Pinnularia tupensis A.C. Pereira, Melo & Torgan, 2014

Pinnularia tupensis A.C. Pereira, Melo & Torgan sp. nov. ( Figs 13–17 View FIGURES 2–21 , 26–32 View FIGURES 26–32 )

Type: — BRAZIL. Amazonas: Tupé Lake 03 o 02'35.4''S, 60 o 15'17.5''W, 23 September 2008, Pereira, A. C., sediment, station 3, (Holotype HAS slide n o 6494! holotype specimen = Figure 13 View FIGURES 2–21 , row sample HAS 109581 GoogleMaps ; isotype BR 4321 ! GoogleMaps ).

Valves elliptic-lanceolate with strongly protracted capitate ends ( Figs 13–17 View FIGURES 2–21 , 26, 30 View FIGURES 26–32 ), valve length 52–64.2 µm, breadth 10.8–13 µm, length/breadth ratio is 4.75–4.93. Axial area narrow, widening towards the central area. Central area present, forming symmetric fascia. Raphe straight, filiform, proximal raphe endings slightly bent in same direction ( Fig. 29 View FIGURES 26–32 ), terminal fissures bayonet-shaped ( Figs 31, 32 View FIGURES 26–32 ). Terminal raphe endings curved towards secondary side of valves, while drop-like central pores deflect to primary side ( Figs 29, 30 View FIGURES 26–32 ). Internally, terminal fissures end in a prominent helictoglossa ( Fig. 27 View FIGURES 26–32 ). Striae (11–12 in 10 µm) radiate at middle, convergent at poles. Alveoli pattern with 3–6 rows of rounded areolae, each row with 12–13 areolae in 2 µm ( Fig. 31 View FIGURES 26–32 ).

Etymology: —Dedicated to study area Tupé Lake. Tupé means mat in the Tupy Guarany language.

Observations:— P. tupensis resembles in its outline P. brauniana (Grunow) Studnicka (1888: 737) , P. rostratissima Hustedt (1965: 397) and P. rostratissima Hustedt var. ventricosa Metzeltin & Krammer in Metzeltin & Lange-Bertalot (1998: 186) but differs from these species mainly by the shape of the ends, area axial and striae pattern. P. rostratissima and P. rostratissima var. ventricosa have capitate rounded ends, wide axial area strongly expanded towards center of the valve and short striae. P. tupensis differs from P. brauniana by the valve breadth and shape of the poles (see table 2).

Pinnularia tupensis was observed in the sediment, and in the plankton, during the fall water with 6.40 m depth, 0.90 m transparency, high temperature (29.9ºC), low pH (4.5) and conductivity (7.60 µS.cm -1).