Fragilaria spectra P.D.Almeida, E.Morales & C.E.Wetzel, 2016

Almeida, Pryscilla D., Morales, Eduardo A., Wetzel, Carlos E., Ector, Luc & Bicudo, Denise C., 2016, Two new diatoms in the genus Fragilaria Lyngbye (Fragilariophyceae) from tropical reservoirs in Brazil and comparison with type material of F. tenera, Phytotaxa 246 (3), pp. 163-183 : 174-176

Fragilaria spectra P.D.Almeida, E.Morales & C.E.Wetzel , sp. nov. ( Figs 54–84 )

Frustules narrowly rectangular in girdle view ( Fig. 55 ). Valves linear-lanceolate gradually narrowing towards the poles ( Figs 54–71 ). Apices acute-rounded, with variation in width within the same population ( Figs 62–71 ). Central area broader, limited by short adjacent striae ( Figs 66–71 ), visible only with phase contrast ( Fig. 58 ), without evident ghost striae ( Figs 72–75 ). Sternum lanceolate and narrow ( Figs 63 , 72, 73 ). Striae very difficult to observe, with indistinct areolae ( Figs 56–61 ), alternate at the centre of valve, becoming opposite toward the ends ( Figs 72, 74 ). Spines absent ( Figs 72, 74 ). Striae composed of up to 5 areolae located on valve face ( Figs 72, 74 ). Areolae rounded and small ( Figs 76–84 ). Volae not observed.Apical pore fields of the ocellulimbus type with 2–3 rows of poroids ( Figs 76, 81–84 ). Two rimoportulae present per valve ( Figs 73–75 ), but indistinct in LM. Girdle bands open, not shown here. Colonies not observed. Plastids numerous and elongate ( Figs 54, 55 ). Length: 40.5–73.0 μm, width: 1.5–2.5 μm, striae density 24–25 in 10 μm.

Type:— BRAZIL. São Paulo: Salesópolis, Paraitinga Reservoir, 23°31’22.0” S 45°54’17.8” W, 760 m a.s.l., A. C. R. Rocha & D. C. Bicudo, 14 January 2010 ( Table 1) (holotype SP!, population on slide SP 427984, partially illustrated here in LM as Figs 54–71 and SEM as Figs 72–84 . Isotype: BR! slide 4433).

Etymology:— The specific epithet of the species refers to delicate appearance of the valves of this taxon, in the Epicurean philosophy, spectra is an emanation from physical objects giving rise to visual and mental images.

Ecology:—Found as epiphytic on Salvinia sp. and as part of the plankton.Acidophilous, oligo- to mesotraphentic, living in reservoirs as single cells, with low pH and TP ( Table 3).

Figures

FIGURES 54–71. LM. Fragilaria spectra P.D.Almeida, E.Morales & C.E.Wetzel, sp. nov. 54, 55. Periphytic cells fixed with lugol. 56–61. Population from phytoplankton. 62–71. Population from type material SP427984 (periphyton). Scale bar = 10 μm.

FIGURES 72–84. SEM. Fragilaria spectra P.D.Almeida, E.Morales & C.E.Wetzel, sp. nov. Population from type material (SP427984). 72, 74. Valves in external view. 73, 75. Valves in internal view. 76, 81, 82. Apices showing external view of rimoportulae. 77. Central area in external view without spines or ghost striae. 78. Central area in internal view. 79, 80, 83, 84. Apices showing rimoportulae in internal view. Scale bar = 20 μm in Figs 72–75. Scale bar = 5 μm in Fig. 82. Scale bar = 4 μm in Fig. 77. Scale bar = 3 μm in Figs 76, 78, 81. Scale bar = 2 μm in Figs 79, 80. Scale bar = 1 μm in Figs 83, 84.