Eunotioforma mattogrossiana Kociolek, Burliga & Salomoni, 2013

Burliga, Ana Luiza, Kociolek, John Patrick, Salomoni, Saionara Eliane & Figueiredo, Daniela, 2013, A new genus and species in the diatom family Eunotiaceae Kützing (Bacillariophyceae) from the Amazonian hydrographic region, Brazil, Phytotaxa 79 (2), pp. 47-57 : 50-51

Eunotioforma mattogrossiana Kociolek, Burliga & Salomoni sp. nov. ( Figures 1–4 )

Valves large, arcuate, margins parallel, slightly arcuate, ends slightly inflated and broadly rounded. In some specimens there is a slight indentation near the apices. Length 74.0-360.0 µm (X = 218.6± 56.06 µm); breadth 8–14 µm (X = 10.1± 1.32 µm); (n = 100); length/width ratio 5.3–33.9 (X = 22.26 ± 5.76 µm). Punctate striae interrupted near middle of valve, slightly towards ventral margin. Striae density 18-24 in 10 µm throughout length of valve. Areolae round, about 8 in 10 um. Raphe highly curved to U-shaped, external proximal end terminates at about centre of valve at apex. Helictoglossae large, positioned and situated close to ends. Raphe nearly exclusively on valve face. Between two and four rimoportula present at or near apex. Individual valves may have different numbers of rimportulae between one apex and the other, and two valves of the same frustule may also have different numbers of rimoportulae. Number of rimportulae per apex on a single valve ranges from 1–5, with the largest number for one individual valve being 9, the smallest 3.

This species is differentiated from other large taxa with the raphe almost entirely on the valve face and interruptions of the striae near the centre of the valve as opposed to near the ventral margin, such as Eunotia synedraeformis Hustedt and E. curvula Hustedt , by the larger number of rimoportulae (up to 8 per valve) and distinctive valve shape ( Hustedt 1952; Kociolek 2000).

Type: — Do Sangue River , Mato Grosso, MT, Brazil, Holotype Slide HAS 6426 ( Figure 1B is the holotype specimen). Isotypes: Slides 448099 and 448100 in the J.P. Kociolek Collection at the University of Colorado Museum of Natural History.

Etymology: —The specific epithet refers to occurrence in Mato Grosso State.

Figures

FIGURES 1: A–E. Light microscopy, Valve views. Figure 1B is of the holotype. Figures 1A-C are typical valves. Figures 1D, 1E are of deformed valves. Scale bar = 20 µm.

FIGURES 2A–E. Light microscopy of valve detail. Figs 2A-C show end of valve with rimoportulae present. Figs 2A and 2B are of typical valves, figs 2C and 2D are of deformed valves. Fig. 2E is taken in the valve center. Scale bars = 10 µm.

FIGURES 3A–C. SEM, valve exterior. Figs 3A, 3B are of the valve apex showing the raphe, presence of siliceouis nodules and spinules on the valve face and external openings of rimoportulae. Fig. 3C. Valve center showing sternum positioned about at the center of the valve. Areolae are small, round. Scale bars = 2 µm for all figures.

FIGURES 4A–E. SEM, valve interior. Fig. 4A. Valve view. Scale bar = 20 µm. Figs 4B-D showing apex of valve with raphe branch, helictoglossa and rimoportulae evident. Fig. 4E. Central portion of the valve with interruption of striae evident in the center of the valve. Scale bars = 2 µm for figures 4B–D.