Wallaceago porostriatus Arsad, Witkowski, Luthfi & 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

Wallaceago porostriatus Arsad, Witkowski, Luthfi & M. Rybak sp. nov.

Holotype.

Slide number SZCZ 28814 at the repository of the University of Szczecin.

Type locality.

Rock scrape in Tanjung Perak , Poso Pesisir Regency, Central Sulawesi / Celebes, Tomini Gulf, Indonesia

Etymology.

This species is dedicated to Alfred Russel Wallace in gratitude for his contribution to exploring the Indonesian archipelago. The term porostriatus is a Latin adjective that means having porous striations or with striations composed of pores.

Distribution.

The new species so far is only found in Tanjung Perak, Sulawesi, Indonesia.

Description.

Light microscopy (Fig. 4 A – J ): The valves are dorsiventral, apices dull without protracted ends. The narrower valves are weakly protracted. Valve length 7.1–14.8 µm (n = 17) and width 1.6–3.1 µm (n = 17). Raphe branches cannot be found. The central area is resolvable with LM, marked by a light color in the middle of the ventral margin.

Scanning electron microscopy (Fig. 4 K – R ): Valves exhibit semi-lanceolate dorsiventral morphology, transitioning to pyramidal form. The valve face presents as flat and smooth, devoid of striae ornamentation both externally and internally (Fig. 4 K – R ). The dorsal mantle transitions gradually from the valve face, while the ventral mantle transition is abrupt, characterized by a distinct groove resembling a rabbet at the valve face edge (Fig. 4 L, M ). Ventral mantle seriation is uniseriate, with 70–80 areolae per 10 µm. Areolae are rounded and separated by a pore-free, hyaline silica thickening, forming a stauros (Fig. 4 M ). Seriation grooves are prominently marked internally (Fig. 4 P – R ). The dorsal mantle lacks areolae (Fig. 4 P, R ). The raphe externally filiform with a simple, rabbet-like profile, positioned close to the ventral valve margin (Fig. 4 L – N ). External proximal raphe ends simply, slightly deflected ventrally, and somewhat distant from each other (1.1 µm). Distal raphe endings are simple, lacking fissures, and bent towards the ventral margin. Internally, raphe endings straight, terminating slightly towards the dorsal valve at the central area (Fig. 4 O, P ). Distal raphe endings are straight and situated close to the apices (0.5 µm), with indistinct or absent helictoglossae (Fig. 4 Q, R ). Girdle bands were not observed in the specimens examined.

Figures

Figure 4. Wallaceago porostriatus Arsad, Witkowski, Luthfi & M. Rybak, sp. nov. (A – R) A – J light microscopy images K – R SEM images K – N external valve view O – R internal valve view L, M striation in mantle consists of 2–5 tiny areolae (white arrowhead, L), proximal and distal raphe ends bent in the same direction towards the ventral side (black arrowheads, L) M a presence of stauros (black arrowhead), ornamented raphe and the edge of the valve by a rabbet (white arrowheads) O – Q raphe straight with simple ends R distinct virgae on the mantle with unoccluded pores. Scale bar: 10 µm (A – J).