Navicula vanseea Yilmaz, Gastineau, Solak & Witkowski, 2024
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publication ID |
https://dx.doi.org/10.3897/phytokeys.241.118903 |
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persistent identifier |
https://treatment.plazi.org/id/915AD59D-E312-50A1-B37D-AA72AC865D3D |
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treatment provided by |
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scientific name |
Navicula vanseea Yilmaz, Gastineau, Solak & Witkowski |
| status |
sp. nov. |
Navicula vanseea Yilmaz, Gastineau, Solak & Witkowski sp. nov.
Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4
Type material.
Holotype: Slide number SZCZEY2172 in the collection of Andrzej Witkowski at the University of Szczecin, Poland. Valves representing the holotype population are illustrated in Fig. 2L View Figure 2 .
Isotype: Slide number TR_ Erciş _Van_2021 deposited in Kütahya Dumlupınar University (Turkey).
Registration.
http://phycobank.org/xxx.
Type locality.
Erciş Van, Türkiye (38°99'64.748"N, 43°40'04.257"E) collected by: Elif Yilmaz, 31 July 2021.
Etymology.
The name given to the species refers to the German name of Lake Van (Vansee, the sea of Van) as it was used in the work of Legler and Krasske and is meant as a tribute to these authors and their work.
Distribution and ecology.
The taxon was exclusively observed within benthic epilithic assemblages in Lake Van (salinity 21.4‰ and pH 9.5).
Description.
LM (Fig. 2A-Y View Figure 2 ) Valves: smaller specimens elliptic, tapering towards cuneately rounded apices, larger specimens linear-elliptic-lanceolate narrowly rounded, with narrowly rounded poles, which are occasionally slightly protracted (Fig. 2E, K, N View Figure 2 ). Valve dimensions (n = 39): length 11.0-28.0 μm, width 5.0-6.5 μm. Raphe filiform, straight. Central area small and rounded, axial area narrow. Striae strongly radiate, sometimes irregularly shortened around the central area, 12-13 in 10 μm, lineolae difficult to resolve in LM, ca. 50 in 10 μm.
SEM External valve surface (Figs 3A-D View Figure 3 , 4D-F View Figure 4 ): Valve surface flat (Fig. 3G, H View Figure 3 ), areolae apically elongated (Figs 3B-D View Figure 3 , 4B View Figure 4 ). Raphe sternum slightly elevated above the valve face level (Fig. 4G View Figure 4 ). Axial area very narrow, central area very slightly expanded, small, asymmetric (Figs 3B View Figure 3 , 4A, B View Figure 4 ). Proximal raphe endings drop-like, slightly deflected unilaterally (Fig. 4B View Figure 4 ). Distal raphe endings strongly hooked in the same direction (Fig. 3C, D View Figure 3 , which are the two ends of the same valve and Fig. 4A View Figure 4 ).
SEM Internal valve surface (Figs 3E-H View Figure 3 , 4D-F View Figure 4 ): valve surface slightly arched with transapical striae positioned in relatively deep grooves, bordered by virgae that become thicker towards to the centre of the valve (Figs 3H View Figure 3 , 4D, F View Figure 4 ). Central area asymmetric, usually only slightly expanded (Figs 3E, F View Figure 3 , 4F View Figure 4 ), but sometimes more strongly (Fig. 4D View Figure 4 ). The internal lineolae openings are slit-like (Fig. 3F-H View Figure 3 ), narrower than the vimines. Lineolae occluded by hymens (Fig. 4F View Figure 4 ); two isolated lineolae are present at the valve apex. Raphe sternum slightly widened at the centre to form a fusiform ridge enclosing the central raphe endings, which are simple, straight and separated (Figs 3F View Figure 3 , 4F View Figure 4 ). Distally, the raphe terminates in well-developed helictoglossae (Figs 3G, H View Figure 3 ).
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