Pseudostaurosira moralesii Graeff, Kociolek & S.R. Rushforth, 2013

GRAEFF, C. L., KOCIOLEK, J. P. & RUSHFORTH, S. R., 2013, New and Interesting Diatoms (Bacillariophyta) from Blue Lake Warm Springs, Tooele County, Utah, Phytotaxa 153 (1), pp. 1-38 : 12

Pseudostaurosira moralesii Graeff, Kociolek & S.R. Rushforth , sp. nov. ( Figs 56–63 ; figure 59 =

holotype)

Valves lanceolate to elliptical with apices narrowly rounded to rounded (in smaller, elliptical valves) ( Figs 56–61 ). Length 6.0– 17.5 µm, breadth 3.5–4.0 µm. Striae marginal, narrow, with “ghost”-like striae extending towards the center of the valve ( Figs 58–59 ). Striae 16–18/ 10 µm. Axial area wide, lanceolate. Small pore fields are present at each terminus of the valves.

In the SEM the valve exterior has areolae that include a single opening on the valve face interrupted by the margin and continue onto the mantle ( Fig. 62 ). Ridges border the openings, giving the impression of depressions extending from the areolae towards the center ( Fig. 62 ). At the ends of the valve small ocellimbi occur on the mantle ( Fig. 62 ). Internally, the areolae are occluded by fine, fimbriate siliceous occlusions ( Fig. 63 ). The central area is very wide and smooth on the interior ( Fig. 63 ). Ocellilimbi are small, appearing more like a simple pore field, with a few divisions to form individual porelli ( Fig. 62 ).

Type: — USA. Blue Lake , Tooele Co., Utah. ( COLO 439035 , holotype! (= Fig. 59 ); COLO 8506 , BM 101678, isotypes)

Etymology:—Named in honor of Dr. Eduardo Morales, for his many contributions to our understanding of those pennate diatoms without a raphe system.

Distribution:— Pseudostaurosira moralesii can be found very rarely in the main basin of Blue Lake (COLO 8506).

Observations:— Pseudostaurosira moralesii can be distinguished from other species by its shape, being less rounded than the commonly reported species P. brevistriata (Grunow) Williams & Round (1987: 276 , basionym: Fragilaria brevistriata Grunow in Van Heurck 1885: 157) (e.g. Morales 2010, Krammer & Lange- Bertalot 1991, Patrick & Reimer 1966) and its single areolate marginal striae.

Figures

FIGURES 56–61. LM. Pseudostaurosira moralesii. Valve views showing the size diminution series. Figure 59 is the holotype. Scale bar: 10 µm.

FIGURES 62–63. SEM. Pseudostaurosira moralesii. Valve views of two specimens. Fig. 62, External valve view showing areolae, small ocellilimbi with few porelli at the apices, and ridges across the valve center. Fig. 63, Internal valve view showing the fimbriate occlusions of the areolae. Scale bars: 1 µm.