Luticola elliptica M.Rybak & Peszek, 2024

Rybak, Mateusz, Peszek, Lukasz, Luthfi, Oktiyas Muzaky, Arsad, Sulastri, Kociolek, John Patrick & Witkowski, Andrzej, 2024, Description of five new Luticola D. G. Mann (Bacillariophyta, Diadesmidaceae) species from Indonesia with comments on the morphological boundaries of the genus, PhytoKeys 237, pp. 1-22 : 1

Luticola elliptica M.Rybak & Peszek sp. nov.

Description.

LM observations (Fig. 1AD-AN). Valves elliptic with broadly rounded apices. Range of valve dimensions (n = 20): 9.0-20.0 μm long, 4.3-5.5 μm wide and 20-24 striae in 10 µm. Striae clearly punctate. Central area asymmetrical, side with isolated pore wider than the opposite site, axial area linear and narrow becoming slightly wider near to central area. Isolated pore clearly visible in central area located halfway between the margin and the centre. Raphe filiform with proximal endings slightly bent away from isolated pore, hooked distal raphe endings visible.

SEM observations (Fig. 6A-H ). External view: striae composed of 2-3 round to slightly elongated areolae (Fig. 6A-G ). Single row of round areolae, interrupted at valve apices, present on valve mantle (Fig. 6A-D, F ). Central area bordered by 4-7 areolae on side with isolated pore and 2-4 on opposite side (Fig. 6A-G ). Raphe filiform with weakly-hooked distal endings continuing on to valve mantle (Fig. 6A-G ). Proximal raphe endings deflected away from isolated pore and slightly enlarged (Fig. 6A-G ). Opening of isolated pore round and not connected by areolae with striae (Fig. 6A-G ). Girdle bands open with two rows of poroids.

Internal view: Areolae occluded by hymenes forming a continuous strip (Fig. 6H ). Raphe slits straight (Fig. 6H ). Proximal raphe endings simple and straight (Fig. 6H ), distal raphe endings forming finishing on to weakly-developed helictoglossae (Fig. 6H ). Isolated pore opening with small lipped structure (Fig. 6H ). Longitudinal channels visible along valve (Fig. 6H ).

Type.

Indonesia, Banda Besar, 4°31'29.93"S, 129°56'51.69"E, 19 m a.s.l., coll. 23 June 2018, holotype slide no. SZCZ29103! and the unmounted material with the same number in the Szczecin Diatom Collection (University of Szczecin, Poland), isotype slide no. 2018/440 and the unmounted material with the same number at the University of Rzeszów , Poland. The type population is illustrated in Figs 1AD-AN, 6A-H.

Etymology.

Name refers to the valve shape of the species.

Distribution.

Species has been observed in various locations in Southeast Asia. It was also observed on Borneo Island, Palambak Island, Sulawesi Island and Banda Besar (Rybak - unpublished data).

Ecology and associated diatom flora.

The species was observed in a sample characterised by a slightly acidic pH (5.8) and conductivity was 1250 µS /cm. The species co-occurred with: Luticola insularis sp. nov., L. bandanensis sp. nov., L. minima Levkov, Metzeltin & Pavlov, two unidentified small-celled Nitzschia sp., Nitzschia vitrea G.Norman and Tryblionella debilis Arnott ex O’Meara.

Figures

Figure 6. SEM microphotographs of Luticola eliptica sp. nov. external (A-G) and internal (H) views. Arrow indicate a longitudinal channel. Scale bars: 4 µm (A, C-G); 5 µm (B, H).