Sellaphora queretana D.Mora, N.Abarca & J.Carmona, 2017

Mora, Demetrio, Carmona, Javier, Jahn, Regine, Zimmermann, Jonas & Abarca, Nelida, 2017, Epilithic diatom communities of selected streams from the Lerma-Chapala Basin, Central Mexico, with the description of two new species, PhytoKeys 88, pp. 39-69 : 41-43

Sellaphora queretana D.Mora, N.Abarca & J.Carmona sp. nov. Figs 133-144

Holotype.

B 40 0042009; Figure 137 represents the holotype.

Isotypes.

B 40 0042010 (SEM stub), QMEX DIAT0003 (Slide).

Cleaned unmounted material is available under the numbers B 40 0042011 and QMEX DIAT0004.

Type locality.

stream Los Ailes 1, close to the town San Pedro, Huimilpan, Querétaro, Mexico (20°19'58.72"N; 100°15'17.09"W; 2358 m a.s.l). Collected by Demetrio Mora on 18.09.2013.

Registration.

http://phycobank.org/100102

Description.

the valves are linear-elliptical with broadly rounded apices (Figs 133-140 ). The axial area is narrow-linear throughout most of the valve, slightly widening close to the central area. The central area is asymmetrical due to irregular shortenings of the striae bordering it (Figs 141 , 142 and 144 ). Length: 5.6-8.4 µm, width: 2.8-3.9 µm, length/width ratio: 1.9-2.4; striae in 10 µm: 19-22. The raphe is filiform with enlarged proximal raphe endings and slightly deflected to the same side of the valve; the distal raphe endings are strongly bent to the same side of the valve and extended onto the mantle (Figs 141 , 142 and 144 ); the deflection of both proximal and distal raphe endings in external valve face is in the same direction (Figs 141 , 142 and 144 ). Internally, the proximal raphe endings are straight and distally the raphe ends in helictoglossa (Fig. 143 ). The striae are biseriate and radiate throughout, however becoming uniseriate near the central area (Figs 141 , 142 and 144 ). The areolae are lunate in form and are internally occluded by a hymen (Fig. 143 ). The hymenes are close to the foramina (seen on external view) (Figs 141 , 142 and 144 ).

Differential diagnosis.

there are no known taxa with the same combination of valve outline and areola type. The outline of S. queretana resembles that of Sellaphora chistiakovae (Kulikovskiy & Lange-Bertalot) C.E. Wetzel, Ector, Van de Vijver, Compère & D.G. Mann; the linear-elliptical forms of Sellaphora crassulexigua (E. Reichardt) C.E. Wetzel & Ector; and that of Sellaphora nigri (De Notaris) C.E. Wetzel & Ector. But S. chistiakovae has uniseriate to irregularly biseriate striae ( Kulikovskiy et al. 2010); S. crassulexigua and S. nigri have uniseriate striae ( Wetzel et al. 2015). Taxa with similar striae, with hymenes close to the foramina, include Sellaphora labernardierei Beauger, C.E.Wetzel & Ector, Sellaphora rhombelliptica (Gerd Moser, Lange-Bert. & Metzeltin) C.E. Wetzel & Ector, Sellaphora rhombica (Gerd Moser, Lange-Bert. & Metzeltin) D. Mora, N. Abarca & R. Jahn, comb. nov. (see new combination below) and Sellaphora thioense (Gerd Moser, Lange-Bert. & Metzeltin) C.E. Wetzel, Ector, Van de Vijver, Compère & D.G. Mann. But the valves of S. labernardieri are linear to linear-elliptical, slightly inflated at the center and have consistently more striae 10 µm (20-28, mainly 24-25) ( Beauger et al. 2016). Sellaphora rhombelliptica has more striae (25), which are uniseriate and the valves are rhomboelliptic ( Moser et al. 1998). Sellaphora rhombica has similar number of striae (17-21) but the valve outline is rhombic to rhombic-lanceolate ( Moser et al. 1998). Sellaphora thioense has slender elliptical valves (2.5-2.8) with higher striae density (27-28) ( Moser et al. 1998).

Etymology.

this new Sellaphora species takes its name from the demonym of the Mexican state Querétaro, from where it was collected.

Distribution.

so far only known from the type locality (sampling site 11 in this study) and from stream Laguna de Servín 2 (site 13) located 4 km away from the type location, in acidic waters (pH 5.9-6.2) with low conductivity (77-88 μS /cm).

Based on morphological similarities with other small Sellaphora species, Eolimna rhombica Gerd Moser, Lange-Bertalot & Metzeltin is transferred to Sellaphora :

Figures

Figures 133 - 144. Sellaphora queretana D. Mora, N. Abarca & J. Carmona, sp. nov. LM (133 - 140) and SEM (141 - 144). 133 - 137 type material, from stream Los Ailes 1, Queretaro, Mexico, collected on 18.09.2013 137 designated as holotype 138 - 140 population from stream Laguna de Servin 2, collected on 29.09.2013 141 - 144 from type material: 141, 142, 144 external views of entire valves 143 internal view of an entire valve. Scale bars 5 μm (133 - 140); 1 μm (141 - 144).