France

France (fr)

Région Nouvelle Aquitaine

Département de la Haute-Vienne

River Ardour at Folles village

 s.c.

2017-7-24

46° 6' 18'' N ; 1° 27' 17.964'' E

46.105 ; 1.45499

LM : Valves typically lanceolate with clearly convex margins, gradually tapering towards the non–protracted, acutely to cuneately rounded apices. Valve dimensions (n= 28): length 20–32 μm, width 5.5–7.0 μm. Axial area very narrow, linear, only weakly widening at the central area. Central area small, asymmetrical, rounded to occasionally, bordered by irregularly shortened central striae. Raphe branches straight with weakly expanded, almost straight central endings and hardly discernible terminal raphe fissures. Striae clearly radiate for most of the valve length, weakly geniculate near the central area, becoming parallel at the Voigt discordance to convergent at the apex, 13–15 in 10 μm. Lineolae weakly resolvable under the LM. SEM : Raphe sternum externally slightly raised (Figs 22, 27). Raphe branches slightly curved, weakly eccentric on the sternum. Central raphe endings deflected to the secondary side, weakly drop–like expanded (Figs 23, 24). Terminal raphe fissures unilaterally strongly hooked towards the secondary side (Figs 22, 23, 25). Striae uniseriate, composed of apically elongated lineolae, 27–30 in 10 μm. Lineolae longer than the virgae (Figs 24, 25, 28). At the apices, several irregular slits visible (Fig. 26), probably scattered lineolae, irregularly oriented around the apex. Internally, raphe running weakly lateral of the raphe sternum with the raphe slit opening on the side (Figs 30, 31). Sternum weakly but distinctly widened at the central area (Fig. 32). Central raphe endings located in the middle of the central area (Fig. 32). Lineolae internally covered by individual hymenes (Figs 32, 33, 34)

River periphyton