Sellaphora ashinovii, Tseplik & Glushchenko & Maltsev & Genkal & Iurmanov & Kulikovskiy, 2025

Tseplik, Natalia, Glushchenko, Anton, Maltsev, Yevhen, Genkal, Sergey, Iurmanov, Anton & Kulikovskiy, Maxim, 2025, Molecular and morphological investigation of Sellaphora ashinovii sp. nov. and Planothidium paisiusii sp. nov. - two new diatom species from Oromia Region, Ethiopia, Phytotaxa 701 (2), pp. 161-176 : 170-171

Sellaphora ashinovii sp. nov.

Sellaphora ashinovii sp. nov. is morphologically close to S. saugerresii (Desmazières) C.E. Wetzel & D.G. Mann in Wetzel et al. (2015: 209) (see Table 3). These species are similar in valve width (3.5–4.5 μm in S. ashinovii sp. nov. and 3–4 μm in S. saugerresii ) and in the shape of the central area (bowtie-shaped, formed by shortened striae). The main differentiating feature between these species is the striae structure: S. ashinovii sp. nov. is characterized by uniseriate striae, while in S. saugerresii the striae are always biseriate. The striae density also differs (24–26 in 10 μm in Sellaphora ashinovii sp. nov. vs. 18–22 in 10 μm in S. saugerresii ). Another distinguishing trait is the shape of the axial area which is weakly widening towards the central area in Sellaphora ashinovii sp. nov. and linear in S. saugerresii .

S. atomoides (Grunow) Wetzel & Van de Vijver in Wetzel et al. (2015: 219) also resembles Sellaphora ashinovii sp. nov. (see Table 3) in valve shape, striae pattern, and structure of central and axial area, the central area being formed by shortened striae in both species. These species can be differentiated by valve width (3.5–4.5 μm in Sellaphora ashinovii sp. nov. vs. 2.6–3.7 μm in S. atomoides ) and striae density (24–26 in 10 μm in Sellaphora ashinovii sp. nov. vs. 30–36 in 10 μm in S. atomoides ).

Lastly, Sellaphora ashinovii sp. nov. is similar to S. subseminulum (Hustedt) C.E. Wetzel in Wetzel et al. (2015: 218) (see Table 3). These species resemble each other in valve shape, striae pattern, and shape of axial and central areas. They can be differentiated by valve width (3.5–4.5 μm in Sellaphora ashinovii sp. nov. vs. 3.3–3.8 μm in S. subseminulum ). The axial area in the new species is narrow, widening weakly towards the central area, while in S. subseminulum the axial area does not widen ( Wetzel et al. 2015, figs 180–182). The central area is bordered by 3–4 shortened striae in Sellaphora ashinovii sp. nov. and by 5–6 very short striae in S. subseminulum (see Table 3). The striae density is 24–26 in 10 μm in Sellaphora ashinovii sp. nov. and 20–24 in 10 μm in S. subseminulum .

On the phylogenetic tree, the strain of S. ashinovii sp. nov. forms a separate branch that is sister to strains of Sellaphora minima ( Fig. 26 ). Unfortunately, there are no vouchers available for the strain TCC524 of S. minima , thus a morphological comparison with our new species cannot be carried out. Strain BM42, identified as S. cf. minima , was illustrated with a single image in Evans et al. (2008, Fig. 8c ), which is also insufficient for a proper morphological comparison. Even so, judging by the one available image, this strain differs from S. ashinovii sp. nov. by valve outline, size of central area, and striae density. Currently, according to Wetzel et al. (2015), S. minima is regarded as a synonym for S. saugerresii which was discussed above.

Representatives of Sellaphora Mereschkowsky have been fairly well studied with the use of morphological and molecular analysis ( Evans et al. 2008; Mann et al. 2009; Vanormelingen et al. 2013, Wetzel et al. 2015), with new species being described in recent years from different parts of the world ( Andreeva et al. 2018; Kochoska et al. 2021; Glushchenko et al. 2022; Ni et al. 2022 and others). Nevertheless, acquisition of molecular data from new strains from various geographical locations is essential for correct identification of taxa in floristic and ecological studies, as well as for taxonomical investigations, especially since the genus Sellaphora contains difficult species complexes, e.g. Sellaphora pupula ( Mann et al. 2004; Evans et al. 2008, etc.).

Figures

FIGURE 26. Phylogenetic position of Sellaphora ashinovii sp. nov. (indicated in bold) within the Sellaphoraceae based on Bayesian inference for a concatenated alignment of 44 partial rbcL and partial 18S rDNA sequences. The total length of the alignment is 1,117 characters. Values above the horizontal lines are bootstrap support from ML analyses (<50 are not shown); values below the horizontal lines (or to the right of the slash) are Bayesian posterior probabilities (<0.9 are not shown). Strain numbers (if available) and GenBank numbers are indicated for all sequences.

FIGURES 5–18. Sellaphora ashinovii sp. nov. LM, DIC. Slide no. 05556 from oxidized culture, strain CBMC129ef. Holotype represented by fig. 13. Scale bar = 10 μm.