Spiniferomonas septispina Nicholls 1984: 104–105

Bessudova, Anna, Firsova, Alena D. & Likhoshway, Yelena V., 2024, New data on the stomatocysts of Spiniferomonas septispina Nicholls (Chrysophyceae, Chromulinales), Phytotaxa 670 (1), pp. 72-76 : 73

Spiniferomonas septispina Nicholls 1984: 104–105 , 107 ( Figs. 1–3 ).

= Paraphysomonas spinapunctata Wujek & Gardiner 1985

≡ Chrysosphaerella septispina (Nicholls) Kristiansen & Tong 1989

Description: The cells are spherical, up to 10 μm in diameter, with 5–12 cone-shaped, narrowed spines that measure 6–18 μm in length. Each spine consists of a wide conical base plate, 3–4.5 μm in diameter, separated from the shaft by a septum. Positioned above the septum, in the shaft wall, approximately 0.1–1 μm from the base plate, there is a rounded pore approximately 0.2 μm in diameter. The tip of the spine is bifurcated. The plate scales are flat and elliptical, ranging from 1.5–2.3 μm in length and 2.3–3.5 μm in width, with a thickened rim along the edge measuring 0.05 μm wide. In TEM images, the submarginal ridge is poorly developed and intermittent, with short curved ribs and shallow depressions.

Stomatocyst 302 Firsova in Firsova & Likhoshway 2006 emend. Firsova & Bessudova, this paper ( Figs. 4–9 )

Biological affinity: Spiniferomonas septispina ( Firsova et al. 2017)

Negative number:19112_

Location: Lake Baikal

SEM description: Stomatocysts are spherical, with 4.1–7.5-μm diameters, and feature a widely flared obconical collar (1.4–2-μm basal diameter; 1.5–2.7-μm apical diameter) ( Fig. 2 G ). The pore is concave (0.2–0.5-μm diameter) and is surrounded by a swollen annulus (0.3–0.5-μm diameter). The surface is irregularly covered with short, petallike ridges extending along the apical border (40–100 in total), with heights of 0.4–0.9 μm and lengths of 0.4–1.5 μm. Small spiny outgrowths are also present. Additional SEM studies have expanded the description provided by Firsova et al. (2017).

Ecology: The morphotype was found in Lake Baikal during the open water period in October, with water temperatures ranging from 8.8 ℃ to 9.6 ℃.

Figures

FIGURES 1–9. Micrographs of Spiniferomonas septispina. SEM. Figure 1. A decayed cell from plate and spine scales. Figure 2. Plate scales and a wide conical base plate with a rounded pore. Figure 3. Plate and spine scales. Figures 4–8. Stomatocysts covered with plate and spine scales. Figures 8, 9. Stomatocysts. Scale bars: 2—2 μm; 3–9—5 μm; 1—10 μm.