Catenula decusa Luthfi, Witkowski, Arsad & M. Rybak, 2024

Luthfi, Oktiyas Muzaky, Arsad, Sulastri, Kryk, Adrian, Risjani, Yenny, Yunianta,, Rybak, Mateusz, Peszek, Łukasz, Wróbel, Rafał J., Pappas, Janice L., Bąk, Małgorzata & Witkowski, Andrzej, 2024, New genera and new species of Catenulaceae (Bacillariophyta) from Coral Reef habitat of two Indonesia islands — Bawean and Sulawesi — A morphological approach, PhytoKeys 248, pp. 263-291 : 263-291

Catenula decusa Luthfi, Witkowski, Arsad & M. Rybak sp. nov.

Type materials.

Holotype: Slide number SZCZ 27552 at repository of University of Szczecin.

Isotype: Slide number SZCZ 28814 at repository of University of Szczecin (Fig. 7 S ) .

Type locality.

Sand and coral boulder of coral reef at Gili Iyang harbour , Bawean Island, East Java, Indonesia.

Etymology.

The species name is derived from the Latin word decus which literally means an ornament, decoration, or embellishment. The new species exhibits a distinct central area.

Distribution.

The diatom species C. decusa has a unique distribution, being found exclusively in Bawean and Sulawesi Islands, Indonesia. Interestingly, both of these locations share a similar habitat, characterized by the presence of coral reef areas.

Description.

Light microscopy (Fig. 7 A – Q ): The valves are semi-lunate or semi-lanceolate dorsiventrally. Thickening silica in the central area is very clear under LM. A row of linear areolae can be distinguished in the dorsal margin (Fig. 7 F ). Valve length 8.2–16.5 µm, n = 18 and width 1.9–2.9 µm, n = 17. Apices broadly rounded with indistinct, dot-like helictoglossae. The frustule is rectangular in girdle view, 1.1 µm depth. Raphe slits observed in ventral area.

Scanning electron microscopy (Fig. 7 R – Y ): Frustules semi-circular to semi-lanceolate, dorsiventral; valve face flat, smooth, abruptly transitioning to mantle. Distinct rhomboidal central nodule observed on ventral and dorsal sides (Fig. 7 S, T ). Valve face devoid of transapical striae; striae present on dorsal and ventral mantle (Fig. 7 R ). Raphe sternum positioned near ventral margin; raphe slits straight medially, curving towards apices. External proximal raphe ends simple, slightly expanded; distal ends simple, close to apices (x – = 0.72 μm, n = 21), deflected dorsally. Central nodules and helictoglossae indistinct. Dorsal mantle striation density 35–40 in 10 μm; ventral mantle 40–50 in 10 μm. Internal raphe filiform, straight (Fig. 7 T, U, Y ); mantle areolae occluded, flask-shaped (Fig. 7 X ). Girdle open, comprising multiple unperforated plain bands (Fig. 7 R, U ).

Figures

Figure 7. Catenula decusa Luthfi, Witkowski, Arsad & M. Rybak, sp. nov. A – Q light micrographs R – Y SEM images R, S, V external view T, U, W – Y internal view R external view of frustule with three cingula S external valve view with rectangular central area created by striation interruption in dorsal and ventral margin T, Y internal view of entire valve U valve with open unperforated girdle band V external view an arcuate raphe with simple proximal and apical end W straight raphe slit in internal valve view X rectangular central area with interrupted dorsal and ventral mantle striation. Scale bar: 10 µm (A – Q).