Mallomonas fimbriata E.S. Gusev, 2015

Gusev, Evgeniy S., 2015, A new species of the genus Mallomonas (Synurales, Chrysophyceae), Mallomonas fimbriata, sp. nov., Phytotaxa 195 (4), pp. 291-296 : 292

Mallomonas fimbriata E.S. Gusev , sp. nov. ( Figs. 2–16 )

Cells dimensions unknown. Scales are thick, 3-layered, without dome. Base plate with small pores.The internal layer consists of reticulation with irregularly polygonal meshes. It is covered by the upper silica layer with or without small warts. There are three types of scales: body, caudal and apical. Body scales are oval, 3.9–5.0 × 1.7–3.0 μm, with pits (0.15–0.20 μm in diameter), arranged along the V-rib, anterior flange and scattered on the shield ( Figs. 2–6, 9, 11–13 ). The V-rib is asymmetrical, with one long arm continuous along one scale margin and short arm placed on the other side. Posterior border is wide and asymmetrical. Apical scales are 7.1–7.4 × 2.7–2.8 μm, elongated, widened to distal part, with highly asymmetrical V-rib and large pits on the shield and along the V-rib ( Fig. 14 ). Caudal scales are small, with robust, long, smooth spines ( Figs. 7–8 ). There is a window (split) without upper silica layer surrounded by the thick border in the central part of caudal scales. Scales dimensions with spines are 10–15.2 × 1.3–1.8 μm. The tip of the spine is bifurcating. Bristles and cysts unknown.

Type: — VIETNAM. Khanh Hoa Province, Cam Ranh Peninsula, 12° 04’ 39” N, 109° 11’ 08” E, E. S. Gusev s. n. SEM stub CR86 (holotype IBIW!, see Fig. 2 ), sample “CR86”, 01.06.2012, in collection E.S. Gusev.

Distribution and habitat:— This species was found in the type locality and in Malaysia ( Dürrschmidt & Croome 1985).

Etymology:— Epithet refers to the fimbriated (fringed) margin of the shield of the body scales, formed by lobate structures divided by pits.

Observations:— Mallomonas fimbriata was found in a shallow bog pool with low pH values (4.6),low conductivity (79 μS cm-1) and high temperature (31 °C). Previously, scales of Mallomonas fimbriata were reported from Malaysia as Mallomonas sp. 3 ( Dürrschmidt & Croome 1985, p. 294, Fig. 49).

Figures

FIGURES 2–16. Mallomonas fimbriata, sp. nov. TEM and SEM images of different types of scales. Figs. 2–6. Body scales, TEM. Fig. 7. Caudal scale, TEM. Fig. 8. Caudal scale, SEM. Fig. 9. Group of body scales, SEM. Fig. 10. Group of scales including two caudal scales with short spines, SEM. Figs 11–13. Body scales, SEM. Fig. 14. Apical scale, SEM. Fig. 15: Body scale, bottom view, SEM. Fig. 16. Group of scales including two scales lying on the edge (lateral view), SEM. Scale bars: Figs. 2–8: 2 μm; Figs. 9–16: 1 μm.