Pseudofrustulia lancea Sawai et Nagumo, 2016

Sawai, Yuki, Nagumo, Tamotsu & Nelson, Alan R., 2016, A brackish diatom, Pseudofrustulia lancea gen. et sp. nov. (Bacillariophyceae), from the Pacific coast of Oregon (USA), Phytotaxa 267 (2), pp. 103-112 : 104

Pseudofrustulia lancea Sawai et Nagumo , sp. nov. ( Figs. 1–23 )

A single H-plastid per cell ( Figs. 5, 6 ). Living specimens forming colonies with mucilage tubes ( Figs. 5–7 ). Living specimens gliding within the mucilage tubes. Valves lanceolate-elliptic with rounded apices ( Figs. 1–4 ); length 20 to 70 μm, width 7 to 12 μm. Striae punctate, parallel, about 30–45 in 10 μm ( Figs. 5–10 ). Areolae about 35–40 in 10 μm ( Figs. 10–13 ). The areolae are poroids, occluded internally by vela with fine pores ( Figs. 17, 18 ). Raphe straight between two internal axial ribs ( Figs. 14–16 ), with a nodule at the proximal ends ( Figs. 15, 16 ), enclosed by rounded rib-like structures (helictoglossae) at the distal ends ( Figs. 14, 15 ). The two internal ribs are parallel, or slightly curved at the central area, along the axial area ( Fig. 15 ). Ribs expanded, separated around proximal raphe ends ( Fig. 15 ). Valvocopula opening fimbriated, with a series of slits ( Figs. 19–23 ). The proximal area of the valvocopula with spines in a notch (an arrow in Figs. 7 and 23 ). Pleura doubly perforated ( Figs. 21, 22 ).

Type:— U.S.A. Oregon: Alsea Bay , 44° 26’ 10” N, 124° 01’ 32” W, sample collected from the upper few millimeters of surface sediment on the salt marsh (holotype ANSP GC65229 , shown in Fig. 4 ; isotype ANSP GC65230 ) .

Etymology: — the specific species name “ lancea ” is derived from the spearhead-shaped feature around the distal ends of raphe on LM images (arrows in Figs. 1 and 2 ).

Ecology: — this species is found on surface sediments in the high salt marsh. Salinity range is approximately from 0 to 10 ppt. Relative abundance of Pseudofrustulia lancea and accompanying species in a sample from Alsea Bay: Pseudofrustulia lancea (25.1 %), Frustulia vulgaris (2.9 %), Gyrosigma eximium (12.7 %), Nitzschia scalpelliformis (4.2 %), Nitzschia sigma (9.3 %), Tryblionella debilis (3.4 %), Tryblionella levidensis (2.6 %).

Figures

FIGURES 1–7. Pseudofrustulia lancea. Light microscopy (LM), holotype and other specimens. 1–3. Treated materials. In distal area, a spearhead-like triangle feature is recognized (arrows in Figs 1–2). 3. Specimen from holotype slide. 4. Holotype. 5–6. Living valves showing H-shaped plastids and colony structures in the mucilage tube. 7. Girdle views (two on the right), specimens from holotype slide. Arrows indicate the notched feature. All scale bars = 10 μm.

FIGURES 8–13. Pseudofrustulia lancea. Scanning (8–11) and transmission (12–13) electron microscopy (SEM, TEM) images. 8. Full view of the frustule. Central area of the valve edge has a notched feature. 9. Close-up view of the apical area of the valve. 10–13. SEM and TEM images of close-up views of the valve surface in proximal (10, 12) and distal (11, 13) areas. Scale bars = 5 μm (8), 2 μm (9), 1 μm (10–13).

FIGURES 14–20. Pseudofrustulia lancea. Scanning (14–16, 18–20) and transmission (17) electron microscopy (SEM, TEM) images. 14–16. Internal views of the frustule. 17–18. Poroid areolae are occluded internally by vela. 19–20. Valvocopula are open and have a series of slits or pores. Scale bars = 0.5 μm (14, 16–18), 5 μm (15), 1 μm (19, 20).

FIGURES 21–23. Pseudofrustulia lancea. 21. Close-up view of valvocopula and pleura having a series of slits and perforations. 22. Fimbriated valvocopula in internal view. 23. A close-up view of the notched feature. Scanning electron microscopy (SEM). Scale bars = 1 μm (21, 23), 0.5 μm (22).