Luticola ventricosa D. G. Mann

Luticola ventricosa (Kützing) D.G.Mann (Figs 1–30) ≡ Navicula mutica var. ventricosa (Kützing) Cleve & Grunow (in Cleve & Grunow 1880: 41) ≡ Navicula mutica f. ventricosa (Kützing) Cleve (in Cleve 1894: 129) ≡ Placoneis mutica var. ventricosa (Kützing) Mereschkowsky (in Mereschkowsky 1903: 12) ≡ Navicula ventricosa (Kützing) F.W.Mills nom. illeg. (in Mills 1934: 1176) ≡ Luticola mutica var. ventricosa (Kützing) P.B.Hamilton (in Hamilton & al. 1994: 309) ≡ Luticola mutica f. ventricosa (Kützing) Bukhtiyarova (in Bukhtiyarova 1995: 421) = Navicula neoventricosa Hustedt (in Hustedt 1964 [1966]: 612, fig. 1612 [first 4 illustrations]) Basionym: Stauroneis ventricosa Kützing, Die Kieselschaligen Bacillarien oder Diatomeen, p. 105, pl. 30: fig. 27, 1844. Lectotype (here designated): BM 17826, original slide in the Kützing collection made from sample 24 and labelled ‘ Amphora atomus – Nordhausen’. Fig. 13 illustrates a specimen from this slide representative of the type. Registration (of the lectotypification): http://phycobank.org/105203 Type locality: Nordhausen, Thuringia, Germany. Description: Valves weakly asymmetrical, slightly bent, lanceolate-elliptic with clearly convex margins. Valve apices protracted, capitate to mostly rostrate in smaller specimens. Valve dimensions (n=25): length 12–18 μm, valve width 5.5–6.5 μm. Axial area narrow, linear, weakly widening near central area. Central area forming a wide, asymmetrical, bowtie-shaped stauros, bordered by 3–4 isolated round areolae on each side. Internally, central nodule thickened forming a stauros. One buciniportula present at the end of a short stria in the central area. Internally, buciniportula semilunate. Raphe branches straight to weakly curved, filiform. Central raphe endings unilaterally bent, away from the buciniportula. Terminal raphe fissures hooked, relatively long, occasionally shorter and then deflected. Striae uniseriate, composed of 3–4 rounded to elongated areolae, 19–22 in 10 µm. Areolae decreasing in size from the valve margin towards the axial area. Internally, areolae occluded by strip-like continuous perforated, hymenes.