Pseudostaurosira cf. brevistriata (Grunow) Williams & Round,

Ruwer, Daiane Trevisan & Rodrigues, Liliana, 2021, Sediment diatoms from Upper Paraná River floodplAiN lAKeS: New recordS, Iheringia, Série Botânica (e 2021012) 76, pp. 1-16 : 3-5

Pseudostaurosira cf. brevistriata (Grunow) Williams & Round,

Diatom Res., 2: 276, figs. 28-31. 1988.

( Figs. 24-27 )

Valves are lanceolate in larger specimens to elliptical in smaller specimens. Rostrate ends to rounded ends in smaller specimens. Presence of a broad lanceolate axial area and short striae found near the edge of the valve. Striae parallel to radiate in the central of the valve to slightly radiate toward the valve ends. Length: 6.2-19 μm; width: 2.9-4.3 μm; striae 12-16 in 10 μm. This taxon differs from other Pseudostaurosira Williams & Round and Staurosirella Williams & Round species by the presence of delicate and shortened marginal striae. The specimens observed are similar to those registered by Brassac et al. (2003) and Taylor et al. (2007). The study specimens are similar to the Staurosirella krammeri Morales, Chávez & Ector and Pseudostaurosira sajamaensis Morales & Ector ; however, P. brevistriata differs concerning the length and shape valve ( Morales et al. 2010, 2012). For a clear separation of these taxa, an ultra-structural analysis is required.

Material examined: BRAZIL, MATO GROSSO DO SUL: Batayporã, Garças Lake , 21.IX.2017, sediment, D.T. Ruwer (Nupélia UEM - 18071-72 , 18074 , 18076 , 18084- 97 ); Taquaruçú, Patos Lake , 23.III.2018, sediment, D.T. Ruwer (Nupélia UEM - 18119 ).

Occurrence: first citation for Upper Paraná River floodplain.

Figures

Figure 2-40. Sediment diatoms from subtropical floodplain lakes (LM). 2-3. Discostella stelligera; 4-6. Aulacoseira ambigua; 7-9. Aulacoseira distans; 10-11. Aulacoseira granulata; 12-13. Aulacoseira italica; 14-16. Aulacoseira herzogii; 17-18. Aulacoseira pusilla; 19-23. Fragilariforma brasiliensis; 24-27. Pseudostaurosira cf. brevistriata; 28-31. Staurosira sp.1; 32-37; Staurosirella sp.1; 38-40. Staurosirella crassa. (Scale bar:10 μm).