Luticola tropica Levkov, Metzeltin & Pavlov

Rybak, Mateusz, Witkowski, Andrzej, Peszek, Lukasz, Kociolek, John P., Risjani, Yenny, Nguyen, Duc Hung, Zhang, Jinpeng, Yunianta,, Nguyen, Van Duy, Gastineau, Romain, Duong, Thi Thuy, Rosa, Philippe & Meleder, Vona, 2021, Marine and brackish Luticola D. G. Mann (Bacillariophyta) species from the Java Sea and South China Sea coasts with the description of three new species, PhytoKeys 183, pp. 115-142 : 115

Luticola tropica Levkov, Metzeltin & Pavlov

Figure 12

Description LM.

Valves elliptic-lanceolate with triundulate margins with rostrate and broadly rounded apices, 11.8-21.2 μm in length, 7.5-11.1 μm in width (n = 25). Axial area narrow linear, slightly broadening towards valve middle, expanding into rectangular central area bordered on each margin by 2-4 shortened striae. Transapical striae clearly punctate, radiate becoming strongly radiate toward apices, 17-20 in 10 μm. Stigma slightly elongated, close to the valve margin.

Description SEM.

Valve face flat, raphe filiform and straight, distally strongly hooked at the apices. External proximal raphe endings strongly bent to the side opposite the stigma, expanding into thread-like grooves that are variable in shape. Internally, raphe straight, only proximal endings slightly bent, distal raphe endings terminate in small helictoglossae. Transapical striae composed of 4-5 round to slightly elongate areolae. Single row of areolae also occurs on the valve mantle. Internally, areolae occluded with hymen forming continuous strips. A few ghost areolae present within central area. Slightly elongate stigma positioned close to the valve margin. Internal stigma opening with large-lipped structure, located midway between raphe endings and valve margin. Internally, longitudinal channel present along the valve margin, with small siliceous flap on side opposite the stigma.

Distribution.

This species was abundant in epilithic sample from a sampling site called Fenjiezhou Island located on the coast of Hainan Island, NW South China Sea (China) in sample SZCZ27176, and in Xuân Thúy Mangrove in NE Vietnam, as biofilm from wild oysters, sample SZCZ26472.

Figures

Figure 12. LM micrographs of Luticola tropica Levkov, Metzeltin & Pavlov in size diminution series (A-T) and isolated open copula U external view of valve (V, W) Detailed external views showing distal raphe ending X stigma opening Y proximal raphe endings with thread-like grooves (Y, Z) and areolae structure (X-Z). Internal view of valve AA detailed internal close-ups showing distal raphe ending AB proximal raphe endings and stigma opening AC. Scale bars: 10 µm (A-U), 5 µm (V, W, AA), 4 µm (X, Y, AB, AC), 3 µm (Z).