Catenula boyanensis Luthfi, Witkowski & 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 boyanensis Luthfi, Witkowski & M. Rybak sp. nov.

Holotype.

Slide number SZCZ 27552 at the repository of the University of Szczecin.

Type locality.

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

Etymology.

The species name is derived from local Bawean Island people called Boyan.

Distribution.

The diatom species C. boyanensis has been regularly observed in samples from the harbour of Gili Iyang on Bawean Island.

Description.

Light microscopy (Fig. 5 A – G ): The valves are semi-lanceolate, dorsiventral. Raphe is clearly observed through the ventral area with proximal raphe endings distant from each other and distal raphe endings distant to apices (Fig. 5 A – F ). Valve length 8.2–22.2 µm, n = 29 and width 2.1–4.9 µm, n = 17. Transapical striae can be observed on the dorsal face. Apices obtusely rounded with distinct helictoglossae.

Scanning electron microscopy (Figs 5 , 6 ): Frustules exhibit significant dorsiventral. Several non-perforated girdle bands compose the frustule (Fig. 5 H, M ). Valves display strong asymmetry around the apical axis, with a gently arched dorsal margin and straight ventral margin (Fig. 5 K, L ). The raphe sternum is positioned near the ventral margin, with nearly straight raphe slits (Fig. 5 L ). Raphe occupies a more central location rather than along the ventral margin, with proximal raphe endings distantly spaced (1.5–3.8 µm) (Fig. 5 K, L ). External proximal and apical ends are filiform, short, and straight (Fig. 5 I ). Transapical striae appear as shallow grooves on the valve face, with a row of striae visible on the dorsal mantle (Fig. 5 H, J, M ). The internal valve face is flat. Small areolae on the valve surface are covered by a thin hymen layer. Internally, raphe slits bend very slightly toward the dorsal margin, maintain straight proximal ends, and terminate apically in helictoglossae (Fig. 6 D ).

Figures

Figure 5. Catenula boyanensis Luthfi, Witkowski & M. Rybak, sp. nov. A – G light microscopy images H – O SEM images in external view H, M girdle view of frustule showing rectangular with obtuse shape on corners and a row of elongated striae on mantle (M, black arrowhead) I detail of raphe branch J detail of apical part of a frustule with girdle band M the mantle of valve K – L external valve view showing transapical irregular grooves and the central area N open unperforated cingulum O detail of frustule central part. Scale bar: 10 µm (A – G).

Figure 6. Internal view of Catenula boyanensis Luthfi, Witkowski & M. Rybak, sp. nov. SEM images A – D internal valve view showing arcuate raphe slit, a row of linear areolae on mantle D detail of raphe branch and proximal raphe endings with apical raphe ending bent and finishing with small helictoglossae (arrowhead).