Luticola cribriareolata M.Rybak, Witkowski, Risjani & Yunianta, 2021

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 cribriareolata M.Rybak, Witkowski, Risjani & Yunianta sp. nov.

Description LM.

Valves elliptic-lanceolate to elliptic with rounded apices. Valves 9.8-28.3 μm in length, 6-11.6 μm in width (n = 30). Raphe filiform, axial area narrow at apices becoming broader towards valve middle part, expanding into asymmetrical central area, broader opposite the stigma and bordered by 2-3 areolae. Stigma present close to valve margin. Transapical striae easily distinguishable with LM, radiate throughout, 14-16 in 10 μm.

Description SEM.

Valve surface flat with the transition to the mantle abrupt and marked with distinct hyaline stripe. Axial area narrow becoming broader toward the valve middle, expanding into the rectangular central area. Raphe filiform and straight, external proximal raphe endings close to each other, clearly bent to the valve primary side and associated with irregular in shape shallow grooves expanded in the direction opposite the stigma. External raphe distal ends strongly hooked on valve face and terminating in an indistinct groove in central area, at apical part of mantle. Valve mantle steep with a single row of oblong areolae. Girdle composed of a few copulae each with two rows of small circular pores. Internally, raphe branches straight, with proximal endings slightly bent. Internally, raphe terminates in a small helictoglossae. Transapical striae composed of 2-5 large areolae. Areolae on both valve face and valve mantle are deeply embedded, and occluded with reticulated cribra positioned on the inner valve surface. Within central area ghost areolae are often observed, oblong to strongly elongated in shape. Elongated stigma positioned close to margin of the valve primary side. Externally, stigma small and slightly elongated. Internal stigma opening with large-lipped structure. Internally, longitudinal channel visible, with small silica flap on site opposite to stigma. Internally, areolae and longitudinal channel occluded with irregular hymenate structure.

Holotype.

Slide SZCZ27007 stored in A. Witkowski Diatom Collection of the Institute of Marine and Environmental Sciences, University of Szczecin, represented here by Fig. 2AS.

Isotype.

Slide no. 2018/425 and unmounted material with the same number at the University of Rzeszów, Poland.

Type locality.

Indonesia. Java Island: Pantai Bentar in Probolinggo on the north coast, a periphyton from a boulder, 07°46'41"S, 113°16'34"E, leg. Y. Risjani, Yunianta and A. Witkowski, 1st March 2020.

Etymology.

The species name is derived from its areola occlusions which are in the shape of reticulated cribra, hence the stem “cribr-” of the word “cribrum” is left, the connecting vowel “-i-” and “areolata” are added = Luticola cribriareolata .

Distribution.

Observed thus far from the holotype sample SZCZ27007, and in periphyton from the plastic pier at Pantai Bentar in Probolinggo and in sample SZCZ27006 very close to the holotype habitat.

Taxonomic comment.

Luticola cribriareolata has valve shape similar to Luticola orientalis sp. nov., however, the two species can be easily distinguished based on the stria density, which is coarser in L. cribriareolata . Luticola cribriareolata sp. nov. is also similar in terms of valve outline to L. nosybeana and L. madagascarensis described from Nosy Be Island from NW Madagascar. The newly described species has simple proximal raphe endings, whereas both L. madagascarensis and L. nosybeana have external proximal raphe endings with distinct grooves ( Bąk et al. 2019) (Table 2 ).