31 SEM: 28, 28 a outside valve surface; 29 - 31 inside valve surface; 32 - 35 LM. Scale bars: 5 µm (28, 29, 30); 2 µm (28 a); 1 µm (30 a); 10 µm (31 - 34).